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Journal of Fish Biology May 2023Critical thermal maxima methodology (CTM) has been used to infer acute upper thermal tolerance in fishes since the 1950s, yet its ecological relevance remains debated.... (Review)
Review
Critical thermal maxima methodology (CTM) has been used to infer acute upper thermal tolerance in fishes since the 1950s, yet its ecological relevance remains debated. In this study, the authors synthesize evidence to identify methodological concerns and common misconceptions that have limited the interpretation of critical thermal maximum (CT ; value for an individual fish during one trial) in ecological and evolutionary studies of fishes. They identified limitations of, and opportunities for, using CT as a metric in experiments, focusing on rates of thermal ramping, acclimation regimes, thermal safety margins, methodological endpoints, links to performance traits and repeatability. Care must be taken when interpreting CTM in ecological contexts, because the protocol was originally designed for ecotoxicological research with standardized methods to facilitate comparisons within study individuals, across species and contexts. CTM can, however, be used in ecological contexts to predict impacts of environmental warming, but only if parameters influencing thermal limits, such as acclimation temperature or rate of thermal ramping, are taken into account. Applications can include mitigating the effects of climate change, informing infrastructure planning or modelling species distribution, adaptation and/or performance in response to climate-related temperature change. The authors' synthesis points to several key directions for future research that will further aid the application and interpretation of CTM data in ecological contexts.
Topics: Animals; Fishes; Temperature; Acclimatization; Biological Evolution; Adaptation, Physiological; Climate Change
PubMed: 36880500
DOI: 10.1111/jfb.15368 -
International Journal of Molecular... Nov 2020Drought is a serious threat to the farming community, biasing the crop productivity in arid and semi-arid regions of the world. Drought adversely affects seed... (Review)
Review
Drought is a serious threat to the farming community, biasing the crop productivity in arid and semi-arid regions of the world. Drought adversely affects seed germination, plant growth, and development via non-normal physiological processes. Plants generally acclimatize to drought stress through various tolerance mechanisms, but the changes in global climate and modern agricultural systems have further worsened the crop productivity. In order to increase the production and productivity, several strategies such as the breeding of tolerant varieties and exogenous application of growth regulators, osmoprotectants, and plant mineral nutrients are followed to mitigate the effects of drought stress. Nevertheless, the complex nature of drought stress makes these strategies ineffective in benefiting the farming community. Seed priming is an alternative, low-cost, and feasible technique, which can improve drought stress tolerance through enhanced and advanced seed germination. Primed seeds can retain the memory of previous stress and enable protection against oxidative stress through earlier activation of the cellular defense mechanism, reduced imbibition time, upsurge of germination promoters, and osmotic regulation. However, a better understanding of the metabolic events during the priming treatment is needed to use this technology in a more efficient way. Interestingly, the review highlights the morphological, physiological, biochemical, and molecular responses of seed priming for enhancing the drought tolerance in crop plants. Furthermore, the challenges and opportunities associated with various priming methods are also addressed side-by-side to enable the use of this simple and cost-efficient technique in a more efficient manner.
Topics: Acclimatization; Crops, Agricultural; Dehydration; Droughts; Feasibility Studies; Germination; Seedlings; Seeds; Stress, Physiological
PubMed: 33158156
DOI: 10.3390/ijms21218258 -
Evolution; International Journal of... Aug 2022Developmental and adult environments can interact in complex ways to influence the fitness of individuals. Most studies investigating effects of the environment on...
Developmental and adult environments can interact in complex ways to influence the fitness of individuals. Most studies investigating effects of the environment on fitness focus on environments experienced and traits expressed at a single point in an organism's life. However, environments vary with time, so the effects of the environments that organisms experience at different ages may interact to affect how traits change throughout life. Here, we test whether thermal stress experienced during development leads individuals to cope better with thermal stress as adults. We manipulated temperature during both development and adulthood and measured a range of life-history traits, including senescence, in male and female seed beetles (Callosobruchus maculatus). We found that thermal stress during development reduced adult reproductive performance of females. In contrast, life span and age-dependent mortality were affected more by adult than developmental environments, with high adult temperatures decreasing longevity and increasing age-dependent mortality. Aside from an interaction between developmental and adult environments to affect age-dependent changes in male weight, we did not find any evidence of a beneficial acclimation response to developmental thermal stress. Overall, our results show that effects of developmental and adult environments can be both sex and trait specific, and that a full understanding of how environments interact to affect fitness and ageing requires the integrated study of conditions experienced during different stages of ontogeny.
