Cooperative Fish and Wildlife Research Units Program: New Mexico
Education, Research and Technical Assistance for Managing Our Natural Resources

In New Mexico, Rio Grande chub (Gila pandora) is a cool-water fish listed as a species of greatest conservation need and state-listed as sensitive due to habitat alterations and competition with non-native fishes. Characterizing the patterns of genetic structure and genetic diversity of populations will assist with conservation efforts by providing a baseline of genetic variation in New Mexico. Genetic relatedness within and among G. pandora populations throughout New Mexico was characterized using a suite of 11 microsatellites loci among 15 populations in three disparate river basins (Rio Grande, Pecos and Canadian). Allelic richness across 11 loci was highest in the Rio Ojo Caliente (northern range of the Rio Grande basin) while the lowest allelic richness was expressed in the Upper Rio Bonito (southern portion of the Pecos basin). Mean observed and expected heterozygosity was relatively high across all populations with low inbreeding coefficient. AMOVA revealed that moderate genetic differentiation existed among the 15 populations of G. pandora and a low genetic variation among populations within respective Rio Grande and Pecos basins. Finally, there was low genetic variation among the three basins. The STRUCTURE analysis and optimal K suggested that the 15 populations clustered into seven genetic clusters with the Upper Rio Bonito displaying the greatest genetic differentiation compared to all populations. Evaluating Q-values, populations within the upper Rio Grande drainage basin were the least structured, while the Pecos drainage populations were the most genetically differentiated. Patterns of genetic diversity among populations of G. pandora revealed that while northern Rio Grande populations contain the bulk of genetic diversity, the southern populations continue to persist despite isolation events. These patterns can be used to ensure genetic diversity is maintained by identifying source populations and improving migration to reduce the chance of local extinctions.