Background
The authors write that "one important phenomenon that is often overlooked and is poorly documented is the ability of agro-systems to rapidly adapt to environmental variations," noting that such adaptations can occur by either the adoption of new varieties or by the adaptation of existent varieties to a changing environment.

What was done
Working in "one of the driest agro-ecosystems in Africa, the Sahel," Vigouroux et al. "analyzed samples of pearl millet landraces collected in the same villages in 1976 and 2003 throughout the entire cultivated area of Niger," in order to see how the agro-system had responded to recurrent drought over that time interval. This they did by studying "phenological and morphological differences in the 1976 and 2003 collections by comparing them over three cropping seasons in a common garden experiment."

What was learned
The fifteen researchers report that "compared to the 1976 samples, samples collected in 2003 displayed a shorter lifecycle and a reduction in plant and spike size." They also found that an early flowering allele "increased in frequency between 1976 and 2003," and they say that this increase "exceeded the effect of drift and sampling, suggesting a direct effect of selection for earliness on this gene."

What it means
Vigoruoux et al. conclude that "recurrent drought can lead to selection for earlier flowering in a major Sahelian crop," reinforcing the similar earlier findings of Franks et al. (2007), Franks and Weis (2008, 2009) and Jump et al. (2008), thereby adding to the likelihood that other important food crops, as well as the native vegetation of natural ecosystems, can respond to environmental changes in an analogous fashion.

References
Franks, S.J., Sim, S. and Weis, A.E. 2007. Rapid evolution of flowering time by an annual plant in response to a climate fluctuation. Proceedings of the National Academy of Sciences USA 104: 1278-1282.

Franks, S.J. and Weis, A.E. 2008. A change in climate causes rapid evolution of multiple life-history traits and their interactions in an annual plant. Journal of Evolutionary Biology 21: 1321-1334.

Franks, S.J. and Weis, A.E. 2009. Climate change alters reproductive isolation and potential gene flow in an annual plant. Evolutionary Applications 2: 481-488.

Jump, A.S., Penuelas, J., Rico, L., Ramallo, E., Estiarte, M., Martinez-Izquierdo, J.A. and Lloret, F. 2008. Simulated climate change provokes rapid genetic change in the Mediterranean shrub Fumana thymifolia. Global Change Biology 14: 637-643.