Historical, abiotic, and biotic drivers influence contemporary lacustrine fish community composition in the glacial Lake Agassiz basin

Historical determinants and local ecological filters tend to drive
community assembly at large and smaller spatiotemporal scales,
respectively. We examined the effects of differential contact to the
Wisconsinan deglaciation dispersal corridor, Lake Agassiz, and habitat
heterogeneity and species interactions on contemporary lacustrine fish
community composition in 261 northwestern Ontario lakes. Species
composition varied significantly across lakes grouped by their most recent
glacial lake coverage, driven by turnover, and the number of connections
(not-covered, single, and secondary contact) to the dispersal corridor
over time, explained by nestedness. Maximum lake depth, elevation, and
most recent stage of glacial lake coverage were dominant drivers of
community composition patterns; and most of the significant species
co-occurrence relationships were positive. While the dominant
environmental variables reflect the effects of habitat heterogeneity and
isolation from the dispersal corridor, the species co-occurrence analysis
results reflect the influence of environmental niche filtering and biotic
interactions in shaping lacustrine fish communities. The spatiotemporal
evolution of Lake Agassiz played a role as a historical determinant, and
habitat heterogeneity and local species interactions were ecological
determinants.