July 31, 2009

Rodent changes linked to people, climate

Changes in the head shape and overall size of rodents has been linked to human population density and climate change, a Chicago researcher said.

The size and head shape of rodents has shifted substantially during the last 100 years, with some larger and some smaller, Oliver Pergams, a researcher at the University of Chicago said in a statement released Friday.

Pergams studied 1,300 specimen rodents from museums around the world, including Chicago's Field Museum and the Smithsonian Institution in Washington.

He then compared specimens from sparsely populated islands to those from the mainland, where human populations were denser. Pergams found increases and decreases in 15 anatomic traits, with changes as great as 50 percent over 80 years.

Ten of the 15 traits were linked to changes in human population density, temperature and precipitation, he said.

Species can adapt quickly to rapid environmental changes -- quicker than many people have thought, especially for mammals, said Pergams. Those mammals that can adapt quickly have a much higher chance to survive big environmental changes caused by humans.