A frugivore-generated seed rain combines propagules from source trees located all over the landscape. By selecting deposition sites, frugivorous vertebrates set the maternal genetic correlations in the seed rain, i.e., how maternal progenies become distributed over the landscape relative to the source tree and other conspecifics. This aspect remains virtually unexplored, despite its central effect on the demographic and genetic structure in plant populations. We examined three components of maternal genetic correlations in the seed rain: the number of distinct contributing maternal trees (maternal richness), the genetic relatedness among contributing trees (maternal relatedness), and the probability that two seeds drawn from the same seed trap come from the same maternal tree (correlated maternity). Based on the multilocus genotypes provided by microsatellites markers we identified the unambiguously the source tree of seed dispersed into seed-traps distributed among six microhabitat types. Then we identified the source tree of dispersed seeds and characterized the maternal correlations among them.
Results/Conclusions
Our results showed that highly selective foraging by frugivores in heterogeneous landscapes derives in a limited distribution of maternal progenies to certain microhabitat types and a spatial aggregation of a maternal-related progeny in the seed traps, overall generating a complex pattern of maternal genetic correlations in the seed rain. Maternal genetic correlations among seeds reaching the same seed trap showed a spatial aggregation of maternally related seeds that varied among microhabitats in relation to the frugivore assemblage that visited them. We found: i) seed traps with high maternal richness and low genetic relatedness in sites dominated by high shrubs, frequently visited by most of frugivore species; ii) seed traps with low maternal richness, high relatedness, and increased correlated maternity values resulting from recurrent dispersal from few isolated source trees to sites dominated by non-fleshy fruited species; and iii) and seed traps under pine trees with high maternal richness and relatedness (but low correlated maternity) due to long-distance dispersal events from several closely-growing source trees. Overall, these results evidenced that dispersal activity assisted by vertebrates derives in a genetic limitation (i.e., the failure of source trees to reach all microhabitats). Therefore, frugivory activity in heterogeneous landscapes is expected to determine plant recruitment dynamics and spatial genetic patterns within populations, beyond dispersal distance limitation, by imposing a spatial aggregation of maternal-related seeds coupled with genetic limitation.
