Life-history characteristics and landscape attributes as drivers of genetic variation, gene flow, and fine-scale population structure in northern Dolly Varden (Salvelinus malma malma) in Canada

Abstract

The northern Dolly Varden (Salvelinus malma malma) displays variable life-history types and occupies freshwater habitats with varying levels of connectivity. Here, we assayed microsatellite DNA variation in northern Dolly Varden from the western Canadian Arctic to resolve landscape and life-history variables driving variation in genetic diversity and population structure. Overall, genetic variation was highest in anadromous populations and lowest in those isolated above waterfalls, with stream-resident forms intermediate between the two. Anadromous and isolated populations were genetically divergent from each other, while no genetic differentiation was detectable between sympatric anadromous and stream-resident forms. Population structure was stable over 25 years, hierarchically organized, and conformed to an isolation-by-distance pattern, but stream-isolated forms often deviated from these patterns. Gene flow occurred primarily among Yukon North Slope populations and between sympatric anadromous and resident forms. These results were sex-dependent to some extent, but were influenced more by reproductive status and life history. Our study provides novel insights into the life history, population demographic, and habitat variables that shape the distribution of genetic variation and population structure in Arctic fluvial habitats while providing a spatial context for management and conservation.Résumé : L'omble Dolly Varden (Salvelinus malma malma) présente différents types de cycle biologique et occupe des habitats d'eau douce caractérisés par différents degrés de connectivité. Nous avons évalué les variations de microsatellites d'ADN chez les Dolly Varden de l'ouest de l'Arctique canadien afin d'établir quelles variables du paysage et du cycle biologique agissent sur les variations de la diversité génétique et de la structure des populations. Globalement, les variations génétiques étaient les plus grandes dans les populations anadromes et les plus faibles dans les populations isolées en amont de chutes, les formes résidentes de cours d'eau étant intermédiaires entre les deux. Les populations anadromes et isolées étaient génétiquement divergentes les unes par rapport aux autres, alors qu'aucune différentiation génétique n'était décelable entre des formes anadromes et résiden-tes de cours d'eau sympatriques. La structure des populations était stable sur plus de 25 ans, organisée de manière hiérarchique et concordait avec un motif d'isolement par la distance, mais les formes isolées dans des cours d'eau présentaient souvent des motifs divergents. Un flux génétique était présent principalement parmi les populations de la pente nord du Yukon et entre des formes anadromes et résidentes sympatriques. Ces résultats dépendent du sexe dans une certaine mesure, mais sont plus fortement influencés par l'état de reproduction et le cycle biologique. L'étude jette un nouvel éclairage sur les variables relatives au cycle biologique, à la démographie des populations et à l'habitat qui définissent la répartition des variations gé...

Genetic Stock Identification and Relative Contribution of Arctic Char (<i>Salvelinus alpinus</i>) from the Hornaday and Brock Rivers to Subsistence Fisheries in Darnley Bay, Northwest Territories + Supplementary Appendix Tables S1 to S4 (See Article Tools)

“…Ground-truthing would be required to confirm that this is also true for LAKE-A and LAKE-B but aerial observations did not lead us to suspect these lakes were inaccessible. Finally, our values of genetic differentiation between the LAKE-A/LAKE-B samples and anadromous samples are consistent with those reported between other landlocked or isolated and anadromous salmonines (Harris et al, 2015;May-McNally et al, 2015). Additional work, however, is required to confirm whether LAKE-A and LAKE-B are truly landlocked stocks that are physically isolated from anadromous Hornaday River Arctic char or whether they are freshwater-resident forms that are reproductively isolated from anadromous char in the region.…”

New Insights into the Biology of Anadromous Dolly Varden in the Canning River, Arctic National Wildlife Refuge, Alaska

“…; Harris et al. ), we assume the postspawning fish were natal to the Canning River, while the natal origins of those originally classified as nonspawners were unknown. The overall interdrainage exchange rate was estimated to be 0.37 (95% CI = 0.27–0.48).…”

Genetic Stock Structure of Anadromous Arctic Char in Canada's Central Arctic: Potential Implications for the Management of Canada's Largest Arctic Char Commercial Fishery

“…Because the genetic structure resolved in our study area was weak and because an initial STRUCTURE run was not informative given the high degree of admixture (see Supplementary Figure S.1), we opted to incorporate priors on sampling location information (LOCPRIOR), which is recommended for detecting structure when there are lower levels of divergence (Hubisz et al 2009). The STRUCTURE analyses were first run on the entire data set, and subsequent rounds of clustering were then used to test for hierarchical stock structure in our system (e.g., Harris et al 2014Harris et al , 2015. Once the major stock structure was revealed after the first round of clustering, additional rounds of clustering were performed (i.e., hierarchical STRUCTURE analysis) on each genetic cluster until no further genetic structure could be resolved.…”

“…Dispersal and gene flow, however, can be remarkably variable among salmonid species and among stocks within a species (see Hendry and Stearns 2004 for a review). For example, in a study of the closely related Northern Dolly Varden S. malma malma, Harris et al (2015) resolved virtually no dispersal or gene flow among anadromous stocks in the western Canadian Arctic, with the exception of the Joe-Firth and Babbage rivers. This resulted in a high degree of differentiation and an average F ST of 0.108 among stocks.…”