J Syst Evol

• Research Articles •    

Phylogenomics enables biogeographic analysis and a new subtribal classification of the Andropogoneae (Poaceae – Panicoideae)

Cassiano A. D. Welker1+, Michael R. McKain2+, Matt C. Estep3, Rémy S. Pasquet4, Gilson Chipabika5, Beatrice Pallangyo6, and Elizabeth A. Kellogg7*   

  1. 1Universidade Federal de Uberlândia, Instituto de Biologia, Rua Ceará s/n, Uberlândia, MG 38400-902, Brazil

    2The University of Alabama, Department of Biological Sciences, 411 Mary Harmon Bryant Hall, Tuscaloosa, AL 35487, USA

    3Appalachian State University, Department of Biology, Boone, NC 28608, USA

    4Université de Montpellier, DIADE, IRD, F-34394 Montpellier, France

    5Zambia Agriculture Research Institute, Mount Maluku Central Research Station, Private Bag 7, Chilanga, Zambia

    6Biocontrol Program, PO Box 30031, Kibaha, Tanzania

    7Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63121, USA

  • Received:2020-06-18 Accepted:2020-09-20

Abstract: The grass tribe Andropogoneae (PoaceaePanicoideae) includes several important crops such as maize, sugarcane and sorghum, and dominates the tropical grasslands of the world. We present here a plastome phylogeny of the tribe with the largest sample of genera to date (about 73%), including 65 newly assembled plastomes, together with a broad biogeographic analysis of Andropogoneae. Major relationships found in previous phylogenetic studies were confirmed here, with most nodes having higher resolution and support, including those of the backbone of the tree, which had been a major problem in previous phylogenies of the tribe. Our dated tree suggests that Andropogoneae diverged from Arundinelleae in the Early Miocene, while the “core Andropogoneae” clade originated in the Late Miocene. The tribe originated in East Asia, but intercontinental dispersal has been common, with many independent dispersal events to Africa and the New World. Based on the plastome phylogeny, we propose here a new classification of Andropogoneae as most of its previously accepted subtribes are not monophyletic. Our classification comprises 14 subtribes, 92 genera, and approximately 1,224 species. About 90% of the Andropogoneae species could be assigned to a subtribe, which represents a major step toward clarification of the taxonomy of the tribe. The remaining taxa were placed incertae sedis pending additional molecular data. The new subtribes Chrysopogoninae and Rhytachninae are described herein. Our plastome trees also indicate that several Andropogoneae genera are para- or polyphyletic and require additional studies to define their circumscriptions.

Key words: Gramineae, Miocene, dated phylogeny, East Asia, intercontinental dispersal, subtribe, whole chloroplast genome