Harvesting consequences on genetic diversity and metapopulation effective size in a spatially stratified system, the Kogaluk river drainage in northern Labrador

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A fundamental question in evolutionary and conservation biology is how changes in habitat fragmentation (i.e., number, size, spatial arrangement and connectivity among habitat fragments) affect the maintenance of genetic diversity and the effective size of a metapopulation (metaNe). This is an issue that despite its importance for biodiversity conservation has largely been explored only from a theoretical perspective. Early models uniformly reached the somewhat paradoxical conclusion that the effective size of a fragmented system was generally higher than that of a panmictic system of equal total size, a conclusion that followed from the restrictive model assumption of equal contribution to the next generation by all subpopulations. A more recent model that includes the possibility of subpopulation extinction and recolonization demonstrates that metaNe can indeed be significantly reduced when subpopulations are allowed to contribute differentially to the next generation. This theory has remained largely unmatched by empirical data. Our goal in this project is thus to reduce this gap. We will examine the relationship between subpopulation size and diversity, gene flow (asymmetry) and metaNe in a freshwater community of three fish species differing in life histories: Lake trout (Salvelinus namaycush), longnose sucker (Catostomus catostomus), white roundfish (Prosopium cylyndraceum) and coexisting sympatrically in the Kogaluk river drainage in northern Labrador. This drainage comprises a number of hierarchically or dendritically interconnected shallow lakes on the barren grounds that drain onto a deep fjord lake. Our research using molecular markers will allow us to predict which components of the metapopulations are more likely to affect metaNe if affected and which should thus receive highest conservation priority when faced with harvesting and/or climate induced changes in landscape. Our research, conducted in collaboration with the Wildlife Division of the Newfoundland and Labrador Department of Environment and Conservation fits within the Strategic Target Area Natural Resources and Energy and research topic (b) NR Optimizing Resource Extraction, Harvesting and Renewal.