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Data from: Drivers of contemporary lacustrine fish species richness in the glacial Lake Agassiz basin
Illyes, Edina; Campbell, Sara E.; Mandrak, Nicholas E. — 2022-12-07 <p><strong>Aim</strong>: Biological communities are the result of a stepwise spatiotemporal filtering process, driven by large-scale historical and local contemporary determinants. The biogeographical pattern and species richness of North American fishes are predominantly determined by historical processes of past glaciations and postglacial dispersal and by contemporary environmental and ecological processes. Here, we evaluate the effects of postglacial dispersal through glacial Lake Agassiz and habitat heterogeneity, as represented by lake surface area, on contemporary freshwater fish species richness patterns of northwestern Ontario lakes.</p> <p><strong>Location</strong>: Northwestern Ontario, Canada</p> <p><strong>Taxon</strong>: Freshwater fishes</p> <p><strong>Methods</strong>: We applied the theory of island biogeography and species-area curves to examine the effects of isolation from the past dispersal corridor of glacial Lake Agassiz and habitat heterogeneity on species richness across 264 contemporary lakes in northwestern Ontario, Canada. While controlling for correlations among the predictor variables, generalized linear models were constructed between species richness, as the response variable and the explanatory variables of lake elevation and surface area and connection to the dispersal corridor of Lake Agassiz.</p> <p><strong>Results</strong>: Differential cover by glacial Lake Agassiz led to variation in fish species richness across contemporary lake basins and species richness is higher in lakes that were covered by Lake Agassiz relative to basins remaining outside of the boundaries of the glacial lake. Lake surface area is the strongest predictor of species richness, while lake elevation is the strongest factor predicting isolation as species richness decreases with increasing altitudes.</p> <p><strong>Main Conclusions</strong>: Habitat heterogeneity and postglacial colonization have led to differences in fish richness within the same geographical region. Fish species richness increases with lake surface area and decreases with elevation, likely driven by greater niche diversity facilitating the assembly of more diverse communities and isostatic rebound and fluctuating levels of Lake Agassiz isolating lakes at high elevations from the dispersal route earlier during the colonization process, respectively. These patterns underscore the importance of incorporating historical and environmental community determinants in biodiversity studies.</p>
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Data from: Environmental DNA detection of rare and invasive fish species in two Great Lakes tributaries
Balasingham, Katherine D.; Walter, Ryan P.; Mandrak, Nicholas E.; Heath, Daniel D. — 2017-10-26 The extraction and characterization of DNA from aquatic environmental samples offers an alternative, non-invasive approach for the detection of rare species. Environmental DNA, coupled with PCR and next-generation sequencing (“metabarcoding”), has proven to be very sensitive for the detection of rare aquatic species. Our study used a custom designed group-specific primer set and next-generation sequencing for the detection of three species at risk; (Eastern Sand Darter, Ammocrypta pellucida; Northern Madtom, Noturus stigmosus; and Silver Shiner, Notropis photogenis), one invasive species (Round Goby, Neogobius melanostomus) and an additional 78 native species from two large Great Lakes tributary rivers in southern Ontario, Canada; the Grand River and the Sydenham River. Out of 82 fish species detected in both rivers using capture-based and eDNA methods, our eDNA method detected 86.2% and 72.0% of the fish species in the Grand River and the Sydenham River, respectively, which included our four target species. Our analyses also identified significant positive and negative species co-occurrence patterns between our target species and other identified species. Our results demonstrate that eDNA metabarcoding that targets the fish community as well as individual species of interest provides a better understanding of factors affecting the target species spatial distribution in an ecosystem than possible with only target species data. Additionally, eDNA is easily implemented as an initial survey tool, or alongside capture-based methods, for improved mapping of species distribution patterns.
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Data from: Estimating potential global sources and secondary spread of freshwater invasions under historical and future climates
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Hubbard, Justin; Drake, D. Andrew R.; Mandrak, Nicholas E. — 2023-08-01 <p>Aim: We employ a climate-matching method to evaluate potential source regions of freshwater invasive species to an introduced region and their potential secondary spread under historical and future climates.</p> <p>Location: Global source regions, with primary introductions to the Laurentian Great Lakes and secondary introductions throughout North America</p> <p>Methods: We conducted a climate-match analysis using the CLIMATE algorithm to estimate global source freshwater ecoregions under historical and future climates with an ensemble of general circulation models for climate change scenario SSP5-8.5. Given existing research, we use a climate match of ≥ 71.7% between ecoregions to indicate climatic conditions that will not inhibit the survival of introduced freshwater organisms. Further, we estimate the secondary spread of freshwater invaders to the ecoregions of North America under historical and future climates.</p> <p>Results: We identified 54 global freshwater ecoregions with a climate match ≥ 71.7% to the recipient Laurentian Great Lakes under historical climatic conditions and 11 additional ecoregions were predicted to exceed the threshold under climate change. Three of the 11 ecoregions were located in South America, a continent where no matches existed under historical climates and eight were located in the southern United States, southern Europe, Japan, and New Zealand. Further, we identify 34 North American ecoregions of potential secondary spread of freshwater invasions from the Great Lakes under historical climatic conditions, and five ecoregions were predicted to exceed the threshold under climate change.</p> <p>Main conclusion: We provide a climate-match method that can be employed to assess the sources and spread of freshwater invasions under historical and future climate scenarios. Our climate-match method predicted increases in climate match between the recipient region and several potential source regions, and changes in areas of potential spread under climate change. The identified ecoregions are candidates for detailed biosecurity risk assessments and related management actions. The identified ecoregions are candidates for detailed biosecurity risk assessments and related management actions.</p>
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Data from: Hierarchical analysis of genetic structure in the habitat-specialist Eastern Sand Darter (Ammocrypta pellucida)
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Ginson, Robert; Walter, Ryan P.; Mandrak, Nicholas E.; Beneteau, Courtney L.; Heath, Daniel D. — 2016-01-08 Quantifying spatial genetic structure can reveal the relative influences of contemporary and historic factors underlying localized and regional patterns of genetic diversity and gene flow – important considerations for the development of effective conservation efforts. Using 10 polymorphic microsatellite loci, we characterize genetic variation among populations across the range of the Eastern Sand Darter (Ammocrypta pellucida), a small riverine percid that is highly dependent on sandy substrate microhabitats. We tested for fine scale, regional, and historic patterns of genetic structure. As expected, significant differentiation was detected among rivers within drainages and among drainages. At finer scales, an unexpected lack of within-river genetic structure among fragmented sandy microhabitats suggests that stratified dispersal resulting from unstable sand bar habitat degradation (natural and anthropogenic) may preclude substantial genetic differentiation within rivers. Among-drainage genetic structure indicates that postglacial (14 kya) drainage connectivity continues to influence contemporary genetic structure among Eastern Sand Darter populations in southern Ontario. These results provide an unexpected contrast to other benthic riverine fish in the Great Lakes drainage and suggest that habitat-specific fishes, such as the Eastern Sand Darter, can evolve dispersal strategies that overcome fragmented and temporally unstable habitats.

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(Author: Mandrak, Nicholas E.)

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