Full text
| |
| Author(s): |
Caetano Troncoso Oliveira
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2015-09-11 |
| Examining board members: |
Jose Rubens Pirani;
Jimi Naoki Nakajima;
Mara Rejane Ritter
|
| Advisor: | Jose Rubens Pirani |
| Abstract | |
This work performed a systematic study of Mikania Willd., the greatest genus of vines plants in Asteraceae, accounting for more than 400 known species. This work\'s main focus was the phylogenetic study of the genus, aiming to reevaluate the organization of previously published infrageneric groups and to provide a new phylogenetic classification. Additionally, a Nomenclator of the genus was compiled. In the first chapter, a construction of the phylogenetic hypothesis for Mikania is presented based in data from four molecular markers (two plastids and two nuclear) obtained from 128 terminals of the genus and four external groups. The resulting topology of the Bayesian analysis showed satisfactory resolution, with well supported clades (highlighting the divergence between the two greatest lineages in the base of the tree), allowing the reconstruction of the evolution of nine characters previously used for the infrageneric classification of Mikania. One of the central hypothesis developed from the phylogeny is the gain of climbing habits in Mikania\'s ancestral, which may have facilitated its great irradiation exploring the forests\' edges, with some recent events of erect habit reversion, apparently linked to the occupation of open habitats in different lineages of the group. The patterns of sinflorescence evolution also revealed a strong phylogenetic signal, as well as the position of the subinvolucral bracts, number of pappus bristels and some other characters, although always homoplasic. In the second chapter, a chronological review of the infrageneric classifications of Mikania is presented, following a proposal for a new classification system based in the molecular phylogeny developed in the first chapter, besides a genus Nomenclator containg all correct 426 names, protologue citation and nomenclatural types, and the geographic distribution and position of each species in the classification. Eight lectotypifications were done, four status changes and four new sections were described. Mikania is now organized in two subgenus, M. subg. Mikania (with 182 species distributed in the New and Old Worlds, divided in two sections and two subsections), and M. subg. Cylindrolepis (with 218 species, restricted to the American continent, distributed in six sections). The third chapter presents the description of a new species of the genus occurring in Minas Gerais federal state, which was found during the studies for the development of the thesis. It is intended that the results generated by this work may contribute for the knowledge of the evolution and diversification of Mikania, and may the proposed infrageneric classification system, to the extent of containing only monophyletic groups, allow the direction of future studies, especially morphologic and taxonomic studies in particular clades of this megadiverse genus (AU) | |
| FAPESP's process: | 12/12325-9 - Phylogeny and sectional study of Mikania Willd. (Eupatorieae - Asteraceae) |
| Grantee: | Caetano Troncoso Oliveira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |