How Small Jaws Got Bigger in Prairie Cornfields

Image from Doudna and Danielson (2015).

It can be hard to grasp how much humans have reshaped the landscape—particularly in agricultural regions like the Midwest. I struggle to picture prairie where corn and oak-lined subdivisions now stand. One window into these changes is to look at how our farms have widened some of the smallest of mammal mouths.

The arrival of massive corn and soybean fields forced prairie deer mice to shift their diets, according to a study by John Doudna and Brent Danielson of Iowa State published in the journal PLOS ONE this June. The researchers compared museum collections of deer mice skulls from before major agriculture to mice they trapped during 2012 and 2013 from the same regions. Instead of tiny wildflower seeds, deer mice started eating the many-times larger corn and soybean seeds left behind in Midwestern fields. The selective pressure of the new food sources led to populations with larger, more robust jaws able to handle cracking corn. I hope to give this topic a fuller treatment soon. For now, check out the original study!

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Citation
Doudna, J.W., and B.J. Danielson. 2015. Rapid morphological change in the masticatory structures of an important ecosystem service provider. PLOS ONE 10. doi:10.1371/journal.pone.0127218.