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Speciation in the Fishes of the Genus Menidia

William A. Gosline
Evolution
Vol. 2, No. 4 (Dec., 1948), pp. 306-313
DOI: 10.2307/2405521
Stable URL: http://www.jstor.org/stable/2405521
Page Count: 8
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Speciation in the Fishes of the Genus Menidia
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Abstract

The phylogeny of the genus Menidia was approached through a study of morphological characters, ecology, and geographical distribution of the four species now attributed to the genus. The two fresh-water species, audens (Lower Mississippi Valley) and extensa (Lake Waccamaw, North Carolina), appear to be recent (Pleistocene or later) derivatives of the stock of beryllina, a species now abundant in coastal salt and fresh water along the Atlantic Coast from Vera Cruz, Mexico to Massachusetts. The two coastal species, beryllina and menidia, seem to have evolved from a single ancestral form through geographical isolation and differentiation in a northern group of populations, now represented by menidia, and a Gulf of Mexico population, now represented by beryllina. There is some hybridization between the species menidia and beryllina in northern Florida, and a preliminary analysis indicates that this hybridization has not altered the phenotypic characters of populations of the parent species menidia from the same area.

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