1. Unit 11 - Evolution Part 1: Principles of Evolution – Evolution by Natural Selection (Ch. 10 Sec. 1-5, Ch. 12 Sec. 1 & 2)

2. Evolution Part 1 Principles of Evolution—Evolution by Natural Selection (Ch. 10 Sec. 1-5, Ch. 12 Sec. 1 & 2)
Look at the star-nosed mole. (p. 285)
What sorts of modifications are obvious?
2. How might these traits arise in the first place?
These will then be passed on to future generations.
Ray-like feelers extending from snout, poor eyesight, and prominent claws
--Mutations in DNA
mutations

3. What is Evolution? (Ch. 10.1-10.2)
Evolution is change in species over time
Process of biological change by which descendants come to differ from their ancestors (p. 286)
Change happens in characteristics of a population from one generation to the next
Populations evolve, individuals do not!

4. Name things that have changed over time
Example: Radios

5. Vocabulary
Population – all of the individuals of a species that live in an area (p. 294)
Variations – differences in the physical traits of an individual from those traits of individuals in the population

6. Vocabulary
Species – group of organisms are that are closely related and can mate to produce fertile offspring
Dogs (Canis familiaris) are all the same species; just like all modern humans are all Homo sapiens.
We have different dog breeds based on their genetic variations but they are all the SAME species. No two people look exactly alike due to genetic variation within the human population
Speciation – process in which new species are formed over time

7. Vocabulary
Adaptation – a feature that allows an organisms to better survive and reproduce in its environment; this can lead to genetic change in a population over time.

8. Charles Darwin – the father of evolution (p. 290-291)
born in 1809, in England
was asked to sail on the H.M.S. Beagle to chart stretches of the South American coast

9. This voyage lasted from 1831 to 1836.
Charles Darwin – the father of evolution (p )
This voyage lasted from 1831 to 1836.

10. Charles Darwin – the father of evolution (p. 290-291)
Voyage of H.M.S. Beagle
5 year unpaid voyage
Darwin studied plants, animals, collected fossils
found fossils of extinct animals that were similar to modern species.
during his voyage, he made observations that led him to his theory of evolution.

11. Charles Darwin – the father of evolution (p. 290-291)
On the Galapagos Islands in the Pacific Ocean he noticed many variations among plants and animals of the same general type as those in South America.
Darwin noticed there were several types of finches on these islands, and that they all looked like a bird he had seen on the South American continent.

12. Charles Darwin – the father of evolution (p. 290-291)
The most distinct difference among finch species is their beaks
Why would beaks be different in different locations on an island?
they are adapted for the specific diets available on the islands.

13. Charles Darwin – the father of evolution (p. 290-291)
Darwin hypothesized that some of the birds from South America migrated to the Galapagos
once on the islands, the birds must have changed over the years, explaining the numerous species of birds present

14. Charles Darwin – the father of evolution (p. 290-291)
After returning from the Galapagos and studying all the different types of plants & animals he collected during the voyage, Darwin concluded that organisms change over time.
Darwin called this evolution, which means change in species over time.
Darwin called the mechanism for evolution natural selection (a.k.a. survival of the fittest).

15. How does Evolution Happen?
Natural Selection
Mutations
Artificial Selection
Geographic Separation/Isolation
Genetic Drift
Gene Flow (migration)

16. Natural Selection – the main mechanism of evolution (Ch 10.3 & 11.2)
Natural selection explains how evolution can occur.
natural selection – a mechanism by which individuals that are better fit for their environment have a greater chance to survive and mate/reproduce (p. 293)
aka- Survival of the fittest
What does it mean to be “fit”?
fit means they have inherited beneficial adaptations which allow them to be more likely to survive and reproduce more offspring.
the genetic traits of “fit” individuals become more common or frequent over time.
The genetic traits of less fit individuals become less common or frequent over time.

