The Incubation Environment Shapes the Inflammatory Response and Enables Expression of Maternal Effects on Sea Turtle Hatchling Body Size

Female turtles are believed to select nesting sites that optimize conditions for egg development and allocate resources accordingly. Although relocating clutches to shaded hatcheries enhances hatchling survival, growth, and immune configuration, the impact of these unexpected environments on maternal investment remains uncertain. Herein, the effects of maternal (body size, as well as hematological and biochemical indicators) and environmental (sand temperature and moisture in both unshaded and shaded nests) variables on local inflammation after a challenge (as a proxy of immune function) and offspring size were evaluated using a split-clutch design. The association of maternal parameters with reproductive investment, as well as the relationship of incubation conditions to survival indicators (hatching and emergence success), was also evaluated. Hatchlings from shaded nests showed less intense inflammation and were heavier and longer compared to offspring from unshaded conditions. The incubation conditions influenced inflammation in hatchlings, as well as their body mass, straight carapace width, and survival. Maternal leukocytes differentially interacted with the environment to determine hatchling length. Maternal amylase and creatinine concentrations were related to clutch size and mass, respectively, while shading enhanced survival indicators. The results indicate that the incubation condition is the primary factor influencing hatchling phenotypes, both directly and indirectly by facilitating the expression of maternal effects. These findings suggest that while optimal environmental conditions and maternal quality do not synergize to enhance offspring fitness, environmental conditions can override the effects of maternal investment. This highlights the relevance of the incubation environment to guarantee hatchling phenotypes.