Diversification dynamics of vegetation during the Cenozoic in the Neotropics: a palynological perspective from Colombia

Abstract The Neotropics host the highest diversity of plants on the Earth today and have done since at least the late Paleogene (~58 Ma). Several mechanisms have been proposed to explain this elevated diversity, but the empirical patterns of Neotropical plant diversification that would test key aspects of those mechanisms are still unclear. We use an extensive palynological database from northern South America to characterize patterns of extinction, origination, and diversity and their possible drivers since the Paleogene. The foreland Llanos basin of Colombia preserves the evolutionary history of Neotropical vegetation as well as the geological evolution of northern South America, offering a unique opportunity to study the relationship between the geological and fossil records. The palynological record of the Llanos basin has been intensely studied mainly for oil exploration, and we use this information to infer the evolutionary history of Neotropical vegetation in Colombia during the Cenozoic. There is no straightforward relationship between global temperature and Neotropical plant diversity. Nevertheless, environmental change had an important influence on the dynamics of diversification, especially during volatile climate intervals such as the Paleocene–Eocene and the Pleistocene. Pulses of regional extinction were driven by large-scale temperature excursions, including both warming and cooling phases. Time-lagged origination pulses results in rapid floral replacement on a timescale of 1 Myr. Origination and extinction are essentially balanced on long timescales, leading to a near-zero long-term net diversification rate. Regional geological events, like the uplift of the Andean Cordillera, and changes in paleogeography also played an important role in Neotropical plant diversification.