J Syst Evol

• Research Articles •    

Back to the brink: Phylogeography and demographic history of the endangered Torreya jackii

Xin Tong1†, Jian‐Hui Li1,2†, Kai Jiang1,3, Yuan‐Yuan Li1, Chao‐Nan Liu1, Shekhar Biswas1, Rong Wang1, and Xiao‐Yong Chen1,4*   

  1. 1 Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, Shanghai Key Laboratory for Urban Ecological Processes and Eco‐Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China
    2 Department of Environmental Engineering, College of Chemistry and Materials Engineering, Quzhou University, Quzhou 324000, Zhejiang, China
    3 Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Chenshan Botanical Garden, Shanghai 201602, China
    4 Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
  • Received:2020-08-07 Accepted:2021-01-12 Online:2021-02-01

Abstract: Both paleoclimatic change and anthropogenic habitat destruction can have adverse effects on species demography and, in turn, could lead a species towards being endangered and rare. Understanding the relative importance of these natural and anthropogenic factors driving species endangerment and rarity is thus crucial for effective conservation planning but remains elusive. Here, we examine the phylogeography and demographic history of an endangered conifer species in China, Torreya jackii Chun, and assess the relative importance of natural and anthropogenic factors that might have put the species in its endangered state. We collected tissue samples from all the 13 extant wild populations, and analyzed the genetic variation using eight nuclear microsatellites and four chloroplast and one mitochondrial DNA fragments. We found low genetic and nucleotide diversities, which could explain the absence of spatial and phylogeographic structure. Using a hierarchical approximate Bayesian computation technique, we identified the demographic scenario that best fits the genetic data and found that effective population size was low at least 200 000 years ago but expanded after the last glacial maximum (LGM). The paleoclimatic niche model revealed a profound effect of precipitation on the distribution of T. jackii and predicted that the current distribution areas were suitable during the LGM. Despite the post-LGM expansion, the best-supported scenario showed a dramatic population collapse during the past 300 years, when anthropogenic disturbances also increased dramatically. Overall, our study sheds light on how historical factors and human impacts jointly threaten the persistence of a species, and these aspects should be duly considered in species conservation planning.

Key words: demographic inference, endangered species, hierarchical approximate Bayesian computation, Torreya jackii