- 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.