Evidence is piling up that climate change has led to genetic modifications in a diverse range of animals including birds, squirrels and mosquitoes, scientists said on Thursday.
These genetic changes are a result of altered seasonal events, not to the expected direct effects of increasing temperatures, according to William Bradshaw, a professor at the University of Oregon, and Christina Holzapfel, a research associate at the university.
Their findings were published on the June 9 issue of the journal Science.
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, the researchers said. Because of this, animal species are extending their range toward the poles and populations have been migrating, developing or reproducing earlier, they said.
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, "phenotypic plasticity" is not the whole story. Over the past several decades, rapid climate change has led to heritable, genetic changes in animal populations, they said.