. Gradualism is an importantassumption of evolutionary theory.

A. A complexstructure like the eye would be unlikely to emerge from a singlelarge-scale mutation. How does gradualism help evolutionistsaddress the evolution of complex adaptations, such as the eye?

B. How do ringspecies support a gradualist model of speciation? Explain.

     

2. Use the comparative methodto answer the following questions about selection and adaptation,discussed Chapter 8.

A. What areconvergent evolution and divergent evolution?

B. Why wouldselection ever delete a trait after having built it? Explain howcave-dwelling species lost the eyes that had evolved in theirancestors.

C. Why are disablingmutations in an olfactory receptor gene more likely to be“tolerated” by selection in a species with full trichromatic visionthan in species without it?

D. Do you seeparallels between increased loss of olfactory genes in species withtrichromatic vision and the evolution of eyelessness incave-dwelling species? Explain.

3. Altruistic traits, by definition, harm the individualmanifesting the trait and help others.

A. What doesHamilton’s Rule say about the conditions under which kin selectionshould favor altruism?

B. In the woodpeckernest-helper example from class, explain how it can be in theevolutionary interests of a young bird to help their mother orsister breed when there are not enough nest holes to breed on theirown.

C. Even when thereare nest holes available, young birds sometimes help their mothersbreed instead. How do “Selfish Genes” explain the evolution ofbehavior that is not in the interests of the individual (notfacultative altruism).

     

D. In the case ofreciprocal altruism, explain how reciprocity can maintain altruismeven without close genetic relatedness.