Predicting the functional morphology of lotic and lentic populations of the invasive Mozambique tilapia Oreochromis mossambicus (Peters, 1852)

A better understanding of the mechanism which connects the morphology of fishes and their ecological performance is a major goal in evolutionary studies. As accepted widely, intra-species polymorphism mostly arises from divergent selection pressures between different environments. The present study sought to understand the functional morphological variations exhibited by Mozambique tilapia Oreochromis mossambicus (Peters, 1852) inhabiting heterogeneous habitats, using functional indices derived from the body. We found that O. mossambicus exhibited clear functional responses to divergent habitats indicating trait-habitat linkages. Fishes differed in three out of fifteen indices compared, which are mainly related to swimming performances. Fishes collected from the river possess more streamlined bodies and achieve higher values in indices related to swimming efficiencies. However, there were no significant intra-species differences in the indices related to feeding between habitats, indicating that functional divergences in O. mossambicus are mainly related to swimming and locomotion. The study confirmed that the morpho-functional variations observed in this species are primarily of selection pressure caused by habitat heterogeneities. The present findings further confirm our understanding of the predictive power of the trait-environment approach and indicate that fishes tend to change their traits related to swimming and foraging with changing ecological conditions of the habitat.