scholarly journals Individual variation in thermal plasticity and its impact on mass-scaling

2019 ◽  
Author(s):  
Fonti Kar ◽  
Shinichi Nakagawa ◽  
Christopher R Friesen ◽  
Daniel W.A. Noble
Keyword(s):  
Environmental Change ◽  
Metabolic Rate ◽  
Population Level ◽  
Standard Metabolic Rate ◽  
Theoretical Research ◽  
Level Variation ◽  
Scaling Exponents ◽  
Mass Scaling ◽  
Thermal Plasticity ◽  
Multi Level

1.Physiological processes of individuals can be highly variable and there is mounting evidence that individuals can differ in how they respond to environmental change. The ability for individuals to reversibly adjust their metabolic rate in response to temperature (i.e., metabolic thermal plasticity) may affect mass-scaling at the population level. This process has rarely been investigated before. 2.This study characterised the repeatability of metabolic thermal plasticity and tested how mass-scaling exponents change at different temperatures in the delicate skink (Lampropholis delicata). We repeatedly measured standard metabolic rate of forty-two individuals at six temperatures over the course of three months (N[measurement] = 2418). We explicitly accounted for multi-level variation in our data in order to quantify more precise estimates of mass-scaling exponents at different environmental temperatures.3.Making use of two analytical frameworks, we found that metabolic thermal plasticity was significantly repeatable. Average standard metabolic rate increased as a function of temperature, which was associated with individuals responding more predictably (a decrease in within-individual variance) at higher temperatures. Interpretation of repeatability estimates and cross-temperature correlations varied slightly between the analytic approaches, but they were mostly in agreement. 4.After taking into account within- and among-individual level variation in our data, our estimates for mass-scaling did not change with temperature and were in line with published values for snakes and lizards. This suggests that repeatable plastic responses may contribute to thermal stability of scaling exponents. 5.Our work contributes to our understanding of whether phenotypic plasticity has the capacity to respond to selection which is particularly important for animals coping with rapid environmental change. Acknowledging multi-level variation in body mass and metabolic rate is not only important for comparative studies interested in mass-scaling across the animal kingdom, but also to theoretical research interested using the predictive power of mass-scaling.

scholarly journals Components of standard metabolic rate variability in three species of gammarids

Web Ecology ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Milad Shokri ◽  
Mario Ciotti ◽  
Fabio Vignes ◽  
Vojsava Gjoni ◽  
Alberto Basset
Keyword(s):  
Body Size ◽  
Metabolic Rate ◽  
Body Condition ◽  
Population Level ◽  
Functional Trait ◽  
Standard Metabolic Rate ◽  
Individual Variability ◽  
Population Variation ◽  
Metabolic Rates ◽  
Individual Level

Abstract. Standard metabolic rate is a major functional trait with large inter-individual variability in many groups of aquatic species. Here we present results of an experimental study to address variation in standard metabolic rates, over different scales of organisation and environments, within a specific group of aquatic macro-invertebrates (i.e. gammarid amphipods) that represent the primary consumers in detritus food webs. The study was carried out using flow-through microrespirometric techniques on male specimens of three gammarid species from freshwater, transitional water and marine ecosystems. We examined individual metabolic rate variations at three scales: (1) at the individual level, during an 8 h period of daylight; (2) at the within-population level, along body-size and body-condition gradients; (3) at the interspecific level, across species occurring in the field in the three different categories of aquatic ecosystems, from freshwater to marine. We show that standard metabolic rates vary significantly at all three scales examined, with the highest variation observed at the within-population level. Variation in individual standard metabolic rates during the daylight hours was generally low (coefficient of variation, CV<10 %) and unrelated to time. The average within-population CV ranged between 30.0 % and 35.0 %, with body size representing a significant source of overall inter-individual variation in the three species and individual body condition exerting only a marginal influence. In all species, the allometric equations were not as steep as would be expected from the 3∕4 power law, with significant variation in mass-specific metabolic rates among populations. The population from the transitional water ecosystem had the highest mass-specific metabolic rates and the lowest within-population variation. In the gammarid species studied here, body-size-independent variations in standard individual metabolic rates were higher than those explained by allometric body size scaling, and the costs of adaptation to short-term periodic variations in water salinity in the studied ecosystems also seemed to represent a major source of variation.

scholarly journals The scaling and temperature dependence of vertebrate metabolism

2005 ◽  
Vol 2 (1) ◽  
pp. 125-127 ◽  
Author(s):  
Craig R White ◽  
Nicole F Phillips ◽  
Roger S Seymour
Keyword(s):  
Body Size ◽  
Metabolic Rate ◽  
Temperature Dependence ◽  
Body Mass ◽  
Standard Metabolic Rate ◽  
Power Scaling ◽  
Scaling Exponents ◽  
Magnitude Variation ◽  
Over 40 Years

