TAG: GS 3: ECOLOGY AND ENVIRONMENT
THE CONTEXT: A recent groundbreaking study suggests that carefully selected, captive-bred Arabian leopards could be reintroduced into the wild to significantly aid the recovery of this Critically Endangered species.
EXPLANATION:
- The study, conducted by an international team of researchers from the UK and Oman, provides hope for the survival of the Arabian leopard by outlining a genetic rescue plan to enhance the dwindling wild populations in Oman.
Alarming Decline in Wild Arabian Leopard Population
- The study, published in the journal Evolutionary Applications, surveyed the remote Dhofar mountain range in southern Oman to determine the remaining population of Arabian leopards.
- Using camera traps and DNA analysis from wild leopard scat, the researchers estimate that only 51 wild leopards remain in Oman, distributed among three isolated, genetically impoverished but distinct subpopulations.
- The wild population has extremely low levels of genetic diversity, while captive leopards, particularly those from Yemen, harbor higher levels of genetic diversity.
Genetic Diversity in Captive Populations
- There are extremely low levels of genetic diversity found in the wild leopard population in Oman.
- The researchers discovered higher levels of genetic diversity in captive leopards across the region, particularly among several individuals originating from neighboring Yemen that helped found 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.
Genetic Rescue: The Key to Recovery
- The researchers suggest that the dwindling regional wild population could most effectively be recovered through ‘genetic rescue’.
- It involves the introduction of offspring from captive-bred leopards — which harbor the greatest amount of genetic diversity — into the wild population.
- However, their predictions indicate that for genetic rescue to establish the most viable populations through leopard reintroductions, the benefit that new genes can bring needs to be carefully assessed, particularly because captive leopards may already be inbred.
Detailed Genetic Analysis and Computer Simulations
- The study used conservation genetic analysis, cutting-edge computer simulations, and extensive fieldwork in Oman to closely examine Arabian leopard DNA and assess the risk of future extinction, as well as forecast how genetic rescue can secure the leopard’s viability.
- The authors say their findings could help other threatened species as well.
- The only way to monitor these leopards in the wild is to deploy camera traps high up across the mountain ranges where the leopards live, and to collect the scats they leave behind on the mountain passes, for DNA analysis.”
Risks and Benefits of Genetic Rescue
- Benefits:
- Reintroduction of captive-bred leopards can increase genetic diversity in the wild population, enhancing long-term viability.
- Genetic rescue can reduce the genetic load, which is a major threat to the population’s survival.
- Risks:
- Captive leopards may already be inbred, which could introduce new genetic issues into the wild population.
- There is a risk of genomic incompatibilities between Yemen and Oman populations that could have evolved during reproductive isolation.
- Professor from the University of East Anglia (UEA) highlighted the risks associated with genetic rescue: “The problem is that all individuals are somehow related to each other. They are the descendants of the few ancestors that 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.”
- The researchers acknowledge that there is a risk of introducing other deleterious mutations from the captive population into the wild, so a careful balance is needed when implementing the genetic rescue plan.
Arabian Leopards:
- The Arabian leopard (Panthera pardus nimr) is the smallest leopard subspecies.
- It was described in 1830 and is native to the Arabian Peninsula, where it was widely distributed in rugged hilly and montane terrain until the late 1970s.
- Today, the population is severely fragmented and thought to decline continuously.
- Previously in 2008, an estimated 45–200 individuals in three isolated subpopulations were restricted to western Saudi Arabia, Oman and Yemen.
- However, as of 2023, it is estimated that 100–120 in total remains, with 70-84 mature individuals, in Oman and Yemen, and it is possibly extinct in Saudi Arabia.
- The current population trend is suspected to be decreasing.
