Recently, multiple NSF-funded researchers have documented genetic changes resulting from climate change. These studies suggest that extreme variation in temperature and rainfall are causing genetic shifts in organisms with short life spans.
At the University of California-Irvine, Arthur Weis is studying how a 5-year California drought caused genetic changes in field mustard, a weedy plant that is common throughout the United States. Weis collected seeds from wild plants before and after the drought, then raised them under identical conditions to observe differences between the two samples. Even when provided with sufficient amounts of water, plants grown from post-drought seeds bloomed sooner. During the drought, natural selection favored this particular trait because it allowed the plants to seed successfully before conditions became fatally dry. Building on this study, Weis is organizing an NSF-funded workshop to stimulate a concerted scientific effort to collect and preserve seeds across North America. Called Project Baseline, this undertaking will provide scientists with an important resource for studying future climate change–induced evolutionary events.
On a global scale, Raymond Huey of the University of Washington and George Gilchrist of the College of William and Mary have found genetic changes in fruit flies that correspond to temperature increases. In their study, they examined a certain type of genetic change known as a chromosomal inversion. More than 40 years ago, scientists documented these genetic rearrangements in wild populations of the fruit fly species Drosophila subobscura and noted that the frequency of the inversions correlated with the flies' latitude. Although the exact purpose of the inversion is unknown, it appears to protect the flies against warm temperatures. Huey and Gilchrist used the past data and added information on present-day fruit flies on three continents. Their analysis shows genetic differences between contemporary fruit flies and 1981 populations: Flies at higher latitudes have more of the low-latitude chromosomal inversions. In other words, these flies have undergone genetic adaptation to warmer temperatures.