• carbon stable isotopes;
  • individual specialization;
  • niche variation;
  • Niche Variation Hypothesis


  • 1
    Many natural populations exploiting a wide range of resources are actually composed of relatively specialized individuals.
  • 2
    This interindividual variation is thought to be a consequence of the invasion of ‘empty’ niches in depauperate communities, generally in temperate regions. If individual niches are constrained by functional trade-offs, the expansion of the population niche is only achieved by an increase in interindividual variation, consistent with the ‘niche variation hypothesis’.
  • 3
    According to this hypothesis, we should not expect interindividual variation in species belonging to highly diverse, packed communities.
  • 4
    In the present study, we measured the degree of interindividual diet variation in four species of frogs of the highly diverse Brazilian Cerrado, using both gut contents and δ13C stable isotopes.
  • 5
    We found evidence of significant diet variation in the four species, indicating that this phenomenon is not restricted to depauperate communities in temperate regions.
  • 6
    The lack of correlations between the frogs’ morphology and diet indicate that trade-offs do not depend on the morphological characters measured here and are probably not biomechanical. The nature of the trade-offs remains unknown, but are likely to be cognitive or physiological.
  • 7
    Finally, we found a positive correlation between the population niche width and the degree of diet variation, but a null model showed that this correlation can be generated by individuals sampling randomly from a common set of resources. Therefore, albeit consistent with, our results cannot be taken as evidence in favour of the niche variation hypothesis.