Population Structure of Four Pupfish Species (Cyprinodontidae: Cyprinodon) from the Chihuahuan Desert Region of New Mexico and Texas: Allozymic Variation

Echelle, Alice; Edds, David

Products of 28-30 presumptive gene loci were used to describe variation in four pupfishes from New Mexico and/or Texas. Means of genic heterozygosity (H) and polymorphism (P) were very low in Cyprinodon tularosa and C. pecosensis (H̄ = .017-.027; P̄ = .04-0.7). In C. bovinus and C. elegans the values for those indices of variability were higher (H̄ = .045-.050; P̄ = .13-.15) and near the averages previously reported for fishes. The highest variability (H = .084-.123; P = .25-.29) occurred in two widely separated samples from the Pecos River in Texas where C. pecosensis has hybridized with introduced individuals of C. variegatus. Spatial heterogeneity in allelic frequencies was low ( F ST=.011) in C. bovinus, the species occupying the most continuous, and geographically most restricted habitat (small spring system). The higher heterogeneities in C. tularosa (.19) and C. pecosensis (.08) are associated with relatively strong geographic isolation of subpopulations. High heterogeneity (.11) also occurred in C. elegans, a species of a single complex of springs and irrigation canals. On the average, approx. 8% of the total genic diversity in C. elegans is explained by differences between samples from within the four major populations of the species (three spring systems and an associated creek), while only 3% is due to differences between subpopulations. The difference between populations of C. elegans is primarily due to divergence of the one in Phantom Lake Spring.

Population Structure of Four Pupfish Species (Cyprinodontidae: Cyprinodon) from the Chihuahuan Desert Region of New Mexico and Texas: Allozymic Variation

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