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Thermal Acclimation of Metabolism in Sceloporus Lizards from Different Latitudes

1988; University of Chicago Press; Volume: 61; Issue: 3 Linguagem: Inglês

10.1086/physzool.61.3.30161237

1937-4267

Joyce S. Tsuji,

Species Distribution and Climate Change

After exposure to cool temperatures, ectotherms may increase (compensation), decrease (inverse acclimation), or show no change in standard metabolic rate (SMR). I tested whether these responses may be adaptations to seasonality in temperature with the following hypotheses: (1) winter-active Sceloporus occidentalis from southern California would show compensation to counteract the depressing effects of cool temperatures, whereas (2) winter-dormant S. occidentalis from Washington would show inverse acclimation to conserve energy, and (3) S. variabilis from tropical Costa Rica would not acclimate. Repeated measurements of SMR at 10, 16, and 35 C of these lizards after exposure to warm and cool conditions supported these predictions. Washington lizards in autumn exhibited inverse acclimation at low test temperatures: SMR decreased by 19% at 10 C and 9% at 16 C when lizards were transferred from simulated summer to simulated autumn conditions. Spring animals showed inverse acclimation only at 35 C. The California population showed compensation at 10 C in autumn-collected animals but no acclimation in spring-collected animals. Sceloporus variabilis did not acclimate. Critical thermal minimum was lowest in Washington and highest in Costa Rican lizards but decreased similarly in all populations after cold exposure. These geographic differences in acclimation indicate adaptation to environmental thermal variability.