Two different species of three-spined stickleback fish have been found together in each of five different lakes.Within the same lakes, the larger bottom-dwelling species with a large mouth feeds on large prey close to shore.A smaller surface-dwelling species feeds on small plankton in open water.DNA analysis shows that the two species in each lake are more closely related to each other than they are to any of the other species in the lakes.However, they are reproductively isolated.The habitat specialization of these species is consistent with which prezygotic mechanism that can lead to speciation?
A) Temporal isolation
B) Habitat isolation
C) Mechanical isolation
D) Behavioral isolation
E) Gametic isolation

Question

Quizplus · Accepted Answer

The fact that the two species have different habitats and feed on different types of prey suggest that they have evolved through habitat isolation, which is a prezygotic mechanism of speciation. This means that they are isolated by differences in their ecological niches and are unlikely to mate because they occupy different habitats. This ultimately leads to the evolution of reproductive isolation, as seen in these stickleback fish.

Two Different Species of Three-Spined Stickleback Fish Have Been Found