Pre-AP Biology Evolution Review

Transcription

1 Pre-AP Biology Evolution Review

2 Variation in Beak Size in Medium Ground Finch If you wanted to look for a change in phenotype beak size over time in a population of finch (which would be evidence of natural selection) how would you go sampling the population?

3 Variation in Beak Size in Medium Ground Finch If you wanted to look for a change in phenotype beak size over time in a population of finch (which would be evidence of natural selection) how would you go sampling the population? Capture a large number of finches over a number of years, and measure the height and width of their beaks with a caliper (gives quantative measurements) and perform a statistical test to see if the differences in beak size were statistically significant.

4 Finch Count Seed Abundance (g/m 2 ) ,600 1,400 1,200 1, Winter 1976 Winter 1976 Summer 1976 Winter 1977 Year & Season Summer 1976 Winter 1977 Year & Season Summer 1977 Summer 1977 Winter 1978 Winter 1978 Summer 1978 Summer Describe the pattern of seed abundance over the course of the study: 2. When do you think the drought began? Ended? 3. Do you think small or large seeds were more abundant during the drought? 4. What is the relationship between seed abundance and finch count? Why?

5 Finch Count Seed Abundance (g/m 2 ) Bird abundance matches seed abundance because food = offspring, no food = death via starvation. 0 1,600 1,400 1,200 1, Winter 1976 Summer 1976 Winter 1977 Year & Season Summer 1977 Winter 1978 Summer 1978 The drought occurred starting the summer of 1976 when seed abundance plummeted (till winter 1978) Winter 1976 Summer 1976 Winter 1977 Year & Season Summer 1977 Winter 1978 Summer 1978 The majority of seeds during the drought were large in size

6 1. What is the relationship between beak depth and climate? 2. Why do you think there is this relationship?

7 Dry years tend to favor large-beaked birds because they are able to crack the large-seeds that are available during dry years. They thus survive and have the majority of offspring, passing on the large-beaked genes.

8 If researchers found an allele for large beaks, what pattern would they expect to find in the frequency of this allele over time (as related to climate) on the island?

9 If researchers found an allele for large beaks, what pattern would they expect to find in the frequency of this allele over time (as related to climate) on the island? They would expect to find that the frequency of the large-beak allele increases during dry years.

10 Adaptive Radiation on Islands (Galapagos Finch) 1. How many species of finch were there historically? 2. What does the red ribbon labeled 1 indicate? 3. How many species are there in the end? 4. What role does both habitat-type and lifestyle play in speciation? 5. What other factors could result in speciation?

11 Adaptive Radiation on Islands (Galapagos Finch) Historically there was 1 species of finch from the mainland that made it to island A (red ribbon). Now reproductively isolated from the mainland, species A became species B and colonized additional islands. The species diversified into B E on the islands due to vacant niches available for exploitation and potentially genetic drift due to small population sizes.

12 Using the data provided, make a claim with evidence that genetic resistance to DDT existed in the population of bacteria prior to the first use of the pesticide.

13 Using the data provided, make a claim with evidence that genetic resistance to DDT existed in the population of bacteria prior to the first use of the pesticide. At year 0, when the pesticide was first used, 4% of the population was not killed (thus demonstrating genetic resistance) and they survived and passed the trait on.

14 Frequency of the dark allele Rock Pocket Mouse Data 1. Describe the pattern between time and the frequency of the dark allele: 2. Define microevolution: 3. Make a claim with justification for whether the population evolved over the thirty-year period of the study: 4. Propose an environmental change that may have resulted in the change in allele frequency demonstrated by the data.

15 Frequency of the dark allele Rock Pocket Mouse Data 1. The frequency of the light allele decreased from 1970 to Microevolution is a change in allele frequency over time. 3. Evolution occurred because there was a change in allele frequency. 4. Perhaps a lava flow covered the study site, turning the substrate from light to dark. Mice use color-matching to escape detection from predators.

16 1. What is the relationship between fur-color and soilcolor and the number of mice caught by owls (see data above)? 2. What is the explanation for this pattern?

17 1. What is the relationship between fur-color and soilcolor and the number of mice caught by owls (see data above)? Fewer mice that color-match their background are caught. 2. What is the explanation for this pattern? Colormatching is an adaptation that helps increase the likelihood of survival.

18 1. What was the average # of spines before? 2. What was the average after? 3. How did cacti respond to the javelina? 4. Explain why the cacti responded in this way: 5. Directional, stabilizing, or disruptive selection?

