Estimating seed and pollen dispersal kernels from genetic data demonstrates a high pollen dispersal capacity for an endangered palm species

Abstract

Premise of the Study: Seed and pollen dispersal are key processes shaping plant population dynamics and maintaining genetic diversity. The essence of these processes is the movement of propagules from a parental tree to the site of propagule establishment. The estimation of plant dispersal kernels has remained challenging due to the difficulty of making direct observations. We estimated the dispersal capacity of the endangered palm Euterpe edulis, whose seeds are dispersed by vertebrates and pollen by insects. Methods: We used a hierarchical Bayesian model with genetic data from reproductive plants, juveniles, and embryos to estimate dispersal kernels. Our analyses account for genotyping error and uncertainty in parental assignment. Key Results: We found that seeds were dispersed at most a few hundred meters, but pollen was dispersed up to several kilometers. We hypothesize that this long-distance pollen dispersal is generated mainly by euglossine bees, whereas the main dispersal vectors for short-distance seed dispersal are thrushes. The long-distance dispersal of pollen suggests a high level of gene flow that should maintain genetic diversity of E. edulis. Despite the relation between long-distance dispersal and genetic diversity, we observed low genetic diversity and inbreeding within the local population, which are probably due to restricted gene flow due to the low density of this population and its aggregated spatial distribution. Conclusions: We conclude that if conservation actions are able to restore the population density of E. edulis, the recovery of its genetic diversity will be facilitated because of its high dispersal capacity, especially with regard to pollen.