Background
The authors write that "a key question in ecology and evolution is to what degree variation in ecologically important traits is heritable, because heritability determines the potential for evolutionary change of traits (Fisher, 1930; Falconer and MacKay, 1996)," which phenomenon significantly enhances the ability of a species "to adapt to changing environments (Visser, 2008; Hoffmann and Sgro, 2011)," such as the changes climate alarmists are predicting for the entire planet over the next several decades or more.

What was done
In an attempt to answer this "key question," Zhang et al. conducted a glasshouse experiment in which they tested the response of a large number of epigenetic recombinant inbred lines or epiRILs (i.e., lines that are nearly isogenic but highly variable at the level of DNA methylation, which latter phenomenon can stably alter the gene expression pattern in cells) of Arabidopsis thaliana to drought and increased nutrient conditions.

What was learned
The four researchers say they found "significant heritable variation among epiRILs both in the means of several ecologically important plant traits and in their plasticities to drought and nutrients." And they state that the significant selection gradients of the several mean traits and plasticities they discovered "suggest that selection could act on this epigenetically based phenotypic variation."

What it means
In the concluding sentence of their paper's abstract, Zhang et al. say their study "provides evidence that variation in DNA methylation can cause substantial heritable variation of ecologically important plant traits, including root allocation, drought tolerance and nutrient plasticity, and that rapid evolution based on epigenetic variation alone should thus be possible."

References
Falconer, D.S. and MacKay, T.F.C. 1996. Introduction to Quantitative Genetics, 4th Edition. Longman, New York, New York, USA.

Fisher, R.A. 1930. The Genetical Theory of Natural Selection. Oxford University Press, Oxford, United Kingdom.

Hoffmann, A.A. and Sgro, C.M. 2011. Climate change and evolutionary adaptation. Nature 470: 479-485.

Visser, M.E. 2008. Keeping up with a warming world: assessing the rate of adaptation to climate change. Proceedings of the Royal Society B - Biological Sciences 275: 649-659.