scholarly journals Resource limitation determines realized thermal performance and the potential for metabolic meltdown.

2021 ◽  
Author(s):  
Anna Vinton ◽  
David Vasseur
Keyword(s):  
Temperature Change ◽  
Thermal Performance ◽  
Dynamic Models ◽  
Resource Limitation ◽  
Community Response ◽  
Effect Of Temperature ◽  
Performance Curve ◽  
Vital Rates ◽  
Physiological Tolerance ◽  
Thermal Performance Curve

1) As temperatures rise across the globe, many species may approach or even surpass their physiological tolerance to withstand high temperatures. Thermal performance curves, which depict how vital rates vary with temperature, are often measured under ideal laboratory conditions and then used to determine the physiological or demographic limits of persistence. However, this approach fails to consider how interactions with other factors (e.g. resources, water availability) may buffer or magnify the effect of temperature change. Recent work has demonstrated that the breadth and shape of a consumer’s thermal performance curve change with resource densities, highlighting the potential for temperature interactions and leading to a potential ‘metabolic meltdown’ when resources decline during warming (Huey and Kingsolver 2019). 2) Here, we further develop the basis for the interaction between temperature and resource density on thermal performance, persistence, and population dynamics by analyzing consumer-resource dynamic models. We find that the coupling of consumer and resource dynamics relaxes the potential for metabolic meltdown because a reduction in top-down control of resources occurs as consumers approach the limits of their thermal niche. However, when both consumers and resources have vital rates that depend on temperature, asymmetry between their responses can generate the necessary conditions for metabolic meltdown. 3) Moreover, we define the concept of a ‘realized’ thermal performance curve that takes into account the dynamic interaction between consumers, resources and temperature, and we describe an important role for this concept moving forward. 4) Synthesis. A better understanding of the link between temperature change, species interactions, and persistence allows us to improve forecasts of community response to climate change. Our work elucidates the importance of thermal asymmetries between interacting species, and resource limitation as a key ingredient underlying realized thermal niches.

scholarly journals Phytoplankton thermal responses adapt in the absence of hard thermodynamic constraints

2018 ◽  
Author(s):  
Dimitrios - Georgios Kontopoulos ◽  
Erik van Sebille ◽  
Michael Lange ◽  
Gabriel Yvon-Durocher ◽  
Timothy G. Barraclough ◽  
...  
Keyword(s):  
Thermal Performance ◽  
Thermal Sensitivity ◽  
Meta Analysis ◽  
Habitat Type ◽  
Performance Curve ◽  
Thermal Environments ◽  
Thermal Performance Curve ◽  
Performance Curves ◽  
Minor Influence ◽  
A Minor

AbstractTo better predict how populations and communities respond to climatic temperature variation, it is necessary to understand how the shape of the response of fitness-related traits to temperature evolves (the thermal performance curve). Currently, there is disagreement about the extent to which the evolution of thermal performance curves is constrained. One school of thought has argued for the prevalence of thermodynamic constraints through enzyme kinetics, whereas another argues that adaptation can—at least partly—overcome such constraints. To shed further light on this debate, we perform a phylogenetic meta-analysis of the thermal performance curves of growth rate of phytoplankton—a globally important functional group—, controlling for environmental effects (habitat type and thermal regime). We find that thermodynamic constraints have a minor influence on the shape of the curve. In particular, we detect a very weak increase of maximum performance with the temperature at which the curve peaks, suggesting a weak “hotter-is-better” constraint. Also, instead of a constant thermal sensitivity of growth across species, as might be expected from strong constraints, we find that all aspects of the thermal performance curve evolve along the phylogeny. Our results suggest that phytoplankton thermal performance curves adapt to thermal environments largely in the absence of hard thermodynamic constraints.

