Biological robustness: Paradigms, mechanisms, systems principles

Abstract

Robustness has been studied through the analysis of data sets, simulations, and a vari- ety of experimental techniques that each have their own limitations but together confirm the ubiquity of bio ogica robustness. Recent trends suggest that different types of perturbation (e.g., mutational, environmental) are commonly stabilized by similar mechanisms,and system sensitivities often display a long-tailed distribution with relatively few perturbations representing the majority of sensitivities. Conceptual paradigms from network theory, control theory, complexity science, and natural selection have been used to understand robustness, however each paradigm has a limited scope of applicability and there discussion of the conditions that determine this scope or the relationships between paradigms. Systems properties such as modularity, bowtie eracy, and other topological features are often positively associated with robust however common underlying mechanisms are rarely mentioned. For instance, many system properties support robustness through functional redundancy or through response diversity with responses regulated by competitive exclusion and cooperative facilitation. Moreover, few studies compare and contrast alternative strategies for achieving robustness such as homeostasis, adaptive plasticity, environment shaping, and environment tracking. These strategies share similarities in their utilization of adaptive and self-organization processes that are not well appreciated yet might be suggestive of reusable building blocks for generating robust behavior. © 2012 Whitacre.