Browsing by Author "Puncher, Gregory Neils"

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    Chromosomal inversions in the Atlantic cod genome: implications for management of Canada’s Northern cod stock
    (Elsevier, 2019-08-29) Puncher, Gregory Neils; Rowe, Sherrylynn; Rose, George A.; Leblanc, Nathalie M.; Parent, Geneviève J.; Wang, Yanjun; Pavey, Scott A.
    Following stock collapse and over twenty years of moratoria, the state of Canada’s Northern Atlantic cod (Gadus morhua) remains precarious. To test if recent stock growth was of endogenous or exogenous origin, we performed a whole genome scan (ddRAD) on 135 adults captured in 2015 at three offshore spawning locations spanning the range of the offshore stock along the northeastern Newfoundland and Labrador shelf (Hawke Channel, Notre Dame Channel and Bonavista Corridor), with an additional 105 adults from three more southern locations (St. Anns Bank, Browns Bank and Bay of Fundy). Population structure analysis using 5,077 single nucleotide polymorphisms (SNPs) detected a distinct genetic break off the coast of Nova Scotia near 45 °N. Gene flow between groups north and south of this divide appears to be limited despite the presence of several northern-type and admixed individuals present in the southern area. North of the genetic divide, allele frequencies of neutral loci were indicative of a panmictic population. Several outlier SNPs were found to be associated with ecologically relevant physical characteristics (visual pigments, fin development, response to hypoxia, and various metabolic processes), which may be indicative of different ecological niches.
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    Transborder Gene Flow between Canada and the USA and Fine-Scale Population Structure of Atlantic Cod in the Broader Gulf of Maine Region
    (Wiley, 2021-03-23) Puncher, Gregory Neils; Wang, Yanjun; Martin, Ryan; DeCelles, Gregory; Cadrin, Steven X.; Zemeckis, Douglas; Rowe, Sherrylynn; Leblanc, Nathalie M.; Parent, Genevieve J.; Pavey, Scott A.
    Fishery managers have struggled for decades to rebuild stocks of Atlantic Cod Gadus morhua in the northwestern Atlantic Ocean, and the resolution of current fine-scale population structure will surely help those efforts. Using double digest restriction-site associated DNA sequencing, we analyzed 248 adult and 215 juvenile Atlantic Cod collected from areas bordering the Canada–USA boundary in 2017–2018. Chromosomal inversions from linkage group (LG) 2 and LG 7 contribute the largest amount of variance to the data set. A southwesterly decrease in the proportion of LG 1 inversion haplotypes may indicate gene flow from areas north of 45°N. Samples from both the northern Gulf of Maine and Bay of Fundy were genetically distinct from all other samples, suggesting that local spawning groups may still be active. Genetic similarities between Atlantic Cod from Browns Bank and eastern Georges Bank indicate that transborder gene flow is ongoing. These results will help to better define the stocks in order to guide the implementation of management strategies in the USA and Canada, which should consider rebuilding exhausted and genetically isolated populations.