Abstract Detail


Welker, Cassiano [1], McKain, Michael [2], Kellogg, Elizabeth A. [3].

Plastome phylogenomics of Andropogoneae, a new classification, and biogeography of the tribe.

The great tropical grasslands of the world are dominated by C4 grasses of a single clade, the tribe Andropogoneae. The group encompasses over 1000 species, among them maize, sorghum, and sugarcane, which are some of the world’s most economically important crops. The tribe also includes many species of restricted distribution and specialized habitats that may hold the key to understanding local adaptation. Reconstructing the phylogeny of the group has been challenging.  Most efforts to unravel the history, whether using plastomes or nuclear markers, have found short internal branches in the tree which have been hard to resolve. We have generated a phylogeny for the tribe using 267 complete plastomes for 211 species in 69 genera, or about ¾ of the genera. This dense sampling has produced the most strongly supported tree to date, with only a few nodes still poorly resolved. The phylogeny is congruent with but better supported than previous phylogenies based on plastome loci or genomes. It is also largely congruent with nuclear gene phylogenies except for the placement of a couple of genera, such as Chrysopogon. Given this strong support, we have developed a subtribal classification composed of 15 subtribes, most of them with different circumscriptions compared to previous classifications. In this classification, all but about 10% of the species can be assigned to a subtribe. As found in previous analyses, a number of genera are para- or polyphyletic, most notably the type genus Andropogon. Using this dataset and a time-calibrated phylogeny, several different biogeographic models all demonstrate origin of the tribe in East Asia, followed by extensive and ongoing dispersal throughout the world. We find frequent exchange between East Asia and Africa, whereas dispersal to Australia appears to have been largely unidirectional. Only about 20% of species in the tribe occur in the New World and have arrived via multiple dispersal events from Africa and East Asia. This phylogeny now provides the basis for ongoing studies of morphological and ecological adaptation.

1 - Universidade Federal de Uberlândia, Instituto de Biologia, Rua Ceará s/n, Uberlândia, MG, 38400-902, Brazil
2 - University Of Alabama, 411 Mary Harmon Bryant Hall, Tuscaloosa, AL, 35487, United States
3 - Donald Danforth Plant Science Center, 975 N. Warson Rd., St. Louis, MO, 63132, United States


Presentation Type: Oral Paper
Session: SYS4, Systematics IV: Monocots part B to Rosids part A
Location: Virtual/Virtual
Date: Thursday, July 30th, 2020
Time: 1:15 PM
Number: SYS4004
Abstract ID:743
Candidate for Awards:None

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