17. There are four main principles to the theory of natural selection
Variation – heritable differences that exist in populations
Overproduction – not all offspring will survive due to competition
Adaptation – certain variations can allow an individual to survive better than others (the environment can present challenges for survival)
Descent with Modification – the number of individuals with the advantageous adaptations will increase over each generation

18. A well-studied example of natural selection in jaguars is shown in Figure 3.2 p. 295
View animated biology – 10.3 Principles of Natural Selection (Jaguar)

19. Example: Natural Selection and beetles
beetles have genetic variation
Some are brown, others green
there is a struggle for survival
Predation
more fit individuals leave more offspring
--characteristics of fit individuals increase in a population over time
What would happen if the environment changed from brown stones to green grass?

20. Natural Selection acts on existing variation
Natural selection can only act on traits that already exist.
Natural selection acts on phenotypes; new alleles occur by genetic mutations.
Read p about the 2 examples supporting this concept.
View Animated Biology Natural Selection (fish) (may not work in Chrome; works best
in Safari)

21. Artificial Selection (p. 292)
Artificial Selection – the process by which humans change a species by breeding it for certain traits
Humans determine which traits are favorable and breed individuals that show those traits.
Ex. race horses, show dogs

22. Unit 11 Part 2: Evidence to Support Evolution (Ch. 10. 4-10. 5, Ch. 12

23. Evidence to Support Evolution (Ch 10.4-10.5, Ch. 12.1)
fossil record (p. 298, 306, 348)
Biogeography
Homologies : anatomy, development & molecular (p )

24. Fossil Record (Ch 10.4 & 12.1) Fossil – trace of a dead organism
What is a fossil?
Fossil – trace of a dead organism
Scientists consider three things about fossils: age, location and what the environment was when that organism was alive.
Fossils are dated through radiometric dating and relative dating.

25. Fossil Record
Radiometric dating uses the known time of natural decay of unstable isotopes to calculate the age of the material.
Relative dating estimates the age of fossils by comparing the fossils found in certain rock layers to those in other layers. The oldest fossils are found on the bottom, further from the surface. The youngest fossils are closest to the surface.

26. Fossil Record
Fossils can form in several ways (p. 298, 306, & 348). The most common fossils result from permineralization.

27. Fossil Record What may happen if the organism doesn’t die in sediment?
Fossil doesn’t form; decomposition takes place
Why is the fossil record not complete?
Most living things do not form into fossils when they die since the conditions are not conducive to fossil formation
Many fossils may not have been discovered yet

28. Biogeography (p. 299)
biogeography - Is the study of the geographic distribution of plants, animals and fossils.
it is used to test predictions about the nature, age, and location of certain fossils.
species tend to be more closely related to other species from the same area than to other species with the same way of life but living in different areas.

29. Anatomy and Development (p. 299-304)
homologous structures (p. 302)
homologous structures:
common ancestor
Similar structure
Different function
Example: the long bones of a cat, human, whale and bat are similar in structure (made of bones) but have different functions.

30. Homologous Structures
Similar Structure
Different Function
Common Ancestor

31. Forelimbs of Vertebrates

32. Anatomy and Development (p. 299-304)
analogous structures p. 303
not related
different structures
same function
examples:
bird wing and insect wing

33. Analogous Structures - Quills
Hedgehog (mammal)
Cactus (plant)
not related
different structures
same function
Sea urchin
(invertebrate)

34. Anatomy and Development (p. 299-304)
vestigial structures p. 304
vestigial structures- serve no useful purpose.
examples:
pelvic bone in a whale
human appendix
pelvic bone & hind limb bones in some snakes
human canine teeth & wisdom teeth

35. Vestigial Structures cont’d

36. Examples of Vestigial Structures
Extra pad and nail on dog & wolf paws

37. Vestigial Structures (cont’d)
Eyespot on a cave salamander. This little guy NEVER sees light.

38. Embryology (p. 299-39) Ex. Embryos of vertebrates
Embryology - Similarities in embryological development among organisms is further evidence of shared common ancestry
Ex. Crab and barnacle – adults look very different but the larva can look very similar (Fig 4.4)

39. Molecular Evidence (p. 307)
Very different species have similar molecular and genetic mechanisms. Because all living things have DNA (bacteria, plants, animals, etc.), they share the same genetic code and make most of the same proteins from the same 20 amino acids.
More similarities in DNA (which translates into proteins) between two organisms, the more closely related they are, the more differences; the more distantly related.

