Living at Extremes: Development at the Edges of Viable Temperature under Constant and Fluctuating Conditions

Abstract

In the painted turtle (Chrysemys picta) and the red-eared slider (Trachemys scripta), the temperature that eggs are exposed to during incubation influences many traits of the developing embryo. We tested the effect of fluctuating- versus constant-temperature incubation regimes at the high and low ends of the viable developmental temperature range to assess the effect of incubation environment on offspring development. Eggs were incubated in four treatments: 23 degrees C constant, 23 degrees +/- 3 degrees C, 31 degrees C constant, and 31 degrees +/- 3 degrees C. We assessed incubation duration, hatchling survival, growth, and immune function via a delayed-type hypersensitivity test. We predicted that fluctuations would accelerate developmental time at 23 degrees C and decelerate it at 31 degrees C and that these changes in incubation duration would influence offspring phenotype. We found that fluctuating incubation conditions affected developmental time at both temperatures and that survival, growth, and immune response were increased by temperature fluctuations. These results demonstrate that fluctuating temperatures have a differential impact on offspring phenotype when compared to constant temperatures, and they suggest that hatchling fitness is enhanced under conditions that more closely mimic natural incubation conditions.

State-dependent physiological maintenance in a long-lived ectotherm, the painted turtle (Chrysemys picta)

“…Reduced immunocompetence in young individuals has been shown in a few bird species (reviewed by Hausmann et al, 2005), and is thought to be due to a costly and protracted development of the immune system. Recent research on painted turtles has revealed that hatchling immune function depends on incubation temperatures (Les et al, 2009), thus, variation among the measures of immune function employed in the current study may reflect effects of the nest environment on development of the immune system.…”

“…Physiological maintenance in a long-lived ectotherm Physiological maintenance has been widely studied in birds, mammals and invertebrate model systems, but much less is known about maintenance in ectothermic vertebrates [e.g. reptiles (Saad and El Ridi, 1988;Patnaik, 1994;Nelson and Demas, 1996;Zapata et al, 1992;Muñoz and de la Fuente, 2004;Madsen et al, 2007;Martin et al, 2008;Pitol et al, 2008;Les et al, 2009;Paitz et al, 2009;Sparkman and Palacios, 2009;Zimmerman et al, 2010)]. Ectothermic vertebrates have traits that suggest physiological maintenance patterns should deviate from those seen in previously studied endothermic vertebrates.…”

Effects of night-time warming on temperate ectotherm reproduction: potential fitness benefits of climate change for side-blotched lizards

“…Some of the more obvious terrestrial ectotherms in an ecosystem are the reptiles, for which the thermal biology is especially well studied, making them ideal model organisms for this research. For example, incubation temperatures in reptiles can affect hatching success and hatchling phenotype (Hare et al, 2002;Shine et al, 1997), as well as subsequent growth (Nelson et al, 2004), survival (Hare et al, 2004), immune response (Les et al, 2009) and reproductive success (Warner et al, 2010). Thus, there are both direct and latent thermal effects associated with the incubation environment of reptiles.…”

Temperature Effects on Development and Phenotype in a Free-Living Population of Western Pond Turtles (Emys marmorata)

“…Studies investigating hatching success have shown that there is a range of temperatures in which embryos develop successfully, with hatching success dramatically declining at extremes of the temperature range. The same studies have found that within the range of temperatures that produce viable hatchlings, development tends to proceed more rapidly at higher temperatures (Booth, 1998;Les et al, 2009;). These data, while valuable, do not necessarily reflect the developmental and phenotypic responses to temperature variation inherent to in situ incubation environments.…”