Biogeographic patterns in the Chocó region: A case study of Inga Mill (Leguminosae)

This thesis addresses the Chocó region, recognized as one of the wettest, most biodiverse, and least documented areas on Earth. Here, I present a new ecological delimitation of the Chocó, integrating climatic and geographical data. The proposed area differs from previous delimitations because it includes geographically contiguous and climatically similar rain forests distributed throughout southern Panama, the Colombian Pacific, the humid system of the Magdalena River in northern Colombia, and northern Ecuador, covering an area of 162,800km². The genus Inga (Leguminosae: Caesalpinioideae) is employed as a model to elucidate the biogeographic patterns driving the historical assembly of the flora in this region. While the diversity of the Chocó is explained by its isolation by the Andean cordillera, and it has been classified as the oldest and most isolated Pleistocene refuge in the Neotropics, recent studies suggest plant migration as a complementary phenomenon enhancing its floristic diversity. Inga’s species diversity is concentrated in the Amazon basin (145 species), yet its presence in the Chocó is scantily studied and here I show 78 species and morphological variants of species to be present in the Chocó, nearly doubling estimates in recent taxonomic accounts. This new estimate of species number for the Chocó is based on fieldwork, taxonomic studies of herbarium specimens and phylogenetic analysis of target-capture DNA sequences. Biogeographic analysis using BioGeoBears highlights the role of both dispersal and in-situ speciation in developing the species diversity of Inga in the Chocó after first colonization approximately 10 million years ago. Finally, two new species of Inga (Inga calimaensis and Inga crassanectaria), endemic to the Chocó are described. This study contributes to understanding both the diversification of the flora of the Chocó and refining the taxonomy of the genus Inga.