The developmental basis of worker caste polymorphism in ants

Diverse worker caste systems can be generated through regulation of three aspects of larval growth: critical size, growth parameters, and reprogramming of these factors. Even the most complex caste systems could have evolved simply by the addition of revised programs to the end of an ancestral developmental pathway for workers. Worker castes in ants provide a system in which to study the evolution of reaction norms and developmental switches. In ants, the simplest developmental switch, revision of critical size alone, does not lead to discontinuous phenotypes. Only when changes in growth rules are tied to the decision to revise critical size are distinct phenotypes produced from the alternative developmental programs. -from Author