Body size and temperature are primary determinants of metabolic rate, and the standard metabolic rate (SMR) of animals ranging in size from unicells to mammals has been thought to be proportional to body mass ( M ) raised to the power of three-quarters for over 40 years. However, recent evidence from rigorously selected datasets suggests that this is not the case for birds and mammals. To determine whether the influence of body mass on the metabolic rate of vertebrates is indeed universal, we compiled SMR measurements for 938 species spanning six orders of magnitude variation in mass. When normalized to a common temperature of 38 °C, the SMR scaling exponents of fish, amphibians, reptiles, birds and mammals are significantly heterogeneous. This suggests both that there is no universal metabolic allometry and that models that attempt to explain only quarter-power scaling of metabolic rate are unlikely to succeed.

scholarly journals Ecological and evolutionary consequences of metabolic rate plasticity in response to environmental change

2019 ◽  
Vol 374 (1768) ◽  
pp. 20180180 ◽  
Author(s):  
Tommy Norin ◽  
Neil B. Metcalfe
Keyword(s):  
Environmental Change ◽  
Metabolic Rate ◽  
Intraspecific Variation ◽  
Standard Metabolic Rate ◽  
Metabolic Rates ◽  
Trade Offs ◽  
Fitness Consequences ◽  
Organ Tissue ◽  
Evolutionary Consequences ◽  
Response To Environmental Change

Basal or standard metabolic rate reflects the minimum amount of energy required to maintain body processes, while the maximum metabolic rate sets the ceiling for aerobic work. There is typically up to three-fold intraspecific variation in both minimal and maximal rates of metabolism, even after controlling for size, sex and age; these differences are consistent over time within a given context, but both minimal and maximal metabolic rates are plastic and can vary in response to changing environments. Here we explore the causes of intraspecific and phenotypic variation at the organ, tissue and mitochondrial levels. We highlight the growing evidence that individuals differ predictably in the flexibility of their metabolic rates and in the extent to which they can suppress minimal metabolism when food is limiting but increase the capacity for aerobic metabolism when a high work rate is beneficial. It is unclear why this intraspecific variation in metabolic flexibility persists—possibly because of trade-offs with the flexibility of other traits—but it has consequences for the ability of populations to respond to a changing world. It is clear that metabolic rates are targets of selection, but more research is needed on the fitness consequences of rates of metabolism and their plasticity at different life stages, especially in natural conditions. This article is part of the theme issue ‘The role of plasticity in phenotypic adaptation to rapid environmental change’.

Impact of Developmental Temperatures On The Repeatability of Thermal Plasticity in Metabolic Rate

2021 ◽  
Author(s):  
Fonti Kar ◽  
Shinichi Nakagawa ◽  
Daniel W.A. Noble
Keyword(s):  
Metabolic Rate ◽  
Population Level ◽  
Reaction Norm ◽  
Thermal Reaction ◽  
Reaction Norms ◽  
Thermal Plasticity ◽  
Credible Intervals ◽  
Hot Environments ◽  
Plastic Responses ◽  
Early Developmental

Phenotypic plasticity is an important mechanism that allows populations to adjust to changing environments. Plastic responses induced by early life experiences can have lasting impacts on how individuals respond to environmental variation later in life (i.e., reversible plasticity). Developmental environments can also influence repeatability of plastic responses thereby altering the capacity for reaction norms to respond to selection. Here, we compared metabolic thermal reaction norms in lizards (Lampropholis delicata) that were incubated at two developmental temperatures (ncold = 26, nhot = 25). We repeatedly measured individual reaction norms across six acute temperatures 10 times over ~3.5 months (nobs = 3,818) to estimate the repeatability of average metabolic rate (intercept) and thermal plasticity (slope). The intercept and the slope of the population-level thermal reaction norm did not change with developmental temperatures. Repeatability of average metabolic rate was, on average, 10% lower in hot incubated lizards and was stable across acute temperatures. The slope of the reaction norm was moderately repeatable (R = 0.44, 95% CI = 0.035 – 0.93) suggesting that individual metabolic rate changed consistently with acute temperature, although credible intervals were quite broad. Importantly, reaction norm repeatability did not depend on early developmental temperature. Our work implies that thermal plasticity has the capacity to evolve, despite there being less consistent variation in metabolic rate under hot environments. This capacity for thermal plasticity to evolve will be increasingly more important for terrestrial ectotherms living in changing climate.

