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

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

directional; the curve would shift to the left
directional; the curve would shift to the left

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

Answer 1

directional; the curve would shift to the right

As Earth moved out of an ice age, the selection pressure favoring large black bears would decrease, causing the distribution curve of black bear sizes to shift towards smaller sizes. This is an example of directional selection where one extreme trait becomes less favorable.