A thermal profile of metabolic performance in the rare Australian chelid, Pseudemydura umbrina

2014 ◽  
Vol 62 (6) ◽  
pp. 448 ◽  
Author(s):  
Sophie G. Arnall ◽  
Gerald Kuchling ◽  
Nicola J. Mitchell
Keyword(s):  
Thermal Performance ◽  
Activity Patterns ◽  
Standard Metabolic Rate ◽  
Co2 Production ◽  
Performance Curve ◽  
Thermal Performance Curve ◽  
Performance Curves ◽  
Consumption Rates ◽  
Flow Through ◽  
Metabolic Performance

Thermal performance curves are useful for predicting how organisms might respond to environmental change, and are becoming increasingly applicable for ectothermic animals threatened by climate change. Here we present a thermal performance curve for the critically endangered western swamp turtle (Pseudemydura umbrina) based upon measurements of O2 consumption and CO2 production obtained by flow-through respirometry at temperatures between 15 and 30°C. Standard metabolic rate was significantly higher at 30°C (0.030 mL g–1 h–1 O2, 0.021 mL g–1 h–1 CO2) than at 20°C (0.007 mL g–1 h–1 O2, 0.006 mL g–1 h–1 CO2) and the 20−30°C Q10 for O2 and CO2 were 4.60 and 3.55 respectively. Oxygen consumption rates at 15°C and 25°C were 0.002 (±0.000) and 0.018 (±0.000) mL g–1 h–1, with a corresponding Q10 of 9.21. Beyond ~30°C there was a decline in physiological performance, which was supported by activity patterns reported for P. umbrina in the literature.

scholarly journals Adaptive evolution shapes the present-day distribution of the thermal sensitivity of population growth rate

2019 ◽  
Author(s):  
Dimitrios - Georgios Kontopoulos ◽  
Thomas P. Smith ◽  
Timothy G. Barraclough ◽  
Samraat Pawar
Keyword(s):  
Climate Change ◽  
Growth Rate ◽  
Adaptive Evolution ◽  
Thermal Performance ◽  
Population Growth Rate ◽  
Thermal Sensitivity ◽  
Rapid Evolution ◽  
Performance Curve ◽  
Thermal Performance Curve ◽  
The Relationship

AbstractDeveloping a thorough understanding of how ectotherm physiology adapts to different thermal environments is of crucial importance, especially in the face of global climate change. A key aspect of an organism’s thermal performance curve—the relationship between fitness-related trait performance and temperature—is its thermal sensitivity, i.e., the rate at which trait values increase with temperature within its typically-experienced thermal range. For a given trait, the distribution of thermal sensitivities across species, often quantified as “activation energy” values, is typically right-skewed. Currently, the mechanisms that generate this distribution are unclear, with considerable debate about the role of thermodynamic constraints vs adaptive evolution. Here, using a phylogenetic comparative approach, we study the evolution of the thermal sensitivity of population growth rate across phytoplankton (Cyanobacteria and eukaryotic microalgae) and prokaryotes (bacteria and archaea), two microbial groups that play a major role in the global carbon cycle. We find that thermal sensitivity across these groups is moderately phylogenetically heritable, and that its distribution is shaped by repeated evolutionary convergence throughout its parameter space. More precisely, we detect bursts of adaptive evolution in thermal sensitivity, increasing the amount of overlap among its distributions in different clades. We obtain qualitatively similar results from evolutionary analyses of the thermal sensitivities of two physiological rates underlying growth rate: net photosynthesis and respiration of plants. Furthermore, we find that these episodes of evolutionary convergence are consistent with two opposing forces: decrease in thermal sensitivity due to environmental fluctuations and increase due to adaptation to stable environments. Overall, our results indicate that adaptation can lead to large and relatively rapid shifts in thermal sensitivity, especially in microbes where rapid evolution can occur at short time scales. Thus, more attention needs to be paid to elucidating the implications of rapid evolution in organismal thermal sensitivity for ecosystem functioning.Author summaryChanges in environmental temperature influence the performance of biological traits (e.g., respiration rate) in ectotherms, with the relationship between trait performance and temperature (the “thermal performance curve”) being single-peaked. Understanding how thermal performance curves adapt to different environments is important for predicting how organisms will be impacted by climate change. One key aspect of the shape of these curves is the thermal sensitivity near temperatures typically experienced by the species. Whether and how thermal sensitivity responds to different environments is a topic of active debate. To shed light on this, here we perform an evolutionary analysis of the thermal sensitivity of three key traits of prokaryotes, phytoplankton, and plants. We show that thermal sensitivity does not evolve in a gradual manner, but can differ considerably even between closely related species. This suggests that thermal sensitivity undergoes rapid adaptive evolution, which is further supported by our finding that thermal sensitivity varies weakly with latitude. We conclude that variation in thermal sensitivity arises partly from adaptation to environmental factors and that this may need to be accounted for in ecophysiological models.

