The interplay of biogeographic history, floral morphology, and climatic niche in Palicourea (Rubiaceae), an ecologically important group of Neotropical plants

Investigating how biotic and abiotic factors interact to shape species distributions is critical to understanding current biodiversity patterns. This is particularly relevant in the Neotropics, a species-rich region home to several biodiversity hotspots, where the interplay of factors promoting diversification resulted in the assembly of the world’s richest flora. Using Palicourea, a species-rich and ecologically and morphologically diverse group of Neotropical plants in the coffee family, we aimed to identify patterns resulting from the interaction of biogeographic history, evolution of floral morphology, and climatic niche evolution. We used genome-wide target enrichment data using a family-specific probe set for hundreds of loci, to infer the most completely sampled multi-locus phylogeny of Palicourea to date. To explore abiotic factors driving evolution, we modeled species historical ranges and the probability of climatic niche overlap. We integrated our results with natural history knowledge on inflorescence morphology characters linked to pollination to examine the interplay of biogeographic, floral morphology, and realized climatic niche on the evolution of this remarkably diverse group of Neotropical plants. Our results demonstrate that Palicourea has a highly structured biogeographic history, with limited long distance dispersal events generally occurring between climatically similar regions. Further, we pinpoint an important role of climatic niche conservatism and convergent evolution of characters related to pollination in the evolutionary history of Palicourea. An interaction of biotic and abiotic factors has led to a continental radiation of plants that form an important ecological cornerstone of the Neotropics.