Neutral Genetic and Phenotypic Variation within and among Isolated Headwater Populations of Brook Trout

T. Casey Weathers, David C. Kazyak, Jay Richard Stauffer, Jr., Matt A. Kulp, Stephen E. Moore, Tim L. King, John Edward Carlson

Research output: Contribution to journalArticle

Abstract

Isolated populations are challenging to manage and conserve, as they are particularly vulnerable to genetic drift, allelic fixation, and inbreeding and may express markedly reduced phenotypic variability. We sought to improve our understanding of how spatial isolation, occupancy range, and restricted gene flow influence contemporary phenotypic variation within and among native populations of Brook Trout Salvelinus fontinalis by examining the neutral genetic and phenotypic characteristics of 35 isolated headwater populations from Great Smoky Mountains National Park. Across a suite of 13 neutral microsatellite loci, we observed high levels of allelic fixation and considerable genetic differentiation among populations, subwatersheds, and watersheds that were consistent with patterns of isolation. We found significant positive correlations between allelic diversity and estimates of effective population size. In contrast, we observed considerably less phenotypic structure among streams, subwatersheds, and watersheds. Much of the observed phenotypic variation occurred among individuals within populations. Pairwise Mann–Whitney tests revealed no significant phenotypic differences among the populations of Brook Trout we examined. Similarly, there was no significant relationship between the amount of phenotypic variation within populations and any of the examined measures of genetic diversity or the amount of occupied habitat sampled, which suggests that unmeasured variables may be influencing morphometric and meristic variation within isolated populations. The observed patterns of isolation, genetic drift, and allelic fixation highlight the importance of enhancing population connectivity but also suggest that considerable phenotypic variability may persist within small, fragmented populations. Our results elucidate some challenges associated with managing and conserving isolated populations of Brook Trout and reinforce the importance of conducting genetic studies on fragmented populations to inform management decisions.

Original languageEnglish (US)
Pages (from-to)58-72
Number of pages15
JournalTransactions of the American Fisheries Society
Volume148
Issue number1
DOIs
StatePublished - Jan 1 2019

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Salvelinus fontinalis
isolated population
phenotypic variation
headwater
fixation
genetic drift
genetic variation
watershed
meristics
effective population size
inbreeding
genetic differentiation
gene flow
connectivity
national park
subwatersheds
mountain
habitat
brook
Great Smoky Mountain region

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science

Cite this

Weathers, T. Casey ; Kazyak, David C. ; Stauffer, Jr., Jay Richard ; Kulp, Matt A. ; Moore, Stephen E. ; King, Tim L. ; Carlson, John Edward. / Neutral Genetic and Phenotypic Variation within and among Isolated Headwater Populations of Brook Trout. In: Transactions of the American Fisheries Society. 2019 ; Vol. 148, No. 1. pp. 58-72.
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Neutral Genetic and Phenotypic Variation within and among Isolated Headwater Populations of Brook Trout. / Weathers, T. Casey; Kazyak, David C.; Stauffer, Jr., Jay Richard; Kulp, Matt A.; Moore, Stephen E.; King, Tim L.; Carlson, John Edward.

In: Transactions of the American Fisheries Society, Vol. 148, No. 1, 01.01.2019, p. 58-72.

Research output: Contribution to journalArticle

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