Thermal tolerance plasticity and dynamics of thermal tolerance in Eublepharis macularius: Implications for future climate-driven heat stress
Data files
Jul 31, 2024 version files 77.38 KB
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CTmax_Plasticity_Data.csv
1.88 KB
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CTmax_Plasticity_Script.R
50.43 KB
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Gecko_Cloacal_Temps.csv
21.18 KB
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README.md
3.89 KB
Abstract
The intensity and duration of heat waves, as well as average global temperatures, are expected to increase due to climate change. Heat waves can cause physiological stress and reduce fitness in animals. Species can reduce overheating risk through phenotypic plasticity, which allows them to raise their thermal tolerance limits over time. This mechanism could be important for ectotherms whose body temperatures are directly influenced by available environmental temperatures. Geckos are a large, diverse group of ectotherms that vary in their thermal habitats and times of daily activity, which could affect how they physiologically adjust to heat waves. Data on thermal plasticity are scarce for reptiles, with only one study in geckos. Understanding thermal tolerance and plasticity, and their relationship, is essential for understanding how some species are able to adjust or adapt to changing temperatures. In this study, we estimated thermal tolerance and plasticity, and their interaction, in the crepuscular gecko, Eublepharis macularius, a species that is emerging as a model for reptile biology. After estimating basal thermal tolerance for 28 geckos, thermal tolerance was measured for each individual a second time at several time points (3, 6, or 24 h) to determine thermal tolerance plasticity. We found that thermal tolerance plasticity (1) does not depend on the basal thermal tolerance of the organism, (2) was highest after 6 hours from initial heat shock, and (3) was negatively influenced by individual body mass. Our findings contribute to the increasing body of work focused on understanding the influence of biological and environmental factors on thermal tolerance plasticity in organisms and provide phenotypic data to further investigate the molecular basis of thermal tolerance plasticity in organisms.
Summary:
The datasets described here include individual cloacal body temperatures, measurements for critical thermal maximum, heating rates, and individual characteristics (i.e., body size, mass, sex, time group, etc.).
Software used:
- R v4.3.0 for statistical analyses, with required packaged loaded at the top of the included CTmax_Plasticity_Script.R
Description of data files:
Gecko_Cloacal_Temps.csv
Describes measurements of cloacal body temperatures collected from each individual during CTmax experiments and includes individual characteristics (i.e., body size, sex, mass, etc.).
All temperature measurements are in degrees Celsius.
Variables are described as follows:
Time_min: Time in minutes when cloacal body temperature data was recorded for each individual during experiments.
Temp: Cloacal temperature in degrees Celsius for the individual.
Individual: Number of the individual.
Sex: The sex of the individual (either "M" for male or "F" for female).
SVL_cm: The snout-vent-length of the individual measured in centimeters (cm) before experiments.
Mass_g: The mass of the individual measured in grams (g) before basal CTmax experiments.
Time_group: The time interval in hour(s) (either 0, 3, 6, or 24) when individual cloacal body temperature was measured.
CTmax_Plasticity_Data.csv
Describes measurements of CTmax collected from each individual during experiments, heating rates, adjusted and unadjusted plasticity values, and individual characteristics (i.e., body size, sex, mass, etc.).
CTmax values are measured in degrees Celsius and heating rates are measured as degrees Celsius per minute.
"NA" values represent variables that were not measured for the individual.
Variables are described as follows:
Individual: Number of the individual.
Sex: The sex of the individual (either "M" for male or "F" for female).
SVL_cm: The snout-vent length of the individual measured in centimeters (cm) before experiments.
Mass_g: The mass of the individual measured in grams (g) before basal CTmax experiments.
Mass_after_basal_CTmax_g: The mass of the individual measured in grams (g) before the final CTmax experiments.
Basal_CTmax: The critical thermal maximum of the individual measured as the cloacal body temperature in degrees Celsius. This measurement was taken at time 0 hours during basal CTmax experiments.
Final_CTmax: The critical thermal maximum of the individual measured as the cloacal body temperature in degrees Celsius. This measurement was taken at either time 3 hours, 6 hours, or 24 hours after basal CTmax measurement.
Group: The randomly assigned time-interval treatment group of the individual (either 3h, 6h, or 24h).
Change in CTmax: The calculated difference between basal CTmax and final CTmax of the individual measured in degrees Celsius.
Adjusted_Plasticity: The adjusted change in CTmax values in degrees Celius for the 3h time-interval group and unadjusted change in CTmax values in degrees Celsius for the 6h and 24h time-interval groups.
Basal_Heating_Rate: The calculated slope value for each individual corresponding to the change in cloacal body temperature over time measured every minute at time 0h during basal CTmax experiments. Units are in degrees Celsius per minute.
Final_Heating_Rate: The calculated slope value for each individual corresponding to the change in cloacal body temperature over time measured every minute at time 3h, 6h, or 24h during final CTmax experiments. Units are in degrees Celsius per minute.
Heating_Rate_Difference: The calculated difference between basal and final heating rates for each individual. Units are in degrees Celsius per minute.
In this study, we established the critical thermal maximum (basal upper thermal tolerance), inferred the thermal tolerance plasticity, and assessed their relationship in the gecko, Eublepharis macularius. Thermal tolerance plasticity through heat hardening has been measured as the change in the critical thermal maximum (CTmax) over time. CTmax corresponds to the upper thermal tolerance of an organism, which is the internal body temperature at which the organism loses physiological function and cannot tolerate any higher temperatures. In addition to measuring heat hardening capacity and thermal tolerance within E. macularius, in this work, we also investigate the influence of individual body mass, body size, and sex on heating rates across CTmax experiments.