Flower size evolution in the Southwest Pacific

Abstract

AbstractThe island rule is arguably the most controversial topic in evolutionary biogeography. Previous work has focused almost exclusively on vertebrates. Little is known about the island rule in plants, and no previous study has tested for the island rule in flower size. Here, we provide the first test of the island rule in flowers. Using a newly derived dataset from the Southwest Pacific, we tested whether animal-pollinated and wind-pollinated flowers follow the island rule, or whether they exhibit directional size changes (i.e. gigantism or dwarfism). Results indicate that animal-pollinated flowers follow the island rule, while wind-pollinated flowers do not. Instead, they became consistently larger on islands. We conclude that, whilein situevolution of flower size is widespread on islands in the Southwest Pacific, species belonging to different pollination syndromes exhibit markedly different evolutionary trajectories.