Abstract
Human activities have globally impacted populations, distribution, and biodiversity of wildlife. There is an increasing need for effective biomonitoring tools that can identify the habitat range of reptiles. Environmental DNA (eDNA) has been regarded as an emerging tool to detect specific target species, however, the dynamics of accumulation and degradation of eDNA in soil environments are poorly understood. This study was undertaken to determine the time required for terrestrial snakes to leave enough eDNA behind to become detectable (accumulation time) as well as its persistence (degradation time). Using a controlled laboratory-based model system within a closed terrarium and by targeting mitochondrial cytochrome oxidase subunit I and 12S rRNA genes of captive Corn Snakes (Pantherophis guttatus), I found that eDNA can be detected after 3.5 hours since the snakes had contact with soil and for up to six days after their removal. Estimated accumulation rate of P. guttatus eDNA per gram of snake biomass per hour was 9 µg. After determining accumulation and degradation time under laboratory settings, we targeted mitochondrial cytochrome b gene of a cryptic invasive species in South Florida, the Burmese Python (Python bivittatus). All field soil samples were collected from Gopher Tortoise (Gopherus polyphemus) burrows, which were split into two groups: “known” (i.e., radio telemetry evidence of P. bivittatus presence) and “unknown” (i.e., no radio telemetry evidence of P. bivittatus presence). Our eDNA analysis agreed with a standard burrow camera surveying method, there was no presence of P. bivittatus in the “unknown” burrows. Additionally, I was able to detect the presence of P. bivittatus eDNA in 66.7 % of the “known” sites that fit within our laboratory defined residence and degradation time window. Therefore, I conclude that eDNA technology using soil can be an effective management tool for terrestrial snakes, particularly when used with other traditional tracking and sampling methods.
