Figure 1.

Diagram representing the integration of sexual systems and mechanisms of sex determination in a common framework. The different states are represented as discrete although in fact there is a continuum gradient of possible, intermediate, states. The idea of the evolutionary transitions along a gradient of phenotypic plasticity was postulated by [2,4]. Epigenetic mechanisms underlie and made possible this phenotypic plasticity. Notice that environmental sex determination is mentioned both sensu stricto (*) and sensu lato (**). See §1b. Figure is redrawn and updated from Piferrer [15].