Phenotypic and fitness consequences of maternal nest‐site choice across multiple early life stages

Abstract

Identifying the relative contributions of genetic, maternal, and environmental factors to phenotypic variation is critical for evaluating the evolutionary potential of fitness-related traits. We employed a novel two-step cross-fostering experiment to quantify the relative contributions of clutch (i.e., maternal identity) and maternally chosen nest sites to phenotypic variation during three early life stages (incubation, hibernation, dispersal) of the painted turtle (Chrysemys picta). By translocating eggs between nests in the field, we demonstrated that both clutch and nest site contribute to phenotypic variation at hatching. Because hatchling C. pictahibernate inside nests, we performed a second cross-foster to decouple the effects of the incubation nest with that of the hibernation nest. Incubation nest explained little variation in phenotypes at spring emergence, but winter nest site was important. We found no evidence that mothers select nest sites specific to reaction norms of their own offspring, suggesting that females may select nest sites with microhabitats that broadly meet similar requirements across the population. After hibernation, we released hatchlings to assess performance and phenotypic selection during dispersal. Hibernation nest site influenced physiological performance during dispersal, and we detected nonlinear selection on hatchling carapace length. Our experiment demonstrates that nest-site choice has substantial effects on phenotypic variation and fitness across multiple early life stages. Abstract. Identifying the relative contributions of genetic, maternal, and environmental factors to phenotypic variation is critical for evaluating the evolutionary potential of fitnessrelated traits. We employed a novel two-step cross-fostering experiment to quantify the relative contributions of clutch (i.e., maternal identity) and maternally chosen nest sites to phenotypic variation during three early life stages (incubation, hibernation, dispersal) of the painted turtle (Chrysemys picta). By translocating eggs between nests in the field, we demonstrated that both clutch and nest site contribute to phenotypic variation at hatching. Because hatchling C. picta hibernate inside nests, we performed a second cross-foster to decouple the effects of the incubation nest with that of the hibernation nest. Incubation nest explained little variation in phenotypes at spring emergence, but winter nest site was important. We found no evidence that mothers select nest sites specific to reaction norms of their own offspring, suggesting that females may select nest sites with microhabitats that broadly meet similar requirements across the population. After hibernation, we released hatchlings to assess performance and phenotypic selection during dispersal. Hibernation nest site influenced physiological performance during dispersal, and we detected nonlinear selection on hatchling carapace length. Our experiment demonstrates that nest-site choice has substantial effects on phenotypic variation and fitness acro...

Female lizards choose warm, moist nests that improve embryonic survivorship and offspring fitness

“…Optimizing offspring phenotypes is another important reason for choosing a particular nest site. Our results are consistent with the hypothesis that maternally chosen oviposition sites enhance offspring fitness in this way (Mitchell, Warner, et al., ; Reedy, Zaragoza, & Warner, ; Refsnider & Janzen, ). Toad‐headed agama chose nests with thermal and hydric environments that accelerated offspring development, growth and maturity.…”

Incubation temperature induced phenotypic plasticity in oviparous reptiles: Where to next?

“…However, it is possible to get around this difficulty by setting up nests in the field with mixed clutch designs, labeling eggs and noting their positions within the nest and then allowing them to incubate naturally for most of the incubation period. These nests can then be carefully excavated just before they are predicted to hatch and the eggs incubated for the last 1 or 2 weeks in isolated containers in constant conditions in the laboratory, and the hatchling phenotypes evaluated once they have hatched (e.g., Li et al., ; Mitchell, Warner, & Janzen, ; Shine et al., ). If conducted in conjunction with miniature temperature data loggers in various regions of the nest, such experimental designs allow questions about the importance of nest location, egg position within the nest, and the possible effects of thermal variation within the nest to be evaluated.…”

Maternal body condition influences magnitude of anti-predator response in offspring

“…In species that do not show post-ovipositional parental care, maternal effects are largely limited to egg provisioning [14], including egg size, composition [15,16] and nest location [17]. Maternal influence on size can alter offspring fitness: larger eggs hatch into larger offspring who show advantages in growth and survival [15,18].…”