ECOLOGY/EVOLUTION

Sexual Selection and Speciation

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Science  10 Nov 2000:
Vol. 290, Issue 5494, pp. 1055
DOI: 10.1126/science.290.5494.1055a

One of the tantalizing and enduring questions in evolutionary biology is the process of sympatric speciation: how do populations living in the same place diverge sufficiently to form distinct species? In a study of a highly polymorphic cichlid, Amphilophus citrinellum, in Nicaraguan lakes, Wilson et al. look at the dynamics of species formation, especially the emergence of non-geographical isolating factors. A. citrinellum displays a variety of color morphs and jaw morphs, and exhibits assortative mating. Wilson et al. hypothesize that this should lead to decreased gene flow between populations of different morphs; analysis of DNA microsatellite loci and mitochondrial control region DNA reveals genetic differentiation between color morphs but not between jaw morphs. This result implies that sexual selection (by color) in these fishes is the initial force driving early differentiation, and that ecological specialization (as indicated by jaw morphology and hence feeding) comes later. — AMS

Proc. R. Soc. London B267, 2133 (2000).

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