The evolution of the worldwide leaf economics spectrum

The worldwide leaf economic spectrum (WLES) is a strikingly consistent pattern of correlations among leaf traits. Although the WLES effectively summarizes variation in plant ecological strategies, little is known about its evolution. We reviewed estimates of natural selection and genetic variation for leaf traits to test whether the evolution of the WLES was limited by selection against unfit trait combinations or by genetic constraints. There was significant selection for leaf traits on both ends of the WLES spectrum, as well as significant genetic variation for these traits. In addition, genetic correlations between WLES traits were variable in strength and direction. These data suggest that genetic constraints have had a smaller role than selection in the evolution of the WLES.