SoCal mountain lions found with abnormal sperm, inbreeding indicator exposing threat of extinction

The first signs of inbreeding were spotted in mountain lions monitored in the Santa Monica and Santa Ana Mountains, scientists say, a discovery that highlights a serious threat to the future survival of both populations.

Some of the big cats were recently found to have an average sperm rate of 93% – the first evidence that inbreeding affects the reproductive system, according to a UCLA-led study. Eventually, this could make it more difficult for the cougars to reproduce as the local population faces a lack of genetic diversity, which poses a potential threat of extinction.

“This is a serious problem for an animal that is already endangered locally,” said Audra Huffmeyer, a postdoctoral fellow at UCLA and lead author of the study, in a National Park Service press release. studies fertility in large cat species and is a National Geographic Explorer. “It’s pretty heavy.”

Inbreeding is known to be a problem for mountain lion populations in the Santa Monica and Santa Ana Mountains, with some of the big cats already showing some signs such as tail deformities and testicular defects according to previous research.

The malformed sperm are the latest findings that reveal the extent of the problems each group faces.

Both populations are tied to their respective mountain ranges by busy highways in the greater Los Angeles area, Orange and Riverside counties, making it difficult for them to mate with cougars outside of their own territory.

The National Park Service has been studying the residents of the Santa Monica Mountains for about two decades, and to date tag and track more than 100 big cats.

The latest kittens to enter the study were a litter of four captured in late November, according to valet officials. They were apparently abandoned by their mother, who was not one of the pumas that were tracked down.

Currently, more than a dozen mountain lions are monitored with GPS collars in the Santa Monica Mountains National Recreation Area.

Last year, researchers found nine adult males in both the Santa Monica and Santa Ana series who exhibited symptoms of inbreeding.

In addition, semen samples were taken from five of the puma after their death (from rat poison to an accident with a vehicle). Through the samples, the team discovered that all five had high abnormal sperm rates.

This first evidence of decreased sterility highlights the need for wildlife crossings on local highways so that these animals could continue to roam the urban sprawl and expand their pool of potential partners, according to the press release.

“If we don’t do anything to add genetic diversity to the Southern California mountain lions, we will have more males with reproductive problems, fewer kittens, and lower kitten survival rates,” Huffmeyer said in the press release.

“If we don’t do something to increase genetic diversity, the end is near,” she added. “That sounds dramatic, but we saw that.”

One major problem is that few mountain lions have successfully made it off busy highways such as the 101 and 405, as well as other local roads. Car accidents are one of the leading causes of death for the cougar population in the Santa Monica Mountains.

In some good news for the species, Caltrans is expected to break ground on a wildlife bridge over the 101 Freeway in the Agoura Hills area this month. And a possible crossing of Freeway 15 in Riverside County is also in the early stages of planning, NPS officials said.

But without sustainable action, scientists predict that the big cats in both Southern California’s mountain ranges could potentially be critically endangered this century.

“Although they haven’t seen any evidence yet, once scientists begin to find significant inbreeding depression – which means decreased fertility and decreased kitten survival, extinction is predicted within 50 years, with a median extinction of 12-15 years,” According to the press release, citing research from 2016 and 2019.

The study is scheduled for publication this month in the journal Theriogenology, but is currently available online here.

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