As climate change leads to warmer winters, many tropical plants and animals are moving north, according to a new study appearing this week in the journal Global Change Biology. "Quite a few mosquito species are expanding northward, as well as a lot of forestry pests: bark beetles, the southern mountain pine beetle," said Caroline Williams, associate professor of integrative biology at the University of California, Berkeley, and a co-author of the paper. "In our study, we were really focusing on that boundary in the U.S. where we get that quick tropical-temperate transition. Changes in winter conditions are one of the major, if not the major, drivers of shifting distributions." For more on this, see our press release at Berkeley News.