Phenotypic Plasticity of Anatomical Structures and Its Ecomorphological Significance

Ecomorphologists have thus far paid little attention to phenotypic plasticity of anatomical structures. In this paper we present four cases of phenotypic plasticity in African cichlids, which we suppose to be adaptive responses to environmental changes. On the basis of these cases we hypothesize that the response of a plastic anatomical structure to an environmental change may be constrained by surrounding structures. Alternatively, the surrounding structures may be affected by a plastic structure which changed as a direct response to environmental alterations. We also analyze the morphological and ecological implications of the potentials of growth retardation and accelaration on the phenotypic plasticity in organisms. The flexibility of the reaction norm of an organism may depend on these potentials of heterochrony.