1. How Biological Diversity Evolves MACROEVOLUTION
Chapter 14
How Biological Diversity Evolves
MACROEVOLUTION

2. Biology and Society: The Sixth Mass Extinction
Over the past 600 million years the fossil record reveals five periods of extinction when 50–90% of living species suddenly died out.
© 2010 Pearson Education, Inc.

3. Figure 14.0 Mountain gorillas

4. Our current rate of extinction, over the past 400 years, indicates that we may be living in, and contributing to, the sixth mass extinction period.
Mass extinctions:
Pave the way for the evolution of new and diverse forms, but
Take millions of years for Earth to recover
The most “famous” mass-extinction is the K-T Mass Extinction which included the extinction of the dinosaurs (except birds). This will be discussed in Chapter 17.

5. MACROEVOLUTION AND THE DIVERSITY OF LIFE
Encompasses the major biological changes evident in the fossil record
Includes the formation of new species
Student Misconceptions and Concerns
1. Students might not realize that evolutionary change includes (a) linear events, in which a species changes over time, and (b) branching events, which produce new species and diversity. Some students expect that when new species evolve, they replace their ancestors. Questions such as “If we came from chimps, why are there still chimps alive today” reveal this, and other, misunderstandings.
Teaching Tips
1. Before lecturing about speciation, consider a short writing assignment. Have students work individually or in small groups, without the benefit of books, to define a species.
2. Students might not realize that entire categories of animals have come and gone. Once abundant trilobites and non-avian dinosaurs are now extinct. Birds and mammals are relatively recent additions. Such examples of macroevolution are apparent in the fossil record.

6. THE ORIGIN OF SPECIES Species is a Latin word meaning: “Kind” or
“Appearance.”
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

7. What Is a Species? The biological species concept defines a species as
“A group of populations whose members have the potential to interbreed and produce fertile offspring”
It is also sometimes stated like this:
“A group of populations whose members share a common gene pool and are potentially interbreeding”
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

8. Speciation: Is the focal point of macroevolution
May occur based on two contrasting patterns, non-branching and branching.
Student Misconceptions and Concerns
1. Students might not realize that evolutionary change includes (a) linear events, in which a species changes over time, and (b) branching events, which produce new species and diversity. Some students expect that when new species evolve, they replace their ancestors. Questions such as “If we came from chimps, why are there still chimps alive today” reveal this, and other, misunderstandings.
Teaching Tips
1. Before lecturing about speciation, consider a short writing assignment. Have students work individually or in small groups, without the benefit of books, to define a species.
2. Students might not realize that entire categories of animals have come and gone. Once abundant trilobites and non-avian dinosaurs are now extinct. Birds and mammals are relatively recent additions. Such examples of macroevolution are apparent in the fossil record.

9. In non-branching evolution:
A population transforms but does not create a new species
Actually, it may, but the hypothesis is usually untestable.
Student Misconceptions and Concerns
1. Students might not realize that evolutionary change includes (a) linear events, in which a species changes over time, and (b) branching events, which produce new species and diversity. Some students expect that when new species evolve, they replace their ancestors. Questions such as “If we came from chimps, why are there still chimps alive today” reveal this, and other, misunderstandings.
Teaching Tips
1. Before lecturing about speciation, consider a short writing assignment. Have students work individually or in small groups, without the benefit of books, to define a species.
2. Students might not realize that entire categories of animals have come and gone. Once abundant trilobites and non-avian dinosaurs are now extinct. Birds and mammals are relatively recent additions. Such examples of macroevolution are apparent in the fossil record.

10. In branching evolution, one or more new species branch from a parent species that may:
Continue to exist in much the same form or
Change considerably
Student Misconceptions and Concerns
1. Students might not realize that evolutionary change includes (a) linear events, in which a species changes over time, and (b) branching events, which produce new species and diversity. Some students expect that when new species evolve, they replace their ancestors. Questions such as “If we came from chimps, why are there still chimps alive today” reveal this, and other, misunderstandings.
Teaching Tips
1. Before lecturing about speciation, consider a short writing assignment. Have students work individually or in small groups, without the benefit of books, to define a species.
2. Students might not realize that entire categories of animals have come and gone. Once abundant trilobites and non-avian dinosaurs are now extinct. Birds and mammals are relatively recent additions. Such examples of macroevolution are apparent in the fossil record.

