Population genetics of , an endangered plant species with extremely small populations in China.

, the largest genus of Theaceae, is well-known for having high economic values. demonstrates large beautiful flowers with some primitive characters, such as multiple large and persistent bracteoles and sepals, was listed as Vulnerable species on the IUCN Red List. In this study, we investigated all possible records of the species, and sampled four natural populations and five cultivated individuals. By applying shallow-genome sequencing for nine individuals and RAD-seq sequencing for all the sampled 77 individuals, we investigated population genetic diversity and population structure of the species. The results showed that the population sampled from Fengkai, previously identified as , possessed different plastid genome from other species possibly due to plastid capture; the species possesses strong population structure possibly due to the effect of isolation by distance, habitat fragmentation, and self-crossing tendency of the species, whose effective population size declined quickly in the past 4,000 years. Nevertheless, maintains a medium level of genetic diversity within population, and significant differentiation was observed among the four investigated populations, it is anticipated that more populations are expected to be found and all these extant populations should be taken into instant protection.