Andean orogenesis has driven the development of very high plant diversity in the Neotropics through its impact on landscape evolution and climate. The analysis of the intraspecific patterns of genetic structure in plants would permit inferring the effects of Andean uplift on the evolution and diversification of Neotropical flora. In this study, using microsatellite markers and Bayesian clustering analyses, we report the presence of four genetic clusters for the palm Oenocarpus bataua var. bataua which are located within four biogeographic regions in northwestern South America: (a) Chocó rain forest, (b) Amotape-Huancabamba Zone, (c) northwestern Amazonian rain forest, and (d) southwestern Amazonian rain forest. We hypothesize that these clusters developed following three genetic diversification events mainly promoted by Andean orogenic events. Additionally, the distinct current climate dynamics among northwestern and southwestern Amazonia may maintain the genetic diversification detected in the western Amazon basin. Genetic exchange was identified between the clusters, including across the Andes region, discarding the possibility of any cluster to diversify as a distinct intraspecific variety. We identified a hot spot of genetic diversity in the northern Peruvian Amazon around the locality of Iquitos. We also detected a decrease in diversity with distance from this area in westward and southward direction within the Amazon basin and the eastern Andean foothills. Additionally, we confirmed the existence and divergence of O. bataua var. bataua from var. oligocarpus in northern South America, possibly expanding the distributional range of the latter variety beyond eastern Venezuela, to the central and eastern Andean cordilleras of Colombia. Based on our results, we suggest that Andean orogenesis is the main driver of genetic structuring and diversification in O. bataua within northwestern South America.

Samples collected in northern South America. Young leaf material was collected for DNA extraction using the DNeasy plant mini kit (Qiagen). Seven SSR loci were amplified at 644 samples using Multiplex PCR and fluorescent labeled forward primers.

Microsatellite genotypes of Oenocarpus bataua

Microsatellite genotypes for 644 Oenocarpus bataua samples from Colombia, Ecuador, Peru, Bolivia, and French Guiana, genotyped at 7 SSR loci. The genotype file is in GenAlEx format, which can be easily exported to many other formats. The grid A1 shows the number of loci. The grid B1 shows the number of individualas. The grid C1 shows the number of populations. Following columns in the first row show number of individuals within populations. The second row shows populations names. The third row shows loci names. Following rows show the SSR data.