Problem Set # 4 Comparative method, altruism, and heritability,
1. Let me suggest an idea about the adaptive function of sleep: It did not originally evolve for rest and repair (though those functions may have been layered on later, at least in some species). Instead, I’ll propose that its primary function is to keep the organism out of harm’s way during phases to which it is poorly adapted. For example, day and night can differ dramatically in lighting, temperature, humidity, abundance and type of predators and prey, etc., so an organism that was well adapted to one set of conditions would be relatively poorly adapted to the other. According to this hypothesis, sleep helps organisms avoid temporal regions of lower fitness.
A. How might you use reverse engineering to test this hypothesis?
B. How might you use planned comparisons to test this hypothesis?
2. In Module 9 we asked whether there was any way that the receivers of altruism might cause the altruist’s genes to spread—since the altruist herself is, by definition, no doing so. That could happen if the altruist and the recipient tended to have the same genes.
A. In the model of group selection presented in Module 9, who benefits from an altruist’s generosity?
B. In that model, then, do altruist and recipient tend to have the same genes?
C. How does the model of kin selection (module 10) solve this problem?
D. Is altruism more likely to evolve by group selection or kin selection; how do your answers to 2A-C support this conclusion?
E. Does the model of reciprocity depend on shared genes between the altruist and the recipient?
F. How does reciprocity maintain altruistic genes in the population?
3. Remember that heritability (h2) = Vg / (Vg + Ve).
A. OK, in words, what is heritability?
B. Environmentality (e2) is the mathematical complement of heritability, that is:
[e2 = 1-h2]. So, in words, what is environmentality?
C. Let’s think about a locus (call it the “pair-bonding”