Genic variation and differentiation of remnant natural populations of the desert pupfish, 'Cyprinodon macularius'

Turner, Bruce

Six remnant natural populations of the desert pupfish, Cyprinodon macularius, a formerly broadly distributed Colorado basin species, have been surveyed for allozyme variation at the products of 38-39 structural gene loci. The samples included four populations from the Salton Sea area (including one from an adjacent relatively pristine natural desert spring habitat), one from the Sonoyta basin (Quitobaquito Springs), and one ultimately from near the delta of the Colorado River. The comparison revealed the following: 1. Mean heterozygosity values (H) are within the range reported by others for ecologically comparable Aphanius populations, and are not strikingly low. 2. Eight loci display statistically significant differences in gene frequency. Differences are detectable among Salton Sea populations, and among all three geographic areas. The general pattern of the differentiation is temporally (and geographically) hierarchical, and is consistent with previous perceptions of the relationships of the populations based on morphology. 3. The overall level of differentiation is low. The minimum genetic similarity (IN) measured was .959, and the average (between areas) is .970. These values are in the range of within-drainage population comparisons in other teleosts. The effect of geographic isolation per se on the divergence of pupfish populations has almost certainly been overestimated.

Genic variation and differentiation of remnant natural populations of the desert pupfish, 'Cyprinodon macularius'

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