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Marine Protected Areas (MPAs) have been adopted globally as a tool to combat biodiversity loss and restore marine ecosystems. Successful application of MPAs will be predicated on the ability to monitor biodiversity in a synoptic and noninvasive manner. Environmental DNA (eDNA) methods have important advantages over traditional biodiversity survey methods for monitoring conservation areas. To evaluate the efficacy of eDNA metabarcoding for fish biodiversity monitoring, we sampled 19 coastal eelgrass (Zostera marina) beds in Canada, as eelgrass beds are known for high biodiversity and significant conservation value. At each site, beach seines were used to survey fish and water samples were collected contemporaneously for eDNA metabarcoding. In total, beach seining caught 32 672 individuals across 59 fish taxa, and eDNA detected 129 fish taxa. eDNA captured site-level variation and detected higher species richness at both site and regional levels compared to seining. eDNA abundance had a positive association with capture abundance. Collectively these results highlight how eDNA metabarcoding offers an efficient approach for monitoring fish biodiversity in coastal eelgrass beds, thus providing a valuable and noninvasive tool for MPA planning and coastal monitoring. Les aires marines protegees (AMP) ont ete adoptees partout dans le monde comme outil pour contrer la perte de biodiversite et restaurer les ecosystemes marins. L'application efficace des AMP dependra de la capacite de surveillance synoptique et non invasive de la biodiversite. Les methodes reposant sur l'ADN environnemental (ADNe) presentent d'importants avantages par rapport aux methodes traditionnelles devaluation de la biodiversite pour la surveillance des aires de conservation. Afin d'evaluer l'efficacite du metacodage a barres de l'ADNe pour la surveillance de la biodiversite des poissons, nous avons echantillonne 19 herbiers de zostere (Zostera marina) cotiers au Canada, puisqu'il est etabli que ces derniers presentent une forte biodiversite et une importante valeur pour la conservation. Dans chaque site, des sennes de plage ont ete utilisees pour recenser les poissons et des echantillons d'eau ont ete preleves en meme temps pour les fins du metacodage a barres de l'ADNe. Au total, 32 672 specimens de 59 taxons de poissons ont ete pris a la senne de plage et l'ADNe a permis de detecter 129 taxons de poissons. Les donnees d'ADNe font ressortir des variations a l'echelle du site et une plus grande richesse specifique a l'echelle tant regionale que du site que la peche a la senne. L'abondance d'ADNe est positivement reliee a l'abondance des prises. Collectivement, ces resultats soulignent le fait que le metacodage a barres de l'ADNe constitue une approche efficace pour la surveillance de la biodiversite des poissons dans les herbiers a zostere cotiers, offrant ainsi un important outil non invasif pour la planification des APM et la surveillance cotiere. [Traduit par la Redaction], Introduction Awareness of the implications of global biodiversity loss has increased over the past two decades, as has acknowledgement that biodiversity conservation should be part of broader economic and political [...]

Estimating egg deposition for Atlantic salmon population assessments is made difficult by their lack of sexual dimorphism prior to the autumn spawning season. We quantified the effect of sex misclassification from subjective examination of external morphology on egg deposition estimates in four Atlantic salmon populations across multiple years. Sex classification of Canadian salmon using the genetic sex marker (sdY) was accurate (>97%), whereas sex classification based on subjective examination of external morphology was inaccurate, with misclassification rates dependent on sea age, life history, and sampling season. Sex misclassification led to annual egg deposition estimates that ranged from −36% to +56%. We found that sex could not be discriminated based on measures of external morphology. [ABSTRACT FROM AUTHOR]

