High connectivity among argali sheep from Afghanistan and adjacent countries: Inferences from neutral and candidate gene microsatellites

We quantified population connectivity and genetic variation in the Marco Polo subspecies of argali mountain sheep (Ovis ammon polii) by genotyping 9 neutral and 8 candidate gene microsatellite loci in 172 individuals noninvasively sampled across five study areas in Afghanistan, China, and Tajikistan. Heterozygosity and allelic richness were generally high (mean H = 0.67, mean A = 6.1), but were significantly lower in the China study area (H = 0.61, P < 0.001; A = 4.9, P < 0.01). One marker in an immune system gene (TCRG4) showed an excess of rare alleles compared to neutral expectations. Another immune system gene (GLYCAM-1) showed excessive differentiation (high F (ST)) between study areas. Estimates of genetic differentiation were similar (F (ST) = 0.035 vs. 0.033) with and without the two loci deviating from neutrality, suggesting that selection is not a primary driver of overall molecular variation, and that candidate gene loci can be used for connectivity monitoring, as long as selection tests are conducted to avoid biased gene flow estimates. Adequate protection of argali and maintenance of inter-population connectivity will require monitoring and international cooperation because argali exhibit high gene flow across international borders.