Abstract
The assembly of the world’s most biodiverse region, the Neotropics, was
traditionally considered the result of long-term environmental
stability. Studies gathered during the last decades suggest that
environmental “instability” instead, specially the dramatic
modifications caused by the uplift of the Andes, was responsible of the
Neotropical diversity. Yet a comprehensive understanding has been
hindered by a lack of large-scale comparative data across wide
phylogenetic and ecological contexts. Here, we evaluate the timing and
drivers of Neotropical diversification in a large sample of Neotropical
clades: 150 phylogenies (12,524 species) of seed plants and major
tetrapods (amphibians, mammals, squamates, and birds). We unveil five
trends: (1) biodiversity levels before the Quaternary were comparable
(or higher) to those of the present,; (2) half of the clades diversified
at constant rates; (3) past environmental variations correlate with
diversification changes in 37% of the lineages, but with contrasting
responses: (4) birds and mammals diversified extensively during warm
periods and global cooling resulted in synchronized slowdowns of
diversification; plant diversification generally increased during
cooling; and (5) the rise of the Andes mostly impacted amphibians and
squamates. Our study suggests that environmental instability over
macroevolutionary scales may in fact act as a driving force of
Neotropical diversification.