Community-wide Arctic DNA barcode library

Today, Molecular Ecology Resources just released a publication that establishes the to-date most comprehensive library of DNA Barcodes for a terrestrial site, including all known macroscopic animals and vascular plants of an intensively-studied area of the High Arctic, the Zackenberg Valley in Northeast Greenland.

In an earlier study the site was used to understand how feeding interactions are structured by focusing on one of the simplest food webs on Earth: the moths and butterflies of Zackenberg Valley, as attacked by their specialist enemies, parasitic wasps and flies developing on their host, killing it in the process. The work was the result of a five-year exploration of insect food webs of a rather simple system with perhaps only a handful of species to keep track of. A food web structure of manageable complexity which made researchers much more confident to have captured the full system and to have ruled out interactions that were not part of it. It turned out that this allegedly simplest food web one could possible find in the world was far more complex that previously thought. The game changer was the inclusion of DNA Barcoding technology and it indeed changed every measure of the food web structure with three times as many interactions between species as known before. On average, most types of predator proved less specialized than assumed, and most types of prey were attacked by many more predators than previously thought.

Now the colleagues took it up a notch. They barcoded 403 terrestrial animal and 160 vascular plant species recorded by morphology-based techniques. To demonstrate the utility of this reference library, the researchers used it to identify nearly 20 000 arthropod individuals from two Malaise traps, each operated for two summers.

Drawing on this material, we estimate the coverage of previous morphology-based species inventories, derive a snapshot of faunal turnover in space and time, and describe the abundance and phenology of species in the rapidly changing arctic environment.

The Malaise trap catches revealed 122 BINs (aka species) that hadn't been not detected by past sampling  efforts. Interestingly, the arctic insect community was strongly dominated by a very few hyperabundant taxa. Only five BINs were represented by more than ten individuals per trap day during at least one season – but of these, the two most abundant ones accounted for 5230 and 2256 individuals.

The authors also found substantial species turnover in space and time:
Focusing on the one year (2014) in which both Trap A and B were operated, we detected a difference of more than half of local species over a distance of less than 1 km (Fig. 1; Appendix S5). Examination of patterns in time similarly revealed large turnover. Year 2013, which was characterized by an early spring and unusually little snow, was different from the years of 2012 and 2014 which shared a late snow melt.

The new wealth of data and the fact that future research can build on a comprehensive barcode reference library allows the colleagues to go back to their foodweb analysis even though it will likely mean that the complexity will strongly increase. Nevertheless, understanding who feeds on whom and how often is the basis for understanding how nature is built and works.