We tested the relative influence of habitat patch size and connectivity on genetic structure and effective population size in eight brook trout (Salvelinusfontinalis) habitat patches in a watershed in Virginia, USA. Variation at eight microsatellite loci in 2229 young-of-the-year brook trout for two successive cohorts (2010 and 2011) was examined. Genetic differentiation across all populations was pronounced. Overall F'ST was 0.397 (95% CI: 0.322-0.525) and overall FST was 0.124 (95% CI: 0.096-0.159). Above-barrier patch size had a strong positive relationship with genetic diversity, Nb, and genetic differentiation. Our analysis is consistent with greater extinction risk in smaller above-barrier patches. Larger above-barrier patches contained greater genetic diversity but reduced Nb relative to adjacent below-barrier patches. The primary effect of barriers may be to reduce available above-barrier spawning habitat, even for larger above-barrier patches. Below-barrier patches also showed evidence of reduced genetic diversity and lack of connectivity. Genetic monitoring focused at gaining a broader understanding of the relationships here will be necessary to fully evaluate local extinction risks.
|Number of pages
|Canadian Journal of Fisheries and Aquatic Sciences
|Published - May 2013