Dissertations, Theses, and Capstone Projects

Date of Degree

9-2015

Document Type

Dissertation

Degree Name

Ph.D.

Program

Biology

Advisor

Fabian Michelangeli

Subject Categories

Biology

Keywords

Atlantic Forest; Bromeliaceae; Caribbean; Choco-Tumbes-Magdalena; Core Bromelioideae; Neotropics

Abstract

The systematics, biogeography and evolution of the 'Ronnbergia Alliance,' a nested lineage within the Core Bromelioideae, were investigated. In the first chapter, the phylogenetic relationships of the Ronnbergia Alliance were reconstructed using three chloroplast and three nuclear DNA sequence markers in combination with a wide species sampling across the Core Bromelioideae and a nearly complete species-level sampling of the five species complexes that likely comprise the Ronnbergia Alliance. The analysis indicates that the Ronnbergia Alliance is a robust monophyletic group sister to the remaining Core Bromelioideae, and it is composed by species of the polyphyletic genera Aechmea, Hohenbergia and Ronnbergia. The first of main lineage within the Ronnbergia Alliance, here called the Pacific Clade, contains species of that occur exclusively in the forests of southern Central America to northwestern South America. The second clade, called the Atlantic Clade, contains species mostly limited to the central corridor of the Atlantic Forest and the Greater Antilles. The combination of apically spreading tubular corollas and unappendaged ovules are diagnostic for the Ronnbergia Alliance, whereas flower size, corolla tube length, and petal pigmentation are important characters to differentiate the Pacific and Atlantic Clades. A new taxonomic reorganization and synopsis for this clade was proposed in the second chapter. Here, all the species of the Pacific Clade were placed in Ronnbergia, whereas the species of the Atlantic Clade were relocated in the resurrected genus Wittmackia. In the third chapter, a complete taxonomic revision of the Caribbean clade of Wittmackia was conducted. In the fourth chapter, the biogeographic history and evolutionary rate dynamics of the Ronnbergia Alliance were analyzed. These analyses showed that one vicariant event that separated Ronnbergia from Wittmackia in South America, and a later long-distance dispersal event allowed the separation of Wittmackia between the Atlantic Forest and Jamaica. Although the evolutionary rate dynamics remained constant during the diversification of Ronnbergia, these rates were heterogeneous during the radiation of Wittmackia. This is the first species-level approach that combines phylogenetic, ecological, geographic and morphological information to reveal fine-scale processes that shaped the evolution of highly diverse lineages of Bromeliaceae.

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