Heritability and developmental plasticity of growth in an oviparous lizard

Selective processes act on phenotypic variation yet the evolutionary potential of any given trait relies on underlying heritable variation. Developmental plasticity is an important source of phenotypic variation, but it can also promote changes in heritability by modifying environmental sources of variability. Here, we quantified the influence of developmental temperature on an important fitness trait, growth, in delicate skinks (Lampropholis delicata). We partitioned the total phenotypic variance using an animal model fitted with a genomic relatedness matrix. We measured mass growth for 262 individuals (nhot = 126, ncold = 136) over 16 months (nobservations = 3,002); estimating heritability and maternal effects over time from animals experiencing two thermal developmental environments. Our results show that lizards reared in cold developmental temperatures had a higher initial mass 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. Interestingly, heritability increased with age, whereas maternal effects decreased upon hatching but increased again at a later age. Our work suggests that evolutionary potential of growth is complex, age dependent and not overtly affected by extremes in natural nest temperatures.