The plant tribe Senecioneae is a large group of plants in the Asteraceae (Sunflower) family, with approximately 3000 described species worldwide. It has an almost cosmopolitan distribution and harbors enormous diversity in morphological adaptations. Yet there has been no attempt to reconstruct the evolutionary relationships within this enormous plant group despite the numerous and detailed studies on the Asteraceae as a whole and for all other tribes in this family, thereby creating a large gap in our understanding of one of the largest families of vascular plants. The aim of the proposed research is to improve our understanding of the evolutionary success of Senecioneae by reconstructing its evolutionary history and by examining the origin of summer-dry / winter-wet habitats (mediterranean climates) in which so many members of this group live; such climates appeared between 2 and 6 million years ago and resulted in regions with specialized floras on five continents. Utilizing biogeographic and molecular dating methods, the time and place of origin for the Senecioneae will be estimated, and dispersal pathways leading from ancestral area(s) into regions with Mediterranean climates will be reconstructed and dated. The patterns of diversification that subsequently followed colonization into Mediterranean regions will be further examined and routes of migration into areas with other climates will be inferred. Thus, it will be determined if the descendents of Mediterranean lineages remained confined to these summer-dry areas, or alternatively, became main elements of other contemporary floras. A final goal is to use the reconstructed relationships of Senecioneae as a basis for a new classification for the tribe that reflects evolutionary history. The merits of this proposal will be a better understanding of the evolution of Mediterranean-climate plants, in general, by providing insight into the relationship between climate change and diversification. Furthermore, this project will contribute to a better understanding of the evolution of one of the largest, most diverse, and successful families of flowering plants. The impacts of this research include contributions to the education of students and teachers through research training, to the general public through the increased availability of information on the Internet, as well as to the scientific community through publication in journals and presentations. The proposed research will give opportunities for Miami University of Ohio students to complete their research requirements for graduation, and opportunities for graduate students to serve as research mentors. In addition, the proposed research will be available to students who apply to the University's Summer Scholars Program and to in-service primary and secondary school teachers in the Masters of Teaching Program. Photographs, descriptions, phylogenies, and nomenclatural information will be incorporated into the Tree of Life website for access by the general public with links to important databases. Similarly, information will be provided for the website of The International Compositae Alliance, an international consortium of scientists studying the evolution of the sunflower family.