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L567 (2006): study questions for second exam. Penultimate set, updated 22 Nov,
2006. Changes in red. This is the final draft.
1. 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 on 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 sex? Contrast the primary ecological theories for the maintenance
of cross-fertilization in the face of this cost.
5. How is the lottery model related to selection on the size-number compromise in
variable environments?
6. How is the tangled bank model conceptually related to the Hawk-Dove game?
7. Contrast hard selection and soft selection. How do they relate to the different theories
for cross-fertilization?
8. How is the Red Queen model conceptually related to the Rock Paper Scissors game?
Why could host-parasite coevolution select for recombination.
9. What is linkage disequilibrium (give a verbal and mathematical description). Under
what conditions does natural selection generate linkage disequilibrium?
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. Give an example of meiotic drive. How did meiotic drive figure into female choice
of males in the stalk-eyed flies of Malaysia? From the Beeman et al paper: describe the
action of the MEDEA gene.
17. What is Hamilton’s rule?
17. 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”?
18. 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?
29. Write your own question on aspects of the material covered in this section of the
course, and answer it.
20. What was the conceptual gist of the Zeh & Zeh paper on intergenomic conflicts and
speciation rates in viviparous organisms?
21. What was the conceptual gist of the Schemske and Bradshaw paper on the genetics
of adaptation? What was the point of making F2 hybrids and placing them into the field?
What was the evidence for or against the effects of major gene action?
What was the conceptual gist of the Nature paper on flycatchers? Why was having a
phylogeny important to the argument? Was there selection against hybrids between the
two species in sympatry?
What was the conceptual gist of McPhail’s idea on the evolution of character
displacement in stickleback fish (see overheads from 21 Nov. 06).
22. What in your view are the most general statements that can be made about
speciation? How does speciation work? What kinds of organism- (or clade-) specific
characteristics affect the rates of speciation and extinction?
23. 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?
23.5. 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?
24. 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.
25. 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?
26. 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?
27. Is there selection for speciation?
29. What is meant by "macroevolution"? Give an example of how selection on lifehistory could effect marcoevolution (hint: the Jablonski example).
30. 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.
31. Describe the Price equation. Why is it considered to be so general. How can it be
related to kin selection? The breeders equation? And Fisher’s Fundamental Theorem?
32. Describe Taylor and Frank’s method for studying kin selection. How was
relatedness derived?