The green–brown polymorphism of grasshoppers and bush-crickets represents one of the most penetrant polymorphisms in any group of organisms. This poses the question of why the polymorphism is shared across species and how it is maintained. There is mixed evidence for whether and in which species it is environmentally or genetically determined in Orthoptera. We report breeding experiments with the steppe grasshopper Chorthippus dorsatus, a polymorphic species for the presence and distribution of green body parts. Morph ratios did not differ between sexes, and we find no evidence that the rearing environment (crowding and habitat complexity) affected the polymorphism. However, we find strong evidence for genetic determination for the presence/absence of green and its distribution. Results are most parsimoniously explained by three autosomal loci with two alleles each and simple dominance effects: one locus influencing the ability to show green color, with a dominant allele for green; a locus with a recessive allele suppressing green on the dorsal side; and a locus with a recessive allele suppressing green on the lateral side. Our results contribute to the emerging contrast between the simple genetic inheritance of green–brown polymorphisms in the subfamily Gomphocerinae and environmental determination in other subfamilies of grasshoppers. In three out of four species of Gomphocerinae studied so far, the results suggest one or a few loci with a dominance of alleles allowing the occurrence of green. This supports the idea that brown individuals differ from green individuals by homozygosity for loss-of-function alleles preventing green pigment production or deposition.

蚱蜢和灌木蟋蟀的绿-棕色多态性代表了任何生物群中最具渗透性的多态性之一。这就提出了为什么跨物种共享多态性以及如何维持多态性的问题。关于直翅目中它是否以及在哪些物种中由环境或遗传决定的证据不一。我们报告了草原蝗虫Chorthippus dorsatus的育种实验，一种存在和分布绿色身体部位的多态物种。变形比率在性别之间没有差异，我们没有发现饲养环境（拥挤和栖息地复杂性）影响多态性的证据。然而，我们发现了关于绿色存在/不存在及其分布的遗传决定的有力证据。结果最简单地用三个常染色体位点解释，每个位点有两个等位基因和简单的显性效应：一个位点影响显示绿色的能力，具有绿色的显性等位基因；具有抑制背面绿色的隐性等位基因的基因座；和一个带有隐性等位基因的基因座，在侧面抑制绿色。我们的研究结果有助于在 Gomphocerinae 亚科中绿-棕色多态性的简单遗传遗传与其他蝗虫亚科中的环境决定之间出现对比。在迄今为止研究的四分之三的 Gomphocerinae 物种中，结果表明一个或几个具有等位基因优势的基因座允许出现绿色。这支持了这样的观点，即棕色个体与绿色个体的区别在于功能丧失等位基因的纯合性阻止了绿色色素的产生或沉积。