Fifty years. That's how long it could take for two populations of mountain lions in Southern California to go extinct under current conditions, according to new research.

"We'd be losing the top predator from these two mountain ranges and we see mountain lions as an important component of a functioning, healthy, intact ecosystem,” said John Benson, the study’s lead author and professor with the University of Nebraska.

It’s not that the populations are too small, Benson said. It’s a genetic diversity problem due to inbreeding and connectivity issues. Cities, real estate and freeways keep the lions from breeding with other populations.

Benson says the research predicts rapid extinction is almost certain.

"It's not enough to just say we have mountain lions in the state, so we don't need them in these mountain ranges,” Benson said. “We think there is value to maintaining their ecological role within these two isolated mountain ranges.”

He says there are about 30 mountain lions within both ranges. But the entire study isn't pessimistic. The trend could change if more animal bridges are built over highways.

“These populations can persist with relatively modest increases in landscape connectivity,” Benson said. “If we can maintain healthy populations of mountain lions — a species that roams widely and requires such large spaces — here in greater Los Angeles, that bodes well for our ability to conserve large carnivores anywhere.”

But making the necessary changes will take a lot of work, Benson says.

Still, there efforts are underway to correct the issue. Report co-author T. Winston Vickers with UC Davis’s Karen C. Drayer Wildlife Health Center says in the Santa Monica Mountains, lions are most at risk when crossing Interstate 15. There they are often killed by cars or after a lion eats or attacks livestock or pets, he said in a press release.

“Efforts are underway with highway engineers to improve wildlife crossing structures or build new ones on both the I-15 and 101 freeways to enhance movement into and out of both mountain ranges,” Vickers said.

For more than two decades National Park Service wildlife ecologist Seth Riley has studied mountain lions in the Santa Monica mountains. He said it’s “sobering to see the fast rates of extinction the predictions predicted … However, it’s also really heartening to see how much of a difference increasing connectivity can make for these isolated populations.”