Snake populations at northern range limits face ecological challenges that may affect dispersal, gene flow, and ultimately genetic population structure.

Conservation challenges may be exacerbated for populations at range peripheries, where extreme environments and naturally sparse distributions interact with anthropogenic activities to generate additional risk factors. It is only recently that snake populations at range peripheries (e.g., ) or in extreme environments (e.g., ) have become the focus of conservation genetics studies. It is clear that intrinsic and extrinsic factors may interact to produce constraints to dispersal and gene flow in snakes however, most studies have addressed populations at the core of known geographic ranges (e.g. showed that anthropogenic habitat loss caused enhanced genetic isolation in the copperbelly water snake ( Nerodia erythrogaster neglecta, a habitat specialist) by hindering dispersal. Dispersal and associated gene flow among breeding groups may also be influenced by extrinsic factors such as natural or man-made barriers. natal philopatry, home range size, specific habitat requirements), as well as the ability of individuals to disperse. The variation among species is likely due to a wide variety of biological traits (e.g. Sistrurus catenatus catenatus, Nerodia erythrogaster neglecta, Vipera berus, Coronella austriaca, Crotalus triseriatus, ). Rhinoplocephalus nigrescens, Crotalus horridus, ), while others show a high degree of differentiation over small spatial scales (e.g. Some snake species show only very modest levels of subdivision or none at all (e.g. The genetic population structure of snakes can vary markedly based on a number of intrinsic and extrinsic factors. Department of Energy under Award Number DE-FC09-07SR22506 to the University of Georgia Research Foundation.Ĭompeting interests: The authors have declared that no competing interests exist. This research was partially supported by U. įunding: We thank the Science and Innovation Fund of the province of Saskatchewan, the Natural Sciences and Engineering Research Council of Canada, the Canada Research Chairs Program, the University of Regina, the Royal Saskatchewan Museum, Friends of the Royal Saskatchewan Museum, Saskatchewan Parks, the Parks Canada Agency and Grasslands National Park, the Canadian Museum of Nature, the Canadian Wildlife Federation, and Agriculture and Agri-food Canada and Environment Canada’s Inter-Departmental Recovery Fund for financial support. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ĭata Availability: Microsatellite genotypes and associated site information have been uploaded to Dryad: DOI. Received: JAccepted: OctoPublished: November 2, 2017Ĭopyright: © 2017 Somers et al. PLoS ONE 12(11):Įditor: Tzen-Yuh Chiang, National Cheng Kung University, TAIWAN (2017) Conservation genetics of the eastern yellow-bellied racer ( Coluber constrictor flaviventris) and bullsnake ( Pituophis catenifer sayi): River valleys are critical features for snakes at northern range limits. Our findings highlight the importance of major river valleys for snakes at the northern extent of their ranges, and raise the possibility that populations in each river valley may warrant separate management strategies.Ĭitation: Somers CM, Graham CF, Martino JA, Frasier TR, Lance SL, Gardiner LE, et al. Finer-scale subdivision of populations within river valleys was not apparent based on our data, but is a topic that should be investigated further. Bayesian assignment (STRUCTURE) and ordination (DAPC) strongly supported genetically differentiated groups in the geographically distinct river valleys. Fixation indices (F ST) showed that populations in river valleys were significantly differentiated for both species (racers, F ST = 0.096, P = 0.001 bullsnakes F ST = 0.045–0.157, P = 0.001). To test this hypothesis, we used 10 microsatellite loci to examine the population structure of two species of conservation concern in Canada: the eastern yellow-bellied racer ( Coluber constrictor flaviventris) and bullsnake ( Pituophis catenifer sayi) in 3 major river valleys in southern Saskatchewan. Independent colonization histories for the river valleys and barriers to gene flow caused by the lack of suitable habitat between them may have produced genetically differentiated snake populations.

On the North American Great Plains, several snake species reach their northern range limit where they rely on sparsely distributed hibernacula located in major river valleys.

Eastern yellow bellied racer