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Chapter 14 Speciation and Extinction Island: ©Morandi Bruno/Hemis/Corbis Copyright © McGraw-Hill Education. All rights reserved. No reproduction or distribution.

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Presentation on theme: "Chapter 14 Speciation and Extinction Island: ©Morandi Bruno/Hemis/Corbis Copyright © McGraw-Hill Education. All rights reserved. No reproduction or distribution."— Presentation transcript:

1 Chapter 14 Speciation and Extinction Island: ©Morandi Bruno/Hemis/Corbis Copyright © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.

2 What Is a Species? Section 14.1Figure 14.1 Countless small evolutionary changes have accumulated through the last 3.8 billion years, leading to today’s great diversity of life. Bacteria: ©S. Lowry/University Ulster/Getty Images; Tree: ©Corbis RF; Bird: ©IT Stock/PunchStock RF How do small mutations, even if numerous, produce new species? First, we must explore what defines a species.

3 What Is a Species? Section 14.1Figure 14.3 In the 1700s, Carolus Linnaeus defined species by appearance. He also created a naming scheme for species. Butterfly collection: ©IT Stock Free/Alamy RF Each species’ name combines the broader classification genus with the term species. The scientific name for humans, for example, is Homo sapiens. More recently, the biological species concept defines species based on their potential to interbreed and produce fertile offspring.

4 What Is a Species? Section 14.1 Speciation, the formation of new species, occurs when some individuals can no longer interbreed with the rest of the group. Figure 14.3 Butterfly collection: ©IT Stock Free/Alamy RF

5 Clicker Question #1 The biological species concept cannot be applied to A. humans. B. plants. C. extinct organisms. D. organisms that look alike. Flower: © Doug Sherman/Geofile/RF

6 Clicker Question #1 The biological species concept cannot be applied to A. humans. B. plants. C. extinct organisms. D. organisms that look alike. Flower: © Doug Sherman/Geofile/RF

7 Reproductive Barriers Cause Speciation Section 14.2 If the potential to interbreed defines species, reproductive isolation results in new species. Figure 14.5

8 Reproductive Barriers Cause Speciation Section 14.2Figure 14.4 Prezygotic reproductive barriers occur before the formation of the zygote, or fertilized egg. They prevent fertilization.

9 Reproductive Barriers Cause Speciation Section 14.2 Postzygotic reproductive barriers reduce the fitness of offspring produced by members of two different species. They prevent the development of fertile offspring. Figure 14.4

10 Reproductive Barriers Cause Speciation Section 14.2Figure Stilts: ©Tim Fitzharris/Minden Pictures; Sperm: ©Francis Leroy, Biocosmos/Science Source; Chick: ©S. Alden/PhotoLink/Getty Images RF; Stilt: USDA Natural Resources Conservation Service

11 Clicker Question #2 Which of the following is an example of a postzygotic reproductive barrier? A. A cross between a horse and a donkey produces an infertile mule. B. Two types of fireflies lure mates with different flash patterns. C. Bees pollinate one Mimulus plant species; hummingbirds pollinate another. D. Pine sperm cannot fertilize spruce eggs. Flower: © Doug Sherman/Geofile/RF

12 Clicker Question #2 Which of the following is an example of a postzygotic reproductive barrier? A. A cross between a horse and a donkey produces an infertile mule. B. Two types of fireflies lure mates with different flash patterns. C. Bees pollinate one Mimulus plant species; hummingbirds pollinate another. D. Pine sperm cannot fertilize spruce eggs. Flower: © Doug Sherman/Geofile/RF

13 Spatial Patterns Define Three Types of Speciation Section 14.3Figure 14.5 Reproductive barriers arise in three ways, depending on spatial patterns:

14 Spatial Patterns Define Three Types of Speciation Section 14.3Figure 14.5 In allopatric speciation, a barrier physically separates a population into two groups that cannot interbreed. With no gene transfer between the two populations, each proceeds down its own evolutionary line. Eventually, genetic differences between the populations give rise to one or more reproductive barriers.

