Question

What effect does each type of selection have on the mean and variance of the trait in the next generation if it is disruptive?

a) Increases mean, decreases variance
b) Increases mean, increases variance
c) Decreases mean, decreases variance
d) Decreases mean, increases variance

Answer 1

Disruptive selection increases genetic variance in a population by favoring extreme phenotypes over the intermediate, which results in more diverse traits at either end of the distribution curve.

Step-by-step explanation:

The disruptive selection, also referred to as diversifying selection, creates an increase in genetic variance because it favors the extremes of the trait distribution while selecting against the average phenotypes. As a result, this type of natural selection leads to a scenario where if it is disruptive, it would increase the variance within the population because there are two or more favored phenotypes, one at each end of the trait distribution curve.

Contrary to disruptive selection, stabilizing selection would decrease the variance within a population because it favors the average phenotypes and selects against the extreme phenotypes. In the case of directional selection, one extreme is favored over the other, leading to a shift in the mean towards the favored extreme, which may not necessarily increase variance.