Context-dependent trait exaggeration is a major contributor to phenotypic diversity. However, the genetic modifiers instructing development across multiple contexts remain largely unknown. We use the arthropod tibia, a hotspot for segmental differentiation, as a paradigm to assess the developmental mechanisms underlying the context-dependent structural exaggeration of size and shape through nutritional plasticity, sexual dimorphism and segmental differentiation. Using an RNAseq approach in the sexually dimorphic and male-polyphenic dung beetle
Digitonthophagus gazella
, we find that only a small portion (3.7%) of all transcripts covary positively in expression level with trait size across contexts. However, RNAi-mediated knockdown of the conserved sex-determination gene
doublesex
suggests that it functions as a context-dependent master mediator of trait exaggeration in
D. gazella
as well as the closely related dung beetle
Onthophagus taurus
. Taken together, our findings suggest (i) that the gene networks associated with trait exaggeration are highly dependent on the precise developmental context, (ii) that
doublesex
differentially shapes morphological exaggeration depending on developmental contexts and (iii) that this context-specificity of
dsx
-mediated trait exaggeration may diversify rapidly. This mechanism may contribute to the resolution of conflict arising from environment-dependent antagonistic selection among sexes and divergent developmental contexts in a wide range of animals.
Evolution and plasticity of morph‐specific integration in the bull‐headed dung beetle
Onthophagus taurus
