Format: ORAL

Luca D. Moreyra1;Jennifer R. Ackerfield2; Carme Blanco-Gavaldà3; Christian Brochmann4; Juan A. Calleja5; Kazumi Fujikawa6; Mercè Galbany-Casals3; Abel Gizaw4; Cristina Roquet3; Alfonso Susanna¹

1 Botanic Institute of Barcelona (IBB), CSIC-Ajuntament de Barcelona, Spain 2 Department of Biology, Colorado State University, U.S.A. 3 Systematics and Evolution of Vascular Plants (UAB) – Associated Unit to CSIC by IBB, Autonomous University of Barcelona, Spain. 4 Natural History Museum, University of Oslo, Norway. 5 Autonomous University of Madrid, Spain. 6 Kochi Prefectural Makino Botanical Garden, Japan.

The Afromontane archipelago consists of isolated humid and temperate areas on the highest mountains in Tropical and South Africa. This biome hosts a unique flora characterized by a high proportion of endemic species. Despite its uniqueness, the Afromontane flora is understudied from an evolutionary and biogeographic point of view. Several afromontane endemics belonging to subtribe Carduinae (Asteraceae) have traditionally been ascribed to the Carduus-Cirsium group, based on superficially similar morphologies. To investigate their evolutionary origin, we applied the Hyb-Seq approach on 500 samples comprising all genera of subtribe Carduinae. We recovered sequences for 1000 conserved orthologous nuclear loci plus the complete plastome, and conducted phylogenetic inference using concatenated and coalescence-based approaches. The Afromontane species constituted three distinct evolutionary lineages, one of them not even belonging to the Carduus-Cirsium group. Given the evolutionary and morphological distinctiveness of these three lineages, we propose three new genera, all endemic to the Afromontane flora: Afrocarduus, Afrocirsium and Nuriaea. Building on our highly resolved phylogeny, we conducted ancestral range estimation analyses. Our results indicate that these three endemic genera originated after two independent long-distance dispersals from the Mediterranean region. The first occurred during the Middle Miocene and resulted in Nuriaea, and the second occurred in the Late Miocene and gave rise to Afrocarduus and Afrocirsium. The current diversity within the three genera mainly results from speciation during the Pliocene and Pleistocene. The increased orogeny in Tropical East Africa during these periods, combined with the dramatic Pleistocene climate oscillations, likely fueled the diversification.