Why, biologists first asked 60 years ago, do members of the same species have such similar traits, or phenotypes, despite the fact that they have such diverse genes, or genotypes? They couldn't fully explore that question until now - when, aided by computers, they can sift through mountains of experimental data. In the June 24 issue of the Proceedings of the National Academy of Sciences, senior research scientist Aviv Bergman of Stanford's Center for Computational Genetics and Biological Modeling (CCGBM) and postdoctoral scholar Mark Siegal of the Department of Biological Sciences provide a surprisingly simple answer.
Invariant traits - such as having five fingers to a hand instead of four or six - don't become universal because Nature has somehow selected special genotypes that faithfully direct development of the trait under a wide variety of conditions, the researchers argue. Instead, they show, it is the complexity of our genotypes - the many genes that interact in networks during development, inhibiting and activating each other and even regulating themselves - that provides fidelity. Indeed, Bergman and Siegal show that any functional genetic network that is complex enough has this built-in property of fidelity. This is true whether natural selection on the phenotype produced by the network during development is strong, weak or absent. Natural selection may be important in shaping traits that aid in reproduction and survival, but Bergman and Siegal show that it doesn't matter much during development
Contact: Dawn Levy