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.
“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.
