Dispersal and in Situ Speciation as Contributors to Plant Diversity in the Chocó Region: Insights From Inga Mill. (Leguminosae)

Abstract

Aim To investigate the historical processes underlying the assembly of the flora of the Chocó region, with a focus on the relative contributions of dispersal and in situ speciation. Using Inga (Leguminosae) as a model lineage, we evaluate the origin and diversification of species present in the Chocó. Location The Chocó region, a lowland rainforest located across southern Panama, the Pacific coast of Colombia, the Magdalena humid system and northwestern Ecuador. Methods We used a densely sampled phylogeny of 383 accessions representing 209 Inga species and morphospecies, generated through target capture sequencing of 1320 nuclear loci. Time‐calibrated phylogenetic analyses and biogeographic reconstructions were used to infer the timing and direction of dispersal and speciation events. Results Our analyses reveal a heterogeneous biogeographic history for the Chocó Inga flora. Most species arrived via independent long‐distance dispersal events from Amazonia and Central America starting ~9.5 Ma ago. Two distinct clades of endemic Inga species in the Chocó suggest in situ diversification, one originating ~8.2 Ma and another ~4.2 Ma, predating Pleistocene climatic fluctuations. Biogeographic stochastic mapping shows the Chocó has not only received lineages but has also contributed them to surrounding regions. The Andes have not acted as a major barrier for Inga dispersal. Main Conclusions The Chocó represents a dynamic intersection that integrates Inga lineages from across the Neotropics while also contributing lineages to surrounding regions. Despite its relatively small area, the Chocó has supported in situ diversification of Inga prior to late Pleistocene climatic fluctuations.

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