Trophic structure of a neotropical frugivore community: is there competition between birds and bats?

Dietary overlap and competition between frugivorous birds and bats in the Neotropics have been presumed to be low, but comparative data have been lacking. We determined the diets of volant frugivores in an early successional patch of Costa Rican wet forest over a one month period. Ordination of the diet matrix by Reciprocal Averaging revealed that birds and bats tend to feed on different sets of fruits and that diets differed more among bat species than among bird species. However, there was overlap between Scarlet-rumped Tanagers and three Carollia bat species on fruits of several Piper species which comprised most of the diet of these bats. Day/night exclosure experiments on P. friedrichsthalli treetlets provided evidence that birds deplete the amount of ripe fruit available to bats. These results indicate that distantly related taxa may overlap in diet and compete for fruit, despite the apparent adaptation of animal-dispersed plant species for dispersal by particular animal taxa.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47779/1/442_2004_Article_BF00384321.pd

Ultrastructural basis and function of iridescent blue colour of fruits in Elaeocarpus

Iridescent colour, caused by physical effects (thin-film interference, diffraction and Tyndall scattering), is relatively common in animals but exceedingly rare among plants1. Some benthic marine algae produce blue to violet iridescence2,3, and the upper leaf surfaces of a few vascular plants from the shady environments of humid tropical forests are iridescent blue4–6. Blue fruit colour has been assumed to be caused by anthocyanins7. A survey of such fruits (26 species in 18 genera) in Costa Rica, India, Florida and Malaysia, showed this to be the case, except for the iridescent colour in fruits of Elaeocarpus angustifolius Blume (Elaeocarpaceae). There I show that the colour is caused by a remarkable structure in the epidermis, and provide evidence for its selective advantage