Eastern three-lined skink

The specific name, duperreyi, was given by British zoologist John Edward Gray, in order to honour French naval officer Louis-Isidore Duperrey. Duperrey was known for his explorations of Australia and the New Guinea archipelago, where he collected various flora and fauna.[4]

The temperature of incubation and the elevation of the clutch can affect the development of offspring before and after hatching, as well as behaviour throughout the skink's life. Females typically choose where to lay eggs based on the expected average temperature of incubation for their eggs. Experiments have shown that incubation temperatures significantly impact embryogenesis and therefore incubation time, as well as body size and behaviours of hatchlings.[16] Snout-vent length is significantly longer for hatchlings incubated at lower elevations.[9] Survival of eggs also increased at hotter incubation temperatures.[9] Prolonged incubation in cold environments delays hatching and reduces hatchling success.[9] Effects of incubation temperature also impact the sexes differently, contributing to the scientific understanding of temperature-dependent sex determination.[12]

Despite the relationship between incubation temperature and offspring phenotype, Shine and Harlow (1997) found that gravid female duperreyi do not select nest sites to match the phenotypic norms of their offspring.[12] A study that varied thermal environments of eggs during incubation found that variable thermal regimes, rather than a continuously “hot” or “cold” incubation environment, increased the rate embryo development in A. duperreyi, as measured by an increase in embryonic heart rate.[19] Additionally, A. duperreyi hatchlings do not appear to acclimate their embryonic heart rates to their thermal incubation environment, possibly due to thermal variation at nest sites.[17] At the same mean temperature of incubation, temperature fluctuations rather than a stable regime allowed more embryonic development to take place per day.[19] Indeed, data on A. duperreyi nesting patterns suggests that females do lay eggs in areas with high temperature variance during the day.[16]

Studies understanding the effects of incubation temperature on hatchling phenotypes have been used to understand the evolution of viviparity, the birth of live young, in reptiles. Studies in A. duperreyi provide further evidence in favour of the “cold climate hypothesis.” Mimicking in-utero environments through the retention of eggs in high-temperature environments improved hatchling success and viability in cold-incubation eggs, along with increased time of egg retention.[9]

In some vertebrate species, sex is determined genetically, while in others, environmental factors such as temperature impact sex development. A. duperreyi is one of two species of lizard in which sex reversal is confirmed.[6] A. duperreyi has an XX/XY sex determination system. Incubation temperatures of below 20 °C causes the reversal of a genotypic female (XX) to a phenotypic male in experimental conditions.[20] Sex reversal of genotypic females into phenotypic males occurs in the wild, though at a low rate.[6] Appropriately, cool Alpine climates have the highest proportion of sex-reversed males, at 28% in one case.[6][20] It is unclear if these males are fertile.[6]

Additionally, it has been found that larger eggs produced female offspring regardless of incubation temperature.[21] Multiple hypotheses seek to explain this phenomenon. Larger female A. duperreyi produce more eggs, so there may be a selective advantage to conferring larger size to female offspring rather than male offspring.[21]  

Simulations of stress-induced A. duperreyi embryos found that under high-stress conditions, growth rate of hatchlings was increased. Though non-significant, these high-stress simulating treatments resulted in a shifted sex ratio in hatchlings, favouring males.[22] Though the cited study used corticosteroids to simulate stress, another study found that steroid hormone levels (testosterone, estradiol, and dihydrotestosterone) in biopsied egg yolks did not differ significantly between eggs destined to become male or destined to become female.[23] The effects of maternal hormones on hatchling development are therefore unclear.

