The steam and heat from volcanoes allowed species of plants and animals to survive past ice ages, a study has found, offering help for scientists dealing with climate change.
An international team of researchers said their analysis helped explain a long-running mystery about how some species thrived, often in isolation, in areas covered by glaciers, with volcanoes acting as an oasis of life during long cold periods.
"Volcanic steam can melt large ice caves under the glaciers, and it can be tens of degrees warmer in there than outside," said Ceridwen Fraser, the joint team leader from the Australian National University.
"Caves and warm steam fields would have been great places for species to hang out during ice ages.
"We can learn a lot from looking at the impacts of past climate change as we try to deal with the accelerated change that humans are now causing."
The team studied tens of thousands of records of Antarctic mosses, lichens and bugs, collected over decades by hundreds of researchers, and found there were more species close to volcanoes, and fewer further away.
While the study was based on Antarctica, the findings will also help scientists understand how species survived past ice ages in other frigid regions, including in periods when it is thought there was little or no ice-free land on the planet.
Antarctica has at least 16 volcanoes that have been active since the last ice age, 20,000 years ago.
Around 60% of Antarctic invertebrate species are found nowhere else in the world, largely due to the unique conditions that have allowed them to evolve.
"They have clearly not arrived on the continent recently, but must have been there for millions of years," said Peter Convey from the British Antarctic Survey.
"How they survived past ice ages ... has long puzzled scientists."
Aleks Terauds from the Australian Antarctic Division, which ran the analysis that was published by the US-based journal Proceedings of the National Academy of Sciences, said the closer researchers got to volcanoes, the more species were found.
"This pattern supports our hypothesis that species have been expanding their ranges and gradually moving out from volcanic areas since the last ice age," he said.
Another team member, Steven Chown, from Monash University in Melbourne, said the findings could help guide conservation efforts in Antarctica.
"Knowing where the 'hotspots' of diversity are will help us to protect them as human-induced environmental changes continue to affect Antarctica," he said, with Ms Fraser warning that warming temperatures will leave Antarctic environments vulnerable to invasive species.
"As the climate warms, ice is going to melt in areas of Antarctica which will free up ice-free space," she said.
"The most likely species to colonise this new space are going to be species that come in on people, on the vessels that go down to Antarctica."