Abstract
BackgroundArctic ecosystems, especially those near transition zones, are expected to be strongly impacted by climate change. Because it is positioned on the ecotone between tundra and boreal forest, the Churchill area is a strategic locality for the analysis of shifts in faunal composition. This fact has motivated the effort to develop a comprehensive biodiversity inventory for the Churchill region by coupling DNA barcoding with morphological studies. The present study represents one element of this effort; it focuses on analysis of the spider fauna at Churchill.Results198 species were detected among 2704 spiders analyzed, tripling the count for the Churchill region. Estimates of overall diversity suggest that another 10–20 species await detection. Most species displayed little intraspecific sequence variation (maximum <1%) in the barcode region of the cytochrome c oxidase subunit I (COI) gene, but four species showed considerably higher values (maximum = 4.1-6.2%), suggesting cryptic species. All recognized species possessed a distinct haplotype array at COI with nearest-neighbour interspecific distances averaging 8.57%. Three species new to Canada were detected: Robertus lyrifer (Theridiidae), Baryphyma trifrons (Linyphiidae), and Satilatlas monticola (Linyphiidae). The first two species may represent human-mediated introductions linked to the port in Churchill, but the other species represents a range extension from the USA. The first description of the female of S. monticola was also presented. As well, one probable new species of Alopecosa (Lycosidae) was recognized.ConclusionsThis study provides the first comprehensive DNA barcode reference library for the spider fauna of any region. Few cryptic species of spiders were detected, a result contrasting with the prevalence of undescribed species in several other terrestrial arthropod groups at Churchill. Because most (97.5%) sequence clusters at COI corresponded with a named taxon, DNA barcoding reliably identifies spiders in the Churchill fauna. The capacity of DNA barcoding to enable the identification of otherwise taxonomically ambiguous specimens (juveniles, females) also represents a major advance for future monitoring efforts on this group.
Highlights
Arctic ecosystems, especially those near transition zones, are expected to be strongly impacted by climate change
Overview of the spiders of Churchill: diversity and distributions c oxidase subunit I (COI) sequences >500 bp were recovered from 77% of the specimens analyzed (2704/3506) (Additional file 1, Additional file 3)
The joint morphological and DNA barcode analyses revealed 198 species representing 14 families and 98 genera (Table 1). This total includes 41% of the species of spiders known from Manitoba [1,19] and 14% of those recorded from Canada and Alaska [84]
Summary
Especially those near transition zones, are expected to be strongly impacted by climate change Because it is positioned on the ecotone between tundra and boreal forest, the Churchill area is a strategic locality for the analysis of shifts in faunal composition. The present study represents one element of this effort; it focuses on analysis of the spider fauna at Churchill Arctic ecosystems, especially those positioned on transition zones, are recognized as areas where the impacts of climate change will be observed first [1]. Recent studies of several arthropod groups at Churchill, coupling morphological and DNA barcode analysis, have revealed unexpectedly high diversity and many undescribed species [2,3,4,5,6,7,8,9,10] These results have reinforced the need for additional molecular work on the fauna of this region. The present study responds to this need for a key group of invertebrate predators—spiders
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