Geographic isolation: Isolation due to geographic factors (e.g.Hybrid: An offspring that is heterozygous for one or more gene pairs.Postzygotic barriers: Mechanisms that prevent the development of a zygote into a fertile adult offspring.Isolation: The separation of some members of a population from the rest of their species prevents interbreeding and may lead to the development of a new species.Prezygotic barriers: Mechanisms that prevent the formation of a zygote, leading to reproductive isolation.Biological species concept (BSC): Definition of a species as a naturally interbreeding population of organisms that produce viable, fertile offspring.Gene flow: The process of moving genes between populations as a result of the movement of individual organisms.Genetic drift: Random evolutionary changes in the genetic makeup of a (usually small) population.Selective advantages: Characteristics that are good for survival and/or mating.A population is at Hardy-Weinberg equilibrium for a gene if five conditions are met. Selective disadvantages: Characteristics that are bad for survival and/or mating AP Biology practice test that required this calculation.Sexual selection: Selection driven by the competition for mates, in relation to natural selection.Natural selection: Process by which organisms best adapted to their environment survive to pass their genes on through offspring idea pioneered by Charles Darwin.These conditions rarely (if ever) occur together. Hardy-Weinberg equilibrium occurs when genetic distribution remains constant in large, isolated, randomly mating populations with no mutation and no natural selection.Evidence for evolution comes from comparative anatomy (homologous and analogous structures), biogeography, embryology, the fossil record, biological classification, and molecular biology (relatives share DNA).

Parapatric speciation occurs with limited interbreeding between two groups. Sympatric speciation occurs when populations in the same environment adapt to fill different niches. In allopatric speciation, geographically separated populations develop into different species.Biological species concept: a species is a reproductively isolated population able to interbreed and produce fertile offspring.Evolution is shaped by a number of mechanisms, including selective pressures, sources of variation, and random effects, such as genetic drift.

Gene flow ap bio