Abstract
Because of the complexity of the developmental process, many if not all mutations have a variety of effects (pleiotropy), but only a few of them are likely to be adaptive. For that reason any adaptive evolutionary change is a complex mix of adaptive, fitness increasing effects, deleterious side effects and compensatory changes ameliorating these deleterious side effects. This is the likely reason why evolution at the genomic and developmental level is exceedingly complex. I will present a model of evolutionary change that incorporates selection, pleiotropy and compensation by background mutations (SPC), and suggest that this mechanism may underlie the evolution of development, as well as explain phenomena such as developmental system drift. I will show how such modification of pleiotropy by background mutations can be applied to understand instances of autonomization between parts, such as asymmetry, polymorphism and differentiation of serially homologous parts (repeated elements within organisms). The latter will be demonstrated by preliminary work on differentiation between fore and hind limbs.
Mihaela Pavlicev
Department of Theoretical Biology
Faculty of Life Sciences
Vienna University