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Ecological speciation can occur pre-zygotically (barriers to reproduction that occur before the formation of a zygote) or post-zygotically (barriers to reproduction that occur after the formation of a zygote). Examples of pre-zygotic isolation include habitat isolation, isolation via pollinator-pollination systems, and
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 ...
There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric. Whether genetic drift is a minor or major contributor to speciation is the subject of much ongoing discussion.
allopatric speciation. Also called geographic speciation, vicariance, vicariant speciation, and dichopatric speciation. A mode of speciation where the evolution of reproductive isolation is caused by the geographic separation of two or more populations of a single species. [5] allopatric taxa Specific species that are allopatrically distributed ...
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).
In ecotypes, it is common for continuous, gradual geographic variation to impose analogous phenotypic and genetic variation, a situation which leads to the emergence of clines. [1] A well-known example of a cline is the skin color gradation in indigenous human populations worldwide, which is related to latitude and amounts of sunlight.
Examples of speciation affecting gene flow. When gene flow is blocked by physical barriers, this results in Allopatric speciation or a geographical isolation that does not allow populations of the same species to exchange genetic material. Physical barriers to gene flow are usually, but not always, natural.
Allopatric speciation, in which two populations of the same species are geographically isolated from one another by an extrinsic barrier and evolve intrinsic (genetic) reproductive isolation. Peripatric speciation, in which a small group of a population is separated from the main body and experiences genetic drift.