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 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 directional; the curve would shift to the left stabilizing; the curve would become taller in the middle and shorter on each side

Answer 1

The type of selection described in your question is directional selection. This occurs when one extreme phenotype is favored over other phenotypes, leading to a shift in the population's traits over time.

As Earth moved out of an ice age and temperatures began to rise, the sizes of black bears would likely decrease, favoring smaller bears. Thus, the distribution curve of black bear size would shift to the right (indicating a greater representation of smaller sizes). Therefore, the correct response would be:

Directional; the curve would shift to the right.