Made in the Americas: How three lineages of flowering plants evolved and dispersed across the Neotropics and the World

Abstract

Bignoniaceae is a flowering plant family of ca. 850 species. The family has the highest species diversity in the Neotropics, but taxa are also found in tropical Africa and Asia, as well as the temperate zones in both the Northern and Southern hemisphere. This widespread distribution allowed me to ask questions about how three of these lineages- Tecomeae, Jacarandeae, and Crescentieae- achieved their current global, Neotropical, and Central American distributions, respectively. Using a combination of molecular phylogenetic and biogeographic methods, I inferred the evolutionary relationships of species in these groups, then used the resulting phylogenies, along with fossil calibrations and species distributions, to estimate divergence times, perform ancestral state reconstructions, and infer diversification rates to explore temporal and spatial patterns of evolution and dispersal. Tecomeae is inferred to have originated in the Neotropics about 40 Ma, likely achieving its current distribution via a combination of overland and overwater dispersal aided by wind-dispersed seeds. Jacarandeae is estimated to have originated in the Neotropics also, achieving its current distribution by dispersing within and across the many biomes of the region over the past 23 Ma. Crescentieae, restricted to Central America and the West Indies, is unique in the family for having fleshy fruit that is likely adapted for dispersal by now extinct megafauna or water.