11. Similarity between different species Diversity within one species
Figure 14.2 The biological species concept is based on reproductive compatibility
Similarity between different species
Diversity within one species
Figure 14.2

12. The biological species concept cannot be applied in all situations, including:
Fossils
Asexual organisms
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

13. Reproductive Barriers/Isolating Mechanisms between Species
What’s the logic of isolating mechanisms/reproductive barriers? ?
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

14. Reproductive Barriers between Species
Prezygotic barriers prevent mating or fertilization between species.
Below are some examples you can see at MasteringBiology
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.
Video: Albatross Courtship Ritual
Video: Blue-footed Boobies Courtship Ritual
Video: Giraffe Courtship Ritual

15. Figure 14.3 INDIVIDUALS OF DIFFERENT SPECIES Prezygotic Barriers
Temporal isolation
Habitat isolation
Behavioral isolation
MATING ATTEMPT
Mechanical isolation
Gametic isolation
FERTILIZATION
(ZYGOTE FORMS)
Postzygotic Barriers
Figure 14.3 Reproductive barriers between closely related species
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
VIABLE, FERTILE
OFFSPRING
Figure 14.3

16. PREZYGOTIC BARRIERS Temporal Isolation Habitat Isolation
Behavioral Isolation
Mechanical Isolation
Gametic Isolation
Figure 14.4 Prezygotic barriers
Figure 14.4

17. Postzygotic barriers operate if:
Interspecies mating occurs and
Hybrid zygotes form
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

18. Figure 14.3 INDIVIDUALS OF DIFFERENT SPECIES Prezygotic Barriers
Temporal isolation
Habitat isolation
Behavioral isolation
MATING ATTEMPT
Mechanical isolation
Gametic isolation
FERTILIZATION
(ZYGOTE FORMS)
Postzygotic Barriers
Figure 14.3 Reproductive barriers between closely related species
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
VIABLE, FERTILE
OFFSPRING
Figure 14.3

19. Postzygotic barriers include:
Reduced hybrid viability
Reduced hybrid fertility
Hybrid breakdown
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

20. POSTZYGOTIC BARRIERS Reduced Hybrid Viability Reduced Hybrid Fertility
Hybrid Breakdown
Horse
Donkey
Figure 14.5 Postzygotic barriers
Mule
Figure 14.5

21. Mechanisms of Speciation
A key event in the potential origin of a species occurs when a population is severed from other populations of the parent species.
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

22. Species can form by:
Allopatric speciation, due to geographic isolation
Sympatric speciation, without geographic isolation
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

23. Allopatric speciation Simpatric speciation
Figure 14.6 Two modes of speciation
Allopatric speciation
Simpatric speciation
Figure 14.6

24. Allopatric Speciation
Geologic processes can:
Fragment a population into two or more isolated populations
Contribute to allopatric speciation
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.
Video: Lava Flow
Video: Volcanic Eruption
Video: Grand Canyon

25. Ammospermophilus harrisii Ammospermophilus leucurus
Figure 14.7 Allopatric speciation of antelope squirrels on opposite rims of the Grand Canyon
Figure 14.7

26. Speciation occurs only with the evolution of reproductive barriers between the isolated population and its parent population.
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

27. Populations Populations become become allopatric sympatric Populations
interbreed
Gene pools merge:
No speciation
Populations
cannot
interbreed
Geographic
barrier
Figure 14.8 Has speciation occurred during geographic isolation?
Reproductive
isolation:
Speciation has
occurred
Time
Figure 14.8

28. Sympatric Speciation Sympatric speciation occurs:
While the new species and old species live in the same time and place
If a genetic change produces a reproductive barrier between the new and old species
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

29. Polyploids can: Originate from accidents during cell division
Result from the hybridization of two parent species
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

30. Many domesticated plants are the result of sympatric speciation, including:
Oats
Potatoes
Bananas
Peanuts
Apples
Coffee
Wheat
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