Fisheries targeting mixtures of populations risk the overutilization of minor stock constituents unless harvests are monitored and managed. We evaluated stock composition and exploitation of Atlantic salmon (Salmo salar) in a subsistence fishery in coastal Labrador, Canada, using genetic mixture analysis and individual assignment with a microsatellite baseline (15 loci, 11829 individuals, 12 regional groups) encompassing the species' western Atlantic range. Bayesian and maximum likelihood mixture analyses of fishery samples over 6 years (2006-2011; 1772 individuals) indicate contributions of adjacent stocks of 96%-97%. Estimates of fishery-associated exploitation were highest for Labrador salmon (4.2%-10.6% per year) and generally < 1% for other regions. Individual assignment of fishery samples indicated nonlocal contributions to the fishery (e.g., Quebec, Newfoundland) were rare and primarily in southern Labrador, consistent with migration pathways utilizing the Strait of Belle Isle. This work illustrates how genetic analysis of mixed stock Atlantic salmon fisheries in the Northwest Atlantic using this new baseline can disentangle exploitation and reveal complex migratory behaviours. En l'absence de surveillance et de gestion des prises, les peches qui ciblent des melanges de populations posent un risque de surutilisation de stocks mineurs. Nous avons evalue la composition et l'exploitation des stocks de saumons atlantiques (Salmo salar) dans une peche de subsistance sur la cote du Labrador (Canada) par l'analyse des melanges genetiques et l'affectation d'individus a la lumiere de donnees microsatellitaires de reference (15 microsatellites, 11829 individus, 12 groupes regionaux) couvrant l'aire de reparation de l'espece dans la partie ouest de l'ocean Atlantique. Les analyses bayesiennes et de maximum de vraisemblance de melanges d'echantillons tires de cette peche sur une periode de 6 ans (2006-2011, 1772 individus) indiquent que les stocks adjacents constituent de 96% a 97% de cette peche. Les estimations de l'exploitation associee a cette peche etaient les plus elevees pour le saumon du Labrador (de 4, 2% a 10, 6% par annee) et generalement < 1% pour le saumon d'autres regions. L'affection des individus des echantillons de la peche indiquait que les contributions non locales a cette peche (p. ex. de Quebec ou Terre-Neuve) etaient rares et principalement limitees au sud du Labrador, ce qui concorde avec les voies de migration passant par le detroit de Belle-Isle. L'etude illustre comment l'analyse genetique de peches au saumon atlantique de stocks melanges dans le nord-ouest de l'Atlantique a la lumiere de la nouvelle base de donnees de reference peut permettre de discriminer l'exploitation des differents stocks et reveler des comportements migratoirescomplexes. [Traduit par la Redaction], Introduction Mixed stock fisheries target admixtures of populations, presenting both challenges and benefits for fisheries management and conservation (Chase 2003; Schindler et al. 2010; Utter and Ryman 1993). As stock [...]

The identification of landscape or climatic correlates of genetic connectivity can reveal the processes that regulate spatial diversity and inform the management and conservation of exploited or endangered species. Increasingly, the role of local adaptation in regulating spatial structure is gaining recognition, though disentangling its influence from that of dispersal and genetic drift remains challenging. We examined genetic connectivity using 15 microsatellite loci in 3546 Atlantic salmon (Salmo salar) from 47 locations in Newfoundland and Labrador. Cluster analysis revealed regional associations, but examples of unexpectedly high divergence over small spatial scales (500 km) were common with little evidence of isolation by distance ([R.sup.2] = 0.04). We evaluated the hypothesis that spatial structure is less influenced by straying and more by adaptation and (or) drift using sample-associated data on 22 landscape and climate variables and both stepwise multiple regression and redundancy analysis. Landscape variables explained ~40% of the variation in spatial structure with freshwater habitat area as the largest determinant. Linkages were also observed with water chemistry and winter severity, supporting hypotheses of adaptive divergence. Overall, the results suggest Atlantic salmon populations are structured by extensive genetic drift and low rates of effective straying and demonstrate how a landscape genetics approach can inform wildlife management and conservation. L'identification de variables du paysage ou du climat correlees avec la connectivite genetique peut faire ressortir des processus qui regulent la diversite spatiale et eclairer la gestion et la conservation d'especes exploitees ou menacees. Le role de l'adaptation locale dans la regulation de la structure spatiale est de plus en plus reconnu, bien qu'il demeure difficile de demeler son influence de celles de l'expansion et de la derive genetique. Nous avons examine la connectivite genetique a la lumiere de 15 microsatellites dans 3546 saumons atlantiques (Salmo salar) de 47 sites differents a Terre-Neuve-et-Labrador. Si l'analyse typologique a revele la presence d'associations regionales, des exemples de divergence plus forte que prevue sur de petites echelles spatiales (500 km) etaient repandus, alors qu'il y avait peu de preuves d'isolement par la distance ([R.sup.2] = 0,04). Nous avons evalue l'hypothese selon laquelle la structure spatiale etait moins influencee par l'egarement et plus par l'adaptation et (ou) la derive en utilisant des donnees associees a l'echantillon pour 22 variables du paysage et du climat, ainsi que la regression multiple pas a pas et l'analyse de redondance. Les variables du paysage expliquaient ~40 % de la variation de la structure spatiale, l'habitat d'eau douce etant le plus important determinant. Des liens ont egalement ete observes avec la chimie de l'eau et la rigueur de l'hiver, ce qui appuie des hypotheses de divergence adaptative. Globalement, les resultats semblent indiquer que les populations de saumons atlantiques sont structurees par une importante derive genetique et de faibles taux d'egarement effectif et demontrent comment une approche de genetique du paysage peut eclairer la gestion et la conservation d'especes sauvages. [Traduit par la Redaction], Introduction Identifying the geographic scale of intraspecific diversity and the dominant evolutionary and ecological drivers are critical components of successful wildlife conservation and management strategies (e.g., Allendorf et al. 2010; [...]

