DNA Tools Outperform Traditional Methods for Detecting Genetic Risk in Wildlife

Wildlife populations facing decline due to habitat loss and other factors often experience inbreeding, which can threaten their long-term survival. Conservation efforts sometimes involve genetic rescue – introducing individuals from outside the population to increase genetic diversity. But determining whether a genetic rescue has been successful requires accurate monitoring of inbreeding levels.

Genomic Monitoring Provides a More Accurate Picture

A new study from Western University, led by biology professor and chair David Coltman, demonstrates that DNA-based tools are more effective at tracking changes in inbreeding than traditional pedigree methods. The research, published in the journal Evolutionary Applications, focused on a wild population of bighorn sheep (Ovis canadensis) in Ram Mountain, Alberta, Canada, monitored from 1972 to the present.

Pedigree methods estimate genetic health based on family history, while genomic approaches directly analyze DNA. Coltman, graduate student Carson Mitchell, and their collaborators compared these two methods in the bighorn sheep population.

The DNA-based method proved more responsive to population changes, revealing trends that pedigree analysis missed. This is the first study to directly compare these two inbreeding metrics during a genetic rescue event.

The Importance of Conservation Translocation

Conservation translocation – the deliberate movement of organisms to aid conservation – is a common practice in wildlife management. In North America, wildlife managers have performed over 1,500 translocations of bighorn sheep in the past century to strengthen herds and increase genetic diversity [1]. These efforts aim to stabilize smaller populations and ensure the long-term health of the species.

“Translocations are a critical tool used in bighorn sheep management,” said Coltman, a faculty member of Western’s Centre for Animals on the Move. “These are expensive and risky undertakings, and sometimes they succeed at genetically rescuing a struggling population and sometimes they fail.”

Genomic Monitoring for Effective Conservation

Because inbreeding poses a significant threat to many small wildlife populations, these findings have critical implications for conservation management. Genomic monitoring allows for more effective assessment of at-risk wildlife populations.

“Using a snapshot of the genome from a DNA sample, we can now clearly spot the genetic consequences of a translocation, we can better monitor populations at risk and post-rescue, and we can plan for more successful translocations in the future,” Coltman explained.

The long-term dataset from the Ram Mountain field site in Alberta, collected over 55 years by graduate students like Mitchell, was crucial for this research. Mitchell noted that while they expected the DNA-based approach to be more accurate, they were surprised by the extent of the differences between the two methods.

“The pedigree suggested inbreeding was increasing, while the DNA showed it declined after the translocation. Without the DNA data, we could have reached the wrong conclusion about how this population is responding to management,” Mitchell said.