An international team of researchers, including Professor Mary Edwards at the University of Southampton, has used DNA testing to give a unique view of the diet of large mammals which roamed the northern hemisphere in the last ice-age.
The researchers, led by the University of Copenhagen, sequenced DNA taken from samples of frozen soils and the stomachs of creatures preserved in the permafrost of Siberia and Alaska-Yukon – an area many times the size of the UK. Their results show that around 25,000 years ago vegetation in this area was rich in 'forbs' – herbaceous flowering plants usually found in grasslands, meadows and tundra.
Professor Edwards, a physical geographer with expertise in permafrost deposits, says, "Permafrost is frozen soil and sediment which acts like a giant freezer, preserving countless plant and animal remains from ancient ecosystems. It is ideal for this kind of study because the DNA isn't lost to the normal processes of decay.
"By analysing this preserved DNA, we have found that flowering plants, known as forbs, were far more prevalent than previously thought. In fact, forbs have been overlooked in many past studies of ice-age ecosystems, but this study shows they may have been a critical source of nutrition in the diet of mammalian megafauna – huge animals such as mammoth, woolly rhino, bison and horse."
Until now, analyses of vegetation over the past 50,000 years has been based mainly on studying fossil pollen, showing that vegetation in cold environments, supporting large herbivores, was mainly made up of graminoids – plants such as grasses and sedges. However, this latest study gives a new perspective on this, suggesting instead a dominance of forbs, until at least around 10,000 years ago when woody plants and graminoids then become more prevalent.
Professor Edwards comments, "Analysing plant DNA has provided us with a unique perspective on this now extinct northern ecosystem and given new insights into how such large animals could survive extreme cold and harsh ice-age conditions."
The findings, published in the scientific journal Nature, are the result of a large collaboration involving more than 30 groups from around the world. Molecular biologists from the University of Copenhagen, CRNS Grenoble, and the University of Oslo worked with experts on northern ecosystems at the University of Southampton (Professor Mary Edwards), Alberta in Canada and Tromso in Norway to interpret millions of DNA sequences in terms of the ice-age flora and develop an understanding of the composition of the forage and diets of megafaunal mammals.
The article Fifty thousand years of arctic vegetation and megafauna diet is published in the scientific journal Nature and can be found at: http://dx.doi.org/10.1038/nature12921
Notes for editors:
1) Professor Mary Edwards of Geography and Environment at the University of Southampton is an expert on the climate changes associated with the ice ages and their effect on northern ecosystems. http://www.southampton.ac.uk/geography/research/staff/mee.page
2) Professor Mary Edwards worked with Professor Julian Murton of the University of Sussex, who is an expert on the permafrost deposits from which the samples came. Together they sampled the ancient permafrost deposits in Siberia with scientists from Copenhagen led by Professor Eske Willerslev, the Zoological Institute of Russian Academy of Sciences (Saint Petersburg) and the Institute of Applied Ecology of the North (Yakutsk). The project was conducted with the help of over 30 institutions and organisations worldwide.
3) For more information about Geography and Environment at the University of Southampton visit: http://www.southampton.ac.uk/geography/index.page?
4) For more information about the University of Copenhagen, which led on the project, visit: http://www.ku.dk/english/
5) The University of Southampton is a leading UK teaching and research institution with a global reputation for leading-edge research and scholarship across a wide range of subjects in engineering, science, social sciences, health and humanities.
With over 23,000 students, around 5000 staff, and an annual turnover well in excess of £435 million, the University of Southampton is acknowledged as one of the country's top institutions for engineering, computer science and medicine. We combine academic excellence with an innovative and entrepreneurial approach to research, supporting a culture that engages and challenges students and staff in their pursuit of learning. http://www.southampton.ac.uk
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