Format: ORAL

Vincius L. G. Brito

Instituto de Biologia, Universidade Federal de Uberlândia, Uberlândia, Brasil

Buzz-pollinated flowers represent some of the most iconic examples of evolutionary convergence in angiosperms. Typically, buzz-pollinated flowers exhibit a syndrome of convergently evolved traits including poricidal anthers, dimorphic stamens, and pollen as the sole floral reward. This suite of floral traits is thought to have evolved together in ca. 25 angiosperm families. However, at finer taxonomic levels, these traits are not always associated with one another. For example, stamen dimorphism appears to be context-dependent within the Melastomataceae (the most diverse plant lineage with poricidal flowers): dimorphic stamens tend to be associated with pollinator dependence, whereas pollinator-independent species are more likely to have monomorphic stamens. Furthermore, some melastomes have acquired divergent traits which are associated with increased pollinator specialization. For example, independent evolutionary origins of oils by the stamens appear to have made melastome pollen unpalatable to many bees, so that unrelated oil-producing flowers are almost entirely visited by a small subset of buzzing bees those that also collect oil. On the other side of the specialization spectrum, some nectar-producing melastomes have increased pore size, allowing them to be visited by a more diverse range of insects. Together, the shifts towards more specialized or generalized systems suggest a complex pattern of both diverging and converging traits within paraphyletic melastome lineages.