Parapatric speciation
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Parapatric speciation is a form of speciation in which the evolution of reproductive isolating mechanisms occurs when a population enters a new niche or habitat within the range of the parent species. Generally, this occurs when there has been a drastic change to the environment within the original species' habitat. An example of this is the grass Anthoxanthum, which has been known to undergo parapatric speciation in such cases as mine contamination of an area.[1][2] Selection for resistance/tolerance to certain metals occurs. 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.
In parapatric speciation there is no specific extrinsic barrier to gene flow. The population is continuous, but nonetheless, the population does not mate randomly. Individuals are more likely to mate with their geographic neighbors than with individuals in a different part of the population’s range. In this mode, divergence may happen because of reduced gene flow within the population and varying selection pressures across the population’s range.
[edit] References
- ^ "Parapatric speciation." in Understanding Evolution at evolution.berkeley.edu
- ^ "Evolution in closely adjacent plant populations X: long-term persistence of prereproductive isolation at a mine boundary." Heredity. 2006 Jul;97(1):33-7. Epub 2006 Apr 26. Abstract.
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Speciation guide
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| Basic concepts: species | chronospecies | speciation | cline |
| Modes of speciation: allopatric | peripatric | parapatric | sympatric | polyploidy | paleopolyploidy |
| Auxiliary mechanisms: sexual selection | assortative mating | punctuated equilibrium |
| Intermediate stages: hybrid | Haldane's rule | ring species |
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