ABSTRACT
RESUMEN La ecología de la polinización de Syagrus orinocensis fue estudiada durante tres períodos reproductivos, en un bosque de piedemonte en Casanare, Orinoquia colombiana. Syagrus orinocensis crece hasta 10m., produce de una a cuatro inflorescencias bisexuales aunque ocasionalmente son unisexuales. Las bisexuales presentan flores estaminadas y pistiladas agrupadas en tríadas, y las unisexuales llevan sólo estaminadas en díadas. Las inflorescencias protándricas abren de día, y permanecieron activas 26 días; la fase masculina se extendió los primeros 15 días, siguió una fase inactiva por ocho días, y finalmente, la fase pistilada por tres días. Las inflorescencias fueron visitadas por 43 especies de insectos de los órdenes Coleoptera, Hymenoptera y Diptera. Los insectos visitaron las inflorescencias en fase masculina, donde buscaban polen y lugares para reproducirse, mientras que en la fase femenina buscaban néctar. Los polinizadores más efectivos fueron abejas meliponinas (Apidae, Meliponini), que transfirieron adherido a su cuerpo el 83 % del polen. La presencia, constancia y eficiencia de abejas durante el estudio son evidencia sólida de melitofilia en palmas. Este caso de melitofilia permitió proponer los criterios para redefinir este tipo de polinización en palmas silvestres neotropicales.
ABSTRACT The pollination ecology of the Syagrus orinocensis was studied in the course of three consecutive yearly flowering seasons in a foothill forest in Casanare, Colombian Orinoco region. Syagrus orinocensis palms grow up to 10 m high and produce one to four bisexual, occasionally unisexual, inflorescences. The bisexual inflorescences bear staminate and pistillate flowers arranged in triads, whereas the unisexual inflorescences carry only staminate flowers in dyads. The inflorescences are protandric and open during daytime, remaining active for 26 days. The male phase extends for the first 15 days, which are followed by 8 days of an inactive phase; the pistillate phase lasts up to three days. The inflorescences of S. orinocensis were visited by 43 species of insects belonging to the orders Coleoptera, Hymenoptera and Diptera. The presence of anthophilous insects was primarily restricted to the male phase of anthesis, during which the visitors searched for pollen and breeding sites; those which visited inflorescences during the female phase seeked out nectar. The most effective pollinators of S. orinocensis were stingless bees (Apidae, Meliponini), as they transferred in average 83% of the pollen that reached receptive inflorescences. The presence, constancy and efficiency of stingless bees during this study constitute solid evidence of melittophily in S. orinocensis and allows us to propose criteria to redefine this pollination syndrome in Neotropical wild palms.
ABSTRACT
The aim of this work was to identify the pollination and dispersal systems among the species in a disjunct marginal cerrado area and to compare the frequency of these systems to those found in other Neotropical vegetation. The floral and diaspore traits and the pollination and dispersal systems of 176 species were analysed in a cerrado remnant in Southeastern Brazil. The most frequent pollination system was melittophily (63 percent of the studied species) with the remaining 37 percent distributed among diverse pollination systems. Zoochory was the predominant system of dispersal (44.9 percent). The frequencies of melittophily and zoochory observed in diverse tropical areas were the main feature that allowed the formation of distinct groups in the dendrograms generated by cluster analysis.