Geographic source estimation using airborne plant environmental DNA in dust

Area of Science:

• Environmental Science
• Forensic Science
• Molecular Biology

Background:

• Microscopic analysis of dust components like pollen and spores is useful for forensic geolocation.
• Manual analysis is time-consuming and requires specialized expertise.
• Developing automated methods for dust analysis can improve efficiency and accuracy.

Purpose of the Study:

• To develop and validate a pipeline for forensic geolocation using airborne plant environmental DNA (eDNA) in settled dust.
• To assess the accuracy and resolution of eDNA-based geolocation.
• To determine the influence of seasonal variation and species identification on geolocation accuracy.

Main Methods:

• Airborne plant eDNA from settled dust samples was analyzed using metabarcoding.
• Identified plant species' geographic distributions were obtained from the USGS BISON database.
• Probabilistic source estimation was performed using the derived species distributions.

Main Results:

• Regional geolocation (within 600 km²) was achieved for 47.6% of samples collected over 15 months.
• Geolocation accuracy improved with a higher number of identified plant species (66.7% success with ≥20 species).
• Citizen-collected samples from 31 U.S. sites yielded relevant regional attribution in 32.2% of cases.

Conclusions:

• Airborne plant eDNA analysis in settled dust provides a viable method for regional forensic geolocation within the U.S.
• The method offers valuable forensic information, especially when sufficient plant species are identified.
• Seasonal factors significantly impact the number of identifiable plant species and thus geolocation accuracy.