Explored aspects of population dynamics indicate an advantage of ESD over GSD. Starting even from low sizes, populations soon attain equilibrium densities.
Population dynamics of Bonellia appear rather simple and not too sensitive to parameter changes around their measured values, or to changes in distribution and sizes of inhabitable patches. By means of a spatially explicit, individual-based model we examine how this specific form of environmental sex determination (ESD) affects dynamics of Bonellia populations and investigate the selective advantage of ESD over the more widespread genotypic sex determination (GSD). In the echiuran worm Bonellia viridis Rolando, the vast majority of sexually undifferentiated larvae metamorphose into dwarf males that live inside the female when exposed to females, but differentiate into females when developing in the absence of females.