Topics: Acclimatization; Aging; Animals; Coleoptera; Female; Hot Temperature; Male; Temperature
PubMed: 35819127
DOI: 10.1111/evo.14567 -
Ecology Letters Oct 2022Understanding the factors affecting thermal tolerance is crucial for predicting the impact climate change will have on ectotherms. However, the role developmental... (Review)
Review
Understanding the factors affecting thermal tolerance is crucial for predicting the impact climate change will have on ectotherms. However, the role developmental plasticity plays in allowing populations to cope with thermal extremes is poorly understood. Here, we meta-analyse how thermal tolerance is initially and persistently impacted by early (embryonic and juvenile) thermal environments by using data from 150 experimental studies on 138 ectothermic species. Thermal tolerance only increased by 0.13°C per 1°C change in developmental temperature and substantial variation in plasticity (~36%) was the result of shared evolutionary history and species ecology. Aquatic ectotherms were more than three times as plastic as terrestrial ectotherms. Notably, embryos expressed weaker but more heterogenous plasticity than older life stages, with numerous responses appearing as non-adaptive. While developmental temperatures did not have persistent effects on thermal tolerance overall, persistent effects were vastly under-studied, and their direction and magnitude varied with ontogeny. Embryonic stages may represent a critical window of vulnerability to changing environments and we urge researchers to consider early life stages when assessing the climate vulnerability of ectotherms. Overall, our synthesis suggests that developmental changes in thermal tolerance rarely reach levels of perfect compensation and may provide limited benefit in changing environments.
Topics: Acclimatization; Climate Change; Hot Temperature; Plastics; Temperature
PubMed: 36006770
DOI: 10.1111/ele.14083 -
The Journal of Physiology Dec 2022
Topics: Humans; Altitude; Adrenergic Agents; Acclimatization; Hemodynamics; Hypoxia; Regional Blood Flow
PubMed: 36314729
DOI: 10.1113/JP283688 -
The Journal of Experimental Biology Aug 2022Movement is essential in the ecology of most animals, and it typically consumes a large proportion of individual energy budgets. Environmental conditions modulate the... (Review)
Review
Movement is essential in the ecology of most animals, and it typically consumes a large proportion of individual energy budgets. Environmental conditions modulate the energetic cost of movement (cost of transport, COT), and there are pronounced differences in COT between individuals within species and across species. Differences in morphology affect COT, but the physiological mechanisms underlying variation in COT remain unresolved. Candidates include mitochondrial efficiency and the efficiency of muscle contraction-relaxation dynamics. Animals can offset increased COT behaviourally by adjusting movement rate and habitat selection. Here, we review the theory underlying COT and the impact of environmental changes on COT. Increasing temperatures, in particular, increase COT and its variability between individuals. Thermal acclimation and exercise can affect COT, but this is not consistent across taxa. Anthropogenic pollutants can increase COT, although few chemical pollutants have been investigated. Ecologically, COT may modify the allocation of energy to different fitness-related functions, and thereby influence fitness of individuals, and the dynamics of animal groups and communities. Future research should consider the effects of multiple stressors on COT, including a broader range of pollutants, the underlying mechanisms of COT and experimental quantifications of potential COT-induced allocation trade-offs.
Topics: Acclimatization; Animals; Ecosystem; Energy Metabolism; Environmental Pollutants; Mitochondria; Muscle Contraction
PubMed: 35942859
DOI: 10.1242/jeb.243646 -
Respiratory Physiology & Neurobiology Mar 2022The maximal rate of oxygen uptake (V̇Omax) of humans declines with increasing altitude, but represents the upper limit of aerobic endurance performance at low and high...
The maximal rate of oxygen uptake (V̇Omax) of humans declines with increasing altitude, but represents the upper limit of aerobic endurance performance at low and high altitude as well. Before Reinhold Messner and Peter Habeler climbed Mt. Everest first (1978) without supplemental oxygen, physiologists have doubted whether this would be possible due to insufficient V̇Omax remaining when approaching the summit (8849 m). Subsequently, several studies evaluated the decline in the V̇Omax levels at real and simulated extreme altitudes. However, the potential influence of the preexisting individual sea level V̇Omax remained largely unconsidered. Based on available studies and case observations, here we discuss the observed and expected decline of V̇Omax up to 8849 m dependent on the individual sea level V̇Omax. It is concluded that a high sea level V̇Omax and an only moderate decline of arterial oxygen saturation and associated V̇Omax with increasing altitude, due to appropriate acclimatization and ascent strategies, enable certain mountaineers to climb 8,000er summits and even the Everest without supplemental oxygen.
Topics: Acclimatization; Adult; Altitude; Humans; Male; Mountaineering; Oxygen Consumption
PubMed: 34952230
DOI: 10.1016/j.resp.2021.103833 -
Plant, Cell & Environment Jan 2022Interactions between climate change and UV penetration in the biosphere are resulting in the exposure of plants to new combinations of UV radiation and drought. In... (Meta-Analysis)
Meta-Analysis
Interactions between climate change and UV penetration in the biosphere are resulting in the exposure of plants to new combinations of UV radiation and drought. In theory, the impacts of combinations of UV and drought may be additive, synergistic or antagonistic. Lack of understanding of the impacts of combined treatments creates substantial uncertainties that hamper predictions of future ecological change. Here, we compiled information from 52 publications and analysed the relative impacts of UV and/or drought. Both UV and drought have substantial negative effects on biomass accumulation, plant height, photosynthesis, leaf area and stomatal conductance and transpiration, while increasing stress-associated symptoms such as MDA accumulation and reactive-oxygen-species content. Contents of proline, flavonoids, antioxidants and anthocyanins, associated with plant acclimation, are upregulated both under enhanced UV