Meeting Abstract
P1.118 Monday, Jan. 4 Plasticity of python eggshell permeability and its role in a dynamic respiration-hydration tradeoff STAHLSCHMIDT, Z.R.*; HEULIN, B.; DENARDO, D.F.; Arizona State Univ., Tempe; Centre National de la Recherche Scientifique, Paimpont zs@asu.edu
Parental care is a widespread reproductive adaptation, and python egg-brooding behavior exemplifies parental care because it mediates a tradeoff between embryonic respiration and hydration. However, because egg brooding does not adjust to the increasing metabolic requirements of developing offspring, it imposes hypoxic costs to embryos later in incubation as it increases gas exchange resistance between the embryonic and nest environment. Thus, we tested the hypotheses that python eggshells (1) have increased permeability over time to compensate for increasing embryonic respiration, and (2) exhibit permeability plasticity in response to chronic hypoxia. Over incubation, we serially measured the atomic and structural components of Children’s python (Antaresia childreni) eggshells, as well as in vivo and in vitro gas exchange across eggshells. In support of our first hypothesis, A. childreni eggshells exhibited a reduced fibrous layer, became more permeable, and facilitated greater gas exchange as incubation progressed. Our second hypothesis was not supported, as incubation O2 concentration did not affect the shells’ permeabilities to O2 and H2O vapor. Our results suggest that python eggshell permeability changes during incubation, but the alterations over time are fixed and independent of environmental conditions. These findings are of broad evolutionary interest since they demonstrate that, even in relatively simple parental care models, successful parent-offspring relationships depend on adjustments made by both the parent (i.e., egg-brooding behavioral shifts) and the offspring (i.e., changes in eggshell permeability).
