Is Lichen the Linchpin of Woodland Caribou’s Diet?
We’ve all heard the saying “you are what you eat”, but did you know that what we eat can also tell us a lot about how to conserve species? A group of Trent researchers set out to gain a better understanding of the diet of woodland caribou to contribute to the conservation efforts of this threatened species, and they did it by looking at DNA from food that has survived the journey of the caribou digestive tract.
The new paper, published May 12 in the journal FACETS, is based on an undergraduate research thesis by Greniqueca Mitchell, who recently graduated from Trent with a joint major in Forensic Science and Biology. Working closely with Biology professors, Dr. Linda Rutledge and Dr. Paul Wilson, Greniqueca used a technique called DNA metabarcoding to study the diet of caribou in an environment where lichen—their favourite food—was in short supply.
Caribou depend on lichen as their primary winter food source, but what if lichen isn’t available?
“Our findings provide new insight into caribou diet,” says Greniqueca (Otonabee College). “There aren’t many studies on this, especially in the case where DNA reveals such a drastic shift in what they are consuming, compared to the lichen-focused winter diet caribou typically have.”
DNA metabarcoding is still a relatively new tool in ecology but is becoming a very popular way to look at how animals are interacting with their prey or the plants they forage on.
“Fragmented bits of DNA from consumed food survive the digestive process and end up in the scat,” explains Professor Rutledge. “So, we can identify the food items that the animal consumed by comparing the genetic sequences we retrieve from the feces to a reference database of known species-specific sequences.”
Unfreezing the past to provide insights today
For her research, Greniqueca compared archival scat samples collected from the north shore region of Lake Superior (a lichen-rich environment) and from Michipicoten Island (a lichen-poor environment). The samples had been stored at -20°C for over 10 years in the lab of Professor Wilson, who leads a large-scale EcoGenomics research program to noninvasively monitor Canadian caribou.
The research team found that the caribou on Michipicoten Island predominantly consumed yew, confirming the dietary versatility of caribou. Although preliminary in nature, this study contributes valuable data and methodology on archived samples for future research into the dietary habits of woodland caribou and the conservation of these animals.
“The methodology used can be applied across other species to aid in better understanding their diets and how to utilize that information in preserving their species in regard to possible translocation and surviving environmental changes that are occurring,” adds Greniqueca.
Novel research supported by government scientists
Greniqueca had the added advantage working with researchers from the Ministry of Northern Development, Mines, Natural Resources & Forestry (NDMNRF), who work on campus at Trent and often collaborate with faculty researchers. Greniqueca worked with Dr. Brent Patterson, whose research focuses on understanding the dynamics of the predator-prey systems of mammals and determining the factors that cause changes in the distribution and abundance of animals.
She also collaborated with the Riverview Park and Zoo in Peterborough, where she collected scat samples from the reindeer enclosure, which served as a control sample for the study. These collaborations, together with the support and guidance she received from the highly skilled lab technicians in the on-campus genetics labs were also key to the success of Greniqueca’s research project.
“Working with the NDMNRF and the Riverview Park and Zoo was great,” says Greniqueca. “My research topic was fairly new to me and required a lot of research on my end. The NDMNRF really helped in filling in some gaps and was more than happy to answer any questions I had.”
Fostering a love for lab work
For Greniqueca, a highlight has been the opportunity to work in Trent’s state-of-the-art Genomics Laboratory alongside leading researchers.
“Being able to complete the thesis along with my other courses definitely gave me a boost,” Greniqueca explains. “Being able to have the hands-on lab experience, writing a paper, and doing my own analysis made me feel that I was ready to complete a master’s degree and possibly a Ph.D.”
Posted on May 12, 2022