Population subdivision and genetic signatures of demographic changes in Arctic grayling ( Thymallus arcticus) from an impounded watershed

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Stamford, M D, Taylor, E B
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2005
• Subjects: Arctic grayling; Thymallus arcticus
• Online Access: http://dx.doi.org/10.1139/f05-156; http://www.nrcresearchpress.com/doi/pdf/10.1139/f05-156

We examined allelic variation at seven microsatellite loci in 11 samples of Arctic grayling (Thymallus arcticus) from the Peace River watershed, northeastern British Columbia, to (i) assess population subdivision and (ii) test for population size changes promoted by hydroelectric dam construction in the watershed. The number of alleles and expected heterozygosity per locus averaged 2.3 and 0.29, respectively. Overall F st (θ) was 0.21 (P < 0.003), but there was no distinction between age classes (0+ and 3+) within two streams (θ = 0.01, P > 0.05). Seven percent of the microsatellite variation (P < 0.005) was attributable to differences between samples above and below a historical natural barrier to upstream fish migration, the Peace River Canyon (the site of hydroelectric developments since the 1960s). Strong isolation-by-distance among samples was resolved (Mantel r = 0.64, P < 0.01). Coalescent analyses suggested that current Arctic grayling population sizes are less than 1% of historical sizes and that this decline began relatively recently (i.e., <300 years ago) under an exponential model of population size change or earlier in the late Pleistocene under a linear model. Significant microsatellite divergence occurs among Peace River Arctic grayling populations previously characterized by low mtDNA divergence.