A Measure of Genetic Variability of Meda fulgida Based on Microsatellite Allele Frequencies

Meda fulgida is a species of native fish now endemic to the Gila River in New Mexico, a tributary of the Colorado River. M. fulgida was listed by the U.S. Fish and Wildlife Service as a threatened species in 1986 after being extirpated from several rivers in New Mexico and Arizona. This study's purpose is to use microsatellite loci to determine population substructure and estimate levels of genetic variability. Thirteen cross-specific primer sets (developed for Plagopterus argentissimus a sister species of M. fulgida) were screened for optimal loci amplification. Seven primer sets were found to be variable and have been successful for genotyping. Microsatellite analyses show the allelic richness of the population to have decreased from 2009 to 2010 and also suggests that the sites in the lower reaches of the Gila River have greater genetic diversity. All loci in each population sample are consistent with Hardy-Weinberg equilibrium. Pairwise Fst values were significant for the upper reach sites suggesting that the upper sites are genetically divergent from the lower two sites, but not significant for the lower sites. Geographic distance and possible habitat fragmentation may play a role in the level of genetic divergence between the three populations. This genetic information will be used to determine the degree of detrimental effects habitat fragmentation will have upon the species in relation to proposed water development.