Adaptable deer mice came to dominate the small furry communities of northern California as the climate warmed at the end of the last ice age, around 11,700 years ago, an excavation of one ancient woodrat nest shows. Overall, the number of small mammalian species in the area declined by about one-third, say Jessica Blois, currently at the University of Wisconsin, Madison, and her colleagues.
The study, published today in Nature1, emphasizes that concentrating solely on eye-catching species extinctions fails to capture the full impact of climate change on biodiversity. "If we focus only on extinction, we're not getting the whole story," says Blois. The work also suggests that rapidly reproducing, adaptable species — such as the deer mice — could benefit further from future warming.
Tales from rodent nests
The end of the Pleistocene era is famous for its megafauna extinctions, and researchers have been searching for megafaunal remains for at least a century. One of many sites at which such remains have been found is the Samwell Cave along a drainage basin in Shasta County, California — the site of the current study. Blois's team, however, looked for evidence of diversity in smaller creatures. "We were mainly interested in small mammals, the guys that survived the extinction event," she says. The researchers picked through fossilized woodrat nests, called middens, which have been well preserved in caves. Woodrats collect scat and pellets containing, among other things, small mammalian bones, which carnivores such as eagles, owls and foxes have defecated or regurgitated. "You just have to find the midden, and animals have already done all the work for us," says Blois. "The carnivores sample and the woodrats collect the dead and digested animals." Read the full report here.
Source: Janet Fang for Nature News.
