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

functional morphology of lotic and lentic populations of Tilapia

Abstract

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.
Keywords: Cichlids, Ecomorphology, Functional traits, Phenotypic variation, Trophic polymorphism