Chipmunks Toughed
Out Last Ice Age
Small groups of chipmunks thumbed their noses at approaching glaciers during the last Ice Age, and the discovery of their obstinence has proven some commonly held ideas wrong.
Rather than fleeing like other animals, most chipmunks living in Wisconsin and Illinois stayed put behind rocky formations that acted as barriers to approaching glaciers.
"This is counter-intuitive given that organisms would be expected to respond to glacial expansion by shifting their ranges to more suitable climates most often in a southern refuge followed by a northward recolonization as the glaciers receded," said Kevin Rowe, doctoral student in the evolutionary/molecular biology laboratory at the University of Illinois and lead author of a report on the findings in Proceedings of the National Academy of Scientists (in short-form English, "you'd think that animals would flee from glaciers, but these didn't.").
The rocky formations, in an area called the driftless region, probably created pockets of tundra and forest behind them -- perfect homes to the cute little critters.
It would have been a long wait for them, as the glaciers pushed down the continent and later ebbed, possibly 5,000 years. Glaciers covered Wisconsin 18,000 years ago.
Also surprising, Rowe said, is that chipmunks in Wisconsin and Illinois are closely related, but only distantly related to chipmunks in Michigan and Indiana (only surprising until the uglying effects of inbreeding among a small, isolated population of chipmunks too stupid to get out of the way of a slow-moving mass of ice are taken into account).
The findings were based on DNA research on 244 chipmunks.



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