Diet-morphology relationship in a fish assemblage from a medium-sized river of French Guiana: the effect of species taxonomic proximity

We investigated the global relationship between diet and morphology for 42 fish species from a medium-sized river in French Guiana and checked the influence of the species taxonomic proximity on the implication of individual morphological traits in that relation. The 42 species were classified in eight trophic guilds based on analysis of more than 4000 stomach contents. Taxonomic proximity between species was accounted for by an autoregressive model applied to original data of diet and morphology. Original and taxonomic-free data were then submitted to a Canonical Correspondence Analysis in order to detect the relationship between diet and morphology. We compared the results obtained by analyzing the original data and the corrected data. The results confirm the existence of a significant global relationship between diet and morphology. However, morphological traits responsible for that relation were different when considering the taxonomic-free data. Particularly the well known relationship between gut length and detritivory was not observed on the taxonomic free analysis. It is concluded that controlling for phylogeny is essential to the detection of relationships between diet and morphology. It is also concluded that, despite the robustness of some relationships between morphology and diet, many diets cannot be inferred by a ecomorphological approach.