Question

Two populations of a species of frog live around the Gulf of Mexico. One population has a brown back and lives on rocky islands with brown rocks and little vegetation. A second population lives on the mainland among the vegetation and has a back that is speckled with greens and browns. This species is undergoing _______________ selection.

Answer 1

Answer:

Frog species are undergoing disruptive selection.

Explanation:

Natural selection is the result of the phenotype-environment interaction which determines gene destiny in space and time, selecting beneficial alleles and increasing their frequency in the population. There are different types of natural selection: sexual selection, stabilizing selection, directional selection, frequency-dependent selection, and disruptive selection.

Disruptive selection causes an increase in the two types of extreme phenotypes over the intermediate forms. Limits between one extreme and the other are frequently very sharped. Individuals belonging to one phenotype can not live in the same area as individuals belonging to the other phenotype, due to the traits differences between them, competition, predation, etcetera.

In the proposed case, each population of frogs is adapted to its environment: one of them is brow-backed as the color of the rocks it lives on, and the other population is speckled-backed as it lives among vegetation. These adaptations are probably related to survival strategies and help them to avoid predators as they camouflage with the substrate.

Both extreme phenotypes have been favored over intermediated forms, resulting in the develope of two groups with very marked differences.

Disruptive selection can lead to speciation, driving to evolution. This is why it is also called "diversifying selection".