19 1. What was the average # of spines before? What was the average after? How did cacti respond to the javelina? Cacti became more spiny. 4. Explain why the cacti responded in this way: Spiny individual had a survival advantage. 5. Directional, stabilizing, or disruptive selection? directional

20 1. What was the average # of spines before and after? 2. Describe how variation in spine # changed: 3. Explain the reason for this change: 4. Directional, stabilizing, or disruptive selection?

21 1. What was the average # of spines before and after? Describe how variation in spine # changed: variation (range in) spininess decreased 3. Explain the reason for this change: Javalenia selects for increased spines but parasites select for decreased. 4. Directional, stabilizing, or disruptive selection? stabilizing

22 1. What was the average # of spines before? 2. Which type of cacti were selectively harvested? 3. How did this affect the cacti population? 4. Directional, stabilizing, or disruptive selection?

23 1. What was the average # of spines before? Which type of cacti were selectively harvested? Two modes: 80 and How did this affect the cacti population? Low and high spininess increase, medium decreases 4. Directional, stabilizing, or disruptive selection? disruptive

24 Cytocrome c Protein Amino Acid Comparisons Based on the data, did humans share a common ancestor more recently with tuna or pigeon? Use the data to Justify your claim:

25 Cytocrome c Protein Amino Acid Comparisons Humans shared a common ancestor more recently with pigeons (only 12 differences) than with tuna (more differences with 21).

26 Cytocrome c Protein Amino Acid Comparisons Create a phylogenetic tree that shows the evolutionary relationships between tuna, pigeon, rhesus monkey, and humans

27 Cytocrome c Protein Amino Acid Comparisons Human Rhesus pigeon tuna Create a phylogenetic tree that shows the evolutionary relationships between tuna, pigeon, rhesus monkey, and humans

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30 1. How can you identify an outgroup? 2. Why does the mouse and chimp group together? 3. Why does the crocodile group more closely with the pigeon than the lizard?

31 Lamprey (outgroup) has none of the derived traits Only the mouse & chimp have hair & mammary glands The crocodile & pigeon both have gizzards, the lizard does not

32 Discuss how the phylogenetic tree shows the pattern of shared common ancestry of a group of organisms.

33 Existing species are at branch tips (moving towards the root takes us back in time). The closer organism are grouped together, the more recently they shared a common ancestor.

34 Character Table to Cladogram with Character Traits What is a character trait that leopards and turtles share but that is not shared with turtles?

35 Character Table to Cladogram with Character Traits What is a character trait that leopards and turtles share but that is not shared with turtles? Amnion

36 In the diagram above, connectivity increases in the habitat-patch designs from left to right. 1. How would the level of gene flow be affected? 2. How would genetic diversity be affected?

37 In the diagram above, connectivity increases in the habitat-patch designs from left to right. Gene flow would increase as connectivity does. Gene flow would make the effective population size larger (one large population vs. two smaller ones) and would therefore help to maintain genetic diversity

38 A population bottleneck is shown 1. Are allele frequencies likely to be the same after the bottleneck? Explain: 2. What is the likely effect on genetic diversity? Explain:

39 A population bottleneck is shown The allele frequencies after a population bottleneck are likely to change because genetic drift (a type of sampling error) will have a larger effect in a smaller population resulting in a random change in frequencies and loss of genetic diversity.

40 How would one go about studying the evolution of a tetrapod limb from a fish s fin?

41 Compare limb/fin structure of existing related species of fish to tetrapods Figure out the age of rock where the transition from fin to limb occurred Find the locations on Earth where this aged rock layer is at the surface Travel to these areas and search for a transitional fossil

42 Transitional Fossil: Tiktaalik This transitional fossil has characteristics of both fish and tetrapods

43 Discuss how two species of squirrel (Abert and Kaibab) emerged as a result of allopatric speciation:

44 Discuss how two species of squirrel (Abert and Kaibab) emerged as a result of allopatric speciation: Once there was one population of tassel-eared squirrels, able to interbreed with one another. Then the Grand Canyon emerged as a geographic barrier, preventing two (now reproductively isolated) populations of squirrels from interbreeding. Thus new mutations that accumulated in each population could not be shared. Additionally, natural selection could act differently in the two areas.

45 Are the two squirrels from the same species? Tassel-eared squirrel from Flagstaff Tassel-eared squirrel from the N. Rim

46 Biological Definition of a Species: A species is a group of populations whose members have the potential to interbreed in nature and produce viable (live), fertile offspring but do not produce viable, fertile offspring with members of other such groups.

47 1. What is the ultimate (underlying) cause of animal behavior? 2. What is an example?

48 The Ultimate (Underlying) Cause of Behavior Addresses evolutionary significance Developed due to natural selection Increases survival to reproduction in some way Unique among gull species, kittiwakes show an innate aversion to cliff edges; they turn away from the edge. Kittiwake chicks in earlier generations that did not show the edge-aversion response failed to become ancestors to modern kittiwakes.

