All evolutionary modifications of morphology in adult animals presuppose occurrence of changes in developmental programming. While some developmental changes affect rates of trait growth during the entire ontogeny, other developmental changes modify timing and growth rates during limited stages, usually in early development.
developmental changes modifying timing and growth rates during limited stages of early development were more frequent than alterations of trait covariation patterns along the entire ontogeny. This kind of developmental change accounts for a large effect on diversification of adult morphology and emergence of burrowing specializations in spiny rats.
Further analyses are needed for investigating how adult size, as well as ecological and phylogenetic factors might be operating in diversifying the elevation of ontogenetic trajectories. These will provide a better understanding of the factors that determine the evolution of ontogenetic programming.
Common Design 