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Olmstead, R. G.

Publications and source records attributed to Olmstead, R. G..

3 recordsLinked to original sources

A new phylogeny and phylogenetic classification for Solanaceae

Solanaceae are a globally distributed family of considerable economic importance. Recent phylogenetic work on various clades in the family has resulted in a plethora of names at various taxonomic levels. This results in a confusing set of names applied to clades at different ranks, and to the use of informal names that are often not accepted in online resources. To solve this problem, we present here a phylogenetic classification following the PhyloCode for the Solanaceae. Traditional taxon names previously recognized at the ranks of tribe, genus, and section were maintained when associated with clades. We base our clade definitions on a newly constructed phylogeny of the family using 10 plastid and nuclear markers with a broad sampling of 1,474 species, roughly half of the diversity of the family. We complement this marker-based analysis with a phylogenomic analysis of 110 taxa (including 97 of the 102 genera in the family) using the Angiosperms353 probe set. This pair of analyses produced highly concordant phylogenies and provides strong support for the clades included in the classification. In total, we propose and define rank-free names for 38 major clades, including 16 infrageneric taxa within the mega-diverse Solanum. This rank-free system intends to promote name stability as new data become available, avoiding name changes to well-known groups.

evolutionary biology↗

Andean uplift, drainage basin formation, and the evolution of riverweeds (Marathrum, Podostemaceae) in northern South America

O_LINorthern South America is a geologically dynamic and species-rich region. While fossil and stratigraphic data show that reconfiguration of river drainages resulted from mountain uplift in the tropical Andes, investigations of the impact of landscape change on the evolution of the flora in the region have been restricted to terrestrial taxa. C_LIO_LIWe explore the role of landscape change on the evolution of plants living strictly in rivers across drainage basins in northern South America by conducting population structure, phylogenomic, phylogenetic networks, and divergence-dating analyses for populations of riverweeds (Marathrum, Podostemaceae). C_LIO_LIWe show that mountain uplift and drainage basin formation isolated populations of Marathrum and created barriers to gene flow across rivers drainages. Sympatric species hybridize and the hybrids show the phenotype of one parental line. We propose that the pattern of divergence of populations reflect the formation of river drainages, which was not complete until <4 Ma C_LIO_LIOur study provides a clear picture of the role of landscape change in shaping the evolution of riverweeds in northern South America, advances our understanding of the reproductive biology of this remarkable group of plants, and spotlights the impact of hybridization in phylogenetic inference. C_LI

evolutionary biology↗

Phylogeny, classification, and character evolution of tribe Citharexyleae (Verbenaceae)

Premise of the studyTribe Citharexyleae comprises three genera: Baillonia, Citharexylum, and Rehdera. While there is good support for these genera as a clade, relationships between genera remain unresolved due to low sampling of the largest genus, Citharexylum. A molecular phylogenetic approach was taken to resolve intergeneric relationships in Citharexyleae and infrageneric relationships in Citharexylum. MethodsSeven chloroplast regions, two nuclear ribosomal spacers, and six low-copy nuclear loci were analyzed for 64 species of Citharexyleae. Phylogenetic analyses were conducted using maximum likelihood, Bayesian inference, and Bayesian multi-species coalescent approaches. Habit, presence/absence of thorns, inflorescence architecture, flower color, fruit color, and geography were examined to identify diagnostic characters for clades within Citharexylum. Key resultsIntergeneric relationships resolved Rehdera as sister to Citharexylum and Baillonia nested within Citharexylum. Two species, C. oleinum and C. tetramerum, fell outside of Citharexyleae close to tribe Duranteae. There is strong support for seven clades within Citharexylum, each characterized by a unique combination of geography, fruit color/maturation, and inflorescence architecture. ConclusionsBaillonia is included in Citharexylum; Rehdera is retained as a distinct genus. A subgeneric classification for Citharexylum is proposed.

evolutionary biology↗