XVI International Botanical Congess

DNA sequence and restriction-site data show that the Hawaiian lobeliads ­ one of the most striking cases of adaptive radiation in flowering plants ­ are the product of one immigration event, not three to five as previously thought. Their ancestor arrived from Africa or elsewhere in the Pacific roughly 16 My ago, and appears to have been a woody, wind-dispersed, bird-pollinated Lobelia adapted to open, high-elevation habitats. Invasion of moist tropical forests favored the evolution of fleshy fruits and the tree-like habit, and may have accelerated speciation through a previously overlooked mechanism. Avian pollination was favored by cool, moist habitats, hawkmoth pollination, by warmer, drier sites. Within the largest genus Cyanea, extinction was most likely in species with narrow ranges and/or long, highly specialized flowers.