Effects of incubation temperatures on learning abilities of hatchling velvet geckos

Stressful environments in utero can have a profound influence on cognitive functions and learning ability. In lizards, thermal environments experienced by embryos can shape a range of traits, including sex, body size, and locomotor performance, which may influence fitness. Recent studies suggest that incubation temperatures may also influence brain development and learning ability of some lizard species. Therefore, predicted increases in nest temperatures of lizards may not only affect hatchling morphology and performance, but could also affect their learning ability. To investigate how incubation temperatures influence cognitive abilities of hatchlings, we incubated eggs of the velvet gecko, Amalosia lesueurii, under two fluctuating temperature regimes. The warm treatment mimicked the thermal profiles of currently used partly shaded communal nests (mean = 24.3 °C, range 18.4-31.1 °C), and the hot treatment simulated thermal profiles that could be experienced in sun-exposed nests in 2050 (mean = 28.9 °C, range 19.1-38.1 °C). At age three to four weeks, we measured the ability of hatchlings to locate an open shelter in a Y-maze choice test. Both hot and warm-incubated hatchlings successfully learned the task, but hatchlings from the warm-temperature treatment learned the task faster, and made fewer mistakes in the first five trials than hot-incubated hatchlings. These patterns were consistent for hatchlings from two geographic locations, suggesting that thermally stressful conditions in utero may alter the learning abilities of hatchling lizards. Because learning ability can affect the survival of hatchling velvet geckos, future increase in nest temperatures may have wide reaching impacts on populations.