Biogeographic history of the javan leopard Panthera pardus based on a craniometric analysis

The leopard, Panthera pardus, occurs on Java, Indonesia, but is absent from Sumatra and Borneo, the islands that lie between Java and the rest of the leopard's geographic range. Recent molecular research has suggested that Javan leopards are a distinct taxon that split off from other Asian leopards hundreds of thousands of years ago, which raises the question of how the species arrived on Java but apparently bypassed Borneo and Sumatra. I have further investigated this issue by linking the results of a morphometric analysis of 121 leopard skulls to my palaeoenvironmental reconstructions for the region. The results suggest that the Javan leopard is craniometrically distinct from leopards from the rest of Asia. I hypothesize that in the Middle Pleistocene (about 800 × 10³ years ago) leopards migrated to Java from South Asia across a land bridge that bypassed Sumatra and Borneo. During the last glacial maximum, when Java, Borneo, and Sumatra were connected, leopards could not survive on either Borneo or Sumatra because of the islands' relatively low ungulate biomass and competition from other large carnivores that were better adapted to tropical evergreen forest habitat.