We explored the relationships between diet and
morphology in 30 fish species from forested tropical streams of the Bolivian
Amazon. These species were first assigned to eight broad trophic guilds
based on stomach contents analysis. The relationships between diet and
morphology were then examined using Redundancy Analysis, after having
checked for potential phylogenetical effects. Results show that,
independently of any phylogenetic constraints, some of the trophic guilds
could be grossly predicted from few relevant morphological attributes (i.e.
relative intestinal length, standard length and mouth orientation) and thus
suggest a significant link between diet and morphology. In other words,
species having similar diet tend to converge to some extent on some
morphological attributes. This link was nevertheless rather weak, suggesting
that even if morphology may set limits to patterns of resource use, these
limits are broad enough to allow fishes changing their choice of prey
resources to respond to local biotic and/or abiotic conditions.