Conservation Genetics of Lake Sturgeon (Acipenser fulvescens): Nuclear Phylogeography Drives Contemporary Patterns of Genetic Structure and Diversity (original) (raw)
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Journal of Applied Ichthyology, 2011
Lake sturgeon (Acipenser fulvescens) are a species of conservation concern across their range, with impoundments and exploitation acting as significant impediments to their recovery. Northern Ontario contains some of the few remaining intact systems with healthy lake sturgeon populations because of low exploitation and undammed, unregulated watersheds. Although preliminary research suggests that northern Ontario lake sturgeon are genetically distinct from depleted sturgeon populations in the Great Lakes basin, this region represents a large gap in our understanding of genetic diversity of lake sturgeon. Recent identification of hydroelectric development potential in four major rivers in northern Ontario may pose future threats to these populations. The two goals of this study were to address the lack of genetic information from a significant portion of the species range, and to compare levels of local and regional diversity between relatively intact systems and more intensively studied (and fragmented) areas to the south. Comparison of 23 putative populations from three major drainages identified three divergent genetic groups which corresponded with historical drainages more than contemporary watersheds. The three groups reflected colonization from Mississippian and Missourian glacial refugia, as well as a novel third group in western Ontario characterized by low genetic variability. Diversity within populations similarly reflected historical influences more than anthropogenic stressors, including impoundments and population abundances resulting from harvest. Genetic similarities among geographically separated populations within major drainages underscore their historical connections, reflecting lake sturgeon dispersal abilities and the importance of habitat connectivity.
Genetic Population Structure of Remnant Lake Sturgeon Populations in the Upper Great Lakes Basin
Transactions of the American Fisheries Society, 2006
Populations of lake sturgeon Acipenser fulvescens have undergone dramatic declines in abundance and distribution in the Great Lakes basin and are a species of conservation concern throughout their range. While information regarding the genetic population structure of this species is critical for the development of effective management plans, little information currently exists. We examined both microsatellite and mitochondrial DNA (mtDNA) variation as a means of estimating population genetic diversity within, and the degree of spatial population structuring among, 11 remnant lake sturgeon populations in the upper Great Lakes basin. Multiple measures of genetic diversity were consistently high across populations and were not significantly correlated with estimates of current adult population size. Despite substantial population declines, life history characteristics, including longevity and iteroparity, appear to have buffered lake sturgeon populations from losses of genetic diversity. Significant levels of interpopulation variance in both microsatellite allele and mtDNA haplotype frequencies (mean genetic differentiation index ¼ 0.055 over eight microsatellite loci; mean haplotype frequencies ¼ 0.134 for mtDNA) were detected. Population structure is most likely a function of high levels of natal fidelity, a trend observed in other species of sturgeon Acipenser spp. We discuss the implications of these results with regard to the management and conservation of lake sturgeon in the Great Lakes.
Genetic Assessment of Lake Sturgeon Population Structure in the Laurentian Great Lakes
North American Journal of Fisheries Management, 2008
Many populations of lake sturgeon Acipenser fulvescens have decreased in size throughout the Great Lakes basin. To implement management strategies such as stocking, it is important to understand the genetic structure of lake sturgeon spawning populations. Lake sturgeon from 27 spawning locations (25 from the Great Lakes basin and 2 from the Hudson Bay drainage) were analyzed using 12 microsatellite loci. Population structure was detected at different spatial scales. At the largest scale, consistent genetic breaks were observed among three clusters of spawning populations: (1) Hudson Bay-northern Lake Superior, (2) southern Lake Superior, and (3) the rest of the Great Lakes. These clusters were identified using a Bayesian approach that does not define the populations a priori. Within each of the three clusters, sublevels of genetic structure were detected. These sublevel clusters accounted for 8.82% of the genetic variation (P , 0.000), while differences among populations within the clusters accounted for 3.72% of the genetic variation (P , 0.000). At the smallest scale, significant genetic differentiation was detected between most sampled locations through pairwise genetic differentiation index (F ST) tests and pairwise contingency tests. Lake sturgeon showed greater genetic differentiation in Lake Superior than elsewhere, which could be due to the lake's bathymetry. The lower genetic resolution observed elsewhere in the Great Lakes could be due to more recent colonization events. The results can be used to delineate management units and to select appropriate donor populations for supplementation or reintroductions.
