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 (Ne) was obtained considering an assumed
mutation rate of 5x10-5. 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 (Ne) 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 Ne 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.