Medina RG, Fairbairn DJ, Bustillos A, Moo-Valle H, Medina S, Quezada-Euán J J G (2016) Variable patterns of intraspecific sexual size dimorphism and allometry in three species of eusocial corbiculate bees. Insectes Sociaux 63: 493-500
Abstract
Sexual size dimorphism (SSD), in which one sex is larger than the other, has remained understudied in social insects, particularly bees. Using weight and linear structural measurements, we quantified the magnitude of SSD and its variation across nests in three species of corbiculate bees, two belonging to the highly eusocial Apini (Apis mellifera) and Meliponini (Melipona beecheii), and one to the primitively eusocial Euglossini (Euglossa viridissima). We asked if similar to most insects, including Hymenoptera, SSD is female-biased in these eusocial species. Contrary to expectations, we found that SSD was moderately male-biased in the two highly eusocial species and slightly male-biased for weight and not significant for linear size in E. viridissima. The possible roles of queen protogyny and reduced brood provisioning by queens in shaping these patterns of SSD are discussed. The allometry of SSD among nests differed among species as well, ranging from hypoallometry in A. mellifera, to isometry in M. beecheii, to hyperallometry in E. viridissima. This variation indicates that the phenotypic response of body size to differing conditions across nests differs both between sexes and among species. The variation detected among the three studied species in both SSD and allometry for SSD precludes any broad generalizations to other corbiculate bees. However, it does suggest that corbiculate bees can provide a new and diverse framework to analyze the effects of social environment on the evolution of animal sexual dimorphism.
