Full text
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| Author(s): |
Juliana Gastaldello Rando
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2014-11-06 |
| Examining board members: |
Jose Rubens Pirani;
Vidal de Freitas Mansano;
Marcelo Fragomeni Simon
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| Advisor: | Jose Rubens Pirani |
| Abstract | |
This thesis focused on the phylogenetic, taxonomic and biogeographic studies in Chamaecrista, a genus of Leguminosae with the center of diversity in the Neotropics. The studies of systematic, phylogeny and taxonomy, were carried out on 22 species (Chamaecrista series Coriaceae), with most species occurring in Campos Rupestres (Chapter 1 and 2). The study of biogeography covers the entire genus, contributing to the understanding of its history and diversification (Chapter 3). Molecular work were conducted at the Universidade Estadual de Feira de Santana, Bahia, in collaboration with the Prof. Dr. Luciano Paganucci de Queiroz. In Chapter 1, we reconstructed the phylogeny of C. ser. Coriaceae using four molecular markers as well as morphological data. Our objectives were to test the monophyly of the series and to identify possible patterns of morphological evolution in this group. In all analysis the group was not reconstructed as monophyletic because three species appeared outside the clade containing the remaining representatives of the series. This led to a definition of C. ser. Coriaceae sensu strictu, strongly supported as monophyletic by several molecular and two morphological synapomorphies in the combined analyzis. In Chapter 2, we proposed a new circumscription of C. ser. Coriaceae s.s., based on the results of Chapter 1, highlighting the exclusion of the three species emerged out this clade. We present a detailed morphological study of inflorescences, floral structure and extrafloral nectaries in the series, compared to patterns observed in other clades of Chamaecrista, seeking a reevaluation of the current taxonomic circumscription. We produce a complete taxonomic synopsis of the series, including nomenclatural novelties, key identification and diagnostic illustrations. Chamaecrista ser. Coriaceae s.s. includes 19 species and 2 varieties; three neotypification are proposed, a new combination, and two new synonyms. The series is restricted to Brazil, most taxa have a restricted or endemic distribution, especially in the Campos Rupestres of the Brazilian central plateau. This chapter also includes an article published during the PhD about the taxonomic novelties of the series, in which we synonymized a variety and modified the taxonomic category of three varieties to species. In chapter 3, we carried out the dating of the cladogenetic events in Chamaecrista, and the subsequent biogeographic and evolutionary analysis. The taxa sampling covered more than a third of species. We aim to understand when the genus emerged and how the group has distributed in the Neotropics, especially in the Cerrado and Campos Rupestres. Finally, we also explored whether these processes were related with morphological transitions. Our analyses indicated a relatively ancient origin of the group, at the lower Tertiary in South America, though most species seems to have diversified more recently and through different processes, being the most common species dispersion. As observed in other groups of woody plants from Neotropics, Chamaecrista also seems to have forest origin with a subsequent occupation of open areas, in which the genus actually had its greatest diversity. Some derived morphological characters seem to be correlated with the occupation of drier habitats (Cerrado and Campos Rupestres), especially the appearance of glandular trichomes and the transition of habit (AU) | |
| FAPESP's process: | 09/16434-4 - Biogeography of Chamaecrista Moench. and Filogeny and Revision of Ch. sect. Chamaecrista ser. Coriaceae (Benth.) H.S. Irwin & Barneby (Leguminosae-Caesalpinioideae) |
| Grantee: | Juliana Gastaldello Rando |
| Support Opportunities: | Scholarships in Brazil - Doctorate |