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Ecological selection against hybrids in natural populations of sympatric threespine sticklebacks.

Gow, Jennifer L and Peichel, Catherine L and Taylor, Eric B (2007) Ecological selection against hybrids in natural populations of sympatric threespine sticklebacks. Journal of evolutionary biology, 20 (6). pp. 2173-2180. ISSN 1010-061X

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Experimental work has provided evidence for extrinsic post-zygotic isolation, a phenomenon unique to ecological speciation. The role that ecological components to reduced hybrid fitness play in promoting speciation and maintaining species integrity in the wild, however, is not as well understood. We addressed this problem by testing for selection against naturally occurring hybrids in two sympatric species pairs of benthic and limnetic threespine sticklebacks (Gasterosteus aculeatus). If post-zygotic isolation is a significant reproductive barrier, the relative frequency of hybrids within a population should decline significantly across the life-cycle. Such a trend in a natural population would give independent support to experimental evidence for extrinsic, rather than intrinsic, post-zygotic isolation in this system. Indeed, tracing mean individual hybridity (genetic intermediateness) across three life-history stages spanning four generations revealed just such a decline. This provides compelling evidence that extrinsic selection plays an important role in maintaining species divergence and supports a role for ecological speciation in sticklebacks.

Item Type: Article or Abstract
Additional Information: The definitive version is available at For additional information on Author Rights, please visit:
DOI: 10.1111/j.1420-9101.2007.01427.x
PubMed ID: 17887972
Keywords or MeSH Headings: Animals; Ecosystem; Genetic Speciation; Hybridization, Genetic; Microsatellite Repeats; Smegmamorpha/genetics/physiology; Species Specificity;
Subjects: Cellular and Organismal Processes > Evolution
Organisms > Model organisms
Depositing User: Library Staff
Date Deposited: 29 Sep 2008 23:12
Last Modified: 14 Feb 2012 14:42

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