The Metabolic Theory of Ecology

2017 ◽  
Author(s):  
Andrew Clarke
Keyword(s):  
Metabolic Rate ◽  
Resting Metabolic Rate ◽  
Effect Of Temperature ◽  
Thermal Ecology ◽  
Model Data ◽  
Metabolic Theory ◽  
Physical Explanation ◽  
Boltzmann Factor ◽  
Scaling Exponents ◽  
Metabolic Theory Of Ecology

The model of West, Brown & Enquist (WBE) is built on the assumption that the metabolic rate of cells is determined by the architecture of the vascular network that supplies them with oxygen and nutrients. For a fractal-like network, and assuming that evolution has minimised cardiovascular costs, the WBE model predicts that s=metabolism should scale with mass with an exponent, b, of 0.75 at infinite size, and ~ 0.8 at realistic larger sizes. Scaling exponents ~ 0.75 for standard or resting metabolic rate are observed widely, but far from universally, including in some invertebrates with cardiovascular systems very different from that assumed in the WBE model. Data for field metabolic rate in vertebrates typically exhibit b ~ 0.8, which matches the WBE prediction. Addition of a simple Boltzmann factor to capture the effects of body temperature on metabolic rate yields the central equation of the Metabolic Theory of Ecology (MTE). The MTE has become an important strand in ecology, and the WBE model is the most widely accepted physical explanation for the scaling of metabolic rate with body mass. Capturing the effect of temperature through a Boltzmann factor is a useful statistical description but too simple to qualify as a complete physical theory of thermal ecology.

scholarly journals A Multi-level Review of Engineering Ethics Education: Towards a Socio-technical Orientation of Engineering Education for Ethics

2021 ◽  
Vol 27 (5) ◽  
Author(s):  
Diana Adela Martin ◽  
Eddie Conlon ◽  
Brian Bowe
Keyword(s):  
Engineering Education ◽  
Ethics Education ◽  
Engineering Ethics ◽  
Theoretical Research ◽  
Policy And Practice ◽  
Individual Level ◽  
Multi Level ◽  
Engineering Ethics Education ◽  
Four Levels ◽  
The Individual

AbstractThis paper aims to review the empirical and theoretical research on engineering ethics education, by focusing on the challenges reported in the literature. The analysis is conducted at four levels of the engineering education system. First, the individual level is dedicated to findings about teaching practices reported by instructors. Second, the institutional level brings together findings about the implementation and presence of ethics within engineering programmes. Third, the level of policy situates findings about engineering ethics education in the context of accreditation. Finally, there is the level of the culture of engineering education. The multi-level analysis allows us to address some of the limitations of higher education research which tends to focus on individual actors such as instructors or remains focused on the levels of policy and practice without examining the deeper levels of paradigm and purpose guiding them. Our approach links some of the challenges of engineering ethics education with wider debates about its guiding paradigms. The main contribution of the paper is to situate the analysis of the theoretical and empirical findings reported in the literature on engineering ethics education in the context of broader discussions about the purpose of engineering education and the aims of reform programmes. We conclude by putting forward a series of recommendations for a socio-technical oriented reform of engineering education for ethics.

scholarly journals Why is syphilis rising in Europe? Multi-level modelling of alternative hypotheses in 31 countries

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
A Mendez-Lopez ◽  
D Stuckler ◽  
T Noori ◽  
J C Semenza
Keyword(s):  
Risky Sexual Behavior ◽  
Population Level ◽  
Internet Survey ◽  
Probability Models ◽  
Syphilis Infection ◽  
Detection Rates ◽  
Substantial Impact ◽  
Multi Level ◽  
Sex With Men ◽  
Linear Probability

Abstract Background Syphilis transmission has increased markedly over the past two decades in Europe, concentrated in men who have sex with men. We test alternative potential social and behavioral individual- and population-level determinants of this resurgence. Methods Two rounds of the cross-sectional European Men who have sex with men Internet Survey (EMIS 2010 and 2017, n = 272,902) were used to fit multi-level linear probability models to evaluate determinants of the incidence of self-reported syphilis, capturing risky sexual behaviours and pre-exposure prophylaxis use, among others, adjusting for potential sociodemographic confounders. Results Self-reported syphilis incidence rates rose by about 1.8 percentage points (within the last 12 months) and 3.9 (within the last 5 years) between the 2010 and 2017 waves, after adjusting for sociodemographic factors. HIV status was a major risk factor for syphilis infection (27.6 ppt higher incident rate, 95%CI: 24.7 to 30.5). A dose-response relationship was observed between greater numbers of condomless non-steady partners and syphilis infection, with more than 10 partners estimating increases in the probability of diagnosis of over 25 ppt (11-20 partners vs none: 24.5 ppt, 95%CI: 20.5 to 28.5); further, we observed evidence of mediation for number of condomless non-steady partners, which attenuated the estimated rise in 2017 vs 2010 by about 35%. STI testing uptake also accounted for a substantial increase in syphilis incidence signaling higher detection rates over time. While country-level PrEP use was linked to greater number of condomless partners, there was no substantial impact of population-wide factors, including GDP and PrEP use, on overall syphilis trends. Conclusions Risky sexual behavior changes, particularly condomless sex with non-steady partners, appears to be a major contributing factor to rising syphilis incidence. Further research is needed to understand what accounts for this substantial behavior change. Key messages Increased number of condomless non-steady partners accounts for a substantial rise in syphilis trends. Population-level PrEP use was linked to increasing numbers of condomless non-steady partners but had no substantial impact on overall syphilis trends.

