Which of the following occurs with disruptive selection a Na

Which of the following occurs with disruptive selection

a. Natural selection favors phenotypes of one extreme, resulting in a population mean shift over several generations

b. Natural selection favors phenotypes of both extremes, resulting in an increase in intermediate phenotypes over time

c. Natural selection favors phenotype values near the population mean, resulting in no shift in mean trait value over time and a more narrow bell curve

d. Natural selection selects against trait values that are close to the population mean, resulting in a bimodal distribution of trait values

Solution

Disruptive selection happens when conditions favor individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes. one example is a population of black-bellied seedcracker finches in Cameroon whose members show two distinctly different beak sizes. small-billed birds feed generally on soft seeds, whereas large-billed birds specialize in cracking hard seeds. it seems that birds with intermediate-sized bills are comparatively inefficient at cracking both types of seeds and thus have lower relative fitness.