Blue mussels of the genus Mytilus form extensive hybrid zones in the North Atlantic and elsewhere where the distributions of different species overlap. Mytilus species transmit both maternal and paternal mtDNA through egg and sperm, respectively, a process known as doubly uniparental inheritance (DUI), and some females produce offspring with extremely biased sex ratios. These two traits have been shown to be linked and maternally controlled, with sex determination involving nuclear–cytoplasmic interactions. Hybridization has been shown to disrupt DUI mitochondrial inheritance and sex ratio bias; however, the effect of hybridization on reproductive fitness has not previously been examined. We investigated this effect in M. edulis × M. trossulus crosses through histological examination of mature F1 progeny, and spawning of F1 hybrids to monitor survival of their progeny through to the D stage of larval development. For progeny produced from mothers with a strong bias toward female offspring (often 100%) in pure‐bred crosses, there was a clear breakdown in female dominance of progeny and significantly more hermaphrodites in the hybrid crosses produced from sperm with the M‐tr1 mitotype. We also found significant sex‐specific differences among hybrid progeny, with females producing normal eggs while males and hermaphrodites evidenced impaired gonadal development with significantly greater numbers of Sertoli cells, phagocytic hemocytes, and degenerating germ cells, all associated with gonad resorption. Males from crosses where DUI was disrupted and where male progeny were homoplasmic for the female mtDNA were the most severely compromised. Allelic incongruity between maternal and paternal mitotypes in hybrid crosses was associated with significant disruption of male gonadal development. [ABSTRACT FROM AUTHOR]

Abstract: Environmental factors can influence diversity and population structure in marine species and accurate understanding of this influence can both improve fisheries management and help predict responses to environmental change. We used 7163 SNPs derived from restriction site‐associated DNA sequencing genotyped in 245 individuals of the economically important sea scallop, Placopecten magellanicus, to evaluate the correlations between oceanographic variation and a previously identified latitudinal genomic cline. Sea scallops span a broad latitudinal area (>10 degrees), and we hypothesized that climatic variation significantly drives clinal trends in allele frequency. Using a large environmental dataset, including temperature, salinity, chlorophyll a, and nutrient concentrations, we identified a suite of SNPs (285–621, depending on analysis and environmental dataset) potentially under selection through correlations with environmental variation. Principal components analysis of different outlier SNPs and environmental datasets revealed similar northern and southern clusters, with significant associations between the first axes of each (R2adj = .66–.79). Multivariate redundancy analysis of outlier SNPs and the environmental principal components indicated that environmental factors explained more than 32% of the variance. Similarly, multiple linear regressions and random‐forest analysis identified winter average and minimum ocean temperatures as significant parameters in the link between genetic and environmental variation. This work indicates that oceanographic variation is associated with the observed genomic cline in this species and that seasonal periods of extreme cold may restrict gene flow along a latitudinal gradient in this marine benthic bivalve. Incorporating this finding into management may improve accuracy of management strategies and future predictions. [ABSTRACT FROM AUTHOR]

Understanding patterns of dispersal and connectivity among marine populations can directly inform fisheries conservation and management. Advances in high-throughput sequencing offer new opportunities for estimating marine connectivity. We used restriction-site-associated DNA sequencing to examine dispersal and realized connectivity in the sea scallop Placopecten magellanicus, an economically important marine bivalve. Based on 245 individuals sampled rangewide at 12 locations from Newfoundland to the Mid-Atlantic Bight, we identified and genotyped 7163 single nucleotide polymorphisms; 112 (1.6%) were identified as outliers potentially under directional selection. Bayesian clustering revealed a discontinuity between northern and southern samples, and latitudinal clines in allele frequencies were observed in 42.9% of the outlier loci and in 24.6% of neutral loci. Dispersal estimates derived using these clines and estimates of linkage disequilibrium imply limited dispersal; 373.1 ± 407.0 km (mean ± SD) for outlier loci and 641.0 ± 544.6 km (mean ± SD) for neutral loci. Our analysis suggests restricted dispersal compared to the species range (>2000 km) and that dispersal and effective connectivity differ. These observations support the hypothesis that limited effective dispersal structures scallop populations along eastern North America. These findings can help refine the appropriate scale of management and conservation in this commercially valuable species. [ABSTRACT FROM AUTHOR]

Tests the hypothesis that protein kinase C betaII mRNA levels decrease in the striatum and cortex of transgenic Huntington's disease mice. Characterization of the disease condition; Post mortem neurotransmitter receptor changes; Mechanism underlying the reduction in protein kinase C mRNA levels in Huntington's disease.