Environmental Biology of Fishes, 2011
Lake sturgeon (Acipenser fulvescens) are of conservation concern throughout their range. Many populations are dependent on fluvial habitats which have been increasingly impacted and fragmented by dams and human development. Although lake sturgeon were once abundant in the Ottawa River and its tributaries, historical commercial harvests and other anthropogenic factors caused severe declines and low contemporary numbers in lake sturgeon populations. Contemporary habitat fragmentation by dams may be increasing isolation among habitat patches and local rates of decline, raising concerns for persistence of local populations. We used microsatellite DNA markers to assess population structure and diversity of lake sturgeon in the Ottawa River, and analyzed samples from 10 sites that represent more than 500 km of riverine habitat. To test for evidence of anthropogenic fragmentation, patterns of genetic diversity and connectivity within and among river segments were tested for concordance with geographic location, separation by distance and obstacles to migration, considering both natural and artificial barriers as well as barrier age. Despite extensive habitat fragmentation throughout the Ottawa River, statistical analyses failed to refute panmixia of lake sturgeon in this system. Although the long generation time of lake sturgeon appears to have effectively guarded against the negative genetic impacts of habitat fragmentation and loss so far, evidence from demographic studies indicates that restoring connectivity among habitats is needed for the long-term conservation and management of this species throughout this river system.
Journal of Great Lakes Research, 2003
The lake sturgeon (Acipenser fulvescens) has recently become a high priority for restoration management because of the near extinction of the species from many areas of North America. The identification of the level of population differentiation that naturally exists among lake sturgeon populations will be useful in the development of management plans to conserve and restore diversity, and in the choice of donor populations to use for re-introduction. Genetic variation among and within 210 lake sturgeon collected from seven locations (St. Lawrence River, Des Prairies River (tributary to the St. Lawrence River), Mattagami River (Hudson Bay drainage), Menominee River (Lake Michigan drainage), Wolf River (Lake Michigan drainage), Niagara River, and Lake Erie) was examined based on allelic variation at seven microsatellite loci (four disomic and three putative tetrasomic). High levels of variability were detected at these loci. Analyses revealed an average of 8.6 alleles per locus (range 5 to 12 alleles per locus) and heterozygosity values at the four disomic loci ranging from 0.46 to 0.66. Multivariate factor analysis of Nei's genetic distance values produced three distinct population groups that were organized by geography: 1) Mattagami (northern Quebec), 2) Menominee/ Wolf (Lake Michigan-Wisconsin), and 3) St. Lawrence/ Des Prairies/ Niagara/ Erie (lower Great Lakes). Differences based on G-tests summed over all loci occurred between all possible paired comparisons of the collections (P < 0.01). These analyses indicated that lake sturgeon populations are differentiated within the Great Lakes basin. Managers of this species will need to identify individual populations in their jurisdictions and provide separate consideration for their conservation and rehabilitation.
Fisheries Research, 2020
Great Lakes-wide population structure analyses using neutral markers have provided an understanding of broadscale genetic structure of lake sturgeon. To assess the fine-scale genetic structure of lake sturgeon populations in two different rivers, we combined both microsatellites and genome-wide SNP markers. The St. Clair-Detroit River System (SCDRS) is entirely freshwater with no known impediments to sturgeon movement. In contrast, the St. Lawrence River (SLR) outlets into the Atlantic Ocean and is fragmented by hydroelectric dams. Both microsatellites and SNPs provided evidence of differentiation between the rivers. When applied to fine-scale structure, microsatellites failed to detect population structure using a Bayesian approach for within either river and F ST values using microsatellites identified only a low level of differentiation between the upper and lower St. Clair River. Using the full set of SNPs for each comparison yielded similar results to the microsatellite results. Discriminant analysis of principal components using both markers partitioned the samples into spatially structured clusters. The SNP datasets filtered for high F ST values had greater success for detecting fine-scale population structure and had the highest accuracy for reassignment to prior populations. This reduced SNP dataset may represent a more meaningful set of loci that can be used to estimate lake sturgeon fine-scale population structure, which is complicated by their long-generation times.
Biology, Conservation and Sustainable Development of Sturgeons, 2009
For a number of reasons, including their threatened or endangered status and importance in caviar production, much effort has been and is being expended worldwide on the study of the genetic variation of sturgeons and paddlefish. Presented here is a review of the genetic studies that have been conducted on the ten North American acipenseriform taxa and the types of molecular markers that have been used in these studies. The results that have been obtained from this research are invaluable for guiding conservation efforts by increasing our understanding of the relationships among species within the group, identifying intraspecific population structure and shedding light on acipenseriform life history traits.
