Data from: Bioregions are predominantly climatic for fishes of northern lakes

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.