Pollination in Melastomataceae: A Family-Wide Update on the Little We Know and the Much That Remains to Be Discovered

Conducting a literature review of the past 31 years, we here present an update of pollinator observations in Melastomataceae following Renner’s seminal work of 1989. The number of species with documented pollinators has more than doubled, to 272 species across 14 of the 18 major tribes. We detected a strong geographic bias, however, with 90% of observations from New World species, despite 35% of Melastomataceae species diversity contained in the Old World. Further, we report that shifts from the common and most widespread pollination strategy (buzz pollination by bees, ca. 95.5% of species) have occurred both in the New and Old World tropics and likely more than 20 times. These include shifts to nectar-foraging vertebrates (2.5%, six tribes), food-body-foraging vertebrates (0.9%, one tribe) and to generalized pollination systems (1.1%, possibly two tribes). Pollinator shifts commonly associate with floral trait changes, including, for instance, reward type, pollen release mechanisms, and corolla shape. We emphasize the need for more pollination biological studies particularly of Old World species and the four hitherto unstudied clades, as well as comparative investigations across tribes and biogeographic regions to understand the extraordinary success of buzz pollination and the drivers of pollinator shifts in the family.