Data from: Hormonal and metabolic responses to upper temperature extremes in divergent life-history ecotypes of a garter snake

Extreme temperatures constrain organismal physiology and impose both acute
and chronic effects. Additionally, temperature-induced hormone-mediated
stress response pathways and energetic trade-offs are important drivers of
life-history variation. This study employs an integrative approach to
quantify acute physiological responses to high temperatures in divergent
life-history ecotypes of the western terrestrial garter snake (Thamnophis
elegans). Using wild-caught animals, we measured oxygen consumption rate
and physiological markers of hormonal stress response, energy
availability, and anaerobic respiration in blood plasma across five
ecologically relevant temperatures (24, 28, 32, 35, and 38° C; 3-hour
exposure). Corticosterone, insulin, and glucose concentrations all
increased with temperature, but with different thermal response curves,
suggesting that high temperatures differently affect energy-regulation
pathways. Additionally, oxygen consumption rate increased without plateau
and lactate concentration did not increase with temperature, challenging
the recent hypothesis that oxygen limitation sets upper thermal tolerance
limits. Finally, animals had similar physiological thermal responses to
high-temperature exposure regardless of genetic background, suggesting
that local adaptation has not resulted in fixed differences between
ecotypes. Together, these results identify some of the mechanisms by which
higher temperatures alter hormonal-mediated energy balance in reptiles and
potential limits to the flexibility of this response.