Sex and Recombination in Snails

Snails (Mollusca: Gastropoda) are a diverse class of mollusks inhabiting marine, terrestrial, and freshwater ecosystems. Although the most common reproductive system is gonochorism, an astounding diversity of other systems have repeatedly evolved, including apomictic parthenogenesis, protandrous hermaphroditism, and simultaneous hermaphroditism. Some snails have evolved specific mechanisms of sex determination (e.g., sex chromosomes), while others show that environmental contaminants can induce changes in reproductive anatomy (e.g., imposex). Despite the diversity of reproductive systems and strategies that has been observed, and the fact that Gastropods serve as model systems for addressing a wide range of questions, a great deal remains to be discovered.