Recurrent hybridization underlies the evolution of novelty in (Gentianaceae) in the Qinghai-Tibetan Plateau.

The Qinghai-Tibetan Plateau (QTP) and adjacent areas are centres of diversity for several alpine groups. Although it is known that the QTP acted as a source area for diversification of the alpine genus , the evolutionary processes underlying diversity in this genus, especially the formation of narrow endemics, are 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 section as sp. nov., and explore its evolutionary history with complete plastid genomes and nuclear ribosomal internal transcribed spacer sequence data. Genetic divergence within ~3 million years ago was followed by postglacial expansion on the QTP, suggesting Pleistocene glaciations as a key factor shaping the population history of . Furthermore, a mismatch between plastid and nuclear data suggest that participated in historical hybridization, while population sequencing show this species continues to hybridize with the co-occurring congener in three locations. Our results indicate that hybridization may be a common process in the evolution of and may be widespread among recently diverged taxa of the QTP.