Abstract Detail


Koenemann, Daniel Mark [1], Kistler, Logan [2], Burke, Janelle [3].

A First Plastome Phylogeny for Rumex L. (Polygonaceae), with Fossil-Aided Date Calibration.

Heteromorphic sex chromosomes are rare in plants. Yet, despite this rarity, plants provide a compelling system in which to study the development of sex determination and its control at the chromosomal level. Among plant groups, the genus Rumex L. (Polygonaceae) in particular provides a unique system for investigating the evolutionary development of these phenomena because two separate sex chromosome systems are present in the genus. As part of our ongoing efforts to elucidate the evolution of heteromorphic sex chromosomes in Rumex, we have begun collecting next generation sequencing data for the genus to better establish evolutionary relationships. Here we present a first plastome phylogeny for twenty species of Rumex, reconstructed using maximum likelihood (RAxML) and Bayesian (BEAST) criteria. Under both reconstruction methods, Rumex subgenus Rumex (‘docks’) is resolved as monophyletic with high support, and sister to the remaining Rumex clades. Species relationships within subgenus Rumex were also resolved with high support. Additionally, Emex was resolved within Rumex, sister to a clade consisting of Rumex subgenera Acetosa and Acetosella (‘sorrels’). In order to further investigate the difficult taxonomy and historically low phylogenetic resolution among species in subgenus Rumex, we used two fossils to calibrate the BEAST phylogeny, one for the base of Rumex (mid-Pliocene) and one for the base of Polygonaceae as a whole (end-Cretaceous). The fossil calibration of the phylogeny suggested that Rumex diverged from its close relative Rheum in the Paleogene. Species within the subgenera Acetosa and Acetosella appear to have diversified at a relatively constant rate beginning in the Miocene. On the other hand, species in subgenus Rumex, accounting for well over three quarters of the species in the genus, have diversified more recently, entirely within the Plio-Pleistocene. A recent phylogenomic study of Rheum, reported genus-wide evolutionary rates similar to those of subgenera Acetosa and Acetosella. Additionally, the nucleotide diversity among species of Rheum was relatively lower than we found among species of Rumex. We discuss the possible evolutionary processes underlying these results.

1 - Howard University, Biology, Washington, DC, USA
2 - National Museum of Natural History, Anthropology, Washington, DC, USA
3 - Howard University, Dept. Of Biology, 415 College St. NW, Just Hall 328, Washington, DC, 20059, United States

Fossil Calibration

Presentation Type: Oral Paper
Number: PHYLO III014
Abstract ID:204
Candidate for Awards:None

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