Competitive and Coordinative Interactions between Body Parts Produce Adaptive Developmental Outcomes

Large-scale patterns of correlated growth in development are partially driven by competition for metabolic and informational resources. It is argued that competition between organs for limited resources is an important mesoscale morphogenetic mechanism that produces fitness-enhancing correlated growth. At the genetic level, the growth of individual characters appears independent, or "modular," because patterns of expression and transcription are often highly localized, mutations have trait-specific effects, and gene complexes can be co-opted as a unit to produce novel traits. However, body parts are known to interact over the course of ontogeny, and these reciprocal exchanges can be an important determinant of developmental outcomes. Genetic mechanisms underlie cell and tissue behaviors that allow organs to communicate with one another, but they also create evolutionarily adaptive competitive dynamics that are driven by physiological and biophysical processes. Advances in the understanding of competitive and closely related coordinative interactions across scales will complement existing research programs that emphasize the role of cellular mechanisms in morphogenesis. Study of the large-scale order produced by competitive dynamics promises to facilitate advances in basic evolutionary and developmental biology, as well as applied research in fields such as bioengineering and regenerative medicine that aim to regulate patterning outcomes.