Format: ORAL

Ling Yang1,2,3, Si-Qi Liang1,2,3, Jia-Ming Pan1,2,3, Jin-Xin Wei 1,2,3, Tao Ding4, Ri-Hong Jiang5, Yi-Zhen Shao6, Xian-Chun Zhang1,2, Yong-Bo Liu7, Qiao-Ping Xiang1,2

1 State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China 2 China National Botanical Garden, Beijing, China 3 College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China 4 Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and the Chinese Academy of Sciences, Guilin, Guangxi, China 5 Guangxi Forestry Research Institute, Nanning, China 6 College of Life Sciences, Henan Agricultural University, Zhengzhou, China 7 State Environment Protection Key Laboratory of Regional Ecological Process and Functional Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China

Abies beshanzuensis is one of the most endangered species in the world, with only three individuals so far. The accuracy of endangered species delimitation largely determines the efficiency and conservation strategies. The taxonomy of Abies beshanzuensis, A. ziyuanensis and A. dayuanensis, have always been controversial. A. dayuanensis has been considered as the synonym of A. ziyuanensis, whereas A. ziyuanensis is currently treated as a variety of A. beshanzuensis. To test this classification hypothesis, we performed target enrichment sequencing on 23 individuals from eight extant populations and obtained 805 single nucleotide polymorphic sites from 60 single-copy nuclear genes for population genetic analyses. Results of population genetic structure and demographic history analyses showed that this endangered fir group has diverged into two lineages corresponding to A. beshanzuensis and A. ziyuanensis. A. ziyuanensis first diverged from the common ancestor of A. beshanzuensis and A. dayuanensis, the latter two split apart later and more closely related, forming the other lineage. The genetic diversity is low within these populations. Strong genetic differentiation was found among populations. Gene flow is not detected after lineages split, probably because of the fragmented habitats which blocked effective genetic exchanges among populations. Ecological niche comparison showed that the average annual temperature and the temperature of the coldest quarter were significantly higher in the habitats of these endangered firs compared to those of non-threatened firs in East Asia. Therefore, we inferred that global warming is likely to push this group of endangered firs to the edge of extinction. According to the significant population differentiation, we provide genetic evidence that A. dayuanensis is a synonym of A. beshanzuensis, and resurrect A. ziyuanensis as a separate species.We also highlight the necessity to carry out ex-suit conservation in the Hengduan Mountains and the Qingling-Bashan Mountains andconduct in-suit regeneration.