geographic range limit

Studies of the genetic influences on geographic range limits tend to focus on genetic effects that restrict peripheral populations from expanding beyond their range edge.

A geographic range limit is the geographic boundary beyond which a species does not occur, the limit or limits of the range of a species.

For many species of invertebrate animals, the exact geographic range limits have never been precisely ascertained, because not enough scientific field work has been carried in many parts of the world to map distribution more precisely, therefore finding a range extension for species, especially marine species, is not an uncommon occurrence.