31. Sterile hybrid (14 chromosomes) Sterile hybrid (21 chromosomes)
Domesticated
Triticum monococcum
(14 chromosomes)
Wild Triticum
(14 chromosomes) AA BB AB
Sterile hybrid
(14 chromosomes)
T. turgidum
Emmer wheat
(28 chromosomes)
AA BB DD
Wild
T. tauschii
(14 chromosomes)
Figure 14.9 The evolution of wheat (Step 4)
ABD
Sterile hybrid
(21 chromosomes)
T. aestivum
Bread wheat
(42 chromosomes)
AA BB DD
Figure

32. Figure 14.9a Wheat
Figure 14.9a

33. What Is the Tempo of Speciation?
There are two contrasting models of the pace of evolution:
The gradual model, in which big changes (speciations) occur by the steady accumulation of many small changes
The punctuated equilibria model, in which there are
Long periods of little change, equilibrium, punctuated by
Abrupt episodes of speciation
Student Misconceptions and Concerns
1. Students may think that species evolve because of need. However, need has no role in biological evolution. Biological diversity exists and the environment selects. Evolution is not deliberate. It is reactive. Species do not deliberately change. There is no plan. As teachers, we must be careful in how we express evolution to best reflect this process. This use of the passive voice in our descriptions of evolution better reflects the nature of this fundamental process.
2. The concept of “sudden” in geological terms is likely misunderstood. Events such as major floods, earthquakes, or asteroid impacts, which might be so rare as occurring every 1000 years, are actually common in geological terms. Students might not realize that 1000 such events would be expected to occur in a million years.
3. Students might not have considered how species are “naturally” kept separate and unique. Instead, students are more likely to consider species as fixed entities, especially the species to which they belong. As instructors of biology, it can become increasingly difficult to empathize with this perspective. To help ease students into the topic, consider pointing out that species of life do not reflect an even spectrum of diversity. Instead, there are many clear groups of related organisms (fungi, flowers, owls, sharks, beetles, butterflies, and frogs, for example). Ask students to consider why such clumping exists. Is it in any way due to the same reason that a particular human family is distinct from other families? Can this grouping of kinds be related to shared common ancestors?
Teaching Tips
1. Identify or have your students find several commonly recognized and related species of plants or animals in your area and find out what reproductive barriers keep these species from interbreeding. Local examples help to bring a point home.
2. The isolation of a few individuals from a parent population may result from a catastrophic weather or geological event. Ask your students to think back to news footage of torrential rains, massive debris rocketed down a river, and the struggles of animals to haul themselves onto these rafts. Better yet, show them a short news clip of such events. Dramatic weather and geological events may be rare in our lifetimes, but are frequent enough to play a role in speciation.
3. Challenge your students to explain why the field of paleontology has largely been concerned with macroevolution. The broader perspective of evolutionary change studied by paleontologists rarely permits an examination of change within a species.
4. The silvery salamander, Ambystoma platineum, is a triploid, all-female species living in parts of the Midwestern United States. It is believed to have formed by the hybridization of two related species thousands of years ago. It is an unusual example of sympatric speciation in animals. The following website is a good starting point to learn more about this species:
5. Have your students think of analogous examples of punctuated equilibrium in our culture. Perhaps such an example is the switch from vinyl records to compact discs, with the brief transitional form of 8 tracks (do you remember these?). Between the years 1900–2000, there were long periods of stasis (vinyl records) and a relatively short period of transition to the CDs (who knows how long they will last as MP3 files take over). Debating the validity of analogies can be instructive as students articulate the biological principles and use them to test the accuracy of the analogies.

34. Punctuated model Time Graduated model Figure 14.10
Figure Two models for the tempo of evolution
Figure 14.10

35. THE EVOLUTION OF BIOLOGICAL NOVELTY
What accounts for the evolution of biological novelty?
Student Misconceptions and Concerns
1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders.
2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House!
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

36. Adaptation of Old Structures for New Functions
Birds:
Are derived from a lineage of earthbound reptiles
Evolved flight from flightless ancestors
Student Misconceptions and Concerns
1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders.
2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House!
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

37. Artist’s reconstruction
Wing claw
(like reptile)
Teeth
(like reptile)
Feathers
Figure An extinct bird: Archaeopteryx
Long tail with
many vertebrae
(like reptile)
Fossil
Artist’s reconstruction
Figure 14.11

