AP BIOLOGY

Detailed explanation-1: -To an evolutionary biologist, fitness simply means reproductive success and reflects how well an organism is adapted to its environment.

Detailed explanation-2: -Reproductive success is different from fitness in that individual success is not necessarily a determinant for adaptive strength of a genotype since the effects of chance and the environment have no influence on those specific genes.

Detailed explanation-3: -Fitness is a measure of reproductive success (how many offspring an organism leaves in the next generation, relative to others in the group). Natural selection can act on traits determined by alternative alleles of a single gene, or on polygenic traits (traits determined by many genes).

Detailed explanation-4: -Reproductive fitness reflects the ability of individuals to pass on their genes to subsequent generations. Fitness traits, also referred to as life-history traits, include measures of fertility and mortality and are complex phenotypes that are direct targets of Darwinian selection.