Extent of life history trait modification by hatchling lizards with different reproductive modes in response to climate change

Climate change is a major threat to reptiles because they depend almost entirely on nest (oviparous) or maternal temperatures (viviparous) to develop. However, the extent to which species with different reproductive modes can respond to climate change by modifying life history traits is unknown. We will test two core questions: (1) Will predicted mid-century temperatures under scenarios of climate change have a negative effect on life history traits of hatchling lizards? (2) To what extent does reproductive mode (oviparous vs. viviparous) buffer against changing temperatures that affect offspring phenotype? We will take advantage of a model lizard (Saiphos equalis) which differs in its reproductive mode across its range, with one oviparous and one viviparous population, allowing us to directly test hypotheses around our core questions. We will subject gravid females of each population to current and predicted mid-century thermal regimes to evaluate morphological, behavioural and cognitive differences in their offspring. Thermal regimes will be defined using field and preferred body temperatures, along with environmental temperatures and climatic model projections. We will measure body size and weight, and exploration, boldness, anti-predator and foraging behaviours in all offspring. Each offspring will then be tested in a spatial learning task. S. equalis prefers cool temperatures, thus we hypothesise that higher temperatures predicted under scenarios of climate change will have negative impacts on body size, behaviour and cognitive abilities of offspring from both populations. However, we expect viviparous populations to be more vulnerable to the effects of climate change because rapid changes in the mothers’ thermal environment can cause dramatic reductions in their activity time, thus preventing them from meeting the higher energetic demands of pregnancy. This project will provide valuable knowledge on the physiological restrictions and behavioural responses that lizards with different modes of reproduction will experience due to climate change.