Parthenogenesis in Animals

Abstract

Parthenogenesis is a very common phenomenon in the animal kingdom, forms with parthenogenetic reproduction being found in most animal groups. This chapter discusses the modes of reproduction in animals, the occurrence of parthenogenesis in animals, and the systems of parthenogenesis. Parthenogenesis can be considered from the following points of view: mode of reproduction, sex determination, and cytology. The chromosonal conditions in parthenogenetic animal include generative or haploid parthenogenesis, automictic parthenogenesis, and apomictic parthenogenesis. In many parthenogenetic animals, in all those with obligatory parthenogenesis, reproduction is exclusively parthenogenetic. In such forms, males are usually completely unknown. In other parthenogenetic animals, both parthenogenetic and sygogenetic reproduction are present. Such is the case in cyclical parthenogenesis, in which parthenogenetic generations alternate with a bisexual generation. Other species again occur as two races; bisexual and parthenogenetic.