Thermal Performance Curve Analysis for Enhancement of an Air Conditioner in Thailand

2019 ◽  
Vol 27 (03) ◽  
pp. 1930003 ◽  
Author(s):  
Nattaporn Chaiyat
Keyword(s):  
Water Temperature ◽  
Ultrasonic Wave ◽  
Thermal Performance ◽  
Storage Tank ◽  
Electrical Power ◽  
Weather Conditions ◽  
Hot Water ◽  
Air Conditioner ◽  
Performance Curve ◽  
Thermal Performance Curve

This study presents a method for analysing air conditioner efficiency by using a thermal performance curve. Enhancement techniques consisting of the use of a phase change material (PCM), a vapor compression heat pump (VCHP), ultrasound, drop-in refrigerant, a commercial R-32 air conditioner using ultrasound and a double-storage tank are reported under the weather conditions in Thailand. For the PCM, Rubitherm20 (RT-20) in the forms of a paraffin ball and a plastic pack was selected to cool the return air of the evaporator, which directly caused decreases in power consumption of 7.85% and 5.78%, respectively. The R-123 VCHP was integrated with the air conditioner at the condenser to receive and boost rejected heat to the hot water temperature of 60–70∘C. Ultrasonic wave generators at 42[Formula: see text]kHz frequency were installed at the evaporator to improve heat transfer characteristics and reduce the electrical power usage of the air conditioner by 8%. The R-32 drop-in refrigerant technique was tested in an R-410a air conditioner model. The R-32 unit showed the advantages of a smaller environmental impact and a higher cooling energy efficiency ratio (EER) compared with that of the R-410a unit. Moreover, the commercial R-32 air conditioner and a 40 kHz ultrasonic generator were integrated. The combined unit revealed a higher EER of 7.69% compared with that of the conventional commercial R-32 unit. For a double-storage tank, it was shown that the maximum hot water temperature in the storage tank was approximately 49∘C. The highest effective method to enhance the cooling capacity of air-conditioner is the technique of R-32 air conditioner and ultrasonic wave for increasing the cooling efficiency of 8.54%.

scholarly journals Thermal performance curves for aerobic scope in a tropical fish (Lates calcarifer): flexible in amplitude but not breadth

2021 ◽  
Author(s):  
Hanna Scheuffele ◽  
Francesc Rubio-Gracia ◽  
Timothy D. Clark
Keyword(s):  
Thermal Performance ◽  
Growth Rates ◽  
Daily Temperature ◽  
Tropical Fish ◽  
Metabolic Phenotype ◽  
Performance Curve ◽  
Aerobic Scope ◽  
Lates Calcarifer ◽  
Thermal Performance Curve ◽  
Performance Curves

Aerobic metabolic scope is a popular metric to estimate the capacity for temperature-dependent performance in aquatic animals. Despite this popularity, little is known of the role of temperature acclimation and variability in shaping the breadth and amplitude of the thermal performance curve for aerobic scope. If daily thermal experience can modify the characteristics of the thermal performance curve, interpretations of aerobic scope data from the literature may be misguided. Here, tropical barramundi (Lates calcarifer) were acclimated for ∼4 months to cold (23℃), optimal (29℃) or warm (35℃) conditions, or to a daily temperature cycle between 23 and 35℃ (with a mean of 29℃). Measurements of aerobic scope were conducted every 3-4 weeks at three temperatures (23℃, 29℃ and 35℃), and growth rates were monitored. Acclimation to constant temperatures caused some changes in aerobic scope at the three measurement temperatures via adjustments in standard and maximal metabolic rates, and growth rates were lower in the 23℃-acclimated group compared with all other groups. The metabolic parameters and growth rates of the thermally variable group remained similar to those of the 29℃-acclimated group. Thus, acclimation to a variable temperature regime did not broaden the thermal performance curve for aerobic scope. We propose that aerobic scope thermal performance curves are more plastic in amplitude rather than breadth, and that the metabolic phenotype of at least some fish may be more dependent on the mean daily temperature rather than on the daily temperature range.

Sign in / Sign up

Export Citation Format

Share Document