A recent study indicates that a small, isolated population of red foxes in California’s Lassen Peak area is suffering from the effects of inbreeding. The research suggests that implementing genetic rescue strategies could effectively aid in reviving these montane red foxes.
Rescue initiatives can take various forms — it could be a lifebuoy, a firefighting solution, or an aerial evacuation. For animal populations on the decline due to inbreeding, advancements in genetics might offer a path to survival.
Research led by the University of California, Davis, uncovers valuable insights into the historical context of montane red foxes that may be crucial for their future. This study, published in the journal Molecular Biology and Evolution, investigates the possibilities of genetic rescue as a means of replenishing the dwindling populations of these mountain-dwelling red foxes. The findings are particularly significant for the small and declining group of about 30 red foxes remaining in the Lassen Peak region of California.
The study identified that inbreeding is adversely affecting the Lassen red fox population. Historically, red foxes were plentiful and well-connected across nearby regions including Oregon, the Rocky Mountains, and the Washington Cascades, long before their numbers were drastically reduced in the late 19th and early 20th centuries due to trapping and poisoning. This historical connectedness presents an opportunity for genetic rescue, should wildlife managers decide to reconnect different populations.
“Our findings don’t rule out the potential for genetic rescue in red foxes,” stated Cate Quinn, the lead author and a former postdoctoral researcher at UC Davis. She is currently a research biologist with the USDA Forest Service Rocky Mountain Research Station. “The evidence points to genetic rescue being a feasible option for the Lassen population.”
The Role of Genetic Rescue
Genetic rescue is a conservation strategy aimed at mitigating the effects of inbreeding depression, which occurs when inbreeding lowers an animal’s viability and reproductive success. This strategy entails introducing new individuals to a population, thereby increasing genetic diversity and fostering population growth.
Before undertaking such measures, conservation managers must thoroughly assess the degree of inbreeding, what baseline genetic diversity they aim to restore, and the evolutionary connections among the fox populations.
To enhance their understanding, researchers sequenced the complete genomes of 28 montane red foxes from four different subspecies. This research encompassed small, isolated populations located in the Pacific mountains, Oregon Cascades, Lassen Cascades, and the Sierra Nevada, in addition to a larger group in the Rocky Mountains and a subspecies in the Sacramento Valley. By employing genomic technology, the authors were able to trace the historical connectivity among populations and determine when such connections began to deteriorate.
Connected and Diverse History
The findings demonstrated significant recent inbreeding issues among the Lassen and Sierra Nevada red fox populations, pointing to the Lassen population as a top priority for conservation intervention. It has been noted that in over two decades of monitoring, only one additional montane red fox has joined the Lassen population.
Historical data revealed that between 10,000 and 12,000 years ago, montane red foxes in the western U.S. were abundant, well-connected, and genetically varied. Moreover, the Lassen population was likely linked to Oregon’s red foxes until fairly recently, according to Quinn.
A Promising Outlook
Collectively, these findings inspire optimism for the future of the Lassen red foxes and for other similar populations facing related difficulties.
“We believe that trapping significantly reduced their population, but we didn’t previously understand what has kept their numbers low,” remarked Ben Sacks, the senior author and director of the Mammalian and Ecology Conservation Unit at UC Davis. “Now we understand that inbreeding depression is a major factor. If the elements that led to their decline are not present anymore, can we reverse the trend? There’s reason to believe there is hope.”
Quinn concurs: “In the past, this was a diverse and interconnected population. That diversity is still within them. If we could restore them as a collective, these foxes may still carry considerable adaptive potential.”
However, she warns that effective genetic “rescue” means reconnecting the entire subspecies, rather than simply expanding one separate population.
“If we only focus on isolated groups, they face serious risks, but if we consider the entire montane ecosystem, a successful restoration could still be achievable,” noted Quinn.
Co-authors of the study include Sophie Preckler-Quisquater from UC Davis and Michael Buchalski from the California Department of Fish and Wildlife.
The research received funding from the U.S. Fish and Wildlife Service, California Department of Fish and Wildlife, and UC Davis.
