Two species of three-spined stickleback fish have been found together in five different lakes.The larger bottom-dwelling species feeds on large prey close to shore.A 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.These two species are likely to have arisen due to
A) an adaptive radiation.
B) autopolyploidy.
C) allopolyploidy.
D) allopatric speciation.
E) sympatric speciation due to disruptive selection.

Question

Quizplus · Accepted Answer

Sympatric speciation due to disruptive selection is likely because the two species live in the same geographic area (sympatric) but have become reproductively isolated due to adapting to different ecological niches (disruptive selection), as indicated by their different feeding habits and habitats within the same lakes.

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