COI Barcode sequences for arthropod species from the high Appalachian Mountains, USA

Developing systematic conservation plans depends on a wealth of
information on a region's biodiversity. For 'dark taxa'
such as arthropods, such data is usually very incomplete and in most cases
left out from assessments. Sky islands are important and often fragile
biodiversity hotspots. Southern Appalachian high-elevation spruce-fir
forests represent a particularly threatened sky-island ecosystem, hosting
numerous endemic and threatened species, but their arthropods remain
understudied. Here we use voucher-based megabarcoding to explore genetic
differentiation among leaf-litter arthropod communities of these
highlands, and to examine the extent to which they represent dispersed
communities of more or less coherent species, manageable as a distributed
unit. We assembled a dataset comprising >6000 COI sequences
representing diverse arthropod groups to assess species richness and
sharing across peaks and ranges. Comparisons were standardized across taxa
using automated species delimitation, measuring endemism levels by
putative species. Species-richness was high, with sites hosting from
86-199 litter arthropod species (not including mites or myriapods).
Community profiles suggest that around one-fourth of these species are
unique to single sky islands and more than one-third of all species are
limited to a particular range. Across major taxa, endemicity was lowest in
Araneae, and highest in neglected groups like Isopoda, Pseudoscorpionida,
Protura, and Diplura. Southern Appalachian sky islands of spruce-fir
habitat host significantly distinct leaf litter arthropod communities,
with high levels of local endemicity. This is the first work to provide
such a clear picture of peak and range uniqueness for a taxonomically
broad sample. Ensuring the protection of a sizeable fraction of
high-elevation litter species richness will therefore require attention at
a relatively fine spatial scale.