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)
The type of selection being observed here is called directional selection. During warmer periods between ice ages, the selection favors smaller black bears, while during ice ages, the selection favors larger black bears.
As Earth moved out of an ice age and entered a warmer period, the distribution curve of black bear size on a graph would shift towards smaller sizes. This means that there would be a decrease in the frequency of larger black bears and an increase in the frequency of smaller black bears. The mean or average size of black bears in the population would also decrease.