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| Author(s): |
Alice de Moraes Calvente Versieux
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: | 2010-04-06 |
| Examining board members: |
Lucia Garcez Lohmann;
Maria do Carmo Estanislau do Amaral;
Loreta Brandão de Freitas;
Julio Antonio Lombardi;
Maria das Graças Lapa Wanderley
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| Advisor: | Lucia Garcez Lohmann; Daniela Cristina Zappi |
| Abstract | |
Rhipsalis includes 37 species and represents the largest genus of epiphytic cacti. Species of Rhipsalis are mainly endemic to Brazil (81%), and only three species are widely distributed throughout the Neotropics: Rhipsalis micrantha (Peru, Colombia, Venezuela and Costa Rica), Rhipsalis floccosa (Paraguay to Venezuela), and Rhipsalis baccifera (throughout South America, México, Caribbean region and Florida, USA). Rhipsalis baccifera is the only species whose distribution extends beyond the Americas, also occurring in tropical areas of the African continent and part of Asia. Despite recent taxonomic studies in the genus, the identification of taxa within Rhipsalis has remained problematic, mainly due to the natural plasticity of morphological characters, lack of information on the patterns of morphological variation in natural populations, existence of species complexes and cryptic species. In addition, little is known about the biology and evolution of this group. This study focuses on the tribe Rhipsalideae and on the genus Rhipsalis, very abundant and diverse groups of epiphytes in the Neotropics. The study area comprises the Atlantic Forest, which is an extremely important area biologically but also a highly threatened ecosystem. The high diversity of species and high endemism of Rhipsalideae in the Atlantic Forest makes this group particularly interesting for the study of the processes involved in the diversification of species within Mata Atlântica. The objectives of the present project are to: (1) Reconstruct the molecular phylogeny of the tribe Rhipsalideae and test the monophyly of genera within this tribe; (2) Reconstruct the molecular phylogeny of Rhipsalis in order to test the monophyly of its subgenera, study the evolution of morphological features, study the occupation of the rupiculous and epiphytic habitats, as well as the biogeographical history of the group; (3) Propose a new classification for the group based on novel molecular and morphological data; and, (4) Revise the \"wingedstem\" clade (= Rhipsalis subg. Phyllarthrorhipsalis). These four objectives correspond to the four chapters of the present thesis. The first chapter includes a molecular phylogeny of Rhipsalideae based on the molecular markers trnQ-rps16, rpl32-trnL, psbAtrnH and ITS. Information derived from this phylogeny and from a study on the evolution of selected morphological characters, is then used as basis to propose taxonomic changes in Hatiora and Schlumbergera. The second chapter presents a phylogeny of Rhipsalis based on the molecular markers trnQ-rps16, rpl32-trnL, psbA-trnH, ITS and MS. This phylogeny is then used as basis to study the evolution of selected morphological traits, study the evolution of the habit, and the biogeographical history of the genus. In the third chapter, a new infrageneric classification for Rhipsalis is proposed based on the phylogeny of Rhipsalis (chapter 2) and novel morphological information. Lastly, the fourth chapter presents a taxonomic revision of the \"winged-stem\" clade, including descriptions, information on the geographic distribution of species, novel circumscriptions for several taxa, and an identification key for all species of the subgenus Rhipsalis (AU) | |