A geographically distinct race. See subspecies. Populations of the same species that occupy part of a common range and are taxonomically distinct. Formed by adaptation of populations to local geographic conditions. Geographic race is close to ecological race. Geographic race variability exists in the population systems of many fish species. However, because integration is gradual, the boundary between races is rather arbitrary, so that the assignment of a given population to one race or another is also more or less arbitrary. A distinction is usually made between local and geographical races. The former are characterised by relatively small shifts in the frequencies of polymorphic variants; the latter represent regional clusters of local races that differ significantly in their gene pools.