Thelytokie

Thelytokie is a form of parthenogenesis, a natural reproductive method where development of an embryo proceeds without fertilization by a male. In thelytokie, the offspring produced are exclusively female. This contrasts with other forms of parthenogenesis, such as arrhenotoky, where only males are produced, or deuterotoky, where both males and females can be produced parthenogenetically.

This reproductive strategy is found in a variety of organisms, particularly invertebrates like some species of aphids, rotifers, and stick insects. It is also observed in some vertebrates, including certain species of lizards, fish, and even a few species of snakes and birds. Thelytokie can occur through different genetic mechanisms, such as automixis, where a diploid organism produces haploid gametes that then fuse to restore diploidy, or apomixis, where a diploid cell undergoes mitosis to produce a diploid embryo without meiosis.

The prevalence and ecological significance of thelytokie vary greatly among species. In some cases, it allows for rapid population growth, especially in environments where finding mates is difficult or when populations are founded by a single female. However, obligate thelytoky can also lead to reduced genetic diversity, potentially making populations more vulnerable to environmental changes and diseases. Facultative thelytoky, where females can switch between sexual and parthenogenetic reproduction, offers a balance between rapid reproduction and genetic recombination.