AP BIOLOGY

Detailed explanation-1: -Directional selection occurs when individuals at one end of the curve have higher fitness than individuals in the middle or at the other end.

Detailed explanation-2: -Explanation: With regard to evolution and natural selection, fitness refers only to the ability of an organism to contribute to the next generation of its species. In other words, if an organism has a large number of viable offspring, its fitness is high, regardless of other factors like strength, size, and longevity.

Detailed explanation-3: -Directional selection: One of the extreme phenotypes has the highest fitness.

Detailed explanation-4: -When environmental pressures favor the average form of the trait, selection is said to be stabilizing. Directional selection occurs when selection pressures favor one extreme of the trait distribution. Selection is disruptive when the average form of the trait is selected against while either extreme is unaffected.

Detailed explanation-5: -Stabilizing selection results in a decrease of a population ‘s genetic variance when natural selection favors an average phenotype and selects against extreme variations. In directional selection, a population’s genetic variance shifts toward a new phenotype when exposed to environmental changes.