J Syst Evol

• Research Article •    

Plastomic data shed new light on the phylogeny, biogeography and character evolution of the family Crassulaceae

Xiao-Ying Liu1,2, Dan-Qing Zhang1,2, Jian-Qiang Zhang1,2*   

  1. 1 National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest China, College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China;
    2 Key Laboratory of Medicinal Plant Resource and Natural Pharmaceutical Chemistry of Ministry of Education, Shaanxi Normal University, Xi'an 710119, China
    *Author for correspondence: Jian-Qiang Zhang. E-mail: jqzhang@snnu.edu.cn
  • Received:2022-12-21 Accepted:2023-06-01

Abstract: Crassulaceae is a mid-sized family in angiosperms, most species of which are herbaceous succulents, usually with five-merous flowers and one or two whorls of stamens. Although previous phylogenetic studies revealed seven major ‘clades’ in Crassulaceae and greatly improved our understanding of the evolutionary history of the family, relationships among major clades are still contentious. In addition, the biogeographic origin and evolution of important morphological characters delimiting infrafamilial taxa have not been subject to formal biogeographic and character evolution analyses based on a well-supported phylogeny backbone. In this study, we used plastomic data of 52 species, representing all major clades revealed in previous studies to reconstruct a robust phylogeny of Crassulaceae, based on which we unraveled the spatiotemporal framework of diversification of the family. We found that the family may originate in southern Africa and then dispersed to the Mediterranean, from there to eastern Asia, Macaronesia and North America. The crown age of Crassulaceae was dated at ca. 63.93 million years ago (Mya), shortly after the Cretaceous-Paleogene (K-Pg) boundary. We also traced the evolution of six important morphological characters previously used to delimit infrafamilial taxa, and demonstrated widespread parallel and convergent evolution of both vegetative (life form and phyllotaxis) and floral characters (number of stamen whorls, petals free or fused, and flower merism). Our results provide a robust backbone phylogeny as a foundation for further investigations, and also some important new insights into biogeography and evolution of the family Crassulaceae.

Key words: biogeography, character evolution, Crassulaceae, phylogeny, plastome