The release of genetically selected Arabian leopards into the wild can significantly help these animals recover and avoid extinction, according to a study published in the scientific journal Evolutionary Applications.
An international team, including researchers 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), surveyed the Dhofar mountain range of southern Oman to determine how many of Arabia’s last big cat are left.
The team used camera traps to follow individual animals and collected leopard scat samples for DNA analyses. Results show that only around 50 wild leopards remain in Oman, distributed between three isolated and genetically impoverished populations.
These wild populations may have dangerously low levels of genetic diversity, but the team found higher levels of genetic diversity in captive leopards. This is particularly visible among captive animals from neighbouring Yemen, representing a vital resource to help recover the Arabian leopard.
According to the authors, the decreasing wild population could be recovered with a “genetic rescue,” including introducing offspring from captive animals (with higher genetic diversity) into the wild population. However, it’s still essential to assess these animals’ genetic makeup to ensure that they’re not inbred.
The study used conservation genetic analysis (done at the University of Kent), cutting-edge computer simulations (done at the University of East Anglia), and extensive fieldwork conducted in Oman to analyse the DNA of real Arabian leopards and assess the risk of their future extinction. The aim was to predict whether genetic rescue can secure the leopard’s viability in the future. The authors hope their findings could help other threatened species.
“In collaboration with the Diwan of Royal Court in Oman, we surveyed and collected leopard scats from across the Dhofar mountain range and extracted DNA from them which we analysed using microsatellite DNA markers to quantify genetic diversity. Using the genetic information, we determined the number of leopard individuals that remain in the wild. We could then compare levels of genetic diversity between the wild leopard population and those in captivity,” said Professor Jim Groombridge from the University of Kent.
“By using the genetic information from the wild and captive populations, we were able to forecast the best plan for genetic rescue to ensure long-term viability for this Critically Endangered big cat,” added Thomas Birley from the University of East Anglia.
“The problem is that all individuals are somehow related to each other. They are the descendants of the few ancestors who managed to survive a major population crash. Hence, it becomes virtually impossible to stop inbreeding, and this exposes ‘bad’ mutations, what we call genetic load. In turn, this can increase the mortality rate, causing further population collapse,” concluded Professor Cock van Oosterhout from the University of East Anglia. “The genetic load poses a severe threat, but it can be alleviated by genetic rescue, and our study has projected the best way to do this. The wild population needs ‘genetic rescue’ from more genetically diverse leopards bred in captivity. These leopards are genetically more diverse and 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 that we will need a careful balance.”
Al Hikmani H, van Oosterhout C, Birley T, Labisko J, Jackson HA, Spalton A, Tollington S, Groombridge JJ. Can genetic rescue help save Arabia’s last big cat? Evol Appl. 2024 May 23;17(5):e13701. doi: 10.1111/eva.13701.