A ten year study of the Santa Monic mountain lions published in the August 14 edition of Current Biology paints a grim picture of the future. The population, researchers say, is almost completely isolated from other mountain lion populations which has created dangerously low levels of genetic diversity.

The diversity level is so low that a single male that immigrated and mated in 2009, the only new arrival over the period of the study, substantially the enhanced genetic diversity of the entire population by himself. Normally 75% of young lions, including all of the males, would disperse to different regions.

“Many of these phenomena, including very low genetic diversity and close inbreeding, have only been previously seen in Florida panthers, an endangered and completely isolated population of mountain lions. In our case, the fact that lions in the Santa Monica Mountains are completely surrounded by roads and development likely lead[s] to behaviors that would be rare or nonexistent if normal population and social processes could occur,” said Seth Riley of the National Park Service in a statement.

The researchers found evidence of close inbreeding, including breeding between fathers and daughters. The study also reports evidence of interspecies violence, including the killing of mates, siblings and offspring. These behaviors would be rare or nonexistent with enhanced movement between populations according to Riley and his colleagues.

Increased connectivity is critical to the long-term survival of mountain lions and would have a positive impact on the ecosystem and wildlife of the region.

“If wildlife connectivity is not considered and planned for, or improved in places like southern California where it has mostly been lost, large carnivores, which exist at very low densities and need to move great distances, will not persist,” said Riley.

Fortunately the one male to immigrate demonstrates that it would not take much migration to improve biodiversity.