Using a coalescent approach to assess gene flow and effective population size of Acrocomia aculeata (Jacq.) Lodd. Ex Mart. in the Brazilian Atlantic Forest

Acrocomia aculeata is a tropical palm tree native to Central and South America that has significant economic, social, and environmental potential. However, land encroachment due to the expansion of agribusiness, and other factors such as urban sprawl, have resulted in the fragmentation and destruction of its habitat, leading to the loss of genes and genotypes in A. aculeata populations. In this context, the objective of this study was to characterize the genetic variability of A. aculeata populations by estimating gene flow and effective population size using an approach based on coalescent theory. Four populations located in the municipalities of Teodoro Sampaio (TSI and TSII), Rosana (RA), and Amparo (AP) in São Paulo State, Brazil, were genotyped with nine microsatellite markers. Gene flow and effective population size were estimated using a coalescent-based Bayesian inference implemented in the MIGRATE-N software. The effective population size ( N e ) was obtained considering an assumed mutation rate of 5 × 10 −5 . Gene flow ( Nm ) for pairwise populations ranged from 0.28 to 1.17, with higher levels of migration between the three geographically proximal locations (TSI, TSII, and RA). The estimates of effective population size ( N e ) were 444, 835, 838, and 874 for AP, TSII, RA, and TSI, respectively, showing that the effects caused by genetic drift may be more pronounced when N e is smaller. The coalescent-based results add to our understanding of A. aculeata population genetics and suggest that some traditional assessment methods may be ineffective in characterizing historical evolutionary processes.