Assessing Subterranean Arthropod Diversity through COI Barcoding in Two Ecoregions of Southwestern Virginia, USA

Subterranean arthropod communities are important components of North American ecosystems, contributing numerous ecosystem services and essential food-web functions. Despite this, fundamental information about species diversity in these communities remains unknown, and their taxonomic composition and ecological diversity have scarcely been assessed. Subterranean pitfall traps are a commonly used method for sampling endogean and hypogean soil habitats in Europe but have never been widely implemented in North America. Here, I employed this method to sample subterranean arthropod communities in the Ridge and Valley and Blue Ridge ecoregions of Virginia, USA in the winter and spring. In total, 2,260 arthropod specimens were collected constituting 319 distinct species. I extracted and purified DNA and amplified the mitochondrial gene: cytochrome C oxidase subunit I (COI) from each recovered morphospecies and derived a unique COI barcode for each species sequenced. Objective sequence clustering was used to establish molecular operational taxonomic units (mOTUs) for downstream diversity analyses and establishment of dynamic identification resources. Total species richness and average species richness per site were assessed and compared for both regions and seasons. The Shannon-Wiener diversity index, Hutcheson's t-test, and effective numbers of species (ENS) were employed to compare regional subterranean arthropod diversity. The richness, Shannon-Wiener, and ENS comparisons indicated that both ecoregions encompass highly diverse subterranean arthropod communities with those of the Ridge and Valley being significantly more diverse than those of the Blue Ridge.