Abstract
Abstract: Aim We described the diet of the generalist stream fish Knodus chapadae and we tested if the environmental conditions are associated with population’s diet and individual specialization. Methods We analyzed the stomach contents of 287 individuals from 29 streams from the Brazilian savanna (Cerrado). Results The instream physical habitat structure, physiochemical conditions, and adjacent land use explained partially the variation in the diet of populations, but not the variation in the individual specialization. Thus, the diet changes observed at populational level were driven by changes in the average composition of the diet of individuals that, in turn, remained generalists along the environmental gradient. Conclusions Our results show that the trophic opportunism described for small characids was also observed in K. chapadae, whose diet shifts according to changes in environmental conditions. Furthermore, the opportunism expressed at the individual level can explain the trophic plasticity observed on the studied species.
Highlights
Trophic variation in fish assemblages along environmental gradients is driven by species’ turnover with different trophic specialization (Gonçalves et al, 2018) and by changes in the diet of species that persist along the gradient (Ferreira et al, 2012)
Aim: We described the diet of the generalist stream fish Knodus chapadae and we tested if the environmental conditions are associated with population’s diet and individual specialization
The occurrence of the species in streams with different environmental conditions is followed by changes in its diet, probably reflecting the shift in food resource availability
Summary
Trophic variation in fish assemblages along environmental gradients is driven by species’ turnover with different trophic specialization (Gonçalves et al, 2018) and by changes in the diet of species that persist along the gradient (Ferreira et al, 2012). This latter process involves generalist species that exhibit phenotypic plasticity to deal with distinct environmental conditions and differences in resource availability (Bojsen, 2005). Assessing individual variability in diet can contribute to reveal intrapopulation mechanisms that explain species’ niche patterns (Roughgarden, 1972; Bolnick et al, 2011)
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