Question

In a given area, insects live by making burrows in the bark of a tree. These insects are fed upon by a population of birds in the same area. The most correct explanation for the increase in the beak size of the bird population is
A. Increased fitness of the birds, leading to speciation.
B. Decreased fitness of the insects, allowing the birds to catch them more easily.
C. Increased fitness of large-beaked birds, leading to evolution.
D. Decreased fitness of small-beaked birds, leading to speciation.
E. Random mutation and genetic recombination.

Answer 1

Hint: Evolution occurs over a period of time in a generation of species that can benefit from the genetic mutation occurred over the generation of time and this is passed on in heredity.

Complete answer: In a population of insects that live by making burrows in the bark of a tree. They feed upon the birds if the size of the beak increases, this is only possible because of natural selection which leads to evolution in the bird species.
Option A: Increased fitness of the birds, leading to speciation does not indicate exactly if the beak size of the birds is increased or not and the increase in the beak of the birds does not mean that it leads to formation of new species.
Option B: Decreased fitness of the insects, allowing the birds to catch them more easily does not say that the size of the beak in the birds is increased, rather comments on the size of the insects, so this option is rejected.
Option C: Increased fitness of large-beaked birds, leading to evolution is a plausible explanation to the question as during the course of a generation, natural selection would have happened that lead to the evolution that benefited the birds. Thus, the increase in the beak size of birds will allow it to capture the insects that reside in the burrow of the bark of the tree.
Option D: Decreased fitness of small-beaked birds, leading to speciation does not fit the explanation in the question as there was no decrease in the fitness of birds or speciation.
Option E: Random mutation and genetic recombination does not hold true here as it is the result of natural selection.
Hence, the correct answer is option (C).

Note: The Hardy-Weinberg principle holds true only if there is no natural selection, no migration, random mating, no mutation in a large population that gives no change in the allelic and genotypic frequency.