Geology, climate, and competition as drivers of diversification in the neotropical palm genus Geonoma

Understanding why the Neotropics are one of the most biodiverse regions on earth remains a major challenge in ecology and evolutionary biology. We still know little about how the complex interplay between the geological history, climatic fluctuations, and interspecific interactions has led to the build-up of present-day diversity patterns. Here, we explore patterns of diversification in the diverse palm genus Geonoma, encompassing nearly 70 species throughout Central and South America, using phylogenetic analyses, models of diversification and phenotypic evolution. The clade originated in the Andes and subsequently dispersed toward Amazonia and Central America. The speciation rate has been constantly declining through time, possibly related to temperature cooling or increased interspecific competition for resources. We also found an exceptionally high disparity for 28 traits suggesting potential niche partitioning and character displacement, a result partially supported by models of phenotypic evolution. Overall, our study unravels the influence of geological, abiotic, and biotic factors at different stages of the diversification process of Geonoma and illustrates how their complex interactions contribute to the buildup of neotropical diversity.