J Syst Evol ›› 2019, Vol. 57 ›› Issue (3): 234-246.DOI: 10.1111/jse.12433

• Research Articles • Previous Articles     Next Articles

Congruent species delimitation of two controversial gold‐thread nanmu tree species based on morphological and restriction site‐associated DNA sequencing data

Xin Ding1,3, Jian Hua Xiao1,3, Lang Li1, John G. Conran2, and Jie Li1*   

  1. 1Plant Phylogenetics and Conservation Group, Centre for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650223, China
    2School of Biological Sciences and Australian Centre for Evolutionary Biology and Biodiversity and Sprigg Geobiology Centre, University of Adelaide, Adelaide, South Australia, SA 5005, Australia
    3University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2017-11-10 Accepted:2018-05-01 Online:2018-07-11 Published:2019-06-06

Abstract: Species delimitation is fundamental to conservation and sustainable use of economically important forest tree species. However, the delimitation of two highly valued gold‐thread nanmu species (Phoebe bournei (Hemsl.) Yang and P. zhennan S. K. Lee & F. N. Wei) has been confusing and debated. To address this problem, we integrated morphology and restriction site‐associated DNA sequencing (RAD‐seq) to define their species boundaries. We obtained consistent results from the two datasets, supporting two distinct lineages corresponding to P. bournei and P. zhennan. In P. bournei, higher order leaf venation is more prominent, petioles are thicker, and leaf apex angle is narrower, compared to P. zhennan. Both datasets also revealed that the former putative P. bournei populations from northeastern Guizhou belong to P. zhennan. The two species are now distinct in distributions except in the Wuling Mountains, where they overlap. Phoebe bournei occurs mainly in central Fujian, southern Jiangxi, the Nanling Mountains, and the Wuling Mountains, whereas P. zhennan is found in the adjoining eastern regions of the Qionglai Mountains, the southern Sichuan hills, and the Wuling Mountains. The re‐delimitation of P. bournei and P. zhennan and clarification of their ranges provide a better scientific basis guiding the conservation and sustainable utilization of these tree species.

Key words: delimitation, distribution areas, gold-thread nanmu, morphological characters, P. bournei and P. zhennan, restriction site-associated DNA sequencing (RAD-seq)