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Systematics Section / ASPT

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

The Caribbean-centered Moacroton clade within Croton (Euphorbiaceae sensu stricto).

The monophyly of the giant genus Croton, with the exclusion of section Astraea, has been established by a thorough sampling of more than 400 taxa representing almost all of the 40 recognized sections. In molecular analyses, most taxa of Croton cluster into three main clades, two New World and one Old World, which together we refer to as the core Croton. Some of the most problematic and interesting aspects of the phylogeny, biogeography, and evolution of this genus of more than 1,200 species are found in the approximately two dozen species that fall outside of the core Croton. These are the six species of Moacroton and their sister Cubacroton maestrense (all endemic to Cuba), the twelve or so species of Croton section Corylocroton ranging from the Caribbean to South America, Croton alabamensis from Alabama and Texas, Croton megistocarpus from Costa Rica, and a species from Ecuador tentatively identified as Croton olivaceus. Within this group, which we refer to as the Moacroton clade there are repeating patterns of disjunct and relictual distributions, shifts to serpentine endemicity, and the longest branches in the molecular phylogeny. With a distribution centered primarily on the Caribbean, but ranging from the southern U.S. down to South America, this clade provides an opportunity to examine the historical biogeography of plants in this geologically complex region. The phylogenetic position of the Moacroton clade, as well as the relationships within it, were inferred from the nuclear ribosomal ITS region and the chloroplast trnL intron and trnL-F spacer.


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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
Caribbean
Endemism
.

Presentation Type: Oral Paper
Session: 44-3
Location: Salon G - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 8:30 AM
Abstract ID:115


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