Something Fishy in Speciation

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Science  05 Oct 2007:
Vol. 318, Issue 5847, pp. 19-21
DOI: 10.1126/science.318.5847.19d

Adaptation to environmental conditions is believed to drive population divergence and hence demonstrates the predictability of evolutionary change. By investigating the morphology, genetic divergence, and mate choice of Bahamas mosquitofish, which live in isolated pools, Langerhans et al. demonstrate parallel speciation events among pools, in which the presence or absence of a fish predator appears to be driving speciation. In pools with strong predation, mosquitofish have evolved a morphology conducive to high-speed escape swimming. Haplotype and allozyme analyses show that these morphological changes in response to predation have occurred multiple times. As these fish prefer to mate with similar individuals, the presence or absence of a predator drives speciation through mate selection. Taken all together, this set of results shows a direct link between natural selection and speciation: The traits under divergent selection between environments are the same traits used in mate choice, resulting in reproductive isolation between populations inhabiting different environments. — LMZ

Evolution 61, 2056 (2007).

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