Linking genetic structure to landscape structure at multiple spatial and temporal scales: the Carolina flying squirrel Glaucomys sabrinus coloratus in the southern Appalachians.
Wartell, Arlena*,1, 2, 1 University of Georgia, Athens, GA2 Savannah River Ecology Lab, Aiken, SC
ABSTRACT- The Carolina flying squirrel Glaucomys sabrinus coloratus is a federally-listed endangered subspecies that exhibits an island-like distribution on high elevation mountains in the southern Appalachians. These populations are expected to show reduced gene flow and genetic isolation due to the species' limited dispersal abilities and to natural and human-caused habitat alterations. Because the current geographic distribution of this subspecies has been shaped strongly by factors spanning both ecological and evolutionary time scales, this study investigated genetic structure and inferred dispersal patterns among these populations using microsatellite markers and mitochondrial DNA sequence data. Individual tissue and hair samples were collected in 2002-2004 from n=286 individuals in seven mountain ranges spanning the subspecies' range. These samples were genotyped at nine microsatellite loci and mitochondrial sequence diversity was examined for a 418 base pair segment of the D-loop. Sampling sites were separated by distances of up to 150 km and across potential barriers to dispersal. Genetic structure, variation, and gene flow among these regions were characterized at multiple spatial scales using Rst, AMOVA, genotype assignment tests, and genetic distance measures. Results show significant structure among populations and between-region divergence values (Rho) ranging from 0.05 to 0.24. Phylogenetic networks used to infer the subspecies' regional evolutionary history were constructed based on haplotype and nucleotide variation. Patterns of population divergence and variation suggest the importance of suitable habitat size, habitat configuration, and landscape barriers, including human modification of the landscape, in shaping current genetic structure. These data have important implications in delineating evolutionary significant units, determining conservation units for management, and identifying potentially suitable habitat that may act as stepping stones to link existing populations.⋅
Key words: population genetics, habitat fragmentation, gene flow and dispersal, Glaucomys sabrinus
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