New Microsatellite Markers for Examining Genetic Variation in Peripheral and Core Populations of the Coastal Giant Salamander (Dicamptodon tenebrosus)

Rachael Y Dudaniec,Stephen F Spear,Andrew Storfer,John S Richardson,Dee A Carter

doi:10.1371/journal.pone.0014333

Rachael Y Dudaniec, Stephen F Spear + Show 3 more

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https://doi.org/10.1371/journal.pone.0014333

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Abstract

The Coastal Giant Salamander (Dicamptodon tenebrosus) is classified as threatened at the northern periphery of its range in British Columbia (BC), Canada, primarily due to forestry practices and habitat fragmentation. Characterising dispersal behaviour and population connectivity is therefore a priority for this region, while genetic differentiation in core versus peripheral locations remains unstudied in this wide-ranging species. We present seven new polymorphic microsatellite markers for use in population genetic analyses of D. tenebrosus. We examine locus characteristics and genetic variation in 12 streams at the species' northern range limit in BC, and within two regions representing sub-peripheral (North Cascades) and core localities (South Cascades) in Washington State, United States. In BC, the number of alleles per locus ranged from 2–5 and observed heterozygosity ranged from 0.044–0.825. Genetic differentiation was highest between BC and the South Cascades, and intermediate between BC and the North Cascades. Across loci, mean allelic richness was similar across regions, while private allelic richness was highest in the core locality (corrected for sample size). These new microsatellite loci will be a valuable addition to existing markers for detailed landscape and population genetic analyses of D. tenebrosus across its range.

Highlights

Species at the periphery of their range may show reduced genetic diversity that can limit microsatellite variation and the potential for detailed genetic analyses that are relevant for conservation [1]
We describe seven new polymorphic loci specific for D. tenebrosus, complementing existing microsatellite loci developed for D. tenebrosus [2,3] and those previously cross-amplified from D. copei [4]
We present seven new polymorphic microsatellite loci for D. tenebrosus, and show variation in allelic richness and increasing genetic differentiation between peripheral (BC), sub-peripheral (NC) and core (SC) regions of the species’ range

Summary

Introduction

Species at the periphery of their range may show reduced genetic diversity that can limit microsatellite variation and the potential for detailed genetic analyses that are relevant for conservation [1]. In Canada, D. tenebrosus is designated as Threatened and is on the provincial Red List in BC (COSEWIC 2000: http://www.sararegistry.gc.ca/species/speciesDetails), due to high susceptibility to decline from habitat degradation owing to forestry practices [1,2] Such peripheral populations are uniquely positioned to aid conservation management throughout a species’ range, as they can provide information regarding adaptive potential and local adaptation at environmental margins [1]. We provide locus characteristics for two regions in Washington State (WA) to examine for differences in allelic diversity, heterozygosity, and genetic differentiation between peripheral populations in BC, with sub-peripheral (North Cascades) and core (South Cascades) regions of the species’ range These new loci have potential use in other Dicamptodon species and combined with existing loci, will enable range-wide genetic analyses using high-resolution microsatellite data

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