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The authors of a major study on the critically endangered Arabian leopard say the release of captive-bred animals carefully selected for their genes could contribute significantly to the successful recovery of a dwindling wild population and stave off the prospect of extinction.

An international collaboration led by scientists from the Durrell Institute of Conservation and Ecology (DICE) at the University of Kent, the University of East Anglia (UEA), University College London (UCL), Nottingham-Trent University (NTU) and the Diwan of the Royal Court of Oman explored the remote Dhofar mountain range in southern Oman to determine how many of Arabia’s last big cat survived.

By deploying camera traps to identify individual leopards and conducting DNA analyzes of wild leopard droppings alongside samples from the captive population, the team estimates there may be as few as 51 wild leopards left in Oman, spread between three isolated, genetically impoverished but distinct subpopulations.

Despite revealing extremely low levels of genetic diversity in Oman’s wild leopard population, the team found higher levels of genetic diversity in captive leopards across the region, particularly among several individuals originating from neighboring Yemen, which helped discover of today’s captive-breeding population. This important genetic resource has the potential to play a major role in the successful recovery of the Arabian leopard.

The team’s research showed that a dwindling regional wild population can most effectively be restored through “genetic rescue”, namely the introduction of progeny from captive-bred leopards, which contain the greatest amount of genetic diversity, into the wild population. However, the researchers’ predictions suggest that for genetic rescue to establish the most viable populations by reintroducing leopards, the benefits the new genes may bring must be carefully evaluated, particularly because captive leopards may already be related .

The study, published in Evolutionary applications, used conservation genetic analysis at DICE, cutting-edge computer simulations developed at UEA and extensive fieldwork in Oman to closely examine Arabian leopard DNA and assess the risk of future extinction, as well as predict how genetic rescue could ensure viability of the leopard. The authors say their findings may help other endangered species.

Professor Jim Groombridge, who led the research at Kent’s DICE, explained how the genetic analysis was carried out: “In collaboration with the Diwan of the Royal Court of Oman, we surveyed and collected leopard droppings from across the Dhofar mountain range and extracted DNA from them, which we analyzed with using microsatellite DNA markers to determine genetic diversity. Using the genetic information, we were able to determine the number of leopard individuals that remain in the wild in captivity.”

Dr. Hadi Al Hikmani, Head of Arabian Leopard Conservation at the Royal Commission for AlUla in Saudi Arabia, described the motivation for this study: “The Arabian leopard is one of the world’s rarest carnivores and is extremely elusive. The only way to observe these leopards in the wild is to set camera traps high in the mountain ranges where the leopards live and collect the droppings they leave along the mountain passes for DNA analysis.”

Thomas Burleigh, Ph.D. a researcher at UEA who carried out the genetic rescue computer simulations said: “By using genetic information from wild and captive populations, we were able to predict the best genetic rescue plan to ensure the long-term viability of this critically endangered big cat .”

Professor Kok van Oosterhout, from UEA’s School of Environmental Sciences, added: “The problem is that all individuals are somehow interconnected. They are the descendants of the few ancestors who managed to survive after a major population crash. Therefore, it becomes practically impossible to stop the blood supply and this reveals “bad” mutations, which we call genetic load. In turn, this can increase mortality, causing further population collapse.

“Genetic load is a serious threat, but it can be alleviated through genetic rescue, and our study has predicted the best way to do that. The wild population needs “genetic rescue” from more genetically diverse leopards bred in captivity. These leopards are genetically more diverse and they can help reduce the level of inbreeding and genetic load, but there is a risk that we can introduce other bad mutations from the captive population into the wild, so we will need a careful balance. “