Genic diversity in Red River pupfish Cyprinodon rubrofluviatilis (Atheriniformes: Cyprinodontidae) and its implications for the conservation genetics of the species

Abstract

Starch gel electrophoresis of proteins was used to study geographic variation at 26 gene loci in the Red River pupfish (Cyprinodon rubrofluviatílís), a species restricted to west Texas and Oklahoma. Marked differences were detected between populations in the Red and Brazos river drainages, with fixed or nearly fixed differences occurring at five gene loci. In addition, mean heterozygosity was uniformly high for the Red River form (H̄= 0·076–0·101) while samples of the Brazos River form were genetically depauperate (H̄=0·00–0·017). Introduced populations in the South Canadian and Colorado river drainages appear to have been derived from the Red River drainage. The presence of alleles diagnostic of the Red and Brazos river forms supports the suggestion from previous work that they may represent cryptic species. Regardless of taxonomy, however, the presence of two genetically distinct forms must be taken into consideration by those concerned with maintenance of biotic diversity.