Journal of Systematics and Evolution

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  • 收稿日期:2023-01-30 接受日期:2024-03-08

Molecular Phylogeny and Spatio-temporal diversification of the Millettioid/Phaseoloid clade (Fabaceae: Papilionoideae)

Oyetola Oyebanji1,2,3,4,5, Gregory W. Stull1,2, Rong Zhang1,2,3, Fabien R. Rahaingoson1,2, De-Zhu Li1,2*, Ting-Shuang Yi1,2*   

  1. 1 Germplasm Bank of Wild Species, Yunnan Key Laboratory of Crop Wild Relatives Omics, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China;
    2 University of Chinese Academy of Sciences, Beijing 100049, China;
    3 Key Laboratory of Plant Diversity and Specialty Crops, Chinese Academy of Sciences, Beijing 100093, China;
    4 Department of Biology, University of Louisiana, Lafayette 70503, Louisiana, USA;
    5 Department of Biological Sciences, University of Arkansas, Fayetteville 72701, Arkansas, USA
    *Authors for correspondence. De-Zhu Li.;Ting-Shuang Yi.
  • Received:2023-01-30 Accepted:2024-03-08

Abstract: The Millettioid/Phaseoloid (or the Millettioid) clade is a major lineage of the subfamily Papilionoideae (Fabaceae) that is poorly understood in terms of its diversification and biogeographic history. To fill this gap, we generated a time-calibrated phylogeny for 749 species representing c. 80% of the genera of this clade using nrDNA ITS, plastid matK, and plastome sequence (including 38 newly sequenced plastomes). Using this phylogenetic framework, we explored the clade’s temporal diversification and reconstructed its ancestral areas and dispersal events. Our phylogenetic analyses support the monophyly of the Millettioid/Phaseoloid clade and four of its tribal lineages (Abreae, Desmodieae, Indigofereae, and Psoraleeae), while two tribal lineages sensu lato millettioids and phaseoloids are polyphyletic. The fossil-calibrated dating analysis showed a nearly simultaneous divergence of the stem node [c. 62 million years ago (Ma)] and the crown node (c. 61 Ma) of the Millettioid/Phaseoloid clade in the Paleocene. The biogeographic analysis suggested that the clade originated in Africa and dispersed to Asia, Europe, Australia, and the Americas at different periods in the Cenozoic. We found evidence for shifts in diversification rates across the phylogeny of the Millettioid/Phaseoloid clade throughout the Cenozoic, with a rapid increase in net diversification rates since c. 10 Ma. Possible explanations for the present-day species richness and distribution of the Millettioid/Phaseoloid clade include boreotropical migration, frequent intra- and intercontinental long-distance dispersals throughout the Cenozoic, and elevated speciation rates following the Mid-Miocene Climatic Optimum. Together, these results provide novel insights into major diversification patterns of the Millettioid/Phaseoloid clade, setting the stage for future evolutionary research on this important legume clade.

Key words: biogeography, diversification, Fabaceae, long-distance dispersal, the Millettioid/Phaseoloid clade