Trophic ecomorphology of cichlid fishes of Selva Lacandona, Usumacinta, Mexico

Neotropical cichlids exhibit great diversity of morphological traits associated with feeding, locomotion, and habitat use. We examined the relationship between functional traits and diet by analyzing a dataset for 14 cichlid species from rivers in the Selva Lacandona region, Usumacinta Basin, Chiapas, Mexico. Volumetric proportions of ingested food items were used to calculate diet breath and interspecific dietary overlap. Morphometric analysis was performed using 24 traits associated with feeding. Associations between morphological and dietary components were assessed using canonical correspondence analysis. The most common feeding guilds were omnivore, herbivore and carnivore (the latter consuming invertebrates and/or fish), with detritivores represented by relatively few species and strict piscivore by one species. Dietary overlap was highest among carnivores (P. friedrichsthalii and T. salvini), herbivores (C. intermedium and C. pearsei) and detritivore-herbivores (V. melanura and K. ufermanni). Dietary components were strongly correlated with several morphological traits, confirming patterns observed in other cichlids. For example, jaw protrusion and mandible length were positively correlated with consumption of fish and terrestrial invertebrates. A longer gut and a wider tooth plate on the lower pharyngeal jaw were correlated with ingestion of vegetation, algae and detritus. Findings confirmed a high degree of trophic specialization in certain species as well as interspecific divergence of functional traits associated with feeding among cichlids of the Usumacinta Basin, which is consistent with the idea that Middle American cichlids represent an adaptive radiation.