Genetic Evaluation of the Refuge Program for Sonoyta Pupfish Cyprinodon eremus (Cyprinodontidae) in Mexico

Cyprinodon eremus is endemic to the Sonoyta River system, where wild populations comprise two conservation management units, one in Quitobaquito Springs, Arizona, and another small segment of the Sonoyta River, Sonora. Declining habitat from overmining of groundwater threatens both populations. Because of concern for the Sonoyta River population, refuges were built in Sonora and stocked with individuals from the river. Using seven microsatellite loci, we evaluated the genetic diversity of the wild population and three refuge populations. Comparison with earlier results for the wild population suggests that diversity changed little over the 12 years between collections. Two refuge populations established in 2007–2008 had levels of diversity comparable to that of the wild population. This reflects the relatively recent origins and exchange with the wild population. Notably lower measures of diversity occurred in an older refuge population that was established in 1988 and has no history of exchange with other populations. Suggestions for a program of genetic exchange are presented to inform future management.