15 Spatial Patterns Define Three Types of Speciation Section 14.3Figure 14.7 For example, Galápagos tortoises diverged into several subspecies on different islands. Left & right tortoise: ©Tui De Roy/Minden Pictures

16 Spatial Patterns Define Three Types of Speciation Section 14.3Figure 14.5 In parapatric speciation, part of a population enters a new habitat bordering the range of the parent species. Mating can occur between populations, but most individuals mate with their own population. Genetic differences accumulate between the populations, which may make interbreeding less likely.

17 Spatial Patterns Define Three Types of Speciation Section 14.3Figure 14.8 Parapatric speciation may be occurring in little greenbuls.

18 Spatial Patterns Define Three Types of Speciation Section 14.3Figure 14.5 In sympatric speciation, populations diverge genetically while sharing a habitat.

19 Spatial Patterns Define Three Types of Speciation Section 14.3Figure 14.9 Cichlid fish have diversified into several species in a small African lake. Each species specializes in a unique micro- environment, leading to reproductive isolation and speciation.

20 Spatial Patterns Define Three Types of Speciation Section 14.3Figure Sympatric speciation also occurs when gametes unite to form polyploid offspring with more chromosomes than either parent.

21 Spatial Patterns Define Three Types of Speciation Section 14.3 A polyploid organism might form when gametes from two species unite, producing the first cell of a new species. Figure 14.10

22 Clicker Question #3 About 3 million years ago the Isthmus of Panama closed, forming a land bridge connecting North and South America. Snapping shrimp collected from water on one side of the isthmus look similar to those on the other side, but they cannot interbreed. What has occurred? A. allopatric speciation B. parapatric speciation C. sympatric speciation Flower: © Doug Sherman/Geofile/RF

23 Clicker Question #3 About 3 million years ago the Isthmus of Panama closed, forming a land bridge connecting North and South America. Snapping shrimp collected from water on one side of the isthmus look similar to those on the other side, but they cannot interbreed. What has occurred? A. allopatric speciation B. parapatric speciation C. sympatric speciation Flower: © Doug Sherman/Geofile/RF

24 The Pace of Speciation Section 14.4 Figure The fossil record supports two hypotheses about the pace of evolution: Gradualism Punctuated equilibrium

25 The Pace of Speciation Section 14.4 Gradualism suggests that evolution proceeds in small, incremental changes over many generations. Figure 14.11

26 The Pace of Speciation Section 14.4 Punctuated equilibrium suggests that long periods of little change are interrupted by bouts of rapid change. Figure 14.11

27 The Pace of Speciation Section 14.4 Bursts of speciation occur during adaptive radiation: a population inhabiting a patchy or heterogeneous environment gives rise to multiple specialized forms in a relatively short time. Figure 14.11

28 The Pace of Speciation Section 14.4 An adaptive radiation might occur when a key adaptation arises. The first flowering plants, for example, diversified quickly, as flowers provided a new options for reproduction. Figure 14.11

29 The Pace of Speciation Section 14.4Figure Evolution might also occur quickly following a mass extinction. The surviving organisms exploit new resources in the changed environment.

30 14.4 Mastering Concepts Describe the theories of gradualism and punctuated equilibrium. Island: ©Morandi Bruno/Hemis/Corbis

31 Section 14.5Figure A species is extinct when all of its members have died. Extinction Marks the End of the Line

32 Section 14.5Figure Most extinctions occur as part of the background extinction rate, the pace at which species go extinct due to gradually changing environments.

33 Extinction Marks the End of the Line Section 14.5Figure Earth has witnessed five mass extinctions in the last 600 million years. During these periods, many species went extinct in a short time.

34 Extinction Marks the End of the Line Section 14.5Figure Impact theory suggests that meteorites or comets caused some mass extinctions. Rock: ©Francois Gohier/Science Source The debris suspended in the atmosphere after a collision dramatically changed the environment, leading to the extinction of many species.

35 Extinction Marks the End of the Line Section 14.5 Plate tectonics (Earth’s shifting land masses) also might explain mass extinctions.

