Writing in the "Perspectives" section of the June 9 issue of SCIENCE, William E. Bradshaw, professor of biology, and Christina Holzapfel, biology research associate, show that diverse animal populations have changed genetically in response to rapid climate change. These genetic changes are in response to altered seasonal events and not to the expected direct effects of increased summer temperatures.
Global warming is proceeding fastest at the most northern latitudes, resulting in longer growing seasons while simultaneously alleviating winter cold stress without imposing summer heat stress. In short, northern climates are becoming more like those in the south.
"Over the past 40 years, animal species have been extending their range toward the poles and populations have been migrating, developing or reproducing earlier," said Bradshaw. "These expansions and changes have often been attributed to 'phenotypic plasticity,' or the ability of individuals to modify their behavior, morphology or physiology in response to altered environmental conditions."
However, adds Holzapfel, "phenotypic plasticity is not the whole story. Studies show that over the past several decades, rapid climate change has led to heritable, genetic changes in animal populations."
Bradshaw and Holzapfel provide a number of examples of these changes: Canadian red squirrels reproducing earlier in the year; German blackcaps (birds) are migrating and arriving earlier to their nesting grounds; and, North American mosquitoes living in the water-filled leaves of carnivorous plants are using shorter, more "southern" day lengths to cue the initiation of larval dormancy.
In contrast, the authors write that no studies have found genetic changes in populatio
Source:University of Oregon