Skip to main content
Dryad logo

Breaking Free from Thermodynamic Constraints: Thermal Acclimation and Metabolic Compensation in a freshwater zooplankton species

Citation

Yampolsky, Lev et al. (2020), Breaking Free from Thermodynamic Constraints: Thermal Acclimation and Metabolic Compensation in a freshwater zooplankton species, Dryad, Dataset, https://doi.org/10.5061/dryad.c2fqz616k

Abstract

Ectothermic organisms' respiration rates are largely controlled by environment temperatures and the ability to meet metabolic demands at high temperatures sometimes sets their upper thermal limit. Organisms are hypothesized to exhibit acclimatory effects, adjusting their metabolism and physiology by deceleration of metabolic processes including respiration below Arrhenius expectations based in temperature alone. Such deceleration is termed metabolic compensation. We test the hypothesis that either heritable (among genotypes) or plastic (between acclimation regimes) heat tolerance differences can be explained by metabolic compensation in the eurythermal freshwater zooplankton crustacean Daphnia magna. We measured oxygen consumption rates over a range of assay temperatures (5°C - 37°C) in 8 genotypes of Daphnia representing a range of previously reported genotype-specific acute heat tolerance values and, in a narrower range of temperatures (10°C - 35°C) in Daphnia with different acclimation history (either 10°C or 25°C). In a ramp-up experiment we discovered no difference in temperature-specific respiration rates between heat tolerant and heat-sensitive genotypes. In contrast, we observed compensatory differences in respiration rates at both extremes of the temperature range studied. Notably, there was a deceleration of oxygen consumption at higher temperature in the 25°C-acclimated Daphnia relative to their 10°C-acclimated counterparts, observed in active, but not anaesthetized animals, a pattern corroborated by similar changes in filtering rate and, partly, by changes in mitochondrial membrane potential. Daphnia exposed to a sublethal temperature (35°C) with a 24-hour recovery period at a 25°C-acclimation temperature showed no difference in respiration compared to unexposed 25°C-acclimated Daphnia, indicating that the reduction of respiration is not caused by irreversible damage. Response time necessary to acquire the respiratory adjustment to high temperature was much lower than to low temperature, indicating that metabolic compensation at the lower temperatures require slower structural changes.

Usage Notes

Data are available for the following experiments: respiration rates in a Ramp-UP temperature; respiration rates in thermal Acclimation experiments 1 and 2; respiration rates in the Recovery experiment; respiration rates in the Acclimation Reversal time experiment; mitochondrial membrane potential in the Acclimation experiment.

Missing values: In Acclimation experiments 2 both active and basal respiration was measured in some animals, but only either one or the other in others. 

Data consist of the following data columns:

run run ID
assayT Temperature at which O2 consumption measurement was conducted
Slope_mg/sec blank-corrected slope of [O2] over time
SE(Slope_mg/sec) its SE
SlopeUA_mg/sec blank-corrected slope of [O2] over time in urethane-anaesthetizes Daphnia
SE(SlopeUA_mg/sec) its SE
N Number of Daphnia in assay
wweight(mg) Combined wet weight of Daphnia in assay
Clone clone ID
AccT  Acclimation temperature
Treatment: Recovery treatment OR time at new T Treatment in the recovery experiment or time (h) at the new temperature in acclimation reversal experiment
ugO2/min/mgWW oxygen consumed per minute per mg of wet weight
ugO2/min/Daphnia oxygen consumed per minute per individual Daphnia
ugO2UA/min/mgWW oxygen consumed per minute per mg of wet weight in urethane-anaesthetizes Daphnia
ugO2UA/min/Daphnia oxygen consumed per minute per individual Daphnia in urethane-anaesthetizes Daphnia