The crested gecko, Correlophus ciliatus, is a popular species in the pet trade, known for its gentle nature and distinctive eyelash-like crests. Like many reptiles, female crested geckos can lay eggs even without a male partner, which are typically infertile and never develop. However, the fascinating question for owners and biologists is whether these lizards possess a backup method of reproduction, bypassing the need for a male completely.
Parthenogenesis in Crested Geckos
Yes, crested geckos can reproduce asexually, a process known as parthenogenesis. This term translates to “virgin birth,” describing the development of an embryo from an unfertilized egg cell. This form of reproduction is considered facultative in crested geckos, meaning it is not their primary method but an option they can activate in the absence of a male. Parthenogenesis has been documented in female crested geckos that have been isolated from males for years, confirming that sperm is not required to initiate development. While females regularly lay infertile eggs, the spontaneous development of a viable embryo is an infrequent event in this species.
Researchers and keepers have observed this unique event in isolated females, sometimes multiple times over several years. The capacity for a female to essentially self-replicate is a powerful survival mechanism in the wild, though its success rate in Correlophus ciliatus is low.
The Biological Mechanism of Asexual Reproduction
The method crested geckos employ to achieve asexual reproduction is a cellular process called automixis. During normal egg production (meiosis), a single cell divides into four haploid cells, one becoming the egg and the others, known as polar bodies, typically dissolving. In automixis, the egg cell finds a way to restore the full, diploid set of chromosomes without fusing with a sperm cell. This is often achieved through the fusion of the egg nucleus with one of the polar bodies, which contains a complementary set of genetic material.
Because the polar body and the egg originate from the same initial female germ cell, the resulting offspring is a near-clone of the mother. The precise timing and stage of meiosis at which this re-diploidization occurs determine the exact genetic makeup of the offspring.
Offspring Viability and Genetic Outcomes
The parthenogenetic offspring produced by crested geckos are typically clones or near-clones of their mother, inheriting almost all of her genetic traits. This reduced genetic diversity, compared to sexually reproduced offspring, is often associated with lower viability. Many eggs that begin development through parthenogenesis fail to hatch, or the hatchlings exhibit developmental issues, such as visible defects, and struggle to survive long-term.
In reptiles that reproduce through automixis, the resulting offspring are overwhelmingly female. The gender of geckos is not determined by temperature during incubation, but rather by sex chromosomes. In most cases of facultative parthenogenesis, the mechanism of diploid restoration produces female offspring, which can then perpetuate the lineage. While some parthenogenetic hatchlings have survived and grown to adulthood, they may be smaller or less robust than their sexually produced counterparts, highlighting the imperfect nature of this back-up reproductive strategy in this species.