Environmental DNA from Residual Saliva for Efficient Noninvasive Genetic Monitoring of Brown Bears (Ursus arctos)

PLoS One. 2016 Nov 9;11(11):e0165259. doi: 10.1371/journal.pone.0165259. eCollection 2016.

Abstract

Noninvasive genetic sampling is an important tool in wildlife ecology and management, typically relying on hair snaring or scat sampling techniques, but hair snaring is labor and cost intensive, and scats yield relatively low quality DNA. New approaches utilizing environmental DNA (eDNA) may provide supplementary, cost-effective tools for noninvasive genetic sampling. We tested whether eDNA from residual saliva on partially-consumed Pacific salmon (Oncorhynchus spp.) carcasses might yield suitable DNA quality for noninvasive monitoring of brown bears (Ursus arctos). We compared the efficiency of monitoring brown bear populations using both fecal DNA and salivary eDNA collected from partially-consumed salmon carcasses in Southeast Alaska. We swabbed a range of tissue types from 156 partially-consumed salmon carcasses from a midseason run of lakeshore-spawning sockeye (O. nerka) and a late season run of stream-spawning chum (O. keta) salmon in 2014. We also swabbed a total of 272 scats from the same locations. Saliva swabs collected from the braincases of salmon had the best amplification rate, followed by swabs taken from individual bite holes. Saliva collected from salmon carcasses identified unique individuals more quickly and required much less labor to locate than scat samples. Salmon carcass swabbing is a promising method to aid in efficient and affordable monitoring of bear populations, and suggests that the swabbing of food remains or consumed baits from other animals may be an additional cost-effective and valuable tool in the study of the ecology and population biology of many elusive and/or wide-ranging species.

MeSH terms

  • Alaska
  • Animals
  • DNA / analysis*
  • DNA / genetics
  • DNA / isolation & purification
  • Environment*
  • Female
  • Genotype
  • Geography
  • Male
  • Oncorhynchus / classification
  • Oncorhynchus / metabolism*
  • Polymerase Chain Reaction
  • Predatory Behavior / physiology*
  • Saliva / chemistry*
  • Seasons
  • Sequence Analysis, DNA / methods
  • Species Specificity
  • Specimen Handling / economics
  • Specimen Handling / instrumentation
  • Specimen Handling / methods
  • Ursidae / physiology*

Substances

  • DNA

Grants and funding

This work was funded by an NSF GRF to REW, and grants from the International Bear Association, the Alaska Chilkoot Bear Foundation, and the National Geographic Society (grant #14-1544). Publication of this paper was supported, in part, by the Thomas G. Scott Publication Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.