Characterization of the Genetic Structure among Brook Trout in LeConte Creek, Tennessee

Beginning in the early 1900s, the original range and abundance of brook trout within Great Smoky Mountains National Park (GRSM) was drastically reduced due to landscape alterations resulting from increased logging and introduction of nonnative salmonid species. Consequently, brook trout populations retreated to the headwaters of most streams, resulting in geographic isolation due to waterfalls and eventual genetic differentiation of the fish inhabiting these streams. In an effort to reestablish LeConte Creek's extirpated brook trout population, GRSM fisheries managers collected fish from three streams known to support populations of genetically pure “Southern Appalachian” brook trout (Greenbrier, Cosby and Indian Camp Creeks). Brook trout were collected, pooled, and transplanted into LeConte Creek. Upon successful completion of the stocking effort, managers were interested in determining if all three streams contributed equally to the reestablished population or whether one population was better adapted to the conditions of LeConte Creek than another. Seven years post-stocking, minimally-invasive tissue samples were collected from 50 randomly selected brook trout, genotyped at 10 polymorphic microsatellite loci, and compared to the parental populations. Our preliminary, individual-based analyses suggest the LeConte Creek collection represents three separate, but co-existing, populations as 76% of the sampled fish were found to have parents that originated from either same-stream matings (i.e., positive assortative mating) or from some form of post-reproductive isolating mechanism that selected against individuals resulting from out-crossed matings.

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