Gynogenetic reproduction in hybrid mole salamanders (genus Ambystoma)

Abstract

Ambystoma platineum, a unisexual clonal triploid taxon of mole salamander, originated by hybridization between the Mendelian species A. jeffersonianum and A. laterale. A. platineum reproduces gynogenetically, that is, sperm from a sexual host species is required to activate egg development but makes no genetic contribution to the developing embryo. Nevertheless, eletrophoretic diversity in populations of some hybrid Ambystoma suggested continual in situ recreation of unisexual hybrids and bidirectional gene exchange between the parental species and the hybrids. A platineum usually lives with, and is sexually dependent on, one of its parental species, A. jeffersonianum. In C Indiana, however, A. platineum populations have shifted their host dependency to A. texanum. Because genome replacement in A. texanum-dependent populations of A. platineum is irreversible, the persistence of A. platineum in A. texanum-dependent populations demonstrates that the major mode of reproduction in A. platineum populations is clonal: A platineum produces mainly triploid eggs that develop gynogenetically. -from Authors