The eastern three-lined skink has been demonstrated to exhibit certain anti-predatory behaviours. Hatchlings have been found to suddenly stop running away from predators and face them while wiggling their tails in a vertical position.[15] It is hypothesised that such behaviour grants the lizard a chance to escape while the predator is occupied, then seizes, the moving tail. A 2011 study confirmed that slower hatchlings were more likely to exhibit tail-waving behaviour.[15] This weakens the pursuit-deterrent explanation of this behaviour, which posits that anti-predator displays are a true reflection of an individual's ability to escape.[24] This finding supports previous research that hypothesised tail-waving as a behaviour that deflects predators towards an expendable body part.[24] Indeed, after waving its tail, hatchling A. duperreyi ran back towards the stimulated threat during these experiments, further strengthening the hypothesis that this behaviour is designed to misdirect the attention of predators.[24] Hatchling A. duperreyi may make the choice to tail-wave when they are sufficiently tired from escaping, as tail-waving behaviour increased significantly as running distance increases. Males are also slightly more likely to exhibit this behaviour than females. Phylogenetic analysis of studies among lizard families Iguanadae, Lacertidae, Scincidae, and Gekkonidae suggests that the deflection function of tail-waving behaviour may be an ancestral trait, whereas the pursuit-deterrent function is derived.[24]  

Incubation temperature has been linked to the degree of basking behaviour in duperreyi hatchlings. Those hatched from eggs incubated at lower temperatures have shown to bask for longer periods of time following hatching.[15]

A. duperreyi hatchlings have been demonstrated to have the ability to learn to navigate mazes and visual discrimination tasks based on colour.[25] Experimental manipulation of mazes demonstrated that hatchlings use visual colour cues, rather than spatial cues, to locate coloured cap-covered food within mazes.[25] Hatchlings incubated in warmer conditions were significantly better at learning to remove caps to access food, suggesting that incubation conditions may affect learning ability.[25] A 2012 study showed that the better learning ability of hot-incubated hatchlings was not related to body size or locomotor speed, strengthening the proposed connection between better learning and hotter incubation environments.[26] Indeed, a 2017 study found differences in forebrain development between cold-incubated and hot-incubated hatchlings. Greater neural density was found in the telencephalons of hot-incubated hatchlings, which is consistent with their apparent increase in learning ability.[27]

Gravid A. duperreyi intentionally select to lay eggs in communal nesting sites. One study found that captive females chose to lay eggs in nesting sites that contain dummy eggs far more often than what a random-choice null hypothesis would suggest. While there is extensive theory about the benefits of communal nesting for reptiles, including easier nest excavation for females and socialization environments for hatchlings, such hypotheses have yet to be tested in A. duperreyi.[18] So far, the determined benefits of communal nesting are found to be increased hatchling size and running speed.[18]

Experiments have shown that A. duperreyi is more likely to flee from large rather than small prey, and are less likely to attack prey larger than their body size. However, in some of these trials, specimens did attack crickets larger than their own bodies. This skink modifies its method of attack according to the size of prey: large crickets were more likely to be seized by their head or legs first, while small crickets were attacked at the abdomen.[8] Attack success depended on the size of prey, with A. duperreyi being more successful when prey size was smaller. Because of this, less mass was gained in trials when A. duperreyi was enclosed with only the opportunity to feed on large prey. When prey size was greater than 30% of body mass, A. duperreyi lost mass over the course of the experiment. The energy and water expenditure of attempted attacks likely outweighs the gain of successfully feeding on larger prey.

A. duperreyi feeds on small invertebrates, namely insects.[28] Diets of similar species suggest that A. duperreyi is a foraging generalist.[29] Diet does not change significantly in either contents or prey size between juveniles and adults.[8]

Little is known about the predators of this species. Snakes and birds are likely common predators. In particular, the white-lipped snake, D. coronoides, occupies much of the range of A. duperreyi. [30]

A. duperreyi females have changed their nesting behaviour potentially in response to increasing ambient temperature over the past decade. A 2009 study found a 1.5 °C average temperature increase within A. duperreyi nests over a decade. While females did dig deeper nests and laid eggs much earlier in the reproductive season, potentially accounting for these temperature increases, these changes in behaviour were insufficient to reduce warming experienced by eggs late in the incubation period. Such changes can have drastic consequences on the phenotypes of offspring, as it has been demonstrated that incubation temperature has consequences on the size, locomotion speed, sex, and learning ability of A. duperreyi hatchlings.[33]