Print PageMany Neotropical cichlid fishes have morphological and ecological traits that appear to parallel those of Neartic centrarchids (sunfishes). Because they have widely divergent evolutionary histories, cichlids and sunfishes apparently have converged on similar ecomorphological patterns. We examined the morphology and habitat use of 26 species of cichlids from South America and 13 species of centrarchids from North America. We hyphotesized that similarity between habitats (e.g., flow regime, substrate types, foraging opportunities) might create selective pressures resulting in patterns of convergence between these two taxa. We collected fishes from different habitat types in floodplain rivers in South America (Venezuela, Peru) and North America (Texas). Habitat use was assessed in terms of species richness and abundance, and habitat structure was evaluated based on substrate diversity and five other physico-chemical environmental variables. Morphological traits were compared using a set of traditional measurements of body and fin shapes.
Results/Conclusions
There was high overlap in cichlid and centrarchid assemblages morpho-space when compared at the scale of local habitat. Morphological variation of species assemblages in tropical and temperate floodplain rivers were strongly associated with substrate diversity, water velocity and water depth. The distribution of species within morpho-space demostrated correlations between the morphological attributes and their use of larger-scale habitats. Among congeneric species [e.g., Lepomis spp (Centrarchidae) and Crenicichla spp (Cichlidae)], habitat use was greatly overlapped, but these species were separate in morphological space. We found that species in the Cichlidae and Centrarchidae are indeed morphologically convegent and reveal similar distribution of morphological traits within simialr fluvial systems.
