William & Mary

Global warming drives genetic change

Global warming is driving genetic change on three continents, according to research by an international group of biologists, including a William and Mary professor. Associate Professor George W. Gilchrist is one of the authors of a paper published in the respected journal Science, which has linked certain genetic mutations in a species of fruit fly to global temperature change.Gilchrist

“The big message on this research is that natural populations are changing in response to changes in climate,” Gilchrist said. “It’s easier to detect the change in the biology than it is to detect the direct change in the climate. Plants and animals are much better thermometers than what we have.”

The research studied mutations over 25 years in wild fruit flies of the species Drosophila subobscura. These flies are native to a region which originally ranged from North Africa to Scandinavia, but have been introduced to locations on the coasts of North and South America. It’s been long known that some sections of chromosomes in specimens of D. subobscura become inverted. Gilchrist likens the phenomenon to flipping around a section of a UPC bar code. Most significantly, particular chromosomal inversions are correlated with the latitude of the insects’ habitat. He added that flies introduced to the New World soon evolved latitudinal patterns of inversions that paralleled those in Europe.

“Certain inversions occur in a very high frequency in, say, Århus, Denmark, and a very low frequency in Barcelona, Spain,” Gilchrist explained. “We see the same pattern between Port Hardy, British Columbia and Atascadero, California.”

Sampling of 26 populations over 25 years revealed that the chromosomal inversions were reflecting not only latitude of the resident population, but also local changes in average temperature. As average temperatures grew warmer, flies in the cooler, high-latitude populations began showing chromosomal inversions common among their more equatorial cousins, he said. The changes in the inversions were constant in populations in the Old World as well as in North and South America.

“Our findings were stronger than I had imagined them to be,” Gilchrist said. “I had thought that we probably would see some sort of shift. I couldn’t imagine that it would be as similar on all three continents. That surprised me. When you see the same pattern on three continents, you have reason to think it’s not coincidence.”

This research has implications for studies of evolutionary biology as well as for those concerned about global warming. Short-lived, rapidly breeding fruit flies are capable of producing five or six generations a year in the wild, making them ideal subjects for genetic study.

“I’d like for people to think of these flies as just another canary in the coal mine,” he said. “Right now, the story looks pretty good. The climate’s changing, the species are adapting—they’re changing their genetics and they seem to be able to keep up right now. How long will that keep up…and how about organisms that have longer generational times?”

The Science paper reporting the results is titled “Global Genetic Change Tracks Global Climate Warming in Drosophila subobscura.” Other authors areJoan Balanyá, Luis Serra and Josep Oller from the University of Barcelona, Spain, and Raymond Huey, of the University of Washington. The work was supported by grants from the National Science Foundation, as well as Spain's Ministry of Science.