Red‐eared slider hatchlings (Trachemys scripta) show a seasonal shift in behavioral types

Abstract

Correlated and repeatable patterns of behavior, termed behavioral types, can affect individual fitness. The most advantageous behavioral type may differ across predictable environments (e.g., seasonally), and maternally mediated effects may match hatchling behavior to the environment. We measured righting response, an indicator of behavioral type, of juvenile red-eared slider turtles (Trachemys scripta) emerging from early and late season clutches to understand if the production of behavioral types differs across the nesting season. There was a significant effect of season, with early season hatchlings righting more quickly than late season hatchlings, and we explored two potential underlying mechanisms, maternal estrogens and maternal investment (e.g., yolk allocation).We dosed early season eggs with an estrogen mixture to mimic late season eggs and assayed hatchling righting response, but found no significant effect of this maternal effect.We assessed maternal investment by measuring egg, hatchling, and residual yolk masses.We found a seasonal pattern in yolk allocation, where early season eggs have more yolk than late season eggs. Early season hatchlings used more yolk for growth rather than maintenance of existing tissues, resulting in larger hatchlings. Interestingly, across both seasons, hatchlings that received less maternal yolk appeared to be more efficient at converting yolk to tissue, but we found no direct correlation with righting behavior. We demonstrate that the prevalence of behavioral types varies across the nesting season, creating correlated suites of seasonal phenotypes in turtle hatchlings, but it appears that neither maternal estrogens or investment in yolk directly underlie this shift in behavior. K E Y W O R D Sbehavioral types, estrogen, maternal effects, season, Trachemys scripta, yolk

Differential early‐life survival underlies the adaptive significance of temperature‐dependent sex determination in a long‐lived reptile

“…Further, such associations have been shown to be context dependent, with size conferring survival advantages in some years and not others (Ferguson & Fox, 1984; Olsson & Madsen, 2001; Sinervo et al, 1992). Incubation temperature is commonly reported to affect other hatchling traits (Noble et al, 2018) including hatchling behaviour (Miller et al, 2020; Nichols et al, 2019), immune function (Leivesley & Rollinson, 2021; Treidel et al, 2016), and growth trajectories (Deeming & Ferguson, 1989; Marcó et al, 2010; Piña et al, 2007; Rhen & Lang, 1995), across diverse reptile species. It is intriguing to consider that the energetic cost of development may serve as a common underlying mechanism contributing to multiple fitness‐related thermosensitive traits including offspring size and metrics of performance via its influence on the differential allocation of maternally derived resources to development versus the post‐hatching period.…”

Differential early-life survival underlies the adaptive significance of temperature-dependent sex determination in a long-lived reptile

“…The effects of offspring size on survival are known to be context dependent in other reptiles, with size conferring survival advantages in some years and not others (Ferguson & Fox, 1984;Olsson & Madsen, 2001;Sinervo et al, 1992). In addition, incubation temperature is commonly reported to affect other hatchling traits (Noble et al, 2018) including hatchling behavior (Miller et al, 2020;Nichols et al, 2019), immune function (Leivesley & Rollinson, 2021;Treidel et al, 2016), and growth trajectories (Deeming & Ferguson, 1989;Marcó et al, 2010;Piña et al, 2007;Rhen & Lang, 1995), across diverse reptile species. It is intriguing to consider that the energetic cost of development may serve as a common underlying mechanism contributing to multiple fitness-related thermosensitive traits, but future studies directly linking developmental energetics to physiological traits and subsequent hatchling survival are required to test this hypothesis.…”