Heritability and developmental plasticity of growth in an oviparous lizard

Selective processes act on phenotypic variation although the evolutionary potential of a trait relies on the underlying heritable variation. Developmental plasticity is an important source of phenotypic variation, but it can also promote changes in genetic variation, yet we have a limited understanding of how they are both impacted. Here, we quantified the influence of developmental temperature on growth in delicate skinks (Lampropholis delicata) and partitioned total phenotypic variance using an animal model fitted with a genomic relatedness matrix. We measured mass for 261 individuals (n_hot = 125, n_cold = 136) over 16 months (n_observations = 3002) and estimated heritability and maternal effects over time. Our results show that lizards reared in cold developmental temperatures had consistently higher mass across development compared to lizards that were reared in hot developmental temperatures. However, developmental temperature did not impact the rate of growth. On average, additive genetic variance, maternal effects and heritability were higher in the hot developmental temperature treatment; however, these differences were not statistically significant. Heritability increased with age, whereas maternal effects decreased upon hatching but increased again at a later age, which could be driven by social competition or intrinsic changes in the expression of variation as an individual's growth. Our work suggests that the evolutionary potential of growth is complex, age-dependent and not overtly affected by extremes in natural nest temperatures.