Allopatric speciation

Allopatric speciation (also: allopatric speciation or speciation by spatial separation) is one of the main causes of speciation. It can occur when the distribution range of a species is split by external processes such as mountain building, continental drift, climate change or exclusion of competition in two or more parts.

The sub-populations then are not subject to the exact same selection factors and the respective associated selection pressures are different. Thus, they are increasingly independently on the basis of geographical isolation in the separate parts of the range. If the genetic differences so great that the individuals of the two regional stocks can no longer mate, the original species has allopatric split into two or more new species.

As allopatry is called in biology, the non- overlapping ( the complete spatial separation ) of the distribution areas of species, subspecies or populations. In allopatric distribution (separation ) is excluded an encounter and crossing in the wild by geographic isolation. If the distribution areas are immediately adjacent to but not overlapping, then one speaks of parapatrischer distribution. The allopatric also referred to the overlap freedom of habitats of different species or groups.

The contrast to the allopatric represents the sympatry, occur in the closely related species, subspecies or populations in the same geographical area and thus the opportunity to meet and cross there.

An important practice in the special case of allopatric speciation occurs when speciation is due to the isolation of a very small part of the population, such as on an island, of a much larger parent population. In such small populations, it is easier by the founder effect and genetic drift through a rapid shift feature. The emergence of new species under such conditions probably much easier.