From eggs to adulthood: sustained effects of early developmental temperature and corticosterone exposure on physiology and body size in an Australian lizard

As global temperatures continue to rise due to climate change, developing animals may be increasingly exposed to elevated temperatures. Additionally, elevated temperatures could affect developing animals through indirect effects such as increased exposure to maternal glucocorticoid hormones. Exposure to elevated levels of glucocorticoids during development can have immediate and sustained effects on physiological and behavioural traits. Although many studies have examined how elevated temperatures and glucocorticoid exposure during development independently affect animals, far fewer studies have tested the combined effects of elevated temperatures and glucocorticoids. We tested interactions between incubation temperature and prenatal corticosterone exposure in the delicate skink (Lampropholis delicata). Eggs were dosed with one of three corticosterone treatments (high dose corticosterone, low dose corticosterone, or control) and incubated at either 23°C (cool) or 28°C (warm). We measured the effects of these prenatal treatments on development time, body size and condition, growth, and survival from hatching to adulthood. Additionally, we measured the effects of developmental treatments on adult hormone levels (corticosterone, thyroxine, and testosterone in males) and mitochondrial respiration in liver tissue. We found no evidence for interactive effects of incubation temperature and prenatal corticosterone exposure on phenotype. However, incubation temperature and corticosterone treatment each had independent effects on body size at hatching that were sustained into the juvenile period and adulthood. Additionally, we found that prenatal corticosterone treatment affected adult baseline corticosterone levels. We found no direct effects of developmental treatments on adult mitochondrial respiration. However, regardless of treatment, we found positive associations between baseline corticosterone levels and growth rate, suggesting that developmental treatments can have sustained effects on phenotype through effects on corticosterone secretion.