Fruit Protein in Primate Communities
Fruit Protein in Primate Communities from Bristol Zoo Gardens
Fruit protein effects on primate communities in Madagascar and the Neotropic
The ecological factors contributing to the evolution of tropical vertebrate communities are still poorly understood.
The tropical Americas have fewer folivorous but more frugivorous primate (and other mammal) genera than tropical regions of the Old World and especially many more frugivorous genera than Madagascar. Similar patterns are seen in avian communities.
Reasons for this phenomenon are largely unexplored. Based on 11 studies of frugivorous primates (used as a proxy for mammal communities) published until 2004, 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 fruit protein concentrations.
Low fruit protein concentrations in Madagascar would restrict the representation of frugivores in Malagasy communities. We tested the prediction with fruits from six new sites in the Neotropics and six sites in Madagascar. Fruits of the Neotropical test sites contain significantly more nitrogen than fruits from the Madagascar test 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. Thus, selection pressure to develop new adaptations for food which is difficult to digest (such as leaves) might 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 mammals and bird species on this island.
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