40. Molecular Evidence (p. 307)
Comparing Amino Acids
Which organism is most closely related to the human? Why?
Which organism is least closely related to the human? Why?
Chimpanzee; greatest number of similarities with human
Kangaroo; greatest number of differences when compared too human

41. Number of amino acids that differ from a human

42. Molecular Evidence (p. 307)
Remember, the DNA sequence dictates the amino acid sequence through the processes of transcription and translation, therefore, ALL 4 levels (DNA, RNA, amino acids, and proteins) can show evidence of evolution

43. Molecular Evidence (p. 307)
Watch Hox genes video clip (2:44) Section 10.5 “Evolutionary Biology 1” in your online textbook
Sign in to Google or gmail; then go to the online textbook
Select Chapter 10 in dropdown box and click “GO”
Click on Student Resources
Click on Videos
Click on Biology Video Clips
Click on Section 10.5 “Evolutionary Biology 1”

44. Unit 11 Part 3: The Evolution of Populations (Chapter 11)

45. Genetic Variation Within Populations (p. 316-321)
Vocabulary
gene pool – combined alleles of all the individuals in a population

46. Vocabulary alleles – different forms of a gene
flower color gene may be “P” (purple) or “p” (white)
frequency – how often something occurs over time
Ex. If 25 rabbits are white, out of a population of 100 rabbits, the frequency of white rabbits is 0.25

47. Genetic Variation Within Populations (p. 316-321)
Genetic variation in a population increases the chance that some individuals will survive.
Genetic variation comes from two main sources.
Mutation - random change in the DNA of a gene; if the change occurs in the DNA of a reproductive cell (gamete=egg or sperm), then the mutation will be passed on to offspring.
Recombination – new allele combinations in an offspring that occurred during meiosis through crossing over and independent assortment.

48. Other Mechanisms of Evolution (p. 323-327)
Natural selection isn’t the only mechanism through which populations evolve. Other mechanisms include: genetic drift, gene flow, mutation and sexual selection.

49. Other Mechanisms of Evolution (p. 323-327)
gene flow – movement of alleles from one population to another
Population 1
Population 2 over time
Population 2
Individuals in Population 1 migrate to Population 2 and change the frequency of green beetles found there

50. Other Mechanisms of Evolution (p. 323-327)
another word for gene flow is migration (immigration & emigration)
gene flow increases the genetic variation of the receiving population
lack of gene flow between two populations may lead to the formation of different species

51. Other Mechanisms of Evolution (p. 323-327)
Genetic Drift
genetic drift - change in allele (gene) frequency due to chance; results in loss of diversity
Two types of genetic drift
1. Bottleneck effect
2. Founder effect

52. Other Mechanisms of Evolution (p. 323-327)
Genetic Drift
Bottleneck effect - when a population is drastically decreased due to a natural disaster (hurricane, disease)
some genes are completely lost; others are over-represented
some genes are reduced so much they can’t “make a come back” in their new population

53. Other Mechanisms of Evolution (p. 323-327)
Genetic Drift
founder effect – when a small group splits off from a larger population and starts their own population isolated from the original population
Amish in America – original population was 14 individuals that immigrated from Europe

54. Other Mechanisms of Evolution (p. 323-327)
Mutations
a random mutation can happen to one individual in a population, and can ge beneficial, harmful, or neutral
random mutations can increase chances of survival and reproduction

55. Other Mechanisms of Evolution (p. 323-327)
random mutations can decrease chances of survival
if an individual dies before it can reproduce, that mutation is not passed down to another generation

56. Other Mechanisms of Evolution (p. 323-327)
random mutations might not affect an individuals ability to survive and reproduce and will become a natural variation instead of a mutation
Ex. dark spots on pigs

57. Sexual Selection (p. 326)
Sexual selection occurs when certain traits increase mating success.
Ex. Males compete for females such as the head-butting of bighorn sheep; Male peacocks fan out their tails to attract the female.

