Scientists continue to argue the extent that human activities drive global warming, but few would argue that it exists. The International Panel on Climate Change predicts that greenhouse gases will increase global temperatures by 3.6 degrees F by 2100--a rise unprecedented over the past 10,000 years. While the effects of climate change on species' geographic range and population dynamics are increasingly understood, scientists know little about how species respond to climate change at the genetic level. Now it appears that climate change can shape genetic diversity. Elizabeth Hadly and colleagues have analyzed three different dynamic processes--environmental change, population response, and gene diversity fluctuations--and report that climate change influences variation in genetic diversity.

Focusing on two mammal species--the Montane vole and northern pocket gopher--Hadly et al. asked how the two species responded to historical climate-induced habitat alterations in northwestern Wyoming. They gathered fossils from Yellowstone National Park's Lamar Cave, and compared genetic material extracted from fossil samples taken from different time points over the past 3,000 years to genetic data taken from contemporary animals. Studying these populations in space and time--an approach the authors call "phylochronology"--offers an opportunity to analyze the genetic diversity of a species against the backdrop of environmental fluctuation within an evolutionary time frame.

The past 3,000 years includes two periods marked by dramatic climate change--the Medieval Warm Period and the Little Ice Age--that had different effects on local mammal populations depending on their habitat preferences. Habitat specialists, the vole and pocket gopher live in the wet mountain regions of western North America. Though both showed population increases during wetter climates and declines during warmer periods, Hadly et al. predicted and subsequently found that the gene diversity
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Contact: Paul Ocampo
pocampo@plos.org
1-415-624-1224
Public Library of Science
6-Sep-2004

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