Post-glacial dispersal and colonization processes have shaped community
patterns in sub-Arctic regions such as Churchill, Manitoba, Canada.
Important questions remain about the species that colonized this area,
in particular the role of glacial history and biological traits in
governing colonization patterns from refugial and southerly geographic
regions. This study quantifies sub-Arctic beetle phylogenetic community
structure using the net relatedness index (NRI) and nearest taxon index
(NTI); calculated using publicly available data from BOLD; compares
patterns across families with different traits (habitat, diet) using
standard statistical analysis (ANOVA) as well as phylogenetic
generalized least squares (PGLS) using a higher-level beetle phylogeny;
and compares phylogenetic community structure in Churchill with a region
in southern Canada (Guelph, Ontario). The dominant pattern detected in
our study was that aquatic families were much better represented in
Churchill compared to terrestrial families, when compared against
richness sampled from across Canada and Alaska. Individually, most
families showed significant phylogenetic clustering in Churchill.
Closely related species were likely found together due to the strong
environmental filtering present in Arctic environments. There was no
significant difference in phylogenetic structure between Churchill and
Guelph, although the trend was towards stronger clustering in the North.
Similarly, there was no difference in phylogenetic structure metrics
calculated for aquatic vs. terrestrial beetle families, again with a
trend towards stronger clustering in water beetles. By contrast, there
was a significant relationship between traits and community structure.
Predators showed significantly stronger clustering in Churchill compared
to other feeding modes, perhaps due to phylogenetic conservatism of
their overwintering ability or generalist diet of some clades within
families. This study contributes to our understanding of the traits and
processes structuring insect biodiversity and macroecological trends in