Sexual Selection Study Guide

Chapter 11 Know homework answers and online quiz answers.

1. What is sexual dimorphism? Give several real examples.
2. What is sexual selection? How is it related to natural selection?
3. In mammals, do females or males usually invest more resources in each individual offspring?
4. Relate relative investment in offspring to predictions about whether resources or mates limits reproductive success
5. What did Bateman’s experiments with fruit flies (p. 377) demonstrate about limits to reproductive success for males and females? Relate this to the data for sea elephants.
6. Define and distinguish intersexual selection and intrasexual selection. Relate these to “male-male competition” and to “female choice”.
7. Under what conditions do we expect male-male competition?
8. Discuss pre-copulatory and post-copulatory forms of male-male competition.
9. Describe the experimental (yellow dung flies) and comparative evidence that sperm competition causes evolution of larger testes size.
10. What kind of sexual selection are alternative mating strategies?
11. Describe the alternative male mating strategies in fence lizards. How is it related to frequency dependent selection?
12. Give some other examples of alternative mating strategy.
13. Can pre-existing sensory bias lead to sexual selection?
14. Regarding the Galapagos iguanas: What data suggests that male body size is larger than that favored by natural selection? What data suggest that sexual selection is responsible for this larger body size? What is the main form of male-male competition illustrated by Galapagos marine iguanas? How do they monopolize females? What is a second form that occurs in these iguanas? Provide an evolutionary explanation for the size of male and female iguanas.
15. Describe in detail how female choice was demonstrated for barn swallows, gray tree frogs, and sticklebacks (from Reusch paper).
16. What are four hypotheses for what females are choosing when they choose males?
17. What is the evidence that suggests that female barn swallows are choosing males for their good genes? Do female grey tree frogs choose genetically superior males? How do we know (describe the experiment)>
18. What is "runaway sexual selection"?
19. Why do female pipefish compete for males & why are male pipefish choosy about which females they mate with? What is unusual about this example?
20. Consider the fact that female grey tree frogs choose males based on call, and female barn swallows choose males based on plumage appearance/tail length, but that both appear to be getting genetically superior males. What does this suggest about the relationship between good genes and the characters females choose?
21. What is the Hamilton-Zuk hypothesis?
22. Do female sticklebacks choose MHC allele number of MHC genotypes that are dissimilar from their own? What hypotheses were tested by testing each of these two ideas?

Chapter 10.4

What is the comparative method?
Why is it important to account for phylogenetic relatedness when employing the comparative method?
What is the rationale for using the comparative method to infer the action of natural selection?