Format: ORAL

Marco Cedeo-Fonseca1,2,3* Orlando O. Ortiz 1,4,5 Nils Kster1, Astrid de Mestier6 and Thomas Borsch1

1 Botanischer Garten und Botanisches Museum Berlin, Freie Universität Berlin, Königin-Luise-Straße 6-8, D-14195 Berlin, Germany. 2 Herbario Luis Fournier Origgi (USJ), Centro de Investigación en Biodiversidad y Ecología Tropical, Universidad de Costa Rica, Apdo.11501-2060, San José, Costa Rica. 3 Jardin Botánico Lankester, Universidad de Costa Rica, Apartado 302–7050 Cartago, Costa Rica. 4 Herbario PMA, Universidad de Panamá, Panamá, Panamá. 5 Coiba Scientific Station (COIBA AIP), Panamá, Panamá. 6 Institut für Biologie – Systematische Botanik und Pflanzengeographie, Freie Universität, Berlin, Altensteinstraße 6, 14195 Berlin, Germany. * Corresponding author

With 600 currently accepted species and an estimated total of 1500 species,Philodendronis the second largest aroid genus and one of the most diverse genera in Neotropical rainforests. It originated 29 million years ago in the pan-Amazonian rainforests and diversified more intensely from the Late Miocene onwards, coinciding with the rise of the Andes and the formation of the Isthmus of Panama. Being South American in origin, the genus colonized Central America only relatively late from the Pliocene onwards. Nonetheless, the region is one of the centers of diversity and endemism ofPhilodendron, harboring 120 known species in Central America and Mexico.In all available molecular studies, however, representation of species from this region has been poor. In order to understand the evolutionary origin of the high Central American diversity, we used an exhaustive species sampling and a combination of three non-coding plastid regions(petD, rpl16, and trnK/matK).The phylogenetic results support 12 geographically well-defined clades in the large subgenusPhilodendron, 10 of which consist of species from the Amazon, the Andes, and the Choc Biogeographical Region. The vast majority of species from Central America, southern Mexico and the Caribbean were found in two distinctive and diverse Central American clades, apart from five smaller subclades and several single, rather widespread species nested within the South American clades. This pattern suggests at least nine colonization events in the region and several rapid radiations, especially in the Talamanca Mountain range and along the Isthmus of Panama. In summary,Philodendronhas proven to be an ideal model group to study the historical biogeography and evolutionary processes of big plant genera in the Neotropics, the most diverse phytogeographic realm.