Historical Biogeography of the Neotropical Miconieae (Melastomataceae) Reveals a Pattern of Progressive Colonization Out of Lowland South America

Abstract

The Neotropics harbor over a third of all known seed plant species, and their distribution is not homogenous. Understanding how this diversity arose and is maintained is a complex endeavor and likely dependent upon the area, vegetation type, or group of organisms studied. The Miconieae, with ca. 1900 species, are the largest tribe of the plant family Melastomataceae. The clade is strictly Neotropical and composed of mostly shrubs and small trees, but also herbs, epiphytes, and lianas all berry-fruited and important components of Neotropical rain and cloud forests. This makes the Miconieae an ideal model system to study the establishment of modern-day Neotropical forests. We investigated the biogeographic patterns of this diverse group using over 90, 000 distribution records of herbarium specimens for over 1000 species. The biogeographical history of the Miconieae reveals a complex pattern involving relatively few migrations followed by in situ species radiations. The pattern is mostly centrifugal as groups radiated repeatedly out of the Amazonian basin into the Andes, Eastern Brazil, and the Lesser Antilles, and later from the Andes to the Greater Antilles and Central America. While niche conservatism may have played an important role on a broad scale, other local factors, such as biotic interactions, microclimate, and soil characteristics, are important for local diversification.