Sympatry

Sympatry is the partial or complete overlap of the geographic distribution of one population or species by that of another, an important phenomenon in objectively establishing whether two populations are specifically distinct. Populations must be considered separate species if their natural distributions are sympatric. Sympatry normally indicates absence of or adjustment to interspecific competition, but a recent colonizer may not have achieved such equilibrium. High levels of sympatry characterize areas that retained a habitat which disappeared adjacently, usually through climate change.