Biogeographical patterns and floral evolution of Oreocharis (Gesneriaceae)

We examined the geographical distribution ranges and floral traits of Oreocharis and used nuclear ITS1,ITS2 and chloroplast trnL-trnF sequences of 58 Oreocharis species to construct a phylogenetic tree. We then analyzed the adaptation and evolution of floral traits based on the above data. Results showed the Oreocharis could be separated into two clades. Clade A was mainly distributed in Southwest China and predominantly showed yellow corollas with four stamens; Clade B was mainly distributed in South and Southeast China and predominantly showed purple corollas, with several species evolving two stamens. Corolla evolution from zygomorphy to actinomorphy was also detected. All four Hainan-endemic Oreocharis taxa originated from a common ancestor with bright yellow and radial corollas, later evolving orange and bilateral corollas. Geographical isolation, soil heterogeneity, and divergent selection on diverse bee pollinators were identified as key factors in the evolution and diversity of floral traits in Oreocharis.