An argument is made that only through a detailed comparison of mutational mechanisms underlying the evolution of the genetic systems governing development, can the 'logic' of individual development be fully comprehended. To do this, it is essential to choose two or more genes (or their products) that interact in the establishment of a given function, and to compare the molecular basis of that interaction in closely related species. The rationale to this approach arises from observations of molecular co‐evolution between interacting (...) partners involved with given functions which have led to species specificity in the manner in which such functions are effected. Molecular coevolution reveals that divergence in sequence can be tolerated whilst biological functions are maintained, not because it is neutral and dispensable but because successful, compensatory changes can evolve in eukaryotic genomes that are in continuous states of flux. (shrink)

Evolutionary genetics is concerned with natural selection and neutral drift, to the virtual exclusion of almost everything else. In its current focus on DNA variation, it reduces phenotypes to symbols. Varying phenotypes, however, are the units of evolution, and, if we want a comprehensive theory of evolution, we need to consider both the internal and external evolutionary forces that shape the development of phenotypes. Genetic systems are redundant, modular and subject to a variety of genomic mechanisms of “turnover” (transposition, gene (...) conversion, unequal crossingover, slippage and so on). As such the construction and spread of novel combinations of modules by turnover, in particular within gene promoters, contributes significantly to the evolution of phenotypes. Furthermore, redundancy, turnover and modularity lead to ever more complex networks of genetic interactions and ever more functions for a given module. The significant interaction between genomic turnover and natural selection leads to a molecular coevolution between interacting modules and hence facilitates the establishment of biological novelties. BioEssays 22:1153–1159, 2000. © 2000 John Wiley & Sons, Inc. (shrink)