Conservation Genetics and Modeling Potential Geographic Distribution of Corybas taliensis, a Small ‘Sky Island’ Orchid Species in China

Abstract

Background Corybas taliensis is an endemic species of sky islands in the Pan-Tibetan Plateau region of China. Its habitat is fragile and volatile, and it is likely that the species is threatened. However, it is difficult to determine the conservation priority or unit without knowing the genetic background and the distribution of this species. In this study, we used double digest restriction-site associated DNA-sequencing (ddRAD-seq) to investigate the conservation genomics of C. taliensis. At the same time, we modeled the present and future (2030 and 2090) suitable habitats for C. taliensis using the maximum-entropy (MaxEnt) model. Results The results suggested that the related C. fanjingshanensis belongs to C. taliensis and should not be considered a separate species. All the sampling locations were divided into three genetic groups: Sichuan & Guizhou population (SG population), Hengduan Mountains population (HD population) and Himalaya population (HM population), and there was complex gene flow between the sampling locations of HD population. MT was distinct genetically from other sampling locations due to the special environment in Motuo. The genetic diversity (π, He) of C. taliensis was relatively high, but its contemporary effective population size (Ne) was small. C. taliensis might be currently affected by inbreeding depression, while its large population density may be able to reduce the effect. The areas of suitable habitats in higher mountains are not predicted to change significantly in the future, and these suitable habitats is predicted to spread to other higher mountains under future climate change. However, suitable habitats in relatively low altitude mountains may disappear in the future. Which indicated that C. taliensis will be caught in a ‘summit trap’ in low altitude areas. On the contrary, the high altitude of Himalaya and Hengduan Mountains regions play as ‘biological refuges’ for C. taliensis. Conclusions These results not only provide a new understanding of the genetic background and potential resource distribution of C. taliensis, but also lay the foundation for its conservation and management.