A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of both competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true?
A) The amount of available food may have increased.
B) The parental generation of squirrels developed better eyesight due to improved diet; the subsequent squirrel generation inherited better eyesight.
C) The number of predators that prey upon squirrels may have decreased.
D) A and C could be true.
E) A, B, and C could be true.

Question

Quizplus · Accepted Answer

From the given information, it is clear that the survival rate of squirrels increased from 50% to 90% in a single generation, and the population increased to 80. This suggests that either the amount of available food may have increased or the number of predators that prey upon squirrels may have decreased, or both. Therefore, options A and C could be true. However, there is no evidence to support the idea that the parental generation of squirrels developed better eyesight due to improved diet, and the subsequent squirrel generation inherited better eyesight, so option B is not supported by the given information. Therefore, the answer is D.

A Biologist Studied a Population of Squirrels for 15 Years