36 14.5 Mastering Concepts Distinguish between background extinction and mass extinctions. Island: ©Morandi Bruno/Hemis/Corbis

37 Biological Classification Systems Are Based on Common Descent Section 14.6 Taxonomy is the science of describing, naming, and classifying species. Figure 14.15

38 Biological Classification Systems Are Based on Common Descent Section 14.6 The taxonomic hierarchy organizes species into progressively larger groups.

39 Figure Biological Classification Systems Are Based on Common Descent Section 14.6 The more features two organisms have in common, the more taxonomic levels they share. Squid: ©Frank & Joyce Burek/Getty Images RF; Fly: ©Kimberly Hosey/Getty Images RF; Orangutan: ©MedioImages/SuperStock RF; Chimp: ©Anup Shah/Getty Images RF

40 Biological Classification Systems Are Based on Common Descent Section 14.6 Phylogenetics is the study of evolutionary relationships among species.

41 Biological Classification Systems Are Based on Common Descent Section 14.6 Phylogenetic trees depict evolutionary relationships based on descent from common ancestors. Species 1 Species 3 Species 8 Species 2 Species 4 Species 5 Species 6 Species 7 Species 9 Species 10 Common ancestor of species 1-10 Common ancestor of species 6 & 7 Common ancestor of species 1-4

42 Biological Classification Systems Are Based on Common Descent Section 14.6Figure A cladogram is a type of phylogenetic tree. Clades

43 Biological Classification Systems Are Based on Common Descent Section 14.6Figure A clade is a group of organisms consisting of a common ancestor and all of its descendants. Clades

44 Biological Classification Systems Are Based on Common Descent Section 14.6Figure Tracing taxa back to their common ancestor reveals evolutionary relatedness. Clades

45 Biological Classification Systems Are Based on Common Descent Section 14.6Figure According to this cladogram, a bird is more closely related to a dinosaur than a crocodile. Clades

46 Biological Classification Systems Are Based on Common Descent Section 14.6Figure We also know that turtles are more closely related to lizards than to mammals.

47 Biological Classification Systems Are Based on Common Descent Section 14.6Figure Trace lineages from right to left until they intersect to find their common ancestor.

48 Biological Classification Systems Are Based on Common Descent Section 14.6Figure Trace lineages from right to left until they intersect to find their common ancestor.

49 Biological Classification Systems Are Based on Common Descent Section 14.6Figure The common ancestor that appears farther to the right arose more recently.

50 Biological Classification Systems Are Based on Common Descent Section 14.6Figure A recent common ancestor means that turtles and lizards are more closely related than turtles and mammals.

51 Clicker Question #4 What is the most recent common ancestor of species 7, 8, and 9? Species 1 Species 3 Species 8 Species 2 Species 4 Species 5 Species 6 Species 7 Species 9 Species 10 D A C B E Flower: © Doug Sherman/Geofile/RF

52 Clicker Question #4 What is the most recent common ancestor of species 7, 8, and 9? Species 1 Species 3 Species 8 Species 2 Species 4 Species 5 Species 6 Species 7 Species 9 Species 10 D A C B E Flower: © Doug Sherman/Geofile/RF

53 A Cladogram Can Be Drawn in Several Ways Section 14.6Figure These cladograms all show the same evolutionary relationships.

54 Identifying Groups in Cladograms Section 14.6Figure A clade is also called a monophyletic group.

55 Identifying Groups in Cladograms Section 14.6Figure A paraphyletic group excludes some of the descendants of an ancestor. See how birds are excluded?

56 Identifying Groups in Cladograms Section 14.6Figure A polyphyletic group excludes the most recent common ancestor of its members. Birds and mammals are endotherms, but their common ancestor was not endothermic.

57 Clicker Question #5 Using the phylogenetic tree below, is “Protista” a clade? A. Yes, because they all share a common ancestor. B. No, because not all descendants from a common ancestor are included in the group. Flower: © Doug Sherman/Geofile/RF

58 Clicker Question #5 Using the phylogenetic tree below, is “Protista” a clade? A. Yes, because they all share a common ancestor. B. No, because not all descendants from a common ancestor are included in the group. Flower: © Doug Sherman/Geofile/RF


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