Rapid climate change during the last Ice Age caused five \"regional extinctions\" of lemmings with a long-lasting genetic impact, British researchers say. An international research team including scientists from Britain\'s Royal Holloway University has been investigating how Europe\'s small mammals fared during the Late Pleistocene era when large numbers of larger life forms became extinct. Previously, experts had thought small mammals were largely unaffected during the Ice Age periods, but ancient DNA sequences from fossilized remains of collared lemmings from cave sites in Belgium suggested otherwise, Royal Holloway researchers reported. \"What we\'d expected is that there\'d be pretty much just a single population that was there all the way through,\" biologist Ian Barnes said. Instead, the DNA showed genetically distinct populations of lemmings were \"present at different points in time\" during the Late Pleistocene beginning126,000 years ago. That suggests lemming populations had been wiped out multiple times and then re-colonized some time after, possibly from populations in eastern Europe or Russia, the researchers said. \"There\'s an amazing genetic diversity just at this one site in Belgium, compared to the tiny amount of diversity that we see in the modern-day lemmings,\" Barnes said. The scientists suggest climate fluctuations during the Ice Age may have left lemmings unable to adapt to the changes in the vegetation they relied on as a food source.