Question

Question

Paleontologists observed changes in the sizes of black bears as their environment changed. During warmer periods between ice ages, most black bears were small. During ice ages, most black bears were large. Which type of selection is this, and how would a graph of the distribution curve of black bear size change as Earth moved out of an ice age?(1 point)
Responses

directional; the curve would shift to the right
directional; the curve would shift to the right

stabilizing; the curve would become taller in the middle and shorter on each side
stabilizing; the curve would become taller in the middle and shorter on each side

disruptive; the curve would break into two peaks with a dip in the middle
disruptive; the curve would break into two peaks with a dip in the middle

directional; the curve would shift to the left

Answer 1

The situation described indicates that during warmer periods, smaller black bears were favored, while during ice ages, larger bears were favored. This points to a type of directional selection, where one extreme (either small or large) is favored over the other depending on the environmental conditions.

As Earth moved out of an ice age and into a warmer period, the population of black bears would likely show a shift towards smaller sizes. This means that the distribution curve for black bear sizes would shift to the left.

Therefore, the correct response is:

directional; the curve would shift to the left.