Genetic structure of two Acrocomia ecotypes (Arecaceae) across Brazilian savannas and seasonally dry forests

The species of Acrocomia are popularly known as Macaw palm due to their importance as a food source for Anodorhynchus (Psittacidae). They are monoecious, with a mixed reproductive system, and high ecological and economic importance. There is controversy regarding the taxonomic status of Acrocomia aculeata and Acrocomia totai as different species; to avoid misunderstanding, we adopted the ecotype terminology. Using range-wide sampling in Brazil and based on microsatellite data, we aimed to understand the genetic diversity of A. aculeata and A. totai and to evaluate if the genetic structure between them was different. Our results support a separation of Acrocomia aculeata and A. totai based on the patterns of genetic variation between the ecotypes. These findings are supported by the optimal clustering of K = 7, congruent with network analysis, as well as pairwise genetic differentiation and detected barriers to gene flow. We found no evidence of recent bottlenecks in all populations, excepting two. The genetic structure was mainly associated with rivers and topography, but there was also evidence of gene flow among most populations. The association of the genetic structure with the geographical distribution of populations was more evident in A. aculeata than in A. totai . Populations located at the western portion of Brazil showed a high degree of admixture, notably among A. totai populations. The identification of areas with the highest genetic diversity of Acrocomia contributes useful information for plant breeding programs and the detection of potential genotypes of interest for germplasm collections.