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)

Question

Responses

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

directional; the curve would shift to the left

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

directional; the curve would shift to the right

Answer 1

The scenario described indicates a pattern of size variation in black bears in response to environmental changes, where the sizes shift from small to large based on the climate. The shift from a predominance of smaller bears in warmer periods to larger bears in ice ages suggests an adaptation to changing environmental pressures, which fits the concept of directional selection.

As Earth moved out of an ice age and transitioned to a warmer climate, the overall size of the black bear population would likely decrease, hence the distribution curve would shift toward the left, reflecting a predominance of smaller bears.

Therefore, the correct response is:

directional; the curve would shift to the left.