'Evo-Devo' and the Conundrum of Sympatric Speciation.

GENOTYPE-environment interaction; POPULATION genetics -- Mathematical models; EVOLUTIONARY theories; GENETIC regulation; GENETIC polymorphisms; MOLECULAR genetics; GENE expression; GENETIC transcription regulation

Evolution is a spatiotemporal dynamical process, albeit an extremely complex one--too complex to yield to the type of mathematical arguments that over the past 100 years have revolutionized our understanding of the physical universe. Facets of evolution are revealed by mathematical models as researched by Barton Turelli et al. Researchers are at the very beginning of elucidating how genotypes are translated into phenotypes through genetic expression, intracellular biochemical pathways, cellular signaling, organismal growth, and physiology--all of which may be influenced by environmental factors. Rudimentary models linking phenotypes to genes in the context of postzygotic mechanisms of speciation are now being explored. Gene effects in such systems are not additive, as they are in most models used in population genetics, but are nonlinear. In a paper published recently in 'Evolution,' they applied such a model to the question of speciation when selection favors identical new phenotypes in two populations that are only partially isolated with regard to gene flow. The unbranched-chain gene regulation model is a plausible scheme for providing the postzygotic speciation mechanism that is simply decreed in the D-M framework.