49 1. What is genetic drift? 2. What is the relationship between population size and the effect of genetic drift? 3. Can genetic drift result in evolution? Explain: 4. Does genetic drift result in a population being better adapted to its environment?

50 Genetic Drift Involve random events that result in a change in allele frequency Can lead to a loss of genetic variation Plays a significant role in small populations Can result in microevolution but is not adaptive like natural selection 1:2 1:6

51 A visitor leaves the trail at Hawaii Volcanoes National Park. Unknowingly, he steps on a population of endangered Koa beetles, killing two of the green beetles. The beetles come in two color-morphs with brown being the dominant phenotype. Steps to finding the frequency of the recessive (q) and dominant alleles (p): a. Find the frequency of the recessive phenotype (# recessive/total). This is q 2. b. Take the square root of q 2 to get q, which is the frequency of the recessive allele. Before c. Use 1 q to find the frequency 1. of the Find dominant the frequency allele (p). of the recessive allele before the visitor stepped on the beetles. 2. Find the frequency of the dominant allele before the visitor stepped on the beetles. 3. Find the frequency of the recessive allele after the visitor stepped on the beetles. 4. Find the frequency of the dominant allele after the visitor stepped on the beetles. 5. Did the population of beetles evolve? Explain: 6. Would the effect of the visitor be as dramatic if the population was much larger? Explain: 7. Did the population become better adapted to their environment? Explain: After

52 A visitor leaves the trail at Hawaii Volcanoes National Park. Unknowingly, he steps on a population of endangered Koa beetles, killing two of the green beetles. The beetles come in two color-morphs with brown being the dominant phenotype. Steps to finding the frequency of the recessive (q) and dominant alleles (p): a. Find the frequency of the recessive phenotype (# recessive/total). This is q 2. b. Take the square root of q 2 to get q, which is the frequency of the recessive allele. Before c. Use 1 q to find the frequency of the dominant allele (p). After 1. 3/9 = 0.33 = frequency of the recessive phenotype (q 2 ), take the square root to get the frequency of the recessive allele = 0.58 (q) = p = 0.42 is the frequency of the dominant allele 3. 1/7 = 0.14, take the square root to get the frequency of the recessive allele = 0.38 = q = p = 0.62 is the frequency of the dominant allele 5. The population evolved because allele frequencies changed (the frequency of the recessive allele decreased). 6. The effect of random events is much more dramatic in small populations such as that shown here. If their was 300 green beetles and 600 brown beetles, for example, eliminating just two green beetles would not have noticeably change allele frequencies. 7. The population changed randomly (due to sampling error called genetic drift) so the change was not. Only the mechanism called natural selection consistently results in adaptive change.

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54 1. Two (H and H) 2. Mutation x 2 = /30 = /25 = 0.17

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56 Where they were located on the island when the tsunami hit (random not based on genetics) 9. 6 x 2 = /12 = /12 = Evolution occurred because the allele frequency changed. 13. Decreased 14. The island population might be wiped out by malaria because there is no genetic immunity (that allele was lost in the tsunami). 15. Although evolution occurred, it was not adaptive. Only natural selection results in adaptive change. In this scenario allele frequencies dropped because of genetic drift (random) because of a population bottleneck.

57 1. Describe the change in habitat area between 1820 & 1993: 2. Describe the population size change 1930 to 1993: 3. How did the number of alleles per locus change? 4. How did percentage of eggs hatch change? 5. How are all of these data related?

58 1. Describe the change in habitat area between 1820 & 1993: Habitat loss and fragmentation 2. Describe the population size change 1930 to 1993: Decrease in size (population bottleneck) 3. How did the number of alleles per locus change? Decrease in number of alleles = loss of genetic diversity 4. How did percentage of eggs hatch change? Percentage of eggs hatched decreased 5. How are all of these data related? All of these data indicate a loss of genetic diversity

59 1. Describe the pattern in bird population over time: 2. Why did bird population decline in after 1970? 3. Why was the hatch-rate in 1990 so low? 4. When did translocation occur and what does this mean? 5. Why did the hatch-rate improve after translocation and what was the effect on overall population size?

60 1. Describe the pattern in bird population over time: The population decreased (bottleneck) 2. Why did bird population decline in after 1970? Loss of habitat 3. Why was the hatch-rate in 1990 so low? Indication of loss of genetic diversity (and inbreeding) 4. When did translocation occur and what does this mean? About 1992 or Why did the hatch-rate improve after translocation and what was the effect on overall population size? The newly introduced chickens infused new genetic diversity into the population.