DISSERTATION RESEARCH: Phylogeny and Biogeography of Euphorbiaceae Tribe Crotoneae

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This study will use DNA sequence-based phylogenetic analyses and molecularclock calibrations to reconstruct the phylogeny and biogeography of the Crotoneae tribe(Euphorbiaceae). The largest genus in this group is Croton, with 1,200 to 1,300 speciesworldwide, which previous nonmolecular studies placed sister to an Old World group ofEuphorbiaceae. Recent molecular work shows instead that Croton is allied to eight muchsmaller New World genera in a redefined Crotoneae tribe. Croton remains monophyleticexcept for one small South American section, and the Old World members are embeddedwithin New World lineages of the genus. Half of the remaining genera of Crotoneae areendemic to the Caribbean basin and the other half are South American. Many Crotoneaetaxa are rare and therefore of conservation concern. Our study will focus on theCaribbean region and how Croton and its closest relatives evolved in the New World.The broader impacts of the project include training of the co-PI (Ph.D. student),active collaboration with investigators in the U.S., Mexico, Cuba, and Brazil,participation of undergraduates in the research, enhancing knowledge of plant groups inCaribbean biogeography, and research on the evolution of a giant, complex genus.