Genetic diversity and structure of Acrocomia aculeata (Jacq.) Lodd. ex Mart. (Arecaceae) using microsatellite DNA markers in Costa Rica

Acrocomia aculeata is a tree palm species widely distributed throughout the Neotropics, from Mexico to Argentina including some Caribbean islands. The oil from the fruit is used for biodiesel production, human consumption, and biomass fuel. Despite the need to better understand its genetic diversity for commercial use and conservation, genetic diversity and structure knowledge of this species is scarce in Mesoamerica. We used microsatellite markers to analyze 185 samples of A. aculeata, from 18 sampling sites, that essentially covered geographic distribution of this species in Costa Rica. We found low genetic diversity across sampling sites, with He values below 0.50 which, is lower than diversity levels found in South America. Interestingly, samples collected in the national parks Santa Rosa and Rincon de la Vieja National exhibited the highest genetic diversity (He = 0.42 and He = 0.50, respectively). The 18 sampling sites were structured in three clusters. Cluster A contains samples collected in the lower northwestern Pacific, Central Pacific, and Central Region of Costa Rica. Cluster B consisted of samples from sites in the upper northwestern Pacific. Cluster C contains samples from the southeastern Pacific region, being largely separated from Clusters A and B which was supported by the highest differentiation coefficients. This is the first large genetic diversity study of A. aculeata in Mesoamerica; therefore, our results serve as reference for future studies on germplasm diversity studies in this region and a baseline for future conservation and management efforts of A. aculeata.