Asexual reproduction in Lepidodactylus lugubris

Alistair Gamblin

Mourning Geckos are one of a select few reptile species which is known reproduce asexually, through a form known as ‘Parthenogenesis’. Unlike certain plant species- such as Chlorophytum comosum- Mourning Geckos are only able to reproduce asexually due to an amazing feature of the lizards: there are almost no males! Although incredibly rare, some males have been discovered yet these few are almost always sterile and therefore unable to produce offspring. This fact also contributed to their name, as, due to the absence of males in the population, those responsible for their discovery decided that the females were ‘mourning’ the losses of the males.

Their method of reproduction has enabled this species to have a surprisingly large distribution, with populations found in South America, the Galapagos Islands and much of the South Pacific, including Australia. This is also explained through the saltwater- tolerant eggs they produce. Furthermore, as mates do not need to be found, Mourning Geckos can produce large quantities of offspring, with mature individuals laying 1 or 2 eggs every 4 to 6 weeks (with an incubation period of around 2 to 6 months). As with any asexual species, be they plants, fungi or animals, this method of reproduction reduces or eradicates genetic diversity within a population, potentially leaving the survival of the entire species vulnerable to a change in their environment- such as temperature or disease- or to a mutation, which can spread quickly through generations.

In greater detail, parthenogenesis (in this case in animals) is a form of asexual reproduction allowing viable offspring to be produced from a single parent’s egg cell, which does not need to be fertilised by the male gamete, sperm. The term simply means ‘Virgin creation/birth’ due to the absence of intercourse in this method of reproduction. As normal gametes are formed through meiosis, they contain only the haploid number of chromosomes, which usually results in non-viable offspring. For this reason, parthenogenic species must produce young with the diploid number (or full set) of chromosomes, which different species do in different ways. In our Mourning Gecko example, this is achieved through automixis, the fusion of gametes or nuclei from the same individual. The haploid number for Lepidodactylus lugubris is 22 (n), and the diploid number twice that (2n) at 44.

Another surprising addition to the list of parthenogenic reptiles is the Komodo dragon, native to Indonesia, which can reproduce through both this method of asexual reproduction, and sexually. This ability is called facultative parthenogenesis.