SYSTEMATICS AND EVOLUTION OF THE Ronnbergia ALLIANCE (BROMELIACEAE): HISTORY OF DISJUNCT DIVERSIFICATION IN THREE BIODIVERSITY HOTSPOTS OF THE NEOTROPICS

The systematics, biogeography and evolution of the \u27Ronnbergia Alliance,\u27 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

Sinopsis del género aechmea (bromeliaceae) para colombia

Se presenta la sinopsis de Aechmea (Bromeliaceae: Bromelioideae) para Colombia, la cual incluye la descripción del género, una clave para la identificación de las especies y la lista anotada de las mismas. Además, para cada especie se incluyen comentarios sobre el hábito de crecimiento, la categoría de amenaza y la distribución geográfica y altitudinal. Se registran 44 especies de Aechmea para Colombia, de las cuales nueve son endémicas: A. anomala, A. nivea, A. stenosepala, A. subpetiolata y cinco especies nuevas para la ciencia. La mayor parte de las especies prefieren los bosques húmedos de tierras bajas, concentrándose en las regiones amazónica (58%) y andina (51%), particularmente en las subregiones llanura Amazónica (51%), las vertientes magdalenense (33%) y oriental andina (30%) y las serranías de las formaciones del Escudo Guayanés (30%). Por otra parte, las especies se distribuyen desde el nivel del mar hasta 2400 m de altitud, pero la mayor riqueza se encontró por debajo de 800