APOMICTIC PARTHENOGENESIS IN A HERMAPHRODITIC TERRESTRIAL SLUG,DEROCERAS LAEVE(MÜLLER)

Abstract

Electrophoretic studies and breeding experiments show that the terrestrial pulmonate slug, D. laeve, usually reproduces by apomictic parthenogenesis, although reciprocal outcrossing in complete hermaphrodites occurs occasionally. The sexual status of the species is controlled by the environment, with low temperatures and/or exposure to light inhibiting the development of male organs. Both hermaphrodites and females reproduce parthenogenetically. Sampling of an artificially established field population suggests that apomixis is also the rule in nature, and surveys of natural populations reveal that most populations consist of a single clone, based on genetic identity at 20 enzyme loci. In spite of apomictic reproduction there is little heterozygosity in nature, although there is some allelic variation between populations.