Between “design” and “bricolage”: Genetic networks, levels of selection, and adaptive evolution

Abstract

The extent to which ''developmental constraints'' in complex organisms restrict evolutionary directions remains contentious. Yet, other forms of internal constraint, which have received less attention, may also exist. It will be argued here that a set of partial constraints below the level of phenotypes, those involving genes and molecules, influences and channels the set of possible evolutionary trajectories. At the top-most organizational level there are the genetic network modules, whose operations directly underlie complex morphological traits. The properties of these network modules, however, have themselves been set by the evolutionary history of the component genes and their interactions. Characterization of the components, structures, and operational dynamics of specific genetic networks should lead to a better understanding not only of the morphological traits they underlie but of the biases that influence the directions of evolutionary change. Furthermore, such knowledge may permit assessment of the relative degrees of probability of short evolutionary trajectories, those on the microevolutionary scale. In effect, a ''network perspective'' may help transform evolutionary biology into a scientific enterprise with greater predictive capability than it has hitherto possessed. developmental evolution ͉ parallel evolution

Systems biology of stem cells: three useful perspectives to help overcome the paradigm of linear pathways

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The Power of an Evolutionary Perspective in Studies of Endocrinology

“…Much of our understanding of the molecular basis of endocrinology has come from highly productive studies that have focused on specific molecules and their immediate interacting partners, in fact, hormonal systems are a central part. Indeed the specificity of each hormone ligand and receptor pair is maintained in divergent species (Moyle et al 1994), while biochemical entities are developmentally and evolutionarily fluid, with a much wider range of capabilities for alteration in both composition and behavior (Avise and Ayala 2007;Wilkins 2007). Thus intriguing questions concerning how the diversity and specificity occur within these systems remain to be answered.…”

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