DOI: 10.5061/dryad.44j0zpcfc
title: Data from: Bioregions are predominantly climatic for fishes of northern lakes

description: Aim: Recurrent species assemblages integrate important biotic interactions
 and joint responses to environmental and spatial filters that enable local
 coexistence. Here, we applied a bipartite (site-species) network approach
 to develop a natural typology of lakes sharing distinct fish faunas and
 provide a detailed, hierarchical view of their bioregions. We then
 compared the roles of key biogeographic factors to evaluate alternative
 hypotheses about how fish communities are assembled from the regional
 species pool. Location: Ontario, Canada and the Upper Midwest, USA. Time
 period: 1957–2017. Major taxa studied: Freshwater fishes. Methods:
 Bipartite modularity analysis was performed on 90 taxa from 10,016 inland
 lakes in the Southwestern Hudson Bay, Mississippi River, and St. Lawrence
 River drainages, uncovering bioregionalization of North American fishes at
 a large, subcontinental scale. We then used a latent variable approach,
 pairing non-metric partial least-squares structural equation modelling
 with multiple logistic regression, to show differences in the
 biogeographic templates of each community type. Indicators of contemporary
 and historical connectivity, climate, and habitat constructs were
 estimated using a geographic information system. Results: Fish assemblages
 reflected broad, overlapping patterns of postglacial colonization,
 climate, and geological setting, but community differentiation was most
 linked to temperature, precipitation, and, for certain groups, lake area
 and water quality. Bioregions were also marked by non-native species,
 showing broad-scale impacts of introductions to the Great Lakes and
 surrounding basins. Main conclusions: The dominant effects of climate
 across broad spatial gradients indicate differing sensitivities of fish
 communities to rapidly accelerating climate change and opportunities for
 targeted conservation strategies. By assessing biological variation at the
 level of recurrent assemblages, we accounted for the non-stationarity of
 macroecological processes structuring different sets of species on the
 landscape, and thus offer novel inference on the assembly of inland fish
 communities.
description: Fish occurrence records in portions of the Southwestern Hudson
 Bay, St. Lawrence, and Mississippi River drainages were compiled from
 existing datasets in Ontario (Aquatic Habitat Inventory; Dodge, Goodchild,
 Tilt, Waldriff, & MacRitchie, 1987), Michigan (Status and Trends;
 Wehrly, Carter, & Breck, 2021), and Minnesota (Index of Biotic
 Integrity; Drake & Pereira, 2002). Fishes were sampled from lakes,
 ponds, reservoirs, and embayments during the open-water season over a
 60-year period (1957–2017) using a combination of netting, trapping, and
 electrofishing. Records of 132 fish taxa were initially compiled across
 11,112 lakes, but several species and lakes were removed (see manuscript
 for selection details). Our final dataset included 90 taxa
 across 10,016 lakes (mean species richness = 8).
 <strong>References</strong>
 Dodge, D.P., Goodchild, G.A., Tilt, J.C., Waldriff,
 D.G., & MacRitchie, I. (1987). <i>Manual of instructions:
 Aquatic habitat inventory surveys</i>. Ontario Ministry of Natural
 Resources, Toronto, Canada.
 Drake, M.T., & Pereira, D.L. (2002).
 Development of a fish-based index of biotic integrity for small inland
 lakes in Central Minnesota. <i>North American Journal of Fisheries
 Management</i>, 22, 1105–1123.
 Wehrly, K.E., Carter, G.S., & Breck, J.E.
 (2021). <i>Standardized sampling methods for the inland lakes status
 and trends program</i>. Fisheries Special Report. Lansing, MI:
 Michigan Department of Natural Resources.
description: Species at risk
 have been removed for their protection and those not used in analysis have
 also been excluded (see manuscript for selection details). As contractual
 requirements prevent us from releasing detailed sampling records for
 Ontario directly, these data are provided with approximate location
 coordinates. The full set of fish data (including species at risk) are
 readily available for non-commercial purposes from the Ministry of
 Northern Development, Mines, Natural Resources, and Forestry in Ontario
 (https://geohub.lio.gov.on.ca/datasets/aquatic-resource-area-polygon-segment-) and Departments of Natural Resources in Michigan (https://www.michigan.gov/dnr/0,4570,7-350-79137_79765_84005_84013---,00.html) and Minnesota (https://www.dnr.state.mn.us/waters/surfacewater_section/lake_ibi/index.html) through their standard data-sharing agreements.