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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 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
directional; the curve would shift to the right
1 answer
The observed changes in the sizes of black bears based on environmental conditions describe a pattern of directional selection. During warmer periods, smaller bears prevailed, while larger bears were more common during ice ages.
As Earth moved out of an ice age, you would expect the size of black bears to decrease, leading the distribution of bear sizes to shift towards smaller sizes on a graph. Therefore, the correct response is:
directional; the curve would shift to the left.