58. Hardy-Weinberg (p. 328)
two scientists created an equation to test these ideas of probability and chance
Hardy-Weinberg principal - the frequency of alleles in a population does not change unless evolutionary forces act on the population
Characteristics of a Hardy-Weinberg (non-evolving) population:
very large population
no migration (no immigration or emigration)
no mutations
random mating (no individual are “more fit”, they all seem to the same)
no natural selection
A population with all of these criteria is not evolving. This doesn’t happen in nature; therefore all populations in nature are evolving.

59. Isolation of a population can lead to speciation (p. 332)
Reproductive isolation –when members of different populations of the same species can no longer mate successfully.
Reproductive isolation can lead to speciation.
Three barriers that can cause reproductive isolation to occur:
Behavioral barriers – courtship or mating behaviors are now different in the population
Geographical barriers – physical separation of the populations; Ex. mountains, roads, rivers
Temporal barriers – the two populations aren’t ready to mate at the same time of day (ex. Flowers that bloom in morning vs. evening) or in the same season

60. Patterns of Evolution (p. 335-341)
Convergent evolution (word part: co = together)
similarities not because they are related but because they need certain adaptations to survive in their environment; therefore, they have analogous structures

61. Patterns of Evolution (p. 335-341)
Convergent evolution
Example:
Sharks, dolphins, tuna, penguins have streamlined bodies, and fins.
HOWEVER Sharks are cartilaginous fish, dolphins are mammals, tuna are bony fish, and penguins are birds.
they share similarities because they all adapted to the same marine environment and predatory lifestyle.
Convergent evolution is sometimes called parallel evolution

62. Patterns of Evolution (p. 335-341)
Divergent evolution (word part: di = two); the process by which one species begins to split into two distict groups with different traits; therefore, they have homologous structures

63. Patterns of Evolution (p. 335-341)
Divergent evolution
Example:
All canines have long legs, walk on their toes, non-retractable claws, and dew claws because they all come from a common ancestor.
Different populations diverged at different points an created all these species (domestic dogs, wolves, coyotes, foxes, etc.)
Divergent evolution is sometimes called adaptive radiation and may lead to speciation.

65. Phylogenic (or Phylogenetic) Tree
a diagram showing the evolutionary history of a species of an animal.
Is this convergent or divergent evolution?
Divergent

67. Patterns of Evolution (p. 335-341)
Coevolution – process in which two or more species evolve in response to changes in each other.
Ex. ant and acacia tree, crabs & snails, flower structure & bird beak shape (p. 337)

68. Patterns of Evolution (p. 335-341)
Extinction – elimination of a species, usually as a result of its inability to adapt to a change in the environment; Ex. dinosaurs (p. 338)

69. Patterns of Speciation (p. 339)
gradualism- slow changes happen continuously over a long period of time
Ex. Evolution of the horse (p. 339)

70. Patterns of Speciation (p. 339)
punctuated equilibrium- bursts of rapid change in species are separated by periods of little to no change
“spurts in evolution”
traits “appear suddenly” in the fossil record usually due to climate changes or catastrophic events

71. Gradualism vs. Punctuated Equilibrium

72. In Summary…
Life forms reproduce and therefore have a tendency to become more numerous.
The offspring differs from the parent in minor random ways.
If the differences are helpful, the offspring is more likely to survive and reproduce.
This means that more offspring in the next generation will have the helpful difference.
These differences accumulate resulting in changes within the population.
Over time, populations branch off to become new species as they become separated.
This process is responsible for the many diverse life forms in the world.
Haeckel's Paleontological Tree of Vertebrates (c. 1879).