Convergent evolution of sunbird pollination systems of Impatiens species in tropical Africa and hummingbird systems of the New World

The bird pollination systems of the New and Old Worlds evolved independently, and differ in many aspects. New World plants are often presented as those adapted to hovering birds while Old World plants to perching birds. Most Neotropical studies also demonstrate that in hummingbird species rich assemblages, only a small number of highly specialized birds exploits the most specialized plants with long corollas. Nevertheless, recent research on bird-plant pollination interactions suggest that sunbird pollination systems in the Old World have converged more with the highly specialized hummingbird pollination systems than previously thought. In this study we focus on the pollination systems of the bird pollination syndrome Impatiens species on Mt. Cameroon, West Africa. We show that despite the high diversity of sunbirds on Mt. Cameroon, only Cyanomitra oritis appear to be important pollinator of all Impatiens species. This asymmetry indicates the absence of pair wise co-evolution and points to a diffuse co-evolutionary process resulting in guilds of highly specialized plants and birds; a situation well known from hummingbirds and specialized plant communities of the New World. Additionally, the herbaceous habits of Impatiens species, the frequent adaptations to pollination by hovering birds, and the habitat preference for understory in tropical forests or epiphytic growth, resemble the highly specialized Neotropical plants.(c) 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115, 127-133.