Thelytoky

Thelytoky is a form of parthenogenesis, a type of asexual reproduction where offspring develop from unfertilized eggs. In thelytoky, the unfertilized eggs develop into females, resulting in a population composed entirely of females. This contrasts with arrhenotoky, another form of parthenogenesis where unfertilized eggs develop into males, and deuterotoky, where unfertilized eggs can develop into either males or females.

This reproductive strategy has been observed in a variety of organisms, including insects, crustaceans, and even some reptiles and fish. For example, some species of stick insects, aphids, and rotifers reproduce exclusively through thelytoky. In some cases, thelytoky can occur spontaneously, while in others, it can be induced by environmental factors or specific genetic conditions.

The genetic mechanisms underlying thelytoky are diverse. In some species, it involves the restoration of diploidy from a haploid egg, often through processes like automixis, where the egg fuses with a polar body or another haploid nucleus. In other cases, the egg may remain diploid throughout meiosis, or the gametes may be produced by mitosis rather than meiosis. Thelytoky can offer advantages such as rapid population growth in favorable conditions and the ability to reproduce without a mate, which can be beneficial in isolated or colonizing populations. However, it can also lead to a reduction in genetic diversity, potentially making populations more vulnerable to environmental changes or diseases.