Genes offer hope for the survival of Arabia’s last big cat

The authors of a major study into the critically endangered Arabian leopard say the release of captive-bred animals carefully selected for their genes could make a significant contribution to the successful recovery of the dwindling wild population and prevent the prospect of extinction.

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

By using camera traps to identify individual leopards and conducting DNA analyzes of wild leopard feces alongside samples from the captive population, the team estimates that only 51 wild leopards remain in Oman, spread across three isolated, genetically impoverished but different subpopulations.

Despite revealing extremely low levels of genetic diversity in Oman’s wild leopard population, the team discovered higher levels of genetic diversity in captive leopards across the region, particularly in several individuals native to neighboring Yemen who helped find of the current captive leopard population. This important genetic resource has the potential for an important role in the successful recovery of the Arabian leopard.

The team’s research found that the dwindling regional wild population could most effectively be restored through ‘genetic rescue’, namely introducing the offspring of captive-bred leopards – which harbor the greatest amount of genetic diversity – into the wild population . However, the researchers’ predictions indicate that for genetic rescue to establish the most viable populations through leopard reintroduction, the benefit that new genes may provide must be carefully assessed, especially since captive leopards may already be inbred.

The study, published in Evolutionary applications, used genetic analysis for conservation at DICE, advanced computer simulations developed at UEA, and extensive fieldwork in Oman to scrutinize the Arabian leopard’s DNA and estimate its risk of future extinction, and to predict how genetic rescue could improve the viability of can secure the leopard. The authors say their findings could 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 Royal Court in Oman, we examined and collected leopard feces from the Dhofar Mountains, and extracted DNA from these we analyzed using microsatellite DNA markers to quantify genetic diversity. Using the genetic information, we were able to determine the number of leopard individuals still living in the wild captivity.”

Dr. Hadi Al Hikmani, Head of Arabian Leopard Conservation at the Royal Commission for AlUla in Saudi Arabia, described the motivation for this research: “The Arabian leopard is one of the rarest carnivores in the world and is extremely elusive. The only way to keep an eye on these leopards in the wild is to deploy camera traps high above the mountain ranges where the leopards live, and collect the feces they leave behind on the mountain passes for DNA analysis.

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

Professor Cock van Oosterhout, from UEA’s School of Environmental Sciences, added: ‘The problem is that all individuals are related in some way. They are the descendants of the few ancestors who managed to survive a major population crisis. It becomes virtually impossible to stop inbreeding, and this reveals ‘bad’ mutations, which we call genetic load. This in turn could increase the mortality rate, causing further population collapse.”

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