Phylogenetic studies of the Mutisieae

The Mutisieae is one of the most important and problematic tribes for understanding the systematics and evolution of the Asteraceae because it is one of the basal lineages in the family. The tribe is extremely diverse morphologically and geographically, consisting of 84 genera and approximately 900 species. Despite extensive studies using macromorphological, palynological and molecular approaches, delimitation and evolutionary relationships of Mutisieae remain controversial. In this study, molecular systematic approaches were employed to address some of the remaining systematic questions in the tribe.;In the first chapter, phylogenetic analyses of the chloroplast gene ndhF are discussed. This was based upon the assessment of 54 species representing 31 genera of Mutisieae, 11 genera from the remaining five tribes of the subfamily Cichorioideae, and five genera from each of the tribes of the subfamily Asteroideae. This ndhF phylogeny for the Mutisieae provided insights into the circumscription and relationships of the tribes and subtribes concerned, phylogenetic placements of problematic genera, and patterns of character evolution in the family. The results supported the polyphyly of Mutisieae. The subtribes Gochatiinae and Mutisieae are not monophyletic whereas the Nassauviinae is monophyletic. The majority of the South America group of the Gochantiinae were positioned at the basal lineage of the Mutisieae in the ndhF phylogeny. Furthermore, the intergeneric relationships and the pattern of character evolution are discussed in depth.;Chapter 2 focused on the systematic position of Hesperomannia, which has been considered as one of the basal lineages of the Asteraceae and the only a member of the Mutisieae, endemic to the Hawaiian Islands. Phylogenetic analyses indicated that Hesperomannia is nested within the Vernonieae, which contradicts recent morphological studies. Two molecular makers from the chloroplast and nuclear genomes were employed to examine two species of Hesperomannia, a world-wide representation of Vernonieae, and genera of Liabeae as the outgroup. The results indicated that Hesperomannia is most closely allied to African species of Vernonia. Furthermore, the molecular data enabled an estimation of time of divergence between the Hawaii and African clades, and place of origin of this Hawaiian endemic. The estimated divergence time between Hawaiian Hesperomannia and African Vernonia by ITS and ndhF sequence data was 25 and 12-24 million years old, respectively. This suggests the most likely site of arrival of Hesperomannia was located between the French Frigate Shoals and the Midway Island.;The third chapter focused on Mutisia, the largest genus in the tribe Mutisieae having approximately 60 species. Two molecular markers and morphological characters were utilized to perform the phylogenetic analyses for understanding the evolutionary relationships of Mutisia at the generic and infrageneric levels. The morphological tree was incongruent with the molecular, whereas the two molecular trees were congruent except with regard to the position of M. acuminata. This study assessed data incongruence to test the homogeneity of the combined data set and quantified the total incongruence between data sets. To test the competing hypothesis as to putative outgroups, morphological data were utilized. The woody group was favored over the herbaceous group because it generated more parsimonious trees.