Orogeny and High Pollen Flow as Driving Forces for High Genetic Diversity of Endangered (Franch.) Pax Endemic to China.

(Franch.) Pax is an endangered species endemic to China, mainly scattered in the Qinling-Daba Mountains. The genetic diversity of 17 natural populations were analyzed by nuclear DNA (nDNA) and chloroplast DNA (cpDNA) to explore the driving forces for its microevolution. A high level of genetic diversity (nDNA: e = 0.296, cpDNA: t = 0.806) was found in . Genetic variation was mainly within populations (92.52%) based on nDNA, while it was mainly among populations (96.26%) based on cpDNA. The seventeen populations were divided into two groups, corresponding to the subtropical zone (Group I) and temperate zone (Group II), with haplotype 4 (Hap4) and Hap5 being the most common haplotypes, respectively. Consequently, genes associated with heat and heavy metal stress were identified in Group I, while genes related to salt and drought stress were identified in Group II. Haplotype differentiation was driven by the heterogeneous microenvironment caused by the uplifting of the Qinling-Daba Mountains, which was a vital source of its high genetic diversity. Furthermore, the uplifted Qinling-Daba mountains may bridge high pollen flow among populations, whereas rivers can result in low seed flow among populations, which has led to the incongruent genetic structure between nDNA and cpDNA. This study represents a new perspective that geological events, especially orogeny, play an important role in plant microevolution through the establishment of maternal genetic structure and provides a meaningful conservation strategy for . Overall, the Qinling-Daba Mountains not only are cradles for the genetic diversity of but also provided refugia for it during the Quaternary glacial period.