loss of rare alleles in a population as a result of repeated mating of individuals possessing these alleles with wild-type individuals.

classification of organisms based on levels of evolutionary advancement.

an ordering of groups in which larger groups encompass sets of smaller groups.

formation of new diploid species from hybrids between existing species.

in a hybrid F2 generation, the formation of individuals with features surpassing those of the parental species.

rapid speciation and diversification of a group into unoccupied ecological niches.

production by plants of seeds in which the embryo is derived (without fertilization) from diploid cells of the parent.

the replacement at a genetic locus of one allele by another as a result of mutation or recombination; the basic process of genetic change in a population.

change in a measurable aspect of an organism (such as shape) with increase or decrease in size.

the condition of two organisms or groups of organisms inhabiting different places.