A highway runs through it: Mountain lions in southern California face genetic decay

PUBLIC RELEASE DATE:

8-Oct-2014

Contact: Holly Ernest hernest@uwyo.edu 307-766-6605 University of California - Davis @ucdavis

Cut off by freeways and human development, mountain lions in southern California are facing a severe loss of genetic diversity, according to a new study led by the University of California, Davis in partnership with The Nature Conservancy.

The study, published today in the journal PLOS ONE, represents the largest genetic sampling of mountain lions, or pumas, in southern California. It raises concerns about the current status of mountain lions in the Santa Ana and Santa Monica mountains, as well as the longer-term outlook for mountain lions across southern California.

UC Davis School of Veterinary Medicine scientists collected and analyzed DNA samples from 354 mountain lions statewide, including 97 from southern California. Pumas in the Santa Ana Mountains displayed lower genetic diversity than those from nearly every other region in the state.

Santa Ana mountain lions show dramatic genetic isolation and have less in common with their neighbors in the Santa Monica Mountains than with those in the Sierra Nevada, underscoring the increasing seclusion of pumas in southern California.

The Santa Ana Mountain range, located south of Los Angeles and north of San Diego, is surrounded by urbanization and a growing population of about 20 million people. A small habitat linkage to the southeast connects pumas to the Peninsular Range, but it is bisected by Interstate 15 -- a busy 10-lane highway -- and associated human development. The study highlights the urgency to maintain and enhance the little connectivity remaining for coastal mountain lions, particularly across I-15.

The study also showed that the Santa Ana pumas recently went through a "population bottleneck," when the population's size sharply decreased to a fraction of its original size.

"The genetic samples give us a clear indication that there was a genetic bottleneck in the last 80 or so years," said lead author Holly Ernest, a professor with the Karen C. Drayer Wildlife Health Center and the Veterinary Genetic Laboratory at UC Davis at the time of the study. She is now a professor at the University of Wyoming, Laramie. "That tells us it's not just natural factors causing this loss of genetic diversity. It's us people impacting these environments."