What was done
The authors collected seeds of the common field mustard (Brassica rapa L.) plant from a dry area and a moist area in southern California (USA) in May 1997 (prior to a period of significant drought) and June 2004 (after the drought had ended), from which they grew what they called predrought ancestral genotypes and post-drought descendant genotypes. They then used these plants to produce 1997 x 1997 and 2004 x 2004 hybrid crosses that were grown in a greenhouse under both short- and long-season watering regimes, where the plants were watered daily to saturation for 33 and 88 days, respectively, while they observed and recorded a number plant life-history traits.

What was learned
Franks and Weis report that "several life-history traits differed between the ancestral genotypes collected before and descendant genotypes collected after the natural drought," stating that "this shows directly that an evolutionary change in the life-history traits has occurred during a 5-year drought." They also report that "the evolutionary changes in trait levels following the drought are consistent with predictions from life-history theory," since "the drought selected for individuals that flowered earlier, continued to flower for longer given sufficient resources, and produced a more consistent, evenly distributed pattern of flowering over time," which they say is "a true genetically based evolutionary change rather than an expression of phenotypic plasticity."

What it means
Contrary to what climate alarmists continue to blithely claim, this study demonstrates that plants have the capacity to rapidly alter a number of life-history traits that enable them to better deal with the consequences of climate change. Earth's plants, therefore, are likely to be much more resilient to global warming and potential associated changes in precipitation regimes than people have long been misled to believe.