Question

Along the length of a river there exists a species of green sunfish. In order to provide electricity to area homes, a hydroelectric dam is built that separates the lower river area from a newly formed lake above. After many, many years, the green sunfish in the river and lake are sampled and found to be phenotypically very different. Which of the scenarios listed below is the best hypothesis to explain the microevolutionary changes observed?

A. directional selection
B. disruptive selection
C. stabilizing selection
D. sexual selection.

Answer 1

A. directional selection

Step-by-step explanation:

In population genetics, directional selection also called as positive selection. In this type of natural selection extreme phenotype is preferred over other existing phenotype. This preference case shift in allele frequency over time in the direction of preferred phenotype.