Two environmental groups filed a petition Tuesday with the California Fish and Game Commission asking for endangered species protection for six subpopulations of mountain lions in Southern California facing extinction from urban sprawl, freeway collisions, rodenticide poisoning and poachers.

If granted, the filing by the Center for Biological Diversity and the Mountain Lion Foundation could restrict future development in cougar habitat and may require Caltrans to retrofit existing freeways with land bridges or underground culverts to allow isolated lions to roam freely and reproduce — key activities that would grow populations and increase genetic diversity.

The legal move is part of a 30-year effort to preserve Santa Monica Mountain lions cut off by the 101 Freeway in the west San Fernando Valley and Santa Ana Mountain lions hemmed in by the 15 Freeway in southern Riverside County.

The petition asks for “threatened” or “endangered” status for those two, as well as four other lion groupings: in the Eastern Peninsular Range of the San Jacinto and Santa Rosa mountains; San Bernardino Mountains; San Gabriel Mountains and along the coast to the Santa Cruz Mountains.

Also called pumas or cougars, these magnificent creatures have been photographed among urban Los Angeles landmarks. A famous photo of the collared lion, P-22, shows the animal poised along the eastern Santa Monicas in Griffith Park, with the back drop the Hollywood Sign. He is a bona fide L.A. celebrity, with his own Twitter account and Friends of P22 Mountain Lion Facebook page.

Less glamorous photos released by the National Park Service and surveillance cameras show lions being killed while dashing across the 101 or 15 freeways, as young males in isolated populations seek food and mates in failed efforts to establish their own territory.

Sometimes young males are killed by older lions, a result of being jammed into a urban island too small for survival.

The two groups hope by using the California Endangered Species Act, the state agency will accept the petition based on scientific evidence and grant protected status.

“If the mountain lion would be listed, it would provide a clear and legal mandate to preserve the species,” Tiffany Yap, biologist with the Center for Biological Diversity, said in an interview Tuesday. “New projects like new roads, road enhancements or developments would be required to take measures to enhance connectivity, such as building wildlife crossings.”

A $60 million wildlife bridge over 10 lanes of Freeway 101 at Liberty Canyon in Agoura Hills has been designed but not built. Proponents say animal crossings in Canada and Washington State have been completed, so why not California?

However, private fundraising efforts have raised about $8 million, far short of what’s needed. The Nature Conservancy bought 73 acres near the 15 Freeway in Temecula to prepare the way for a crossing, but it has been held up in court.

A housing development approved in Temecula could halt the plans, said Brendan Cummings, attorney for the center, which is suing to stop the development. Cummings said there are only a few “pinch points” where a crossing could be built to allow the isolated Santa Ana cougars west of the 15 to cross into the San Bernardino and San Jacinto mountains, where there are more mountain lions.

“The idea of an overpass where the lions can walk over the freeway is the ecologically better alternative,” Cummings said. “If we plan ahead, we can do it.”

Without bridges to promote circulation, these subpopulations will continue to sustain the effects of inbreeding, which weakens their immune systems and lessens longevity. Many eat animals that have ingested rat poison left out by homeowners, causing them to die a slow death from common diseases such as manage.

Also, they are more likely to perish from car collisions and from permitted kills that occur when a cougar eats a rancher’s goat, said T. Winston Vickers, associate veterinarian at the UC Davis Wildlife Health Center, who has been studying the Santa Ana mountain cougars since 2005.

“Business as usual is not going to cut it for mountain lions,” he said during an interview Tuesday.

If nothing is done, a study by UC Davis with UCLA and the National Park Service estimates the Santa Ana subpopulation could go extinct within 12 years. The Santa Monica population within 15 years, the center reported Tuesday.

Vickers estimated there are 15-20 adults in the Santa Ana subpopulation, plus kittens and juveniles. Since 2005, seven adult males crossed the 15 Freeway. Of those, one died from a permitted killing. One produced 11 offspring, but more than half of the litter died, killed by car collisions or humans. “The mortality rates are high,” he said.

Yap placed the number of mountain lions in the Santa Monica subpopulation at between seven and 12 adults. Such small numbers place them at risk of dying out, she said.

Mountain lions have become extinct in parts of the East Coast, causing an imbalance in the ecosystem. Deer populations have spiked, as have the incidence of tick-borne illness and a higher number of car-versus-deer collisions.

Mountain lions in the West provide food for other animals, Yap explained. When they kill a deer, they leave the carcass for the foxes, condors and beetles to feed on. “That is all very important for the ecosystem.”

The commission will have 90 days to decide if the petition for protected status could be warranted. If the five-member panel votes “yes,” the species becomes a candidate and then the Department of Fish and Wildlife conducts a yearlong review to decide if protection is indeed warranted.

The commission could render a final decision in December 2020, Cummings said.

He said the science is indisputable to support threatened listing as a whole and possibly endangered listing for the Santa Monica and Santa Ana subpopulations. He expects push back from developers, however.

“As Californians, if we want to coexist with mountain lions, we need to figure out how to reimagine and re-engineer our infrastructure to make it mountain lion-friendly,” Cummings said.