The Qinghai-Tibetan Plateau (QTP) and adjacent areas are centers of diversity for several alpine groups. Although the QTP acted as a source area for diversification of the alpine genus Gentiana, the evolutionary process underlying diversity in this genus, especially the formation of narrow endemics, is still poorly understood. Hybridization has been proposed as a driver of plant endemism in the QTP but few cases have been documented with genetic data. Here, we describe a new endemic species in Gentiana section Cruciata as G. hoae sp. nov., and explore its evolutionary history with complete plastid genomes and nuclear ribosomal ITS sequence data. Genetic divergence within G. hoae approximately 3 million years ago was followed by postglacial expansion on the QTP, suggesting Pleistocene glaciations as a key factor shaping the population history of G. hoae. Furthermore, a mismatch between plastid and nuclear data suggest that G. hoae participated in historical hybridization, while population sequencing show this species continues to hybridize with the co-occurring congener G. straminea in three locations. Our results indicate that hybridization may be a common process in the evolution of Gentiana and may be widespread among recently diverged taxa of the QTP.
- phylogenetic analysis
- postglacial evolution