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Selection against hybrids can sometimes (it is possible that nonecological speciation can be attributed) be considered a form of ecological isolation if it originates from an ecological mechanism. [4] For example, the hybrid offspring may be seen as "less attractive" to mates due to intermediate sexual displays or differences in sexual ...
This ecological isolation by distance, according to Wright, can create genetic differentiation among subpopulations, leading to evolutionary change. Individuals within the subpopulation are neighbors in the sense that their gametes may come together and inbreeding within the subpopulation increases homozygosity.
The types of barriers that can cause this isolation include: different habitats, physical barriers, and a difference in the time of sexual maturity or flowering. [6] [7] An example of the ecological or habitat differences that impede the meeting of potential pairs occurs in two fish species of the family Gasterosteidae (sticklebacks).
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.
For example, differential fusion implies greater postzygotic isolation among sympatric species, as this functions to prevent fusion between the species. However, Coyne and Orr found equal levels of postzygotic isolation among sympatric and allopatric species pairs in closely related Drosophila. [8]
Allochronic speciation (also known as allochronic isolation, or temporal isolation) is a form of speciation (specifically ecological speciation) arising from reproductive isolation that occurs due to a change in breeding time that reduces or eliminates gene flow between two populations of a species.
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Their evolution is cited as an example of both natural and sexual selection. [40] [41] A 2008 study suggests that sympatric speciation has occurred in Tennessee cave salamanders. [42] Sympatric speciation driven by ecological factors may also account for the extraordinary diversity of crustaceans living in the depths of Siberia's Lake Baikal. [43]