Sympatry

Sympatry 

a type of species formation in which new species arise from populations with strongly overlapping or coinciding home ranges. Sympatry is only possible when two forms coexisting within the limits of a common home range or in part of a home range do not interbreed. The opposite case, allopatry, is species formation from populations with nonoverlapping areas. As a rule, allopatry is characteristic of all intraspecific groups; exceptions appear to be seasonal varieties of certain plants and winter and spring strains of many fishes having a common reproduction range, although it is used at different times.

Sympatry is only possible for forms that cannot interbreed, that is, in the case of any type of biological isolation. The concepts “sympatry” and “allopatry” are widely used in the analysis of species-formation processes. The existence of sympatric species often results from allopatric species formation and the subsequent settlement of the home range of one species by individuals of another species. Transitional stages between sympatry and allopatry also exist.

REFERENCES

Timofeev-Resovskii, N. V., A. V. Iablokov, and N. V. Glotov. Ocherk ucheniia opopuliatsii. Moscow, 1973.
Mayr, E. Populiatsii, vidy i evoliutsiia. Moscow, 1974. (Translated from English.)