CONICET | Buscador de Institutos y Recursos Humanos

The historical and contemporary loss of large-bodiedfrugivores has disrupted many plant-disperser mutualisms, with potentiallyprofound consequences for plants. Although several aspects of seed dispersal bymegafrugivores have already been examined, the role of these species inpromoting seed-mediated gene flow has remained unexplored. We evaluated therole of the Amazonian tapir (Tapirusterrestris), the largest Neotropical frugivore, in shaping plant geneticstructure through seed-mediated gene flow. We used microsatellites to analyzethe genetic patterns of Syagrusromanzoffiana seedlings recruited in tapir latrines and around conspecificadult palms, the two sites where seeds and seedlings are most frequently found inthis species. While the genetic diversity of seedlings was rather similar inboth sites, the kinship structure was substantially weaker in latrines. Mostseedlings recruited around adult palms were half- or full-sibs originating fromthose adults. In contrast, seedlings recruited in latrines came from several(> 5, on average) contributing mothers other than the nearest adult (95%)and were mostly non-sibs (72%). Kinship patterns indicated that tapir-mediateddispersal promotes the admixture of genotypes across space. Also, our resultssuggested that genetic diversity and the number of contributing mothers inlatrines increase with the number of fruiting adults visited by tapirs beforedefecating and with the accumulation of faeces over time. We provide evidenceof the relevance of tapirs in mobilizing maternal progenies (and genotypes)across the landscape and recruiting clusters of unrelated seedlings. This studysuggests a key role for plant-megafrugivore interactions in seed-mediated geneflow and emphasizes the importance of preserving such mutualisms.