Assessing the evolutionary lability of insulin signaling in the regulation of nutritional plasticity across traits and species of horned dung beetles

Nutrition-dependent growth of sexual traits is a major contributor to phenotypic diversity and a large body of research documents insulin signaling as a major regulator of nutritional plasticity. However, findings across studies raise the possibility that the role of individual components within the insulin signaling pathway diverge in function among traits and taxa. Here, we use RNAi-mediated transcript depletion in the gazelle dung beetle to investigate the functions of forkhead box O (Foxo) and two paralogs of the insulin receptor (InR1 and InR2) in shaping nutritional plasticity in polyphenic male head horns, exaggerated fore legs, and weakly nutrition-responsive genitalia. Our functional genetic manipulations led to three main findings: FoxoRNAi reduced the length of exaggerated head horns in large males, while neither InR1 nor InR2 knock-downs resulted in measurable horn phenotypes. These results are similar to those documented previously for another horned dung beetle species (On..., We use RNAinterference-mediated transcript depletion in the gazelle dung beetle to investigate the functions of forkhead box O (Foxo) and two paralogs of the insulin receptor (InR1 and InR2) in shaping nutritional plasticity in polyphenic male head horns, exaggerated fore legs, and weakly nutrition-responsive genitalia., ,