Anolis Lizards of the Eastern Caribbean: A Case Study in Evolution. II. Genetic Relationships and Genetic Variation of the Bimaculatus Group

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Gorman, G. C, and Y. J. Kim (Biol. Dept., UCLA, Los Angeles, California 90024) 1976. Anolis lizards of the eastern Caribbean: a case study in evolution. II. Genetic relationships and genetic variation of the bimaculatus group. Syst. Zool. 25:62–77.—Anolis lizards of the northern Lesser Antilles were studied with starch gel electrophoresis. A total of 22 genetic loci was analyzed for 15 populations. These data were used to estimate genetic distance between populations, and genetic variation within populations. Genetic distance estimates between populations are considerably lower than the estimates for the ecologically equivalent Anolis roquet species group of the southern Lesser Antilles. The relative proximity of islands in the northern part of the archipelago increases the probability of multiple colonizations, hence introgression, and a relatively slower rate of genetic divergence. The data also suggest that the northern bimaculatus group is evolutionarily younger than the roquet group, hence has had less time for genetic divergence. There is a geographic pattern discernible in the genetic distance data. One very tight cluster involves the southernmost populations studied from Dominica, Guadeloupe, Marie Gallante, and Montserrat; a second cluster includes more northern forms from Redonda, Saba, and St. Martin. Variability is lowest on the three smallest islands, but beyond that, there is no correlation between island size and heterozygosity. Relative degree of heterozygosity may be related to colonization history. Source populations tend to have higher variability than derived populations. The degree of genetic differentiation as estimated electrophoretically is very poorly correlated with differentiation for morphological characters such as body size, color, or pattern.

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