Effects of roads on patterns of genetic differentiation in red-backed salamanders, <Emphasis Type="Italic">Plethodon cinereus</Emphasis> |
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Authors: | David M Marsh Robert B Page Teresa J Hanlon Rachael Corritone Elizabeth C Little David E Seifert Paul R Cabe |
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Institution: | (1) Department of Biology, Howe Hall, Washington and Lee University, Lexington, VA 24450, USA;(2) Present address: BBSRB B306, Department of Biology, University of Kentucky, Lexington, KY 40508, USA;(3) Present address: Medical University of South Carolina, College of Graduate Studies, 173 Ashley Avenue,102 BSB, P.O. Box 250501, Charleston, SC 29425, USA |
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Abstract: | Roads can fragment animal populations by reducing gene flow, which can lead to drift and the loss of genetic diversity. One
of the principle signatures of reduced gene flow is increased genetic differentiation in isolated populations, and evidence
that roads contribute to such differentiation has been reported for several species. We used microsatellites to examine whether
six roads led to increased genetic differentiation in red-backed salamanders (Plethodon cinereus). These six roads included one divided interstate highway, one undivided four-lane highway, and four secondary roads. We
found that the genetic distance between plots that were bisected by the interstate highway was significantly greater than
the genetic distance between equidistant plots on the same side of the highway. However, for the five smaller roads, plots
across the road were no more genetically distinct than were plots on the same side of the road. Bayesian clustering methods
also supported both of these findings. The optimal clustering of plots for the interstate highway consisted of two clusters
that corresponded to the two sides of highway. For the other five sites, the optimal grouping consisted of a single cluster
containing all of the plots. Our findings suggest that gene flow across very large roads is rare and that bisected red-backed
salamander populations are likely to diverge from one another. For smaller roads, our results imply that the indirect effects
of roads on genetic population structure are probably less of a pressing concern for terrestrial salamanders than are the
direct effects of mortality and habitat alteration. |
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Keywords: | Fragmentation Amphibian Highways Dispersal Gene flow |
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