Radiation of the Vernonieae (Compositae) in montane and lowland habitats in the Americas

University Of Hawaii, Honolulu

Investigators

Abstract

A phylogenetic reconstruction of the Compositae tribe Vernonieae, with a focus on the species rich genera Critoniopsis and Vernonanthura, will be used to trace pathways and timings of the radiation of the tribe in the Americas. The Compositae is the largest of all flowering plant families (23,000-30,000 species) and is distributed worldwide. However, the Vernonieae is the only tribe in the family with genera widely radiated in South, Central, and North America in both montane and lowland habitats. Critoniopsis and Vernonanthura have a number of attributes that make them excellent candidates for investigating the effects of the major climatic and geological events that have affected the distribution of many plants and animals in the New World. The radiation spans some of the most biologically significant geologic and climatic events in the region including the uplift of the Andes, the drying of eastern South America, the closure of the Isthmus of Panama (the Great American Interchange) and the formation of the modern West Indian islands. The proposed research will clarify the availability and timing of major dispersal routes between South and North America. DNA sequence data from nuclear and chloroplast genomes will be used to reconstruct the evolutionary histories of Vernonanthura and Critoniopsis. They will be placed within the phylogenetic framework of the tribe thus extending its systematic value. Biogeographical analyses will be conducted using DIVA and likelihood methods in order to explore a range of explanations for the patterns observed. These will be correlated with the phylogenetic position of species in both genera. The research is highly collaborative and involves students and faculty from Brazil, Mexico, University of Hawaii at Manoa and colleagues at the Smithsonian Institution and the Fairchild Botanical Garden. Graduate and undergraduate students will have multiple opportunities to participate in research and data analyses and efforts will be made to reach out to native Hawaiian students. The Vernonieae are particularly well represented in Brazil and a mini-symposium at the University of Sao Paulo is specifically designed to promote collaborative activities of students who are actively working in Compositae systematics and who will be taking the lead in the not-to-distant future. Through the Encyclopedia of Life (EOL) project information will be shared with the wider scientific community.