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L567 (2010): study questions for second exam. Final set, updated 26 Nov 2010.
1. Briefly describe Stanley’s hypotheses for the preponderance of cross-fertilizing plants
and animals. Compare his idea with Nunney’s idea. Why are these ideas considered
“macroevolutionary”?
2. Contrast hard selection, soft selection, frequency-dependent selection, and densitydependent selection. How are they related to ideas concerning the maintenance of
genetic polymorphism? Which one of these ideas are related to the tangled bank
hypothesis and to “multiple-niche polymorphism” theory, and why?
3. Discuss the paper on the evolution of recombination rates by Burt and Bell (1987).
Why do longer-lived species have more recombination? Why do domesticated species
have relatively high rates of recombination?
4. What is the cost of males? Contrast the primary ecological theories for the
maintenance of cross-fertilization in the face of this cost.
8. How is the Red Queen model conceptually related to the Rock Paper Scissors game?
How could host-parasite coevolution select for recombination.
9. What is linkage disequilibrium (give a verbal and mathematical description)?
10. In general, what is the effect of recombination on linkage disequilibrium? Under
what conditions would increased rates of recombination be favored by natural selection?
11. What is epistasis for fitness? Why does epistasis of this kind lead to linkage
disequilibria?
12. What is run-away sexual selection? How does it generate linkage disequilibrium and
genetic correlations? How would you test for the existence of genetic correlations
generated by sexual selection? Do you think the selection experiments on stalk-eyed flies
showed the expected correlated response in females to selection on stalk length in males?
13. Describe Kirkpatrick's model for sexual selection. Does it seem reasonable, testable?
14. What happens to additive genetic variation under run-away sexual selection? What
models, if any, can explain the maintenance of additive genetic variation under strong
female choice for male traits? Describe the Hamilton and Zuk hypothesis. What is
meant by condition-dependent mate choice?
15. Can you suggest a way that run-away sexual selection could lead to speciation?
16. How did meiotic drive figure into female choice of males in the stalk-eyed flies of
Malaysia?
17. What is Hamilton’s rule? What does it mean with respect to the evolution of social
behavior? How is the result by Taylor and Frank (1996) similar to Hamilton’s rule? In
the Taylor and Frank model, the authors derived relatedness as the ratio of two
covariances. What was the ratio? What does it mean? Give an example of how
relatedness, defined in this way, can be very low, even in a group of very close relatives.
18. In Templeton’s example of sickle-cell anemia, how does inbreeding and dominance
affect the initial direction and outcome of natural selection? What is the meaning of the
term “identical by descent”? Will populations evolve to the best possible phenotype in
phenotypic space? What is the inbreeding coefficient?
18.5. The Templeton paper (see web site) does not have an abstract. Write an abstract
with no more than 300 words.
19. Describe the process of shifting balance. What are the three phases? What was the
theory meant to explain? How does Wright’s shifting-balance view of evolution compare
with Fisher’s thinking on evolution?
20. Write your own question on aspects of the material covered in this section of the
course, and answer it.
21. What was the conceptual gist of the Zeh & Zeh paper on intergenomic conflicts and
speciation rates in viviparous organisms? How would it explain the faster speciation
rates in mammals compared to amphibians?
22. What is the conceptual gist of McPhail’s idea on the evolution of character
displacement in stickleback fish (see overheads from 21 Nov. 06)?
23. What in your view are the most general statements that can be made about
speciation? How does speciation work?
24. What is meant by "speciation by reinforcement"? In your view, is it likely to be
general? Was the Drosophila data presented by Coyne and Orr consistent with speciation
by reinforcement? Was the paper in Nature by Saetre et all a convincing case for
speciation by reinforcement? Why or why not?
25. Using a two-locus, two-allele diploid model, show epistasis for fitness in a way that
gives two adaptive peaks. Show how crosses between individuals at these peaks could
lead to low-fitness hybrids.
Similarly, show how different adaptive peaks might correspond to different
environments, and how crossing individuals at these peaks might lead to low-fitness
hybrids.
What are the main differences between the shifting balance model of speciation and the
Dobzhansky-Muller model of speciation?
26. What is effective population size? Why is it an important concept in evolutionary
genetics? Show how sex-ratio bias and variation in offspring production affects Ne.
27. What is meant by "levels of selection"? Demonstrate your understanding of kin
selection. How might kin selection explain the evolution of sterile castes? Why did
Darwin consider the evolution of sterile castes to be an especially difficult problem?
28. Discuss the evolution of cooperation without kin selection. Use the prisoner's
dilemma as guide (if it helps you). How is the outcome expected to be affected if the
organisms interact repeatedly instead of only once?
29. Is there selection for speciation?
30. What is meant by "macroevolution"? Give an example of how selection on life
history could effect marcoevolution (hint: the Jablonski example).
31. What did van Valen mean by the Red Queen hypothesis? Why did he suggest the
hypothesis in the first place? Note that Van Valen's use was the first use of the Red
Queen idea.
32. Write a brief review of the Saetre et al. paper. Recommend accept or decline, and
give your reasons.