Consider the following scenario:
a species of ancestral short-legged shore birds exists. within the population in a given shoreline, there is a range of leg lengths, from a little bit shorter to a little bit longer than the average leg length. leg length is hereditary. high average annual temperatures resulted in shallow shoreline waters and restricted food supplies. competition for food among the birds increased. the birds with slightly longer legs could wade out into deeper water to find food. the longer-legged birds lived longer, were healthier, and therefore more chicks. the birds with the shortest legs did not survive.

it is many years in the future. the shoreline waters have remained shallow. what prediction would you make about the bird population in the area?

a) within the population, the average leg length has increased over time.
b) within the population, the range of leg length has remained constant over time.
c) according to darwin, variation exists so we would expect a variety of leg lengths in the population.
d) the increase in long-legged birds led to increased competition and the number of birds dropped dramatically.