Polyploidy and cross-biome hybrid speciation in the Andes. The case of the Gynoxys-Nordenstamia clade (Asteraceae)

• Applicant: Dr. Salvatore Tomasello
• Subject Area: Evolution and Systematics of Plants and Fungi ; Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 536780963

Natural hybridization and polyploidy are important evolutionary forces regarded as key factors for diversification processes in flowering plants. In Arctic and Alpine environments, polyploidization has been an important mechanism of stabilizing new hybrid lineages in areas heavily affected by past climatic oscillations. However, several areas of the world (e.g., the Neotropics) have been much less investigated under this perspective. Mountain ranges of South America are one of the most prominent hot spots of plant biodiversity, housing about 125,000 vascular plant species. Despite the small area occupied, the Andes concentrates about 10-15 % of the world’s vascular plant diversity. The proposed project aims at investigating the importance of hybridization and polyploidization for the evolution of important floristic elements of the mountain systems of the Neotropics, especially in the frame of past climatic oscillations. More specifically, we would like to find out if reticulation events occurred in the frame of the quaternary climatic oscillations and if they were only intra- or also inter-biome (i.e., between elements of the Pàramo and of the montane forests). We are going to use the sister-genera Gynoxys-Nordenstamia as study system because of the following reasons: 1) This clade is an important floristic element of both the Pàramo and montane forest biomes; 2) It is a group that experienced recent fast radiation and (presumably) hybridization; 3) It is distributed along the entire Andean range. In the first phase of the project, we will collect about 150 taxa across the whole Andes, approximately three samples per taxon. Ploidy level will be estimated for all collected samples via flow-cytometry and chromosome counts. We will produce phylogenomic data via Hyb-Seq, gathering sequence information for about thousand nuclear regions and the entire chloroplast genome. Eventually, we will infer time calibrated phylogenetic networks to pinpoint hybridization event and estimate the time of formation of the hybrid/polyploid taxa.

• DFG Programme: Research Grants
• International Connection: Ecuador
• Cooperation Partners: Dr. Ximena Palomeque; Professorin Dr. Katya S. Romoleroux