Life-history traits evolution across distribution ranges: how the joint evolution of dispersal and mating system favor the evolutionary stability of range limits?

The question of the stability of distribution ranges of species is fundamental in ecology. However, the way in which stable distribution ranges are shaped by natural selection is still poorly studied. For a long time, botanists have studied empirically how self-fertilization and dispersal traits change from the centre to the periphery of species' distribution ranges, but theoretical arguments are lacking. In this commentary, we use a recent evolutionary model by Cheptou and Massol (2009) that analyses the joint evolution of dispersal and the mating system in a metapopulation. Considering that distribution ranges may result in gradients in pollen limitation for plants, habitat availability, or inbreeding depression for plants, we analyse how the association of dispersal and self-fertilization varies across distribution ranges. Interestingly, we show that such gradients result in a change in both traits and may favor evolutionary stable range limits for plant distribution. Based on empirical and theoretical results, we discuss the plausibility of such gradients as a way to explain range limits in plants.