Allopatric speciation is a mode of speciation in which populations of a species become geographically separated to a degree that prevents or interferes with gene flow between them. Once a physical barrier divides a population, the two groups accumulate different mutations and face different selective pressures, and over time this isolation leads to reproductive isolation, so that even if the groups later come back into contact they can no longer interbreed and are recognized as separate species. The snapping shrimp genus Alpheus is a well documented example: phylogenetic studies support fifteen pairs of sister species split across the Isthmus of Panama, whose closure roughly 2.7 to 3.5 million years ago separated Pacific and Caribbean populations that then evolved independently into distinct species. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/
Facts
PeriodicityNot a recurring or periodic event: an ongoing process that plays out over many generations after a geographic separation arises, with no fixed interval or seasonal timing. 1 ScaleOperates at the scale of whole populations separated by geographic barriers as large as continents, mountain ranges and oceans, or as small as a single dispersing group reaching an isolated island. 1 First DescribedThe name and concept draw on Ancient Greek roots for other and fatherland, and the process is also called geographic speciation, vicariant speciation, and, by its earlier name, the dumbbell model. 1 Identification
Distinguishing AppearanceMarked by two populations of the same ancestral species becoming separated by a geographic barrier, then diverging under different selective pressures until, if they meet again, they can no longer interbreed successfully. 1 Connections
Associated With
Source Adaptive radiation (Wikipedia)
Sources
1. Allopatric speciation (Wikipedia)
Lead section, second paragraph, on geographic barriers
Various geographic changes can arise such as the movement of continents, and the formation of mountains, islands, bodies of water, or glaciers.
Lead section, first paragraph, on etymology and alternate names
Its name comes from Ancient Greek ἄλλος (állos) 'other' and πατρίς (patrís) 'fatherland', and is also called geographic speciation, vicariant speciation, and its earlier name the dumbbell model.
Lead section, third paragraph, on reproductive isolation on contact
If the two populations come into contact they will be unable to reproduce-effectively speciating.
Quote
Allopatric speciation 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.
View the SourceAdaptive radiation (Wikipedia)
Wikimedia FoundationAssociated With: Adaptive Radiation, Examples section, Darwin's finches, on the mechanism of initial diversificationQuote, Associated With: Adaptive Radiation, Examples section, Darwin's finches, on the mechanism of initial diversification
One proposition is that the finches were able to have a non-adaptive, allopatric speciation event on separate islands in the archipelago, such that when they reconverged on some islands, they were able to maintain reproductive isolation.
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