38. Exaptations can account for the gradual evolution of novel structures.
An exaptation:
Is a structure that evolves in one context, but becomes adapted for another function
Is a type of evolutionary remodeling
Exaptations can account for the gradual evolution of novel structures.
Student Misconceptions and Concerns
1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders.
2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House!
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

39. Bird wings are modified forelimbs that were previously adapted for non-flight functions, such as:
Thermal regulation
Courtship displays
Camouflage
The first flights may have been only glides or extended hops as the animal pursued prey or fled from a predator.
Student Misconceptions and Concerns
1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders.
2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House!
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

40. Evo-Devo: Development and Evolutionary Novelty
A subtle change in a species’ developmental program can have profound effects, changing the:
Rate
Timing
Spatial pattern of development
Student Misconceptions and Concerns
1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders.
2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House!
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.
© 2010 Pearson Education, Inc.

41. Evo-devo, evolutionary developmental biology, is the study of the evolution of developmental processes in multicellular organisms.
Student Misconceptions and Concerns
1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders.
2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House!
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

42. Animation: Allometric Growth
Paedomorphosis:
Is the retention into adulthood of features that were solely juvenile in ancestral species
Has occurred in the evolution of
Axolotl salamanders
Humans
Student Misconceptions and Concerns
1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders.
2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House!
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.
Animation: Allometric Growth

43. Gills
Figure Paedomorphosis
Figure 14.12

44. (paedomorphic features)
Chimpanzee fetus
Chimpanzee adult
Figure Comparison of human and chimpanzee skull development
Human fetus
Human adult
(paedomorphic features)
Figure 14.13

45. Homeotic genes are master control genes that regulate:
When structures develop
How structures develop
Where structures develop
Mutations in homeotic genes can profoundly affect body form.
Student Misconceptions and Concerns
1. Students are unlikely to appreciate the life history of salamanders and the similarity of a larval salamander to the axolotl form. Students might therefore best understand what happens during salamander paedomorphosis by considering more commonly understood life stages. Ask students to imagine what would result if a caterpillar reproduced and never turned into a winged adult butterfly. Then relate the caterpillar stage to the early larval form of salamanders.
2. Clear examples of evolutionary remodeling include the many variations of the pattern of bones in the vertebrate forelimb. Bat wings, bird wings, penguin flippers, the arms of apes, and the digging forelimbs of moles all show how the ancestral pattern was revised as new functions evolved. Descent with modification is a powerful explanation of such diversity.
Teaching Tips
1. Another way to think about evolutionary remodeling is to make an analogy to remodeling a home. A remodeled home retains many of the “ancestral” traits—perhaps the same plumbing and electrical system. But, where there once was a wall might now be an opening into an enlarged family room, or a window to the outside. Evolution can work like the TV show This Old House!
2. When discussing exaptations, have students consider the many new uses for common household items if they were to have them in a survival situation, stranded on an island or lost in the woods. A handkerchief, a screwdriver, and a pair of pliers might take on new functions in this different context.

46. EARTH HISTORY AND MACROEVOLUTION
Macroevolution is closely tied to the history of the Earth.
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

47. Geologic Time and the Fossil Record
The fossil record is:
The sequence in which fossils appear in rock strata
An archive of macroevolution
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

48. Figure 14.14 A gallery of fossils

49. Figure 14.14a Petrified wood

50. Figure 14.14b Insect fossil in amber

51. Figure 14.14c Dinosaur bone
Figure 14.14c

52. Figure 14.14d Dinosaur footprints

53. Figure 14.14e Mammoth tusks
Figure 14.14e

54. Animation: The Geologic Record Animation: Macroevolution
Geologists have established a geologic time scale reflecting a consistent sequence of geologic periods.
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.
Animation: The Geologic Record
Animation: Macroevolution

55. Table 14.1 The Geologic Time Scale

56. Table 14.1a Precambrian
Table 14.1a

57. Table 14.1b Paleozoic era
Table 14.1b

58. Table 14.1c Mesozoic era
Table 14.1c

59. Table 14.1d Cenozoic era
Table 14.1d

60. Fossils are reliable chronological records only if we can determine their ages, using:
The relative age of fossils, revealing the sequence in which groups of species evolved, or
The absolute age of fossils, requiring other methods such as radiometric dating
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

