Format: ORAL

Lo-Paul Dagallier1 Frank Almeda2 Lucas Bacci3 Agnes Dellinger4 Diana Fernndez-Fernndez5 Robin Fernandez Hilario6 Renato Goldenberg7 Humberto Mendoza-Cifuentes8 Jhon S. Murillo-Serna9 Carmen Ulloa Ulloa10 Lucas C. Majure3 Fabin A. Michelangeli1

1 New York Botanical Garden, Bronx, NY, USA. 2 California Academy of Sciences, San Francisco, CA, USA 3 University of Florida, Gainesville, FL, USA 4 University of Vienna, Vienna, Austria 5 Instituto Nacional de Biodiversidad, Quito, Ecuador 6 CORBIDI, Lima, Peru 7 Universidade Federal do Paraná, Curitiba, PR, Brazil 8 Jardín Botánico de Bogotá, Bogotá, DC, Colombia 9 Universidad de Antioquia, Medellin, Antioquia, Colombia 10 Missouri Botanical Garden, Saint Louis, MO, USA

The tribe Merianieae (Melastomataceae) is a group of trees, lianas and herbs distributed in the American tropics. It contains ca. 288 species within 7 genera. The tribe is distributed in both lowland and highland rainforests, from southern Mexico and Central America, the Greater Antilles to the Central Andes, and eastwards to the Atlantic rain forest. We present the most up-to-date phylogenetic reconstruction of the tribe based on phylogenomic sequence data, including 184 species (ca. 64%) and hundreds of nuclear loci. We used different phylogenetic reconstruction approaches including paralogy resolution steps, and secondary calibration to date the tree. Phylogenetic results are consistent with previous studies based on Sanger sequence data, but phylogenetic placement of some clades (Adelobotrys, Macrocentrum, Salpinga) remains problematic. Indeed, we recovered many gene tree conflicts at both deep and shallow nodes in the Merianieae phylogeny and relate them to reticulate processes of evolution, possibly linked to introgression and rapid radiations. Macrocentrum is not monophyletic and recovered in three clades. Meriania likewise is not monophyletic, because one group (Adelbertia) is more closely related to Adelobotrys, and Axinaea is embedded within the remaining Meriania. Graffenrieda and Centronia form a well supported clade. The group seems to have originated in the Guiana Shield, but most of the diversity is in the Andes, as a result of two distinct radiations (one in Graffenrieda and one in Meriania). Secondary radiations also occurred in the Guayana Shield and the Atlantic Forest. We discuss the impact of the Andes in generating the diversity and the biogeographic history of the clade.