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Allopatric speciation (from Ancient Greek ἄλλος (állos) 'other' and πατρίς (patrís) 'fatherland') – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model [1]: 86 – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.
In peripatric speciation, a subform of allopatric speciation, new species are formed in isolated, smaller peripheral populations that are prevented from exchanging genes with the main population. It is related to the concept of a founder effect, since small populations often undergo bottlenecks. Genetic drift is often proposed to play a ...
River barrier speciation occurs when a river is of sufficient size to provide a vicariance for allopatric speciation, or when the river is large enough to prevent or interfere with a genetic exchange between populations. Population division is initiated either when a river shifts into or forms within the range of a species that cannot cross it ...
A simplification of an allopatric speciation experiment where two lines of fruit flies are raised on maltose and starch media. Laboratory experiments of speciation have been conducted for all four modes of speciation: allopatric, peripatric, parapatric, and sympatric; and various other processes involving speciation: hybridization, reinforcement, founder effects, among others.
[1]: 189 A classic example of habitat isolation occurring in allopatry is that of host-specific cospeciation [1]: 189 such as in the pocket gophers and their host chewing lice [24] or in the fig wasp-fig tree relationship and the yucca-yucca moth relationship—examples of ecological speciation caused by pollinator isolation.
[1] [2] Starting with a single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different morphological and physiological traits. The prototypical example of adaptive radiation is finch speciation on the Galapagos ("Darwin's finches"), but examples are known from around the world.
This is called allopatric speciation and is generally a slow process. [4] On the contrary, sympatric speciation can be more rapid when a species has multiple small demes. [5] This rapid speciation is both observed in plants [6] and vertebrates. [5] Rapid speciation is explained by the ecology and social structure of demes.
Allopatric populations isolated from one another by geographical factors (e.g., mountain ranges or bodies of water) may experience genetic—and, ultimately, phenotypic—changes in response to their varying environments. These may drive allopatric speciation, which is arguably the dominant mode of speciation. [citation needed]