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Abstract— Physarieae is a small tribe of herbaceous annual and woody perennial mustards that are mostly endemic to North America, with its members including a large amount of variation in floral, fruit, and chromosomal variation. Building on a previous study of Physarieae based on morphology and ndhF plastid DNA, we reconstructed the evolutionary history of the tribe using new sequence data from two nuclear markers, and compared the new topologies against previously published cpDNA-based phylogenetic hypotheses. The novel analyses included ca. 420 new sequences of ITS and LUMINIDEPENDENS ( LD ) markers for 39 and 47 species, respectively, with sampling accounting for all seven genera of Physarieae, including nomenclatural type species, and 11 outgroup taxa. Maximum parsimony, maximum likelihood, and Bayesian analyses showed that these additional markers were largely consistent with the previous ndh F data that supported the monophyly of Physarieae and resolved two major clades within the tribe, i.e., DDNLS ( Dithyrea , Dimorphocarpa , Nerisyrenia , Lyrocarpa , and Synthlipsis ) and PP ( Paysonia and Physaria ). New analyses also increased internal resolution for some closely related species and lineages within both clades. The monophyly of Dithyrea and the sister relationship of Paysonia to Physaria was consistent in all trees, with the sister relationship of Nerisyrenia to Lyrocarpa supported by ndhF and ITS, and the positions of Dimorphocarpa and Synthlipsis shifted within the DDNLS Clade depending on the employed data set. Finally, using the strong, new phylogenetic framework of combined cpDNA + nDNA data, we discussed standing hypotheses of trichome evolution in the tribe suggested by ndhF .
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Molecular phylogenetics of Distephanus supports the recognition of a new tribe, Distephaneae (Asteraceae)
Abstract Distephanus Cass. comprises 43 distinctive species of shrubs and small trees that have been placed historically within the ironweed tribe, Vernonieae (Asteraceae). Using the most expansive sampling of Distephanus to date, this study aims to test the monophyly of this genus and facilitate its classification. Molecular phylogenetic analyses were conducted using four molecular markers from the nuclear and plastid genomes. These data also supported divergence dating analyses that were performed to understand the timing of diversification events within Distephanus and other related genera as well as ancestral area reconstruction analyses to infer the biogegraphic history of species diversity in this group. Results from this study indicate that, as currently circumscribed, Vernonieae is not monophyletic and that Distephanus is, in fact, sister to a clade that comprises Vernonieae and another tribe, Moquinieae, which only includes two species restricted to Brazil. On the basis of these findings, Distephanus is classified in a new tribe that we describe here, Distephaneae. This new tribe comprises 41 species of Distephanus that are easily distinguished from Moquinieae and Vernonieae based on the presence of florets with yellow corollas and trinervate leaves.
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- Award ID(s):
- 2210598
- PAR ID:
- 10505164
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Botanical Journal of the Linnean Society
- Volume:
- 206
- Issue:
- 4
- ISSN:
- 0024-4074
- Format(s):
- Medium: X Size: p. 296-312
- Size(s):
- p. 296-312
- Sponsoring Org:
- National Science Foundation
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