The detection and quantification of aquatic reptilian environmental DNA

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Adams, Clare
Major Professor
Fredric J. Janzen
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Ecology, Evolution, and Organismal Biology

Monitoring individuals of a population is aided by sampling techniques for determining organism presence. However, invasive sampling methods may harm target and non-target individuals, not capture a fully representative population demographic, or may be difficult to use due to secretive and seasonally active species. Recent developments in non-invasive technology propose environmental DNA (eDNA) as a solution to mitigate some of these challenges. Environmental DNA is DNA captured from target organisms that is extracted from environmental samples such as water, soil, or air. Although this technique has been widely explored for fish and amphibian species, it is used less often for aquatic reptiles. This thesis attempts to create an eDNA methodology for an imperiled reptilian taxa, turtles, for future monitoring use. We set up four experimental ponds with varying numbers of turtles (0, 11, 23, 38) and sampled once every three days throughout the spring field season to determine effects of painted turtle (Chrysemys picta) density and time on eDNA technique utility. The first chapter compares two common eDNA methodologies, filtration and sodium acetate precipitation in a Midwestern lentic semi-natural environment. The second chapter uses the more efficient filtration to quantify eDNA based upon turtle abundance in the same environment.

We conclude that eDNA may not currently be an effective monitoring method for aquatic turtles. Overall, filtration was a more effective approach to capturing turtle eDNA than sodium acetate precipitation but visual surveys of turtles in our experimental setup led to an even higher rate of detection. Despite developing a sensitive qPCR protocol, we were unable to amplify turtle eDNA sufficiently to distinguish it from the negative control. We nonetheless identified a rank-order trend positively correlated with turtle density despite not obtaining large amounts of species-specific turtle eDNA. Furthermore, we found that total eDNA concentration did not follow a linear pattern throughout the field season. While we cannot recommend eDNA for aquatic turtles at this time, we believe this method could be refined with further technological advances such as better inhibition removers.

Sun Jan 01 00:00:00 UTC 2017