An international team of researchers from Germany and Indonesia has discovered new insights into the evolutionary history of the Javan leopard. The results of the study confirm that Javan leopards are clearly distinct from Asian leopards and probably colonised Java around 600,000 years ago via a land bridge from mainland Asia. The study, published in the scientific journal Journal of Zoology, highlights the urgent need for concerted conservation efforts to preserve the Javan leopard from extinction.
Scientists from the German Leibniz Institute for Zoo and Wildlife Research (IZW), Tierpark Berlin (Germany), Taman Safari Indonesia, Potsdam University (Germany) and Conservation International Indonesia (Indonesia) worked in close collaboration to answer the question whether the Javan leopard is a separate subspecies of the leopard, as this would heighten the need for efforts to improve its viability through active conservation measures. The results show that Javan leopards diverged from mainland Asian leopards in the Middle Pleistocene approximately 600,000 years ago and have already reached a degree of genetic distinctiveness which clearly warrants the classification of Javan leopards as a subspecies (Panthera pardus melas) of the leopard (Panthera pardus).
Leopards likely migrated from mainland Asia to Java during a prolonged period of low sea levels via a Malaya-Java land bridge that by-passed the island of Sumatra. This might be one reason why leopards exist on mainland Asia and on Java today, but do not occur on Sumatra or Borneo. However, fossils show that leopards occurred at least in some parts of Sumatra during the Pleistocene. "We assume that leopards became extinct on this island after the massive eruption of the Toba volcano about 74,000 years ago. On Java, the impact of this eruption was minor, allowing leopards to survive there," explains Andreas Wilting, scientist at the IZW and lead author of the study.
The scientists reconstructed the evolutionary history of the Javan leopard using mitochondrial DNA sequenced from museum specimens of leopards from Java and compared this genetic information to leopard sequences from Asian mainland and Africa. The potential historical distribution was reconstructed using species distribution models with environmental data from the Last Glacial Maximum and the Mid-Holocene.
The Javan leopard is the last big cat still roaming on Java after the Sunda clouded leopard (in the Holocene) and the Javan tiger (in the early 1980s) went extinct. Subjected to anthropogenic pressures such as deforestation, the subspecies has dwindled significantly and is now listed as critically endangered in the IUCN Red List of Threatened Species. With only a few hundred individuals still existing in the wild and 52 living in captivity, the Javan leopard is one of the most threatened subspecies of big cats.
"The data presented in our study highlight the urgent need for concerted conservation efforts for this unique and distinctive subspecies," emphasizes Anton Ario from Conservation International Indonesia. Conservation measures need to combine numerous management activities guided by a One Plan Approach, such as protecting leopard habitats, raising awareness in communities and establishing a coordinated breeding programme for Javan leopards in captivity. A first step for such an integrated approach was established in 2014: an international studbook was established, coordinated by Taman Safari Indonesia and Tierpark Berlin. Now additional measures are required and further conservation actions for the remaining fragmented wild Javan leopard populations are needed to ensure that the last big cats on Java will continue to roam the island for the foreseeable future.
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