Do genes respond to global warming?

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 fluctuations of the two species differed based on their
different ecological behaviors.

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