Format: ORAL

Constantin Kopper, Jrg Schnenberger, Agnes S. Dellinger

University of Vienna, Rennweg 14, Vienna 1030, Austria contact: constantin.kopper@univie.ac.at

Pollination syndromes are defined as suites of floral traits, which have evolved repeatedly across angiosperms in adaptation to distinct functional pollinator groups. The large, pantropically distributed family Melastomataceae is dominated by buzz-bee pollination (95.5%), where pollen is released from tubular, poricidal anthers through vibrations. In seven (of 23) tribes, shifts to other syndromes have occurred. These shifts can be found in the New- and Old-World and have been shown to be correlated with increasing altitude in the Neotropics. We recorded 44 functional floral traits across 411 species, spanning the whole family. We used machine learning algorithms (random forest RF) to identify pollination syndromes for species with documented pollinators and employed these trained models to predict pollinators for species without observations. We combined the results from the RF analyses with climatic and distribution data (elevation) to test if climatic variables and altitudinal gradients correlate with specific pollination syndromes and certain traits. Finally, we investigated if the same mechanisms apply for the New- and Old-World. Our results indicate strong support for four well differentiated pollination syndromes within Melastomataceae: buzz-bee, nectar-foraging vertebrate, food-body-foraging vertebrate, and generalist. Pollination syndromes in Melastomataceae can be discriminated by six system specific floral traits of which reward type and pollen release mechanism are the two most important traits. Climatic variables and altitude explain 67% of the variation found in Melastomataceae, with altitude having a particularly strong impact.Shifts away from the ancestral buzz-bee syndromes, which can be found along the whole elevational gradient but declines towards the top of the mountain, start to appear at about 1500m (except for the generalist syndrome start at about 400m and goes up to 1800m).Also, shifts to the nectar-foraging vertebrate and food-body-foraging vertebratesyndrome are associated with cooler Temperatures.These patterns can be found in the New- andOld-World.