Consequences of habitat fragmentation on genetic structure of Chamaedorea alternans (Arecaceae) palm populations in the tropical rain forests of Los Tuxtlas, Veracruz, Mexico

Resumen

Chamaedorea alternans is a palm species that has suffered from selective extraction, and habitat loss. We collected 11 populations from fragmented and conserved forest. We assess genetic variation of C. alternans, genetic exchange, differentiation, bottlenecks, effective population size and signals of natural selection. Genetic diversity was higher in conserved than in fragmented forest but not significant. Fragmentation did not play a significant role in genetic diversity, possibly due to the populations heterogeneity. C. alternans has been subject to a pronounced isolation of trees as a product of logging, thus raising inbreeding. Bayesian clustering show a trend towards an increased structuring over the course of generations but also, indicates that populations have recently gone through a bottleneck. The bottleneck following deforestation was not severe enough to lower the effective size, this could lead to high standing genetic diversity, providing a buffer against genetic erosion. We observed directional and balancing selection in C. alternans. Maintenance of variability and increased differentiation signify that their populations have been subject to a differential selective pressure at the ecological and the landscape level, combined effect could lead to disturb pollination and dispersion processes, modifying in the long term the effective population size.