Koalas nearly vanished from Australia approximately 100,000 years ago due to severe climate shifts, according to a new genetic study [2].
This finding challenges the assumption that human arrival was the primary driver of early marsupial declines. By identifying a massive population crash that predates human settlement, researchers can better understand how the species responds to extreme environmental stress.
A research team led by scientists at the University of Queensland analyzed the genomes of 457 koalas [1]. The data reveals that the species experienced a severe population decline during the last glacial period [2]. This event pushed the koalas close to extinction long before the first humans reached the continent [1].
The study indicates that the dramatic shift in climate during the ice ages altered the native range and available resources for the animals. Such environmental pressures created a genetic bottleneck, which occurs when a population is reduced to a very small number of individuals [2].
While koalas are currently facing modern threats from habitat loss and disease, this ancient history shows the species has survived previous near-extinction events. The University of Queensland team used the 457 genomes [1] to trace these ancestral patterns and determine the timing of the collapse.
Scientists said that the timing of this decline aligns with significant global cooling and drying trends. These shifts likely reduced the availability of the eucalyptus forests the koalas rely on for food and shelter [2].
“The species experienced a severe population decline about 100,000 years ago.”
This research shifts the narrative regarding koala vulnerability by proving that climate-driven extinction events occurred independently of human interference. It suggests that while the species is resilient enough to survive a massive genetic bottleneck, its long-term survival is inextricably linked to the stability of the Australian climate and forest ecosystems.
