Tiny Antarctic creatures may have survived successive ice ages by sheltering in frozen caves created by hot steam from active volcanoes, scientists say.
Lead authors of the research say it offers an insight into which species are able to adapt to changing climates and which could be destined to die out.
Australian National University lecturer Ceridwen Fraser said there was evidence larger animals such as penguins had travelled north from Antarctica to warmer climates when ice ages struck Earth.
But extensive research on the bugs, mosses and lichens of the frozen continent had found they were genetically very different from those found in other parts of the world, suggesting they had been isolated there for millions of years, she said.
Dr Fraser said scientists had been puzzled as to how the life forms had survived several ice ages, when ice on Antarctica would be much thicker and more extensive than it is today.
Partnering Aleks Terauds from the Australian Antarctic Division, she co-led the study of tens of thousands of existing records to find there was a far larger variety of species living close to volcanoes in Antarctica than there were further away.
Dr Fraser said steam from volcanoes can melt large ice caves under glaciers, creating hideaways tens of degrees warmer than outside, which could have provided shelter to plants and insects unable to move across the seas to somewhere warmer.
''Volcanoes also make general ice free terrain, not just caves below the ice, but the steam can melt areas of ice on top of the volcano, so you'd have exposed but relatively warm ice-free areas around volcanoes as well,'' she said.
Dr Fraser said the study offered lessons on to what degree different species were affected by climate change, which held particular relevance to contemporary challenges posed by rising temperatures.
''I think it's really important to recognise which species can just take climate change on the chin and go where they need to go and which ones really can't, they're trapped,'' she said.
''We got a lot of species in southern Australia now that are just going to drop off into extinction, because they've got nowhere to go and they can't swim.''
Dr Fraser said if ice in Antarctica melted, large areas of land could also open up, exposing the continent to an increased risk of contamination by outside species which could be brought to the continent accidentally by tourists.
There are 16 volcanoes in three clusters on Antarctica which are thought to have been active since the last ice age, which peaked around 20,000 years ago, she said.
Dr Terauds said the findings supported the team's hypothesis that species had been expanding their ranges and moving out from volcanic areas since the last ice age.
Dr Fraser will head to the Antarctic Peninsula in January to continue her research.
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