Question

In 1977, before the drought on Daphne major, the average beak depth in the finch population was 9.2mm. Breeding parents that survived the drought had an average beak depth of 9.7mm. The difference between these values represents:

A. the response to selection (R)
B. the selection differential (S)
C. heritability
D. the mutation rate

Answer 1

The 0.5mm increase in average beak depth in finches from Daphne Major after a drought represents the response to selection (R), illustrating evolution by natural selection.

Step-by-step explanation:

The difference between the average beak depth in the finch population on Daphne Major before the drought (9.2mm) and the average beak depth of the breeding parents that survived the drought (9.7mm), which is 0.5mm, represents the response to selection (R).

This is because the increase in average beak depth is a result of the differential survival and reproduction of finches with larger beaks due to the selective pressure of the drought, which favored finches that could eat the larger and harder seeds that were more abundant. This evolutionary change in beak size exemplifies evolution by natural selection, which is the underlying mechanism that drives changes in traits within a population over time.