Fig. 1

Hypothesis for the developmental origin of mosaic phenotypes. Each larva may develop into a queen or a worker depending on determining factors experienced during its ontogeny. In ants, determining factors are mainly environmental, although genetic influences have also been found in some species. If different modules respond differently to determining factors, intermediate levels of these factors induce the production of mosaic individuals with queen-like morphology for some modules and worker-like morphology for others. For instance, the intercaste depicted here (vertical line for intermediate value of determining factors) has a queen-like module 1 but a worker-like module 2