Question

A population of hummingbirds feeds exclusively on nectar from orchids. Two species of orchids exist in the hummingbirds' habitat. One orchid species has long tubes to store nectar while the other has short tubes to store nectar. The hummingbirds have a range of beak lengths, and the beak length determines which nectar tube an individual can feed from. This population of hummingbirds is splitting into two phenotypic groups.

What scenario best explains why the population is diverging?

A. Hummingbirds with intermediate beak lengths can feed from both species of orchid, but the individuals with the shortest and longest beaks can each only feed from one species.

B. Hummingbirds with short beaks only mate with individuals who have long beaks, ignoring individuals with intermediate and short beaks.

C. Hummingbirds with the longest beaks are better adapted to the environment compared to hummingbirds with short and intermediate length beaks.

D. Hummingbirds with shorter or longer beaks can feed from one of the available orchids, but hummingbirds with intermediate beak lengths cannot feed from either.

Answer 1

Most likely, the correct answer is:

D. Hummingbirds with shorter or longer beaks can feed from one of the available orchids, but hummingbirds with intermediate beak lengths cannot feed from either.

The length of a hummingbird's beak vary depending on its food, but it is usually longer than hummingbirds' bodies. The length is useful for reaching deep into blossoms to lap up nectar.

Answer 2

Answer: D.

Natural selection is the differential survival and reproduction of individuals because of the differences in the phenotypic characteristics. It supports the fact that those organisms, which have phenotypic characteristic favorable to survive in the changing environment as compared to other organisms, and these traits will also be passed to the successive generations.

In the given situation, the hummingbirds those have adapted according to the needs, that is deriving nectar from either from short and long tubes nectar. Therefore, two phenotypic characteristics like short beak and long beaks will become dominant trait in the population of humingbirds as the intermediate beak hummingbirds will not be able to feed from either of the flowers.

Therefore, option D. Hummingbirds with shorter or longer beaks can feed from one of the available orchids, but hummingbirds with intermediate beak lengths cannot feed from either is correct.