61. Radiometric dating: Is the most common method for dating fossils
Is based on the decay of radioactive isotopes
Helped establish the geologic time scale
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

62. (as % of living organism’s Carbon-14 radioactivity
Radioactive decay
of carbon-14
100 75
(as % of living organism’s
Carbon-14 radioactivity
C-14 to C-12 ratio) 50 25
5.6
11.2
16.8
22.4
28.0
33.6
39.2
44.8
50.4
Time (thousands of years)
How
carbon-14
dating is
used to
determine
the vintage
of a
fossilized
clam shell
Carbon-14 in shell
Figure Radiometric dating
Figure 14.15

63. Plate Tectonics and Macroevolution
The continents are not locked in place. Continents drift about the Earth’s surface on plates of crust floating on a flexible layer called the mantle.
The San Andreas fault is:
In California
At a border where two plates slide past each other
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

64. Figure 14.16 California's San Andreas fault

65. About 250 million years ago:
Plate movements formed the supercontinent Pangaea
The total amount of shoreline was reduced
Sea levels dropped
The dry continental interior increased in size
Many extinctions occurred
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

66. Figure 14.17 Present Cenozoic 65 135 Mesozoic 251 million years ago
North America
Eurasia 65
Africa
South
America
India
Madagascar
Australia
Antarctica
Laurasia
135
Mesozoic
Gondwana
Figure The history of plate tectonics
251 million years ago
Pangaea
Paleozoic
Figure 14.17

67. About 180 million years ago:
Pangaea began to break up
Large continents drifted increasingly apart
Climates changed
The organisms of the different biogeographic realms diverged
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

68. Plate tectonics explains:
Why Mesozoic reptiles in Ghana (West Africa) and Brazil look so similar
How marsupials were free to evolve in isolation in Australia
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

69. Mass Extinctions and Explosive Diversifications of Life
The fossil record reveals that five mass extinctions have occurred over the last 600 million years.
The Permian mass extinction:
Occurred at about the time the merging continents formed Pangaea (250 million years ago)
Claimed about 96% of marine species
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.
© 2010 Pearson Education, Inc.

70. The Cretaceous extinction:
Occurred at the end of the Cretaceous period, about 65 million years ago
Included the extinction of all the dinosaurs except birds
Permitted the rise of mammals
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

71. The Process of Science: Did a Meteor Kill the Dinosaurs?
Observation: About 65 million years ago, the fossil record shows that:
The climate cooled
Seas were receding
Many plant species died out
Dinosaurs (except birds) became extinct
A thin layer of clay rich in iridium was deposited
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.
© 2010 Pearson Education, Inc.

72. Question: Is the iridium layer the result of fallout from a huge cloud of dust that billowed into the atmosphere when a large meteor or asteroid hit Earth?
Hypothesis: The mass extinction 65 million years ago was caused by the impact of an extraterrestrial object.
Prediction: A huge impact crater of the right age should be found somewhere on Earth’s surface.
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

73. Results: Near the Yucatán Peninsula, a huge impact crater was found that:
Dated from the predicted time
Was about the right size
Was capable of creating a cloud that could have blocked enough sunlight to change the Earth’s climate for months
Student Misconceptions and Concerns
1. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60 x 60 x 24 x = 31,557,600) or how much money you could spend each day if you spent $1 million a year ($1,000,000/365 = $2,739.73/day).
2. Students also need to be reminded that one billion is 1000 million. Many students (and too many politicians) easily confuse million and billion without realizing the scale of the error.
Teaching Tips
1. The sequence but not absolute ages are revealed by the stratifications in sedimentary rocks. The authors make an analogy to peeling the layers of wallpaper from the walls of a very old house that has been inhabited by many owners. By the sequence we can tell which layers are older, but not the absolute ages of each layer. Cutting into a layered cake is another analogy. Although we do not know the absolute age of each layer, we know the sequence in which the layers were placed.
2. Consider this analogy to help students understand the biological consequences of speciation as continents drifted apart. As your students left high school, and entered the workforce or continued their education, their high school social groups drifted apart. Your students, in their new circumstances, adapted and changed in different ways, separate from the members of their old social groups. A note of caution: This analogy to individual social changes is not an example of biological evolution, which occurs over generations.
3. The consequences of an asteroid impact, large or small, illustrates the role of random forces influencing evolution. Like throwing a dart at a spinning globe, where the asteroid hits and what continents and life are most greatly affected can change greatly if the impact is delayed by a few hours. An asteroid delayed by 12 hours, in what might be a journey of millions or billions of years, will land on the opposite side of the Earth.

