Feeding ecomorphology of seven demersal marine fish species in the Mexican Pacific Ocean

How fish functional morphology shapes species co-existence and assemblage diversity patterns is a fundamental issue in ecological research. In fishes, much is known about the ecomorphological relationships of feeding morphology in coral reef fishes and in freshwater taxa inhabiting distinct environments. However, little is known about the patterns and processes shaping morphological variation in other oceanic taxa; particularly those inhabiting soft bottom habitats. In this study, we assessed patterns of feeding ecomorphology in seven demersal teleost species associated with soft bottoms of the continental shelf in the central Mexican Pacific Ocean. Feeding analyses indicated that some species groups shared similar diets. Likewise, patterns of morphological variation based on geometric morphometrics demonstrated that some taxa did not differ in body shape, while patterns of variation in other species were seen in body length and height, caudal peduncle height and the anal fin anterior insertion point. A multivariate association between diet composition data and overall body shape indicated significant ecomorphological relationships, describing a continuum between species displaying benthopelagic morphology and specializing on prey with high speed swimming ability (Engraulidae), versus species with benthic morphology and specializing on fast escape prey (crustacea). The clear ecomorphological patterns observed for these seven species at both the individual and species levels imply that environmental conditions and resource availability allow these taxa to differentially inhabit and exploit the soft bottom ecosystem. Fish diversity is principally represented by the benthic morphology, although benthopelagic morphology, also show a high degree of success in this environment.