Same Genes, Different Wings: Wing Shape Divergence Among Castes in a Social Wasp

Wings play a central role in shaping dispersal, behavior, and ecological specialization of insects. In social insects, distinct castes with specialized morphologies arise from a shared genome, raising the question of how divergence of traits, such as wings, occurs despite genetic constraints. We investigated genetic constraints and sources of variation in wing shape in the Eastern yellowjacket wasp (Vespula maculifrons), combining geometric morphometrics and quantitative genetic analyses across queens, workers, and males. Landmark-based Procrustes analyses revealed strong divergence in mean wing shape among castes. Males showed greater wing-shape variation than queens and workers, consistent with weaker stabilizing selection. Allometric analyses revealed that individual-level size-shape relationships are weak across all castes, with no caste showing consistent significant allometry across colonies, indicating that size-related developmental programs do not strongly couple wing shape to body size. Wing shape also varied significantly among colonies, revealing a substantial colony-level component of wing-shape variation that may reflect shared environmental, genetic, and socially mediated developmental influences. Additionally, we found that queens and workers from different patrilineal subfamilies differed in wing shape, demonstrating substantial heritable contributions. Our analyses also revealed limited genetic correlations between worker and queen wing shape components, suggesting that shared genetic architecture would not strongly constrain independent caste evolution of wing morphology. Together, these results show that variation in wing shape in V. maculifrons is shaped by a balance of genetic diversity generated by polyandry, colony-level environmental variation, including environmental and genetic influences, and caste-specific selective pressures associated with division of labor. Thus, caste-specialized wing morphology can evolve in insect societies despite a shared genome and genetic constraints.