74. Figure 14.18 Trauma for planet Earth and its Cretaceous life (Step 1)

75. Figure 14.18 Trauma for planet Earth and its Cretaceous life (Step 2)

76. Chicxulub crater Figure 14.18-3
Figure Trauma for planet Earth and its Cretaceous life (Step 3)
Figure

77. CLASSIFYING THE DIVERSITY OF LIFE
Systematics focuses on:
Classifying organisms
Determining their evolutionary relationships
Taxonomy is the:
Identification of species
Naming of species
Classification of species
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

78. Some Basics of Taxonomy
Scientific names ease communication by:
Unambiguously identifying organisms
Making it easier to recognize the discovery of a new species
Carolus Linnaeus (1707–1778) proposed the current taxonomic system based upon:
A two-part name for each species (binomial nomenclature)
A hierarchical classification of species into broader groups of organisms
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

79. Naming Species
Each species is assigned a two-part name or binomial, consisting of:
The genus
A name unique for each species
The scientific name for humans is Homo sapiens, a two part name, italicized and latinized, and with the first letter of the genus capitalized.
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

80. Hierarchical Classification
Species that are closely related are placed into the same genus.
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

81. Figure 14.19 Leopard (Panthera pardus) Tiger (Panthera
tigris)
Lion (Panthera leo)
Figure The four species within the genus Panthera
Jaguar (Panthera onca)
Figure 14.19

82. The taxonomic hierarchy extends to progressively broader categories of classification, from genus to:
Family
Order
Class
Phylum
Kingdom
Domain
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

83. Figure 14.20 Species Panthera pardus Genus Panthera Leopard
Family
Felidae
Order
Carnivora
Class
Mammalia
Figure Hierarchical classification
Phylum
Chordata
Kingdom
Animalia
Domain
Eukarya
Figure 14.20

84. Classification and Phylogeny
The goal of systematics is to reflect evolutionary relationships.
Biologists use phylogenetic trees to:
Depict hypotheses about the evolutionary history of species
Reflect the hierarchical classification of groups nested within more inclusive groups
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

85. Order Family Genus Species Panthera pardus (leopard) Felidae Panthera
Mephitis
mephitis
(striped skunk)
Mephitis
Carnivora
Mustelidae
Lutra
lutra
(European
otter)
Lutra
Figure The relationship of classification and phylogeny for some members of the order Carnivora
Canis
latrans
(coyote)
Canidae
Canis
Canis
lupus
(wolf)
Figure 14.21

86. Sorting Homology from Analogy
Homologous structures:
Reflect variations of a common ancestral plan
Are the best sources of information used to
Develop phylogenetic trees
Classify organisms according to their evolutionary history
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

87. Convergent evolution:
Involves superficially similar structures in unrelated organisms
Is based on natural selection
Similarity due to convergence:
Is called analogy, not homology
Can obscure homologies
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

88. Molecular Biology as a Tool in Systematics
Molecular systematics:
Compares DNA and amino acid sequences between organisms
Can reveal evolutionary relationships
Some fossils are preserved in such a way that DNA fragments can be extracted for comparison with living organisms.
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

89. Figure 14.22 Studying ancient DNA

90. The Cladistic Revolution
Cladistics is the scientific search for clades.
A clade:
Consists of an ancestral species and all its descendants
Forms a distinct branch in the tree of life
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

91. Iguana Outgroup (reptile) Duck-billed platypus Ingroup Hair, mammary
Kangaroo
Ingroup
(mammals)
Hair, mammary
glands
Figure A simplified example of cladistics
Gestation
Beaver
Long gestation
Figure 14.23

92. Cladistics has changed the traditional classification of some organisms, including the relationships between:
Dinosaurs
Birds
Crocodiles
Lizards
Snakes
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

