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
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
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
Skip to navigation
1 answer
This scenario describes directional selection because the size of black bears shifts consistently in one direction (larger during ice ages and smaller during warmer periods). As Earth moves out of an ice age, the trend observed would be a shift toward smaller sizes, indicating that the selection is favoring smaller black bears during warmer periods.
Therefore, the correct response is:
directional; the curve would shift to the left
