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Geographic Variation in North American Colonies of Cepaea nemoralis
Peter F. Brussard
Vol. 29, No. 3 (Sep., 1975), pp. 402-410
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2407253
Page Count: 9
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Starch gel electrophoresis of foot-muscle extracts from more than 1300 individuals of the introduced land snail Cepaea nemoralis collected from 30 different populations in 10 North American localities revealed nine scorable loci. Six of these showed no variation, one (PGM-1) was polymorphic at one locality only, and two (LAP-2 and PGM-2) were polymorphic at four and seven localities, respectively. Three hundred additional C. nemoralis, collected from three populations in Wales, were also examined. In addition to the enzyme loci, all snails were scored for shell color and banding phenotypes. Normalized genetic identities for all colonies were computed, based on the allozyme variability and on the previously established genetics of the shell polymorphisms. Genetic distances between each colony were ordinated to show their affinities by the Bray-Curtis method and by principalcomponents analysis. Both methods showed that the North American populations fall into two clearly recognizable groups: those living in the Piedmont and Valley of Virginia, and those found elsewhere. The latter group clusters with the Welsh snails. It is concluded that the North American pattern results primarily from different sources of introduction; the lowland Virginia snails have come from Italy, while all other North American C. nemoralis originated in northern Europe.
Evolution © 1975 Society for the Study of Evolution