A review of applications of environmental DNA for reptile conservation and management

Abstract

Reptile populations are in decline globally, with total reptile abundance halving in the past half century, and approximately a fifth of species currently threatened with extinction. Research on reptile distributions, population trends, and trophic interactions can greatly improve the accuracy of conservation listings and planning for species recovery, but data deficiency is an impediment for many species. Environmental DNA (eDNA) can detect species and measure community diversity at diverse spatio‐temporal scales, and is especially useful for detection of elusive, cryptic, or rare species, making it potentially very valuable in herpetology. We aim to summarize the utility of eDNA as a tool for informing reptile conservation and management and discuss the benefits and limitations of this approach. A literature review was conducted to collect all studies that used eDNA and focus on reptile ecology, conservation, or management. Results of the literature search are summarized into key discussion points, and the review also draws on eDNA studies from other taxa to highlight methodological challenges and to identify future research directions. eDNA has had limited application to reptiles, relative to other vertebrate groups, and little use in regions with high species richness. eDNA techniques have been more successfully applied to aquatic reptiles than to terrestrial reptiles, and most (64%) of studies focused on aquatic habitats. Two of the four reptilian orders dominate the existing eDNA studies (56% Testudines, 49% Squamata, 5% Crocodilia, 0% Rhynchocephalia). Our review provides direction for the application of eDNA as an emerging tool in reptile ecology and conservation, especially when it can be paired with traditional monitoring approaches. Technologies associated with eDNA are rapidly advancing, and as techniques become more sensitive and accessible, we expect eDNA will be increasingly valuable for addressing key knowledge gaps for reptiles.

Assessing flower‐visiting arthropod diversity in apple orchards through metabarcoding of environmental DNA from flowers and visual census

“…As metabarcoding of arthropod eDNA from flowers can also be applicable both in and outside of agricultural systems to study (agro) ecological networks including plant–animal interactions or the impacts of climate change in wild arthropod populations (Deiner et al, 2017; Liu et al, 2020; Lucas et al, 2018; Nordstrom et al, 2022), future studies should seek to optimize arthropod eDNA detection from flowers. To do so, the metabarcoding workflow can be tweaked such as using two or more primers, which will allow for adequate amplification of low‐quality template DNA (Ficetola et al, 2015; Marquina et al, 2019; Thomsen & Sigsgaard, 2019; Zhan et al, 2014).…”

Integrating eDNA and citizen science observations to model distribution of a temperate freshwater turtle near its northern range limit

“…Relatively few eDNA studies have focused on reptiles compared to other vertebrates like fish or amphibians ( Davy, Kidd & Wilson, 2015 ; but see Piaggio et al, 2014 ), although this is changing as eDNA applications become more widespread ( Nordstrom et al, 2022 ). We designed and validated a probe-based qPCR assay to detect eDNA from S. odoratus .…”

“…Surveyed sites included shallow aquatic environments like littoral zones of lakes and rivers, slow-moving creeks and streams, and large wetlands, all potential musk turtle habitats ( Dreslik & Phillips, 2005 ; COSEWIC, 2012 ). Because eDNA shedding rates can vary markedly among organisms ( Andruszkiewicz Allan et al, 2021 ), and animals with hard keratinized integuments probably shed less DNA ( Nordstrom et al, 2022 ), we wished to test the ability of our eDNA assay to detect musk turtles. Thus, we undertook intensive sampling in the mid-sized Lake Opinicon (44.5°N, 76.3°W), approximately 50 km north of the city of Kingston, ON, where S. odoratus are known to occur ( Larocque et al, 2012 ) and vary in density in different parts of the lake.…”

Spatial prioritisation of survey and management efforts for a threatened pygopodid in south-western New South Wales

“…Dry conditions experienced from 2018 to 2020 may also have contributed to detection difficulties since reptile capture rates may decline following rainfall deficits (Schlesinger et al 2011). More novel detection methods, such as environmental DNA (eDNA), are increasing in use (Nordstrom et al 2022) and may be a more useful method for detecting highly cryptic species.…”

“…2011). More novel detection methods, such as environmental DNA (eDNA), are increasing in use (Nordstrom et al . 2022) and may be a more useful method for detecting highly cryptic species.…”