J Syst Evol ›› 2019, Vol. 57 ›› Issue (5): 508-518.DOI: 10.1111/jse.12479

• Research Articles • Previous Articles     Next Articles

Plastomes of Betulaceae and phylogenetic implications

Xiao-Yue Yang1†, Ze-Fu Wang2†, Wen-Chun Luo1, Xin-Yi Guo2, Cai-Hua Zhang1, Jian-Quan Liu1,2, and Guang-Peng Ren1*   

  1. 1State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
    2Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610000, China
  • Received:2018-07-04 Accepted:2018-11-16 Online:2019-03-21 Published:2019-09-01

Abstract:

Betulaceae is a well‐defined family of Fagales, including six living genera and more than 160 modern species. Species of the family have high ecological and economic value for the abundant production of wood. However, phylogenetic relationships within Betulaceae have remained partly unresolved, likely due to the lack of a sufficient number of informative sites used in previous studies. Here, we re‐investigate the Betulaceae phylogeny with whole chloroplast genomes from 24 species (17 newly assembled), representing all genera of the family. All the 24 plastomes are relatively conserved with four regions, and each genome is ∼158–161 kb long, with 111 genes. The six genera are all monophyletic in the plastome tree, whereas Ostrya Scop. is nested in the Carpinus clade in the internal transcribed spacer tree. Further incongruencies are also detected within some genera between species. Incomplete lineage sorting and/or hybrid introgression during the diversification of the family could account for such incongruencies. Our dating analysis, based on four fossils, suggests that the most recent common ancestors of the extant genera date back to the mid‐ to late Miocene, and confirms that Betulaceae started to diversify in the upper Cretaceous/early Paleocene. Our results highlight the significance of using more informative sites in resolving phylogenetic relationships. Plastome data and increased taxon sampling will help to better understand the evolutionary history of Betulaceae in the future.

Key words: Betulaceae, chloroplast genome, divergence time, fossil calibration, phylogenomics