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

Authors of a major study of the critically endangered Arabian leopard say releasing captive-bred animals carefully selected for their genes can make a significant contribution to the successful recovery of the dwindling wild population and avert the threat 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 Royal A 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 analysis of wild leopard scat along with samples from the captive population, the team estimates that there may be as few as 51 wild leopards left in Oman, spread across three isolated, genetically impoverished but distinct subpopulations.

Although the team uncovered extremely low levels of genetic diversity in the wild leopard population in Oman, they discovered higher levels of genetic diversity in captive leopards across the region, particularly in several individuals that came from neighboring Yemen and founding contributed to today’s captive breeding population. This important genetic resource has the potential to play an important role in the successful recovery of the Arabian leopard.

The team’s research showed that the dwindling regional wild population could be most effectively restored through “genetic rescue,” namely the introduction of offspring of captive-bred leopards – which have the greatest genetic diversity – into the wild population. However, the researchers’ predictions suggest that the benefits that new genes can bring need to be carefully considered so that genetic rescue can create the most viable populations through leopard reintroduction, especially because captive leopards may already be in live offspring.

The study, published in Evolutionary applicationsused conservation genetic analysis at DICE, state-of-the-art computer simulations developed at UEA, and extensive field research in Oman to closely examine the DNA of Arabian leopards and assess the risk of future extinction, as well as predict how genetic rescue can ensure the leopard’s viability . The authors say their findings could help other endangered species.

Professor Jim Groombridge, who led the research at DICE in Kent, explained how the genetic analysis was carried out: “Working with the Diwan of the Royal Court in Oman, we examined and collected leopard scat from across the Dhofar Mountains and extracted DNA from it. They were analyzed using microsatellite DNA markers to quantify genetic diversity. The genetic information allowed us to determine the number of leopards remaining in the wild. We were then able to compare the level of genetic diversity between the wild leopard population and those in captivity.”

Dr. Hadi Al Hikmani, head of Arabian leopard conservation at the Royal Commission for Al-Ula in Saudi Arabia, described the motivation for this study: “The Arabian leopard is one of the rarest carnivores in the world and is extremely elusive. The only way to monitor these leopards in the wild is to set camera traps high in the mountain ranges where the leopards live and collect the excrement they leave behind in the mountain passes for DNA analysis.

Thomas Birley, a PhD student at UEA who carried out the genetic rescue computer simulations, said: “By using the genetic information of the wild and captive populations, we were able to predict the best genetic rescue plan to ensure the long-term viability of these from extinction endangered big cat.”

Professor Cock van Oosterhout, from UEA’s School of Environmental Sciences, added: “The problem is that all individuals are related to each other in some way. They are the descendants of the few ancestors who managed to survive a major population crash. Therefore.” It becomes virtually impossible to stop inbreeding and this brings out “bad” mutations, which we call genetic load. This, in turn, may increase mortality rates and lead to further population collapse.

“Genetic burden is a serious threat, but it can be mitigated through genetic rescue, and our study has shown the best way to do this. The wild population needs a ‘genetic rescue’ from more genetically diverse leopards bred in captivity. These leopards are more genetically diverse and may help reduce levels of inbreeding and genetic load. However, there is a risk that we may introduce other bad mutations from the captive population into the wild, so we must consider carefully.