Environmental DNA breakthrough reveals genetic diversity of invasive fish

Ecologists have demonstrated that genetic material shed by species into their environments can reveal not only the presence of species but also a wide range of information about the genetics of entire populations.

Advances in environmental DNA (eDNA) open new possibilities for protecting endangered and vulnerable species and managing destructive invasive species.

“This achievement is part of an ongoing trajectory of learning more and more about eDNA, as this new study explores genetic variation within a species,” said study co-author David Lodge, the Francis J. DeSalvo Director at Cornell Atkinson Research Center. Sustainability. “In order to preserve biodiversity, we are getting closer and closer to what forensic scientists do every day at crime scenes.”

In the new study published in Proceedings of the National Academy of Sciencesthe researchers demonstrated that their methodology was successful in field sampling invasive round gobies throughout the Great Lakes and New York’s Finger Lakes.

This work builds on a pilot study conducted in Cayuga Lake two years ago, when researchers took tissue samples from round gobies and eDNA samples of the waters the fish inhabited. They found that the two methods provided comparable genetic information.

The first author of both studies is Cara Andres, Ph.D. ’22, a former graduate student in the Lodge lab and now a postdoctoral fellow at Washington University in St. Louis. The paper was written with co-authors Lodge, who is also a professor in the Department of Ecology and Evolutionary Biology in the College of Agriculture and Life Sciences, and José Andrés, a Cornell Atkinson faculty fellow and senior research associate who co-directs the Cornell Core Facility for DNA and Environmental Genomics.

In the cells of most animals, the nucleus contains two copies of the complete genetic code, but each cell contains 100 to 1,000 copies of a smaller, stripped-down version of the genetic code in the mitochondria. Most of the research on eDNA to date has focused on mitochondrial DNA, because it is likely more abundant in environmental samples, Kara Andres said. While mitochondrial DNA works well at distinguishing between species, it provides much less information than nuclear DNA about diversity within species.

“The nuclear genome is much larger and contains a lot of diversity within species,” Cara Andres said. “When I started my PhD, we didn’t know anyone who had tried to look for variation within the nuclear genome in the context of eDNA sampling, and we didn’t even know if it was possible.”

In their Great Lakes study, which involved collecting water and tissue samples from round gobies at 13 sites from Lake Michigan to Oneida Lake, the researchers found that their e-DNA sampling methodology could be used to detect nuclear genetic variations, making it possible to analyze Genetics. Diversity and difference within species. This information is useful to natural resource managers because it can help them track the source of new invasive populations as well as prevent further invasion or reduce damage by determining how invasive species move and how to stop them.

This breakthrough could also help scientists understand the demographics of species at risk without having to actually hunt already rare and vulnerable animals. Species experiencing declining populations can suffer a loss of genetic diversity, and eDNA may allow researchers to detect this decline earlier, Cara Andres said.

“This is a big step in unlocking the full potential of genomics techniques when applied to aqueous eDNA samples,” said José Andres. “In the near future, I expect this technology will allow us to study the status and health of elusive species. I believe this has profound implications, especially in marine environments.”