Interactions among fleshy fruits and frugivore assemblages are presented from a 1-y study in the littoral forest of Sainte Luce, south-eastern Madagascar. This community-level approach allowed us to determine food selection by all consumer species and to evaluate the role different frugivores play in seed dispersal and predation. For this, interactions between 136 consumed fruit species and 13 frugivorous species were studied. Fruit and seed size were the most important physical factors determining food selection of all consumer species. Nutritionally birds favoured and mammals avoided lipid-rich fruits. For Cheirogaleus spp., that go into torpor, there was a trend to select sugar-rich fruit pulp. However, for numerous fruit traits the consumer species had no clear feeding preferences and they seemed to be quite flexible, eating whatever was available. This might be related to unpredictable fruit availability and low fruit productivity in the littoral forest, which may also partially explain the low number of frugivores present. Nevertheless frugivores have different impacts on seed dispersal. Eulemur fulvus collaris is particularly important for the dispersal of large-seeded species, while frugivorous birds and flying foxes ensure plant regeneration between and outside forest fragments. In terms of conservation, heterogeneous seed transport is particularly important for this severely degraded littoral forest.

BackgroundThe ecological factors contributing to the evolution of tropical vertebrate communities are still poorly understood. Primate communities of the tropical Americas have fewer folivorous but more frugivorous genera than tropical regions of the Old World and especially many more frugivorous genera than Madagascar. Reasons for this phenomenon are largely unexplored. We developed the hypothesis that Neotropical fruits have higher protein concentrations than fruits from Madagascar and that the higher representation of frugivorous genera in the Neotropics is linked to high protein concentrations in fruits. Low fruit protein concentrations in Madagascar would restrict the evolution of frugivores in Malagasy communities.Methodology/Principal FindingsWe reviewed the literature for nitrogen concentrations in fruits from the Neotropics and from Madagascar, and analyzed fruits from an additional six sites in the Neotropics and six sites in Madagascar. Fruits from the Neotropical sites contain significantly more nitrogen than fruits from the Madagascar sites. Nitrogen concentrations in New World fruits are above the concentrations to satisfy nitrogen requirements of primates, while they are at the lower end or below the concentrations to cover primate protein needs in Madagascar.Conclusions/SignificanceFruits at most sites in the Neotropics contain enough protein to satisfy the protein needs of primates. Thus, selection pressure to develop new adaptations for foods that are difficult to digest (such as leaves) may have been lower in the Neotropics than in Madagascar. The low nitrogen concentrations in fruits from Madagascar may contribute to the almost complete absence of frugivorous primate species on this island.