Switch from specialized to generalized pollination

The once prevalent view that the evolution of extreme ecological specialization is accompanied by a loss of potential for adapting to new conditions, and thus is irreversible, has been challenged by several recent examples. However, we know of no modern phylogenetic studies showing reversal in pollination relationships from extreme specialization to generalization, although such reversals are theoretically expected. Here we present molecular phylogenetic evidence for an evolutionary shift in Dalechampia (Euphorbiaceae) vines from a highly specialized relationship (pollination by one or a few animal species) with resin-collecting bees to generalized pollination by a variety of pollen-feeding insects. This shift was associated with dispersal from Africa to Madagascar, where the specific resin-collecting pollinators are absent. These results show that plants dispersing beyond the range of their specific pollinators may succeed by evolving more generalized pollination systems.