Field-Testing a Standard Metabolic Rate Estimation Technique for Eastern Red-Backed Salamanders

2016 ◽  
Vol 50 (1) ◽  
pp. 138-144
Author(s):  
Patrick J Ruhl ◽  
Robert N Chapman ◽  
John B. Dunning
Keyword(s):  
Metabolic Rate ◽  
Field Testing ◽  
Standard Metabolic Rate ◽  
Estimation Technique ◽  
Rate Estimation

scholarly journals DNA methyltransferase 3a mediates developmental thermal plasticity

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Isabella Loughland ◽  
Alexander Little ◽  
Frank Seebacher
Keyword(s):  
Environmental Change ◽  
Dna Methyltransferase ◽  
Developmental Plasticity ◽  
Citrate Synthase ◽  
Thermal Sensitivity ◽  
Short Term ◽  
Cold Temperatures ◽  
Knock Out ◽  
Thermal Plasticity ◽  
Dna Methyltransferase 3A

Abstract Background Thermal plasticity is pivotal for evolution in changing climates and in mediating resilience to its potentially negative effects. The efficacy to respond to environmental change depends on underlying mechanisms. DNA methylation induced by DNA methyltransferase 3 enzymes in the germline or during early embryonic development may be correlated with responses to environmental change. This developmental plasticity can interact with reversible acclimation within adult organisms, which would increase the speed of response and could alleviate potential mismatches between parental or early embryonic environments and those experienced at later life stages. Our aim was to determine whether there is a causative relationship between DNMT3 enzyme and developmental thermal plasticity and whether either or both interact with short-term acclimation to alter fitness and thermal responses in zebrafish (Danio rerio). Results We developed a novel DNMT3a knock-out model to show that sequential knock-out of DNA methyltransferase 3a isoforms (DNMT3aa−/− and DNMT3aa−/−ab−/−) additively decreased survival and increased deformities when cold developmental temperatures in zebrafish offspring mismatched warm temperatures experienced by parents. Interestingly, short-term cold acclimation of parents before breeding rescued DNMT3a knock-out offspring by restoring survival at cold temperatures. DNMT3a knock-out genotype interacted with developmental temperatures to modify thermal performance curves in offspring, where at least one DNMT3a isoform was necessary to buffer locomotion from increasing temperatures. The thermal sensitivity of citrate synthase activity, an indicator of mitochondrial density, was less severely affected by DNMT3a knock-out, but there was nonetheless a significant interaction between genotype and developmental temperatures. Conclusions Our results show that DNMT3a regulates developmental thermal plasticity and that the phenotypic effects of different DNMT3a isoforms are additive. However, DNMT3a interacts with other mechanisms, such as histone (de)acetylation, induced during short-term acclimation to buffer phenotypes from environmental change. Interactions between these mechanisms make phenotypic compensation for climate change more efficient and make it less likely that thermal plasticity incurs a cost resulting from environmental mismatches.

scholarly journals Does segregating variation in sexual or microhabitat preferences lead to non-random mating within a population of Drosophila melanogaster ?

2009 ◽  
Vol 6 (1) ◽  
pp. 102-105 ◽  
Author(s):  
Brad R. Foley ◽  
Anne Genissel ◽  
Harmon L. Kristy ◽  
Sergey V. Nuzhdin
Keyword(s):  
Recombinant Inbred Lines ◽  
Random Mating ◽  
Population Level ◽  
Inbred Lines ◽  
Male Mating ◽  
Complex Environment ◽  
Level Variation ◽  
Group Preference ◽  
Female Genotype ◽  
Microhabitat Preferences

Variation in female choice for mates has implications for the maintenance of genetic variation and the evolution of male traits. Yet, estimates of population-level variation in male mating success owing to female genotype are rare. Here, we used a panel of recombinant inbred lines to estimate the strength of selection at many genetic loci in a single generation and attempt to assess differences between females with respect to the males they mated with. We performed selection assays in a complex environment to allow differences in habitat or social group preference to be expressed. We detected directional selection at loci across the genome, but are unable to provide support for differential male success because of variation in female genotype.

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