fundamentals of eDNA

During this module, we made our introductions and talked a little about perceptions of eDNA, what it is, where it comes from, its development and history of use, and its applications. It was interesting to hear from others in the course about their personal experiences of the various perceptions of genetics and eDNA. I tend to only think of genetics and eDNA as a useful tool to better understand the environment. I rarely think of its applications in the medical and human research realms.

On Wednesday, we discussed two papers related to eDNA: Cristescu and Hebert (2018) and Tallbear (2013). The paper by Cristescu and Hebert (2018) is a good overview paper discussing the history, current status and methods, and potential issues of using eDNA. We discussed something we already know, something we learned from this paper, and something we might want to learn more about or explore further. I already knew a little bit about the topics discussed in this paper, but I would like to learn more about mock communities. I do not completely understand how they are made and how they are precisely used. I was surprised to learn about the extent of preservation in sediments. I primarily work with microbes, which are very abundant. So, I generally do not worry about eDNA preservation. I was particularly surprised about how long DNA may persist in terrestrial sediments. I would think that DNA would breakdown relatively fast if the sediments are oxygenated; therefore, fueling mineralization and oxygen-consuming microbial activity. The second paper we discussed by Tallbear (2013) discussed the history and current intersections between genomics and First Peoples. Overall, I had a really hard time reading this paper and had to read sections multiple times in addition to googling various terms and ideas. We were asked to discuss the definition of articulation, something we learned, and how the paper might apply to eDNA. In my own words, I think articulation is taking separate things/ideas and connecting them in new and different ways to form new interpretations, ideas, etc. based on a person’s worldview. I did not previously know that DNA testing was involved in tribal enrollment, which seems strange to me. For me, identity is not purely genetic; it is more about your upbringing, life experiences, and your personal identification. My group discussed how the paper might apply to eDNA and found that the topics in this paper were very related to eDNA, in that, eDNA can be a powerful, useful tool or a threat. For example, using eDNA to test for presence or absence has implications for preserving a species or shutting a fishery down.