Deer mice came to dominate the community

May 24, 2010 07:43 GMT  ·  By
Deer mice adapted to the warming that followed the last Ice Age because they could breed very fast
   Deer mice adapted to the warming that followed the last Ice Age because they could breed very fast

According to researchers, it may be that past instances of global warming had a huge impact on small mammal communities as well. For example, during the last Ice Age, it is estimated that the soaring temperatures killed off about one third of mouse species. This is the same event that led to the extinction of woolly mammoths and other megafauna. Until now, researchers did not believe that the climate change had any bearing on smaller species, but new studies prove them wrong. The warming event took place some 11,700 years ago, Nature News reports.

A research conducted on a recently uncovered woodrat nest reveals the fact that deer mice, which were more adaptable than others, took supremacy in the small mammal communities, primarily due to the fact that they are very fast breeders. Even though this species thrived, investigators say, the overall number of creatures living in the region decreased by more than 33 percent. The research was led by expert Jessica Blois, who is currently based at the University of Wisconsin-Madison (UWM). Details of the work appear in the May 23 issue of the esteemed scientific publication Nature. “If we focus only on extinction, we're not getting the whole story,” the scientist explains.

“We were mainly interested in small mammals, the guys that survived the extinction event,” Blois says. She reveals that woodrats were targeted by the new study for a very precise reason. These animals collect scat and pellets, and then take them into caves, where they set up large nests. Because of this, the animals are also very well preserved when they perish. An additional advantage is the fact that the creatures collect small mammalian bones as well, which are included in the scat. “You just have to find the midden (woodrat nest), and animals have already done all the work for us. The carnivores sample and the woodrats collect the dead and digested animals,” the expert adds.

The investigators accounted for two things in their study – evenness and richness. These concepts refer to the ratio between species, and to the actual number of animals the fossil record reveals. During the climate change event, the number of species (richness) decreased by 32 percent, whereas evenness decreased by 26 percent – due to the emergence of the mice. These creatures had a broad tolerance to temperature, could travel a lot, and were fast breeders. Blois believes that all of these factors may have contributed to its amazing evolutionary success.