Population Genetics of Moapa coriacea

Authors: Danielle Johnson, Mary Peacock

Year: 2013 (xlv)

Abstract

Small, isolated populations of desert fishes are common in the Great Basin and Mojave Desert. Anthropogenic stream modifications and non-native species tend to restrict relict fish populations to reduced ranges. When populations decline, genetic diversity can be lost and inbreeding depression can be a real threat to small populations. Historically, Moapa dace, Moapa coriacea, inhabited several geothermal springs and the Muddy River. Currently, Moapa dace are restricted to three springs which consists of two kilometers of habitat in southeastern Nevada. A Gabion barrier and non-native predator blue tilapia, Oreochromis aureus, restrict the current distribution of Moapa dace. Over 1500 individual dace were captured during bimonthly surveys between October 2009 and September 2012 using minnow traps. Caudal fins were clipped and DNA was extracted from fin clips using QIAGEN DNEasy kits. Ten microsatellite loci were amplified in two multiplex PCR reactions. Microsatellite regions were variable and the number of alleles per loci ranged from 6-23 with a mean of 14.4. Bayesian clustering techniques in program STRUCTURE were used to identify multiple breeding populations within the two kilometers of habitat. Bayesian clustering identified breeding groups, population mixing, and barriers to dispersal. Heterozygosity of Moapa dace was significantly different between stream reaches. A Wilcoxon signed ranks test identified several breeding groups using a two phase mutation model, evidence that the population has endured a genetic bottleneck. Despite the constricted range, Moapa dace contain relatively high levels of genetic diversity.