Journal of Applied Ichthyology, 2017
This study assessed the establishment success of a translocation of adult lake sturgeon (Acipenser fulvescens) upstream of a hydroelectric dam in northern Ontario, Canada, using demographic and genetic data from juveniles and adults. The objectives of this study were to (i) assess the size and demographic structure of the reintroduced population; (ii) determine if juveniles are present; (iii) assess the genetic diversity of the reintroduced and source populations; and (iv) determine whether translocated adults are related to juveniles within the population. Gillnet and trotline sampling in multiple years (2002-2003; 2011-2016) resulted in the capture of many juveniles (n = 126) and some adults (n = 13) at the release site and downstream. The first fin ray of the left pectoral fin was collected for ageing and genetic analysis, and individuals were genotyped at 15 microsatellite loci. Age interpretations from the juvenile samples showed consistent cohorts starting in 2007 (2006-2012). Successful reproduction and recruitment by translocated adults was confirmed through genetic parentage analysis of microsatellite data, which linked juveniles to parents that had retained tags from the original translocation. Based on the microsatellite data, the genetic diversity of the reintroduced population (H O) was comparable to its source (H O = 0.57 ± 0.07 and 0.53 ± 0.06, respectively), although its estimated effective population size (N e) was lower (Mattagami = 20.4 [13.5-30.5]; Adam's Creek = ∞ [72.0-∞]). These results suggest that the experimental translocation of wild adult lake sturgeon was successful, and highlight the value of treating translocation efforts as experimental reintroductions. Rupnik, Emma Harten, Tarryn Adams, and Matt Werner (OMNRF), along with countless volunteers from Timmins Fur Council, Club Navigateur-La Ronde, Glencore Canada Corporation, Kidd Operations, and Lake Shore Gold. Laurent Robichaud for his guidance and knowledge. Staff of the OMNRF Fish Genetics Lab provided invaluable guidance and troubleshooting with lab work and genetic analysis. Funding was provided by Ontario Power Generation (OPG), Lake Shore Gold, and Glencore Canada Corporation, Kidd Operations, the Ontario Ministry of Natural Resources and Forestry (OMNRF), the Ministry of Environment and Climate Change (MOECC), Ontario Community Environment Fund, and managed by the Wintergreen Fund for Conservation.
Population genetic analysis of white sturgeon (Acipenser transmontanus) in the Fraser River
Journal of Applied Ichthyology, 2002
White sturgeon (Acipenser transmontanus) in the Fraser River are listed as imperiled (the second highest possible rating) by the British Columbia Conservation Data Centre. A difficulty in trying to protect this species in the Fraser River and elsewhere is the lack of knowledge regarding their population biology. Variation in the mitochondrial DNA control region and at four microsatellite loci was examined in order to characterize white sturgeon samples from throughout the Fraser River mainstem and from a major tributary, the Nechako River. Samples from the adjacent Columbia River were analyzed for comparison. In contrast to previous work, present data indicate that white sturgeon population structure in this region reflects post-glacial dispersal more than it does recent anthropogenic effects. The data divided the Fraser into four biogeographic regions: (i) the lower Fraser, below Hell's Gate; (ii) the middle Fraser, between Hell's Gate and river km 553; (iii) the upper Fraser, above the Nechako confluence; and (iv) the Nechako River. These four groups are concordant with those suggested by tag and recapture and catch per unit effort data, and are separated by what have been identified as barriers to white sturgeon migration. Based on concordance between these different types of data, it is argued that the four groups identified here merit evolutionarily significant unit (ESU) status.
Transactions of the …, 2000
The Atlantic sturgeon Acipenser oxyrinchus oxyrinchus has a latitudinally broad distribution along the east coast of North America, with extant populations occurring from the Saint Lawrence River to rivers in southern Georgia. This species once supported intensive caviar-based fisheries that resulted in overharvest and sharply reduced population abundances; presently, directed commercial fishing for Atlantic sturgeon is banned in U.S. waters. We sequenced a 203base-pair section of the mitochondrial DNA (mtDNA) control region of 322 Atlantic sturgeon specimens from 11 river systems across their range to elucidate their stock structure. We found a pronounced latitudinal cline in the number of composite mtDNA haplotypes and in haplotypic diversity, which increased from north to south, from previously glaciated and subsequently recolonized systems to the portion of their range unglaciated during the Pleistocene. The observed number of haplotypes per population ranged from 1 haplotype in each of the two northernmost population samples to 17 in the sample from the Savannah River. Haplotypic diversity ranged from 0.0 to 0.90. The greater genetic diversity within and among southern populations is likely a product of the persistence of these populations through the Pleistocene and to the faster mutation rates associated with their shorter generation times. Of 39 composite mtDNA haplotypes found, 64% were unique to particular populations. Monomorphism of the two Canadian populations suggested a strong founder effect. Three haplotypes unique to northern populations were probably the result of base substitutions that occurred within the past 10,000 years. In contrast with an earlier study, we found stock structure among southern populations and evidence of at least seven genetic stocks across this subspecies' range.