Parapatric speciation

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Parapatric speciation is a form of speciation that occurs due to variations in mating frequency of a population within a continuous geographical area.

In this model, the parent species lives in a continuous habitat, in contrast with allopatric speciation where subpopulations become geographically isolated.

Niches in this habitat can differ along a environmental gradient, hampering gene flow, and thus creating a cline.

An example^[1] of this is the grass Anthoxanthum, which has been known to undergo parapatric speciation in such cases as mine contamination of an area. This creates a selection pressure for tolerance to those metals. Flowering time generally changes (in an attempt at character displacement—strong selection against interbreeding—as the hybrids are generally ill-suited to the environment) and often plants will become self-pollinating.

Another example is ring species.

See also

• Adaptive radiation
• Cladistics
• Evolutionary radiation
• Phylogenetics
• Taxonomy

References

1. ^ "Evolution in closely adjacent plant populations X: long-term persistence of pre-reproductive isolation at a mine boundary." Heredity. 2006 Jul;97(1):33-7. Epub 2006 Apr 26. Abstract.

"Parapatric speciation." in Understanding Evolution at evolution.berkeley.edu