Abstract
BackgroundColeoptera is the most diverse order of insects (>300,000 described species), but its richness diminishes at increasing latitudes (e.g., ca. 7400 species recorded in Canada), particularly of phytophagous and detritivorous species. However, incomplete sampling of northern habitats and a lack of taxonomic study of some families limits our understanding of biodiversity patterns in the Coleoptera. We conducted an intensive biodiversity survey from 2006–2010 at Churchill, Manitoba, Canada in order to quantify beetle species diversity in this model region, and to prepare a barcode library of beetles for sub-arctic biodiversity and ecological research. We employed DNA barcoding to provide estimates of provisional species diversity, including for families currently lacking taxonomic expertise, and to examine the guild structure, habitat distribution, and biogeography of beetles in the Churchill region.ResultsWe obtained DNA barcodes from 3203 specimens representing 302 species or provisional species (the latter quantitatively defined on the basis of Molecular Operational Taxonomic Units, MOTUs) in 31 families of Coleoptera. Of the 184 taxa identified to the level of a Linnaean species name, 170 (92.4%) corresponded to a single MOTU, four (2.2%) represented closely related sibling species pairs within a single MOTU, and ten (5.4%) were divided into two or more MOTUs suggestive of cryptic species. The most diverse families were the Dytiscidae (63 spp.), Staphylinidae (54 spp.), and Carabidae (52 spp.), although the accumulation curve for Staphylinidae suggests that considerable additional diversity remains to be sampled in this family. Most of the species present are predatory, with phytophagous, mycophagous, and saprophagous guilds being represented by fewer species. Most named species of Carabidae and Dytiscidae showed a significant bias toward open habitats (wet or dry). Forest habitats, particularly dry boreal forest, although limited in extent in the region, were undersampled.ConclusionsWe present an updated species list for this region as well as a species-level DNA barcode reference library. This resource will facilitate future work, such as biomonitoring and the study of the ecology and distribution of larvae.
Highlights
Coleoptera is the most diverse order of insects (>300,000 described species), but its richness diminishes at increasing latitudes, of phytophagous and detritivorous species
Canadian insect richness tends to be greater in the west, in the Churchill region of northeastern Manitoba, Canada, the transition between boreal forest and open-ground habitats results in increased habitat heterogeneity, and this region is of great importance for understanding postglacial insect distributions [3,8,9,10]
The two Molecular Operational Taxonomic Unit (MOTU) (BINs) of C. unicolor formed a paraphyletic/monophyletic relationship in some NJ reconstructions (“other families” bootstrap analysis; Additional file 3) but a reciprocally monophyletic relationship in others, indicating an uncertain relationship between these MOTUs based upon the analysis presented here
Summary
Coleoptera is the most diverse order of insects (>300,000 described species), but its richness diminishes at increasing latitudes (e.g., ca. 7400 species recorded in Canada), of phytophagous and detritivorous species. Coleoptera is the most diverse order of insects (>300,000 described species), but its richness diminishes at increasing latitudes We conducted an intensive biodiversity survey from 2006–2010 at Churchill, Manitoba, Canada in order to quantify beetle species diversity in this model region, and to prepare a barcode library of beetles for sub-arctic biodiversity and ecological research. We employed DNA barcoding to provide estimates of provisional species diversity, including for families currently lacking taxonomic expertise, and to examine the guild structure, habitat distribution, and biogeography of beetles in the Churchill region. Beetle richness diminishes at increasing latitudes, and only 14% of Canadian beetle families occur north of the tree line [6]. Recolonization of the landscape following the Last Glacial Maximum (LGM) potentially included arctic species from the north and west (Beringia) as well as from the south as the ice receded
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