Individual genotypes from environmental DNA: fingerprinting snow tracks
of three large carnivore species
Abstract
Continued advancements in environmental DNA (eDNA) research have made it
possible to access intraspecific variation from eDNA samples, opening
new opportunities to expand non-invasive genetic studies of wild animal
populations. However, the use of eDNA samples for individual genotyping,
as typically performed in non-invasive genetics, still remained
unachieved. We present the first successful individual genotyping of
eDNA obtained from snow tracks of three large carnivores: brown bear
(Ursus arctos), European lynx (Lynx lynx) and wolf (Canis lupus). DNA
was extracted using a protocol for isolating water eDNA and genotyped
using amplicon sequencing of short tandem repeats (STR) and, for brown
bear, a sex marker, on a high-throughput sequencing platform. Individual
genotypes were obtained for all species, but genotyping performance
differed among samples and species. Multilocus genotyping success for
individual identification was higher for brown bear samples (6 over 7),
than for wolf (7 over 10) and lynx (4 over 9) samples. The sex marker
was genotyped in 5 out of 7 brown bear samples. Results for three
species show that reliable individual genotyping, including sex
identification, is now possible from eDNA in snow tracks, underlining
its vast potential to complement the non-invasive genetic methods used
for wildlife. To fully leverage the application of snow track eDNA,
improved understanding of the ideal species- and site-specific sampling
conditions, as well as laboratory methods promoting genotyping success
are needed. This will also inform efforts to retrieve and type nuclear
DNA from other eDNA samples, thereby advancing eDNA–based individual
and population level studies.