What was done
The authors determined the magnitude and direction of shifts over time [13 to 46 years, mean = 24.1 years] in chromosome inversion frequencies and in ambient temperature for 26 populations of the cosmopolitan fly species Drosophila subobscura on three continents, seeking to see if "ambient temperatures have warmed at these sites and also whether genotypes characteristic of low latitudes have increased in frequency."

What was learned
Balanya et al. report that warming occurred at 22 of the 26 sites they investigated, and that "chromosome frequencies shifted toward a more low-latitude pattern in 21 of the 22 sites that warmed over the sample interval," indicating that "inversion frequencies have changed in step with climate on three continents," such that "genotype frequencies and climate at a given site have become more equatorial over the sample intervals" with the observed shifts being "equivalent to moving the historical sample site ~1° of latitude closer to the equator."

What it means
In the words of the five researchers, the genetic shift they uncovered "is exceptionally rapid," being "detectable even for samples separated by fewer than two decades." In addition, they say that "the ability of D. subobscura (Rodriguez-Trelles et al., 1998; Orengo and Prevosti, 1996; Sole et al., 2002) - and probably other species with short generation times (Bradshaw and Holzapfel, 2001; Umina et al., 2005; Levitan and Etges, 2005; Kinnison and Hendry, 2001) - to respond genetically and rapidly to imposed environmental shifts may partially buffer their persistence in a globally warming world (Bradshaw and Holzapfel, 2006)."

References
Bradshaw, W.E. and Holzapfel, C.M. 2001. From the Cover: Genetic shift in photoperiodic response correlated with global warming. Proceedings of the National Academy of Sciences USA 98: 14,509-14,511.

Bradshaw, W.E. and Holzapfel, C.M. 2006. Evolutionary response to rapid climate change. Science 312: 1477-1478.

Kinnison, M.T. and Hendry, A.P. 2001. The pace of modern life II: from rates of contemporary microevolution to pattern and process. Genetica 112-113: 145-164.

Levitan, M. and Etges, W.J. 2005. Climate change and recent genetic flux in populations of Drosophila robusta. BioMed Central Evolutionary Biology 5: 4.

Orengo, D.J. and Prevosti, A. 1996. Evolution: International Journal of Organic Evolution. 50: 1346.

Rodriguez-Trelles, F., Rodriguez, M.A. and Scheiner, S.M. 1998. Tracking the genetic effects of global warming: Drosophila and other model systems. Conservation Ecology 2: 2.

Sole, E., Balanya, J., Sperlich, D. and Serra, L. 2002. Long-term changes in the chromosomal inversion polymorphism of Drosophila subobscura. I. Mediterranean populations from southwestern Europe. Evolution: International Journal of Organic Evolution 56: 830-835.

Umina, P.A., Weeks, A.R., Kearney, M.R., McKechnie, S.W. and Hoffmann, A.A. 2005. A rapid shift in a classic clinical pattern in Drosophila reflecting climate change. Science 308: 691-693.