Evolutionary patterns within the New World Clade Polygala sections Clinclinia and Monninopsis (Polygalaceae)

Abstract

Members of Polygala sections Clinclinia and Monninopsis, from the New World Clade (NWC), inhabit arid to humid habitats along the American continent. Although knowledge of these sections is currently incomplete, it is crucial for understanding evolutionary and diversification patterns in Polygalaceae. Here, we sample new species from the Polygala NWC with emphasis on these two sections, providing a comprehensive molecular phylogeny based on DNA sequence data from one nuclear (ITS) and three chloroplast (trnL-F intergenic spacer, rbcL, and partial matK-trnK) loci. Furthermore, we conducted comparisons for the main clades in the environmental and geographic spaces using climatic and elevation data processed by ordination and species distribution modelling (SDM) techniques. In addition, an ancestral state reconstruction for the morphological flower traits “violet spots on lateral petals” and “style shape” was carried out. The ancestral flower of the Polygala NWC was reconstructed as not having violet spots on the lateral petals and with a style with superior appendages. Within Polygala sect. Monninopsis, we found three distinct lineages. The North American clade A1 showed a potential distribution found along the Andes, from southern United States to Argentina. The South American P. argentinensis was predicted to be found from central Mexico to Argentina. The Patagonian P. darwiniana was also predicted to be found in northern North America and in the Lower California Peninsula in Mexico. Within Polygala sect. Clinclinia, we also found three distinct lineages. Clade B1 in addition to its empirical distribution found in Chile and Argentina, also showed a potential distribution found in Colombia. Clade B2 in addition to its empirical distribution found in north and central Argentina, southern Bolivia, Paraguay, Uruguay, and southern Brazil, also showed a potential distribution in southern Chile, southern Argentina, and the South Atlantic Islands. Finally, the Argentinian clade B3 was also predicted to be found in central Chile and southern Bolivia. An updated synonymic list of the Polygala sects. Clinclinia and Monninopsis as treated in this study is also provided.