Ch06 Discussion Questions

Ch06 Discussion Questions - Chapter 6 Behavioral...

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Chapter 6: Behavioral Adaptations for Survival 6.1 Many people think that an adaptation is a trait that improves the survival chances of an organism. Under what circumstances would such a trait be an adaptation? Under what other circumstances would a survival-enhancing attribute actually be selected against? A trait that improves the survival chances of individuals can be considered an adaptation only when it also improves their ability to produce offspring that survive to the age of independence. A survival-enhancing trait would be selected against if individuals with this attribute consistently had even slightly fewer surviving offspring than relatively short-lived individuals. 6.2 Stephen J. Gould and Richard Lewontin claimed that adaptationists make the elementary mistake of believing that every characteristic of living things is a perfected product of natural selection [463], when in reality many attributes of living things are not adaptations (see Table 6.1 in the textbook). Moreover, in their eagerness to explain everything as an adaptation, adaptationists have, according to Gould and Lewontin, invented fables as absurd as the fictional “just-so” stories of Rudyard Kipling, who made up amusingly silly explanations for the leopard’s spots and the camel’s hump. How might adaptationists defend themselves against these charges? Do adaptationists have the means to discover whether their tentative explanations for trait X are wrong? In science, there are always going to be incorrect, even silly, hypotheses advanced from time to time, although my reading of the animal behavior journals has turned up no truly absurd ones that have managed to get into print. Why not? Because a scientific hypothesis is intended to be tested, and, without a rigorous test, the hypothesis is very unlikely to be published. Interestingly, Gould and Lewontin picked on a handful of very minor papers, notes really, and they made these examples seem less plausible than they actually were. 6.3 For many evolutionary biologists, the term “adaptation” must be reserved for a characteristic that provides “current utility to the organism and [has] been generated historically through the action of natural selection for its current biological role” [74]. What could “current utility” mean, and what do you think it should mean? Make use of the terms “fitness benefits” and “fitness costs” in your answer. If a trait originated for function X and later took on a different, but still adaptive, biological role Y, does that mean it is not an adaptation? Track down the evolutionary history of the flight feathers on the wings of modern birds (see, for example, [982]). Where did these feathers come from, and what function did their predecessor feathers exhibit? If you go back far enough in time, will the ancestral form of any current trait have the same function that it does now? Current utility could mean a large number of things, ranging from survival-enhancing to
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This note was uploaded on 03/27/2008 for the course BIO 325 taught by Professor Chepko-sade during the Fall '06 term at Iowa State.

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Ch06 Discussion Questions - Chapter 6 Behavioral...

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