Does diet have an impact on fish jaw evolution?
Midas cichlid fish live in Nicaragua and an ancient ancestor, Amphilophus citrinellus, lives in Lake Nicaragua. Its more recently evolved relative, A. zaliosus, can be found in the crater Lake Apoyo. As close relatives, they have been used in the PLASTICITYSPECIATION (Phenotypic plasticity and speciation in cichlids) project to investigate the impact of induced phenotypic plasticity on diversification and speciation. Researchers tested whether a phenomenon known as genetic assimilation was in play during experiments to induce different phenotypes by changing their environment. A reduction in plasticity is expected with genetic assimilation as the selection pressure is directed onto the developmental system. Broods of the two fish species, A. citrinellus and A. zaliosus were caught in the wild and then reared in the lab. The selection pressure applied was diet-based, the fish were given soft or hard food. The heavy jaws with sharp teeth were photographed and jaw dimensions' analysed using Procrustes analysis followed by correction for allometry. Results showed that the mean measurements between treatment and control from A. zaliosus are lower than that in A. citrinellus, an indication of lower levels of plasticity in the evolved species. Project work is set to provide valuable data for evolutionists and conservationists. Opportunities for genomic analysis to accompany studies of this nature could raise ecological awareness in the wake of global climate changes in particular.
Keywords
Evolution, Nicaragua, Midas cichlid fish, plasticity, speciation, conservationist
