Dissertations, Theses, and Capstone Projects

Date of Degree

10-2014

Document Type

Dissertation

Degree Name

Ph.D.

Program

Biology

Advisor

Fabian A. Michelangeli

Subject Categories

Agricultural Science | Agriculture | Plant Sciences

Keywords

Evolution, Leandra, Melastomataceae, Miconieae, Systematics, Taxonomy

Abstract

Phylogenetic studies in the Melastomataceae have demonstrated the need of taxonomic rearrangements in the current classification. Melastomes are among the most diverse groups of plants and several cases of known artificial taxa are observed and awaiting further resolution. One example is the Leandra s.str. clade, which includes the majority of the taxa traditionally treated in the genus Leandra. Some attempts have been made to infer the relationships of Leandra s.str., but the sampling in these earlier studies was sparse and the resolution low inside the clade. The main objective here is to propose a comprehensive phylogenetic framework for this group to address evolutionary questions regarding morphology and biogeography. In Chapter 1, using a species tree approach, I present a phylogenetic hypothesis for Leandra s.str. and discuss incongruent patterns across gene trees and putative processes leading to them. The genus Leandra has been scarcely studied since a review in the 19th Century, and information such as overall distribution, anatomy, cytology, morphology, and even taxonomy is very limited. In Chapter 2, chromosome counts for some species of Leandra s.str. are provided, while in Chapter 6 a taxonomic review of Leandra sect. Leandra is presented and driven by the phylogenetic hypothesis of Chapter 1. The diversity and evolution of flowers in the Leandra s.str. clade is the topic of Chapter 3. Several question regarding the evolution of floral traits are addressed on a continuous framework using comparative phylogenetic methods. Leandra s.str. is nearly restricted to eastern Brazil, and the biogeography of the group is discussed in Chapters 4 and 5. In the former, I investigate disjunct patterns and distributional ranges and their relationship with climatic variables, focusing in the species that occurs outside eastern Brazil. In Chapter 5, I reconstruct the historical biogeography of Leandra s.str., proposing discrete biogeographical areas for ancestral distribution estimation, explore the climatic evolution and discuss the role of sympatry/allopatry in this group.

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