Efforts to rescue endangered species can take many forms, and for the Lassen red fox, genetics may offer a lifeline. Recent genomic research led by the University of California, Davis (UC Davis), explores the potential for genetic rescue to aid in the recovery of this rare mountain-dwelling fox, which is found in the Lassen Peak region of California. The study, published in Molecular Biology and Evolution, reveals important insights that could help revive the population, which currently numbers fewer than 30 individuals.
Impact of Inbreeding on Lassen Red Foxes
The Lassen red fox population has been severely affected by inbreeding, which compromises their fitness and ability to reproduce. This decline has historical roots: thousands of years ago, red foxes in these mountainous areas were not only more abundant, but also better connected to neighbouring populations in Oregon, the Rocky Mountains, and the Washington Cascades. These connections have since deteriorated, reducing genetic diversity. However, the study suggests that these populations were not isolated until relatively recently, making the possibility of genetic rescue a feasible option.
What is Genetic Rescue?
Genetic rescue is a conservation technique used to introduce genetic variation into a population suffering from inbreeding depression. By bringing new individuals into the group, genetic diversity increases, allowing the population to grow and recover. While this method is promising, it requires careful consideration of the degree of inbreeding and a clear understanding of the historical genetic diversity that needs to be restored.
Lead researcher Cate Quinn, a former UC Davis postdoctoral researcher, now with the USDA Forest Service, notes, "Nothing we found disqualifies red foxes from genetic rescue. The study suggests that genetic rescue could be a viable option for the Lassen population."
The Path Forward
The research involved sequencing 28 complete genomes from four subspecies of montane red foxes, including populations from the Pacific Mountains, the Oregon Cascades, the Sierra Nevada, and the Rocky Mountains. The results revealed high levels of recent inbreeding in both the Lassen and Sierra Nevada foxes, with the Lassen foxes highlighted as a priority for intervention. Only one fox has entered the Lassen population in the last two decades.
Additionally, the data show that 10,000–12,000 years ago, red foxes in the Western United States were abundant, diverse, and well-connected. Quinn believes that the Lassen population was connected to the Oregon red foxes until relatively recently, raising hopes for re-establishing these links.
Hope for Restoration
These findings point to a hopeful future for the Lassen red foxes and other fox populations facing similar genetic challenges. Ben Sacks, senior author of the study and director of the Mammalian Ecology and Conservation Unit at UC Davis, highlights that inbreeding depression appears to be the primary factor keeping their population small. "If what drove their decline is gone, can we bring them back? There is hope here," Sacks said.
Quinn adds, "This was once an abundant, connected, diverse population, and that genetic diversity still exists. If we restore them as a group, these foxes may have significant adaptive potential."
However, Quinn stresses that a true genetic rescue requires reconnecting the entire subspecies, not just individual populations. She concludes, "If we only consider each small pocket individually, they're in trouble, but if we look at the whole montane system, restoration is still possible."
The research provides a promising pathway for restoring Lassen red foxes and demonstrates the importance of understanding genetic history when planning conservation efforts.
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