Gilchrist M A, Nijhout H F
Department of Biology, Duke University, Durham, North Carolina 27708, USA.
Genetics. 2001 Sep;159(1):423-32. doi: 10.1093/genetics/159.1.423.
Phenotypes are the products of developmental processes whose dynamics are controlled by genes. In many developmental processes there is a nonlinear relationship between genetic variation and phenotypic variation. These nonlinear relationships can result in the emergence of dominance among alleles that control the developmental process. We explore the properties of dominance relationships in a simple developmental system consisting of a diffusion-gradient-threshold mechanism commonly deployed in pattern formation. We show that a single nonlinear process (diffusion) within this integrated mechanism leads to the emergence of dominance in all components of the mechanism. Unlike the situation in metabolic pathways, where new mutations are most likely to be recessive, the structure of the nonlinearities in this developmental mechanism is such that in certain circumstances new mutations are equally likely to be dominant or recessive. Although the dominance we observe in this system is the result of a physiological process, we also find that dominance can evolve by microevolutionary mechanisms and thus are able to reconcile the opposing views of Fisher and Wright on dominance.
表型是发育过程的产物，其动态受基因控制。在许多发育过程中，遗传变异与表型变异之间存在非线性关系。这些非线性关系可能导致控制发育过程的等位基因之间出现显性现象。我们在一个简单的发育系统中探索显性关系的特性，该系统由模式形成中常用的扩散 - 梯度 - 阈值机制组成。我们表明，这种整合机制内的单个非线性过程（扩散）导致该机制所有组成部分中显性现象的出现。与代谢途径中情况不同，在代谢途径中，新突变最有可能是隐性的，而这种发育机制中的非线性结构使得在某些情况下，新突变同样有可能是显性或隐性的。虽然我们在这个系统中观察到的显性是生理过程的结果，但我们也发现显性可以通过微进化机制演变，因此能够调和费希尔和赖特关于显性的对立观点。
