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

• directional; the curve would shift to the right
O 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
• directional; the curve would shift to the left

Answer 1

The type of selection observed in this scenario is directional selection. During warm periods, most black bears were smaller, indicating a shift in the average size towards smaller bears. Conversely, during ice ages, the average size shifted towards larger bears.

As Earth moved out of an ice age, the distribution curve of black bear size would likely shift to the right, indicating an increase in the prevalence of larger bears as the environment warmed. Therefore, the correct choice is:

• directional; the curve would shift to the right.