Environmental DNA (eDNA) represents a novel species detection method based on the collection and analysis of genetic material shed from organisms into their environment. Although this method has typically focused on soil and water samples, recent research has demonstrated the viability of airborne eDNA collection and analysis, which has the potential to revolutionize the way researchers study and monitor terrestrial plant communities. However, little is known about what influences the release of airborne eDNA and its ecology. The goal of this project was to quantify how human activity on the landscape impacts airborne eDNA detection and analysis.
Plant eDNA signals were analyzed near a honey mesquite removal project which utilized chainsaws and chemical herbicides to manage honey mesquite trees on the study site. To collect airborne eDNA, we deployed passive dust sampling traps in a before, after, control, and impact (BACI) design, with samples in both a treatment and control area, before, during, and after tree removal. Changes in eDNA signals over time were analyzed with quantitative PCR (qPCR) targeting global plant sequences, honey mesquite, and blue grama to understand how eDNA from the two most common species within the study site were impacted by human activity.
Results/Conclusions
The data collected from our airborne eDNA survey helped to show the impact of human activity on the landscape, the ecology of airborne eDNA, and the way airborne eDNA moves through the air. We successfully detected airborne eDNA from both wind pollinated and insect pollinated species. Across all the traps, we detected honey mesquite 100% of the time and blue grama 96% of the time. However, we found on average, .324 pg/µl of eDNA for honey mesquite and 2.21 pg/µl of eDNA for blue grama. Additionally, airborne eDNA samples varied over time and space in relation to human activity on the landscape. These results help to establish the validity of airborne eDNA as a community monitoring tool and provide insight into the ecology of airborne eDNA and the material that is being collected. Furthermore, we illustrated that humans can influence the release of airborne eDNA. In conclusion, further understanding of airborne eDNA ecology will help to establish airborne eDNA as an effective plant community monitoring tool. Future studies should also look to apply a next-generation sequencing approach to analyze airborne eDNA community data.