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Summary: Intrapopulation Diet Variation in Four Frogs (Leptodactylidae) of the
Brazilian Savannah
MA´RCIO S. ARAU´ JO, SE´RGIO F. DOS REIS, ARIOVALDO A. GIARETTA, GLAUCO MACHADO, AND
DANIEL I. BOLNICK
Age and sex-based as well as individual-level diet variation are known to occur in
many natural populations, and may have important ecological and evolutionary
implications. In the case of individual-level diet variation, most examples come from
species-poor, temperate communities, and it is currently believed that it results from
population niche expansion following interspecific competitive release. We investigat-
ed and measured the intrapopulation diet variation in four species of frogs,
Leptodactylus (=Adenomera) sp., Eleutherodactylus cf. juipoca, L. fuscus, and Proceratophrys
sp., that are part of species-rich frog communities of the Brazilian Cerrado.
Specifically, we investigated age and sex-related, as well as individual-level, diet
variation. We measured individual-level diet variation with the IS index of individual
specialization, which is a measure of the degree of overlap between individual niches
and the population niches. We found no ontogenetic shifts or sex-related differences in
the types of prey consumed. However, we found evidence of individual-level diet
variation in the four studied species (IS ~ 0.20.5). There was a negative correlation
between IS and the population niche width (r = 0.980; P < 0.0001), indicating that
interindividual diet variation is more pronounced in more generalized populations.
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