93. Lizards and snakes Crocodilians Pterosaurs Common ancestor of
dinosaurs,
and birds
Ornithischian
dinosaurs
Figure How cladistics is shaking phylogenetic trees
Saurischian
dinosaurs
Birds
Figure 14.24

94. Classification: A Work in Progress
Linnaeus:
Divided all known forms of life between the plant and animal kingdoms
Prevailed with his two-kingdom system for over 200 years
In the mid-1900s, the two-kingdom system was replaced by a five-kingdom system that:
Placed all prokaryotes in one kingdom
Divided the eukaryotes among four other kingdoms
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

95. Animation: Classification Schemes
In the late 20th century, molecular studies and cladistics led to the development of a three-domain system, recognizing:
Two domains of prokaryotes (Bacteria and Archaea)
One domain of eukaryotes (Eukarya)
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
Animation: Classification Schemes

96. Domain Bacteria Earliest Domain Archaea organisms The protists
(multiple
kingdoms)
Kingdom
Plantae
Domain Eukarya
Figure The three-domain classification system
Kingdom
Fungi
Kingdom
Animalia
Figure 14.25

97. Evolution Connection: Rise of the Mammals
Mass extinctions:
Have repeatedly occurred throughout Earth’s history
Were followed by a period of great evolutionary change
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.
© 2010 Pearson Education, Inc.

98. Fossil evidence indicates that:
Mammals first appeared about 180 million years ago
The number of mammalian species
Remained steady and low in number until about 65 million years ago and then
Greatly increased after most of the dinosaurs became extinct
Student Misconceptions and Concerns
1. Students can become frustrated by the changing state of systematics. Perhaps some comfort can be offered by noting that this is true about many active areas of science. For example, scientists continue to learn more and revise advice regarding the causes, treatment, and prevention of heart disease and cancer.
2. Students might express concern over the need to learn scientific names, when common names already seem sufficient. Depending upon where you live, find some examples of common organisms with more than one common name. Fishermen are famous for the various names they assign to the same species, depending upon the geographic region where they fish. Have your students imagine the problems of using common names when communicating with someone in another language. Clearly, there are advantages to scientific names!
3. Students may struggle with many aspects of phylogenetic trees. A) Students may not realize that each node/branch can be rotated to rearrange the groups, without changing the nature of the relationships. For example, in Figure 14.23, the position of the beaver and kangaroo can be reversed without changing any relationships represented in the phylogenetic tree. B) The length of each branch is not meaningful and is not intended to be proportional to time. C) The spacing between groups is not meaningful. The same phylogenetic tree squeezed onto a page or stretched wide does not denote some degree of divergence between the groups.
Teaching Tips
1. The authors note that our hierarchical classification system is analogous to sorting mail first by zip code, then by street, house number, and finally members of the household.
2. Although Linnaeus recognized a hierarchical structure in the natural world, he had no natural explanation for the occurrence of such groups. One might wonder why all life does not blend evenly from one form to another. One of Darwin’s greatest insights was to understand that these clusters reflect similarities due to shared ancestry: that life is grouped into family trees. Further, Darwin proposed a natural mechanism for the formation of new species and the generation of this diversity.
3. Molecular systematics and cladistics are combining to further test and modify classification schemes. This is another opportunity to discuss an important aspect of the scientific method. Scientists value multiple lines of evidence testing the same hypothesis. Most of us do this in our lives. Even our court systems value different lines of evidence all pointing towards the guilt or innocence of a suspect.
4. Phylogenetic trees are tentative hypotheses. As new data are collected, the hypotheses are modified or outright rejected. Students should be cautioned to understand the tentative nature of these systems.

99. Figure 14.26 Ancestral mammal Monotremes (5 species) Reptilian
Extinction of
dinosaurs
Reptilian
ancestor
Marsupials
(324 species)
Eutherians
(5,010 species)
Figure The increase in mammalian diversity after the extinction of dinosaurs
250
200
150
100 65 50
American black bear
Millions of years ago
Figure 14.26

100. Bacteria Earliest organisms Archaea Eukarya Figure 14.UN3
Figure 14.UN3 Summary: domains
Eukarya
Figure 14.UN3