In the northwest Atlantic Ocean, sea scallop (Placopecten magellanicus) has been characterized by a latitudinal genetic cline with a breakpoint between northern and southern genetic clusters occurring at ~45°N along eastern Nova Scotia, Canada. Using 96 diagnostic single-nucleotide polymorphisms (SNPs) capable of discriminating between northern and southern clusters, we examined fine-scale genetic structure of scallops among 27 sample locations, spanning the largest geographic range evaluated in this species to date (~37-51°N). Here, we confirmed previous observations of northern and southern groups, but we show that the boundary between northern and southern clusters is not a discrete latitudinal break. Instead, at latitudes near the previously described boundary, we found unexpected patterns of fine-scale genetic structure occurring between inshore and offshore sites. Scallops from offshore sites, including St. Pierre Bank and the eastern Scotian Shelf, clustered with southern stocks, whereas inshore sites at similar latitudes clustered with northern stocks. Our analyses revealed significant genetic divergence across small spatial scales (i.e., 129-221 km distances), and that spatial structure over large and fine scales was strongly associated with temperature during seasonal periods of thermal minima. Clear temperature differences between inshore and offshore locations may explain the fine-scale structuring observed, such as why southern lineages of scallop occur at higher latitudes in deeper, warmer offshore waters. Our study supports growing evidence that fine-scale population structure in marine species is common, often environmentally associated, and that consideration of environmental and genomic data can significantly enhance the identification of marine diversity and management units.

Environmental factors can influence diversity and population structure in marine species and accurate understanding of this influence can both improve fisheries management and help predict responses to environmental change. We used 7163 SNPs derived from restriction site-associated DNA sequencing genotyped in 245 individuals of the economically important sea scallop, Placopecten magellanicus , to evaluate the correlations between oceanographic variation and a previously identified latitudinal genomic cline. Sea scallops span a broad latitudinal area (>10 degrees), and we hypothesized that climatic variation significantly drives clinal trends in allele frequency. Using a large environmental dataset, including temperature, salinity, chlorophyll a, and nutrient concentrations, we identified a suite of SNPs (285-621, depending on analysis and environmental dataset) potentially under selection through correlations with environmental variation. Principal components analysis of different outlier SNPs and environmental datasets revealed similar northern and southern clusters, with significant associations between the first axes of each ( R 2 adj  = .66-.79). Multivariate redundancy analysis of outlier SNPs and the environmental principal components indicated that environmental factors explained more than 32% of the variance. Similarly, multiple linear regressions and random-forest analysis identified winter average and minimum ocean temperatures as significant parameters in the link between genetic and environmental variation. This work indicates that oceanographic variation is associated with the observed genomic cline in this species and that seasonal periods of extreme cold may restrict gene flow along a latitudinal gradient in this marine benthic bivalve. Incorporating this finding into management may improve accuracy of management strategies and future predictions.

Understanding patterns of dispersal and connectivity among marine populations can directly inform fisheries conservation and management. Advances in high-throughput sequencing offer new opportunities for estimating marine connectivity. We used restriction-site-associated DNA sequencing to examine dispersal and realized connectivity in the sea scallop Placopecten magellanicus , an economically important marine bivalve. Based on 245 individuals sampled rangewide at 12 locations from Newfoundland to the Mid-Atlantic Bight, we identified and genotyped 7163 single nucleotide polymorphisms; 112 (1.6%) were identified as outliers potentially under directional selection. Bayesian clustering revealed a discontinuity between northern and southern samples, and latitudinal clines in allele frequencies were observed in 42.9% of the outlier loci and in 24.6% of neutral loci. Dispersal estimates derived using these clines and estimates of linkage disequilibrium imply limited dispersal; 373.1 ± 407.0 km (mean ± SD) for outlier loci and 641.0 ± 544.6 km (mean ± SD) for neutral loci. Our analysis suggests restricted dispersal compared to the species range (>2000 km) and that dispersal and effective connectivity differ. These observations support the hypothesis that limited effective dispersal structures scallop populations along eastern North America. These findings can help refine the appropriate scale of management and conservation in this commercially valuable species.