Question

For which of the following studies would you recommend the use of Felsenstein's method of phylogenetically independent contrasts? Why?

a. A comparison of feather parasite burden and beak shape in different species of birds.
b. An experiment that tests whether birds whose beak shapes are experimentally altered will end up with greater parasite loads (similar to Clayton et al.'s study).
c. An observational study that measures the correlations among beak shape of individual birds with their preening behavior and with their parasite loads.

Answer 1

Felsenstein's method of phylogenetically independent contrasts (PICs) would be recommended for an observational study that measures the correlations among beak shape of individual birds with their preening behavior and with their parasite loads.

Step-by-step explanation:

Felsenstein's method of phylogenetically independent contrasts (PICs) would be recommended for study c. An observational study that measures the correlations among beak shape of individual birds with their preening behavior and with their parasite loads.

The PICs method is used to examine the relationships between traits while taking into account the evolutionary history of the species. In this study, the researchers want to measure the correlation between beak shape, preening behavior, and parasite loads. By using PICs, they can control for the effects of common ancestry and detect the independent evolutionary changes in beak shape that are related to these factors.

For example, suppose the researchers observe that birds with longer beaks tend to have higher parasite loads. Using Felsenstein's method, they can determine if this correlation is due to common ancestry or if it is a result of independent evolution. If it is found that the correlation is independent of common ancestry, it suggests that natural selection has acted on beak shape to reduce parasite loads.