Newswise — When winter comes, we cope by reaching for a coat and getting accustomed to cooler temperatures. Australian bush rats behave much the same as their larger, human counterparts. Except that, according to a new study, they grow a thicker fur coat and can actually lower their body temperature to compensate for a colder environment.
The article appears in the October 2010 issue of the Journal of Mammalogy. The purpose of the study, conducted at the University of Sydney, Australia, was to determine whether exposure to chronic cold, level of activity, or an interaction between the two worked to reduce the body temperature of an endotherm such as the bush rat.
Australian bush rats were brought into captivity and acclimated to either a cold environment—12° C—or a warm environment—22° C. Each group was then further divided into an exercise group and a sedentary group. Bush rats in the exercise groups were run for 30 minutes on an exercise wheel five days a week.
The bush rats in the cold-acclimated group showed a significantly lower body temperature—reduced by as much as 0.9° C—regardless of level of exercise. The sedentary cold-acclimated rats showed greater fur thickness than the exercised ones; however, both had significantly thicker fur than the warm-acclimated group.
Colder ambient temperature rather than lower levels of activity influenced the bush rats’ response. This decrease in body temperature is due to thermosensation. The current study supports the importance of these environmental sensors distributed throughout the body and skin. Temperature activates these channels, and previous studies with rodents have shown that blocking the receptors can change how the animal responds to the warmth or cold of its environment.
The reduction in body temperature benefits the exercising bush rat in the cold environment by allowing both maintained activity and energy savings. With a lower body heat to achieve, less energy is spent in keeping warm.
Full text of the article, “Advantage to lower body temperatures for a small mammal (Rattus fuscipes) experiencing chronic cold.” Journal of Mammalogy, Volume 91, Issue 5, October 2010, is available at http://www2.allenpress.com/pdf/mamm-91-05-1197-1204.pdf
About the Journal of MammalogyThe Journal of Mammalogy, the flagship publication of the American Society of Mammalogists, is produced six times per year. A highly respected scientific journal, it details the latest research in the science of mammalogy and was recently named one of the top 100 most influential journals of biology and medicine in the past century by the Special Libraries Association. For more information, visit http://www.mammalogy.org/.
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