This study will use DNA sequence-based phylogenetic analyses and molecular clock 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 species worldwide, which previous nonmolecular studies placed sister to an Old World group of Euphorbiaceae. Recent molecular work shows instead that Croton is allied to eight much smaller New World genera in a redefined Crotoneae tribe. Croton remains monophyletic except for one small South American section, and the Old World members are embedded within New World lineages of the genus. Half of the remaining genera of Crotoneae are endemic to the Caribbean basin and the other half are South American. Many Crotoneae taxa are rare and therefore of conservation concern. Our study will focus on the Caribbean 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 in Caribbean biogeography, and research on the evolution of a giant, complex genus.
