Abstract Detail

Systematics Section / ASPT

Gardner, Andrew [1], Van Ee, Benjamin [1], Berry, Paul E. [1].

Pilinophytum, Julocroton, and Argyroglossum: An expanded phylogeny and biogeography of three sections of Croton (Euphorbiaceae sensu stricto).

Croton is a "truly stupendous" genus, as Croizat remarked, and presents a multitude of taxonomic challenges and classification conundrums. Croton species figure importantly in subtropical and tropical communities, and may contain important alkaloids, terpenoids, and other compounds. In 1993, Webster divided Croton into 40 sections with limited suggestions of phylogenetic relationships between some sections. Many of the sectional placements were tentative; for instance, he noted that Croton sellowii's position was "uncertain." Recently, Berry, et al. have published a new phylogenetic understanding of the genus using nuclear ribosomal ITS and chloroplast trnL-F data, which has provided strong evidence for the monophyly of Croton and established sectional relationships. Using these findings as a framework, we have begun to focus on smaller clades within the phylogeny, adding taxa and performing further analysis. This study focuses on three related New World sections: Pilinophytum, Julocroton, and Argyroglossum. Analyses of ITS and trnL-F data sets are used to infer the sister relationships among these three clades, which together make a monophyletic group. Many taxa are changing group affinities as Webster had previously hinted (C. sellowii leaving Argyroglossum, Julocroton remaining firmly within Croton, and others changing sections). Furthermore, the three clades are roughly geographically delineated, as Pilinophytum, Julocroton, and Argyroglossum are centered in the southeastern United States, Central America and the Caribbean, and southeastern Brazil respectively.

Related Links:
Croton Research Network

1 - University of Wisconsin Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, Wisconsin, 53706-1381, USA

Keywords:
Euphorbiaceae
Croton
Phylogenetics
Biogeography
ITS
trnL-F.

Presentation Type: Poster
Session: 33-89
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM
Abstract ID:198