Diversity of ants on palms in Várzea habitats at amazonia (Hymenoptera: Formicidae)

Abstract

Palm leaf sheaths provide shelter to numerous groups of vertebrates and invertebrates, both in dry land and periodically flooded environments. Palm leaf sheaths can be considered strategic microhabitats that can be determinant of the survival of ant species inhabiting Amazon islands that undergo periodic flooding. In this work we studied the existence of positive associations between ant and plant communities of the Arecaceae family in Amazon forests to test the hypotheses that (1) taller palm trees have higher ant species richness; and (2) different palm species were occupied by different ant species richness. Palm tree height did not affect significantly ant species richness. Ant species richness responded to palm species, with a higher number of ant species on Scheelea rostrata Mart. than on the other palm species. The periodic flooding can explain the lack of relationship between plant height and ant species richness. With the loss of the habitats for nesting and foraging, the ant species use the palm leaf sheaths for nesting and the other parts of the plant for foraging. The impossibility of moving to other plants caused by the flooding may also explain why the arboreal ant species richness was not influenced by palm tree height. The palm species can be a determinant factor of ant species richness nesting in the palm leaf sheaths. This might be due to the intrinsic characteristics of the palm species, such as morphological and phenological characteristics. Our study demonstrated that palm identity contributed to ant species richness, besides showing that periodic flooding probably determines ant species richness instead of palm tree height. Thus, we suggest that other studies focus on the importance of other variables of palm leaves for ant species richness and colony size (number of individuals), such as leaf number, sheath number and sheath length.