In the western United States, Clarkia (Onagraceae) taxa vary in mating system, life history, and photosynthetic physiology. Self-fertilizing taxa bloom earlier in the year and have higher rates of photosynthesis than their most closely related cross-pollinating species.
By performing a multi-generational artificial selection experiment, Emms et al. find evidence that these traits evolved independently of one another, rather than in a correlated fashion. This suggests that different genes underlie each characteristic, and that Clarkia populations have the ability to respond to natural selection in multiple ways, with the evolution of one characteristic having little influence on the evolution of the others.