house geckos, with individuals which are larger than typically displaying differentiated gonads. Differentiated gonads are most clearly seen with a swelling at the entrance to the cloaca caused by the copulatory organs in males. Females lay a maximum of two hard-shelled eggs at any single time, with each descending from a single oviduct. Up to four eggs can exist within the ovaries in differing stages of development. This shortens the potential turn around between egg-laying events in gravid females. Females produce a single egg per ovary per cycle. This means they are considered monoautochronic ovulatory. Within the testes, mature sperm are found in the male geckos year-round and are able to be stored within the oviduct of the female. Sperm can be stored for a period of time as long as 36 weeks. This provides a significantly increased chance of colonisation of new habitats, requiring smaller populations to be transplanted for a chance of success. However, longer storage time of sperm within the female is associated with negative survival outcomes and hatching, possibly due to sperm age. Sperm is specifically stored between the uterine and infundibular components of the oviduct. The capacity to store sperm enables a degree of asynchrony between ovulation, copulation and laying of eggs. The capacity to store sperm is useful in island colonisation events, providing females which may be isolated the capacity to reproduce even if they have been separated from a male for some time. In laboratories, one mating event may produce as many as seven viable egg clutches. This eliminates the need for parthenogenesis and allows the young to include both male and female offspring, with one mating event leading to multiple clutches of eggs being laid. This reduced need for asexual reproduction increases the fitness of young through hybrid vigour and increased diversity. As well as this, sexually reproducing geckos are reported to be more robust and have higher survival rates than those which reproduce asexually. There is a positive correlation between size and viability of eggs, with larger geckos having eggs which were more likely to survive. There is also a correlation between warmer year-round temperatures and consistent food supply with reproductive seasonality, with Geckos with constant food and temperatures being less likely to develop fat deposits on their stomach, and more likely to be constantly reproductive. Genetics Two distinct karyotypes of the common house gecko appear to exist, one with 40