The island fox is set to make the fastest recovery of any mammal ever listed under the Endangered Species Act, but it might need some genetic assistance.
After being at the brink of extinction, California Channel Island foxes have made a remarkable comeback, with three of six populations on the road to recovery. However, a new study released by researchers from Colorado State University (CSU) reveals a previously unknown threat to the future viability of some island fox populations.
The recent study, led by Chris Funk, represents the largest and most in-depth genetic analysis conducted on island foxes to date. In addition to confirming that each of the six Channel Island populations warrants designation as a unique subspecies, researchers found those living on San Nicolas Island could require genetic rescue to reduce their risk of extinction.
In other words, the San Nicolas Island fox has the lowest genetic variation ever found in a mammal species, making them especially vulnerable.
"Low genetic diversity may lead to lower survival and reproductive success, and may reduce the ability of a population to adapt to climate change or new, introduced diseases," explained Funk, who is an associate professor in the College of Natural Sciences' Department of Biology and director of the School of Global Environmental Sustainability Global Biodiversity Center at CSU. "With a dwindling population of fewer than 300 adults, actions need to be taken quickly to preserve this important member of the Channel Islands ecosystem."
The idea is that bringing foxes from other islands would help boost the San Nicolas gene pool. Researchers say this approach, known as "genetic rescue," has been successfully implemented in the past to save species such as the Florida panther in 1995.
The island fox is the smallest fox species in the U.S., native to six of the eight California Channel Islands. Following population declines, predation and an epidemic of canine distemper virus, four of the six subspecies, not including the San Nicolas population, were placed on the Endangered Species List in 2004.
"The recent island fox recovery was the result of an impressive collaboration of scientists and land managers. It may now be time to examine whether unconventional methods like genetic rescue are needed for the San Nicolas Island fox," said Scott Morrison, co-author of the study and director of science at The Nature Conservancy.
Pending genetic rescue is the chosen course of action, researchers urge that their findings can be used to select which of the island fox subspecies would be the best source population.
"Long-term monitoring of the island fox and new genomic technologies now give us the capacity for proactive management with far greater precision and a better expected outcome for island foxes in general," co-author Robert Lovich, a U.S. Navy biologist in California, concluded.
Their study was recently published in the journal Molecular Ecology.
