475: A Rapid Shift in a Classic Clinal Pattern in Drosophila Reflecting Climate Change -- Umina et al. 308 (5722): 691 -- Science
Geographical clines in genetic polymorphisms are widely used as evidence of climatic selection and are expected to shift with climate change. We show that the classic latitudinal cline in the alcohol dehydrogenase polymorphism of Drosophila melanogaster has shifted over 20 years in eastern coastal Australia. Southern high-latitude populations now have the genetic constitution of more northerly populations, equivalent to a shift of 4° in latitude. A similar shift was detected for a genetically independent inversion polymorphism, whereas two other linked polymorphisms exhibiting weaker clinal patterns have remained relatively stable. These genetic changes are likely to reflect increasingly warmer and drier conditions and may serve as sensitive biomarkers for climate change.
These flies are adapting to a change in climate. We tend to think of selection and mutation as the forces of evolution, but here's a case where gene flow is causing evolution.