Dietary differentiation in relation to mouth and tooth morphology of a neotropical characid fish community

The relationship between diet and mouth and tooth morphology among eleven characid species is evaluated herein. Specifically, we tested for: (1) significant differences among the diets and (2) corresponding variation of mouth and tooth morphology. Fishes were collected bimonthly during 2012 and 2013 using electrofishing techniques in the Alto Jacuí sub-basin. A total of 1525 stomachs were analyzed representing eleven species of characid fishes. A Permutational Multivariate Analysis of Variance (PERMANOVA) analysis showed significant interspecific differences among the diets, and Similarity Percentage (SIMPER) analysis indicated that the main food items that contributed to this differentiation were variation in the relative consumption of terrestrial and aquatic plants, terrestrial and unidentified aquatic insect, and adult Hymenoptera. Lastly, Constrained Principal Analysis on Coordinates (CAP) analyses showed that several morphological features were associated with dietary patterns. For example, sub-terminal mouth positions were correlated with the ingestion of benthic items (i.e., aquatic insects and organic matter). Large mouths were associated with species that consume large items such as Decapoda (e.g., Aegla) and fish. Species that showed a minor variation in tooth morphology along the outer row of the premaxilla, as well as those that have fewer teeth on the maxilla, consumed high proportions of plants and terrestrial insects. Species with intermediate and high numbers of cusps in the maxilla teeth tended to consume aquatic insects. Here, we demonstrated that eleven species of characid fishes had different diets and that those diets were correlated to a specific mouth and tooth morphology. Therefore, diet and oral morphology likely co-evolved such that divergence in trophic-related morphology likely facilitated dietary differentiation among characid fishes.