Origins, Biogeography and Macroecology of the Southwestern Atlantic Reef Biodiversity

The origin of most reef biodiversity of the southwestern Atlantic Ocean dates back to the Eocene, when the center of diversity of modern reef organisms was in the Tethys Sea, a vast extent of tropical shallow marine habitats situated between the Atlantic and Indian oceans. Following the closure of the Tethys Sea, the Atlantic reef biodiversity became increasingly isolated from the world’s centers of biodiversity (i.e. tropical Indo-Pacific). Moderate rates of origination and extinction shaped endemic lineages and a lower diversity of species compared with the Indo-Pacific. Within the Atlantic, the Brazilian Province is characterized by high endemism and by the presence of a secondary center of biodiversity, driven by a combination of isolation, distinct ecological conditions, and the overlap of tropical and subtropical species. Many evolutionary processes shape the current distribution of species along the coast and in offshore areas such as seamounts and oceanic islands. The taxonomic and functional structure of reef fishes and benthic organisms in the Brazilian Province are related to both historical events and environmental factors, and changes considerably along its latitudinal extent. Today, increased and disordered human development, associated with inadequate conservation measures, is quickly threatening millions of years of eco-evolutionary processes responsible for the origin of this unique biodiversity.