Ontogeny and phylogeny of shape and diet in the South American fishes called piranhas

Abstract

Well documented cases of heterochrony are relatively scarce, in part due to the lack of well founded phylogenies and rigorous methods of quantifying ontogenetic trajectories. Here I attempt to document the importance of heterochronic growth in determining body shape in piranhas, a group of South American fishes. Ontogenetic trajectories for individual species are described and a method of detecting evolutionary changes in such trajectories is presented. Correlations of body shape changes with heterochronic changes in trophic morphology and feeding behavior are also discussed.