AP BIOLOGY

Detailed explanation-1: -Natural selection acts on an organism’s phenotype, or observable features. Phenotype is often largely a product of genotype (the alleles, or gene versions, the organism carries).

Detailed explanation-2: -Natural selection acts on populations. Individuals do not evolve in genetic evolutionary terms. Individuals may mutate, but natural selection acts by shifting the characteristics of the population as a whole.

Detailed explanation-3: -Selection can only operate on the available genetic variation. A cheetah might run faster if it had “faster” alleles-but if faster alleles are not in the population from mutation or gene flow, evolution in this direction will not happen.

Detailed explanation-4: -Natural selection acts on the whole organism; the unit of selection is the individual. NS cannot act on individual alleles (genes). Natural selection acts on the phenotype, not the genotype. But it can cause changes in the genotype.

Detailed explanation-5: -Natural Selection Operates on Phenotype The traits that an individual expresses, its phenotype, are what will give that individual an advantage or disadvantage in the struggle to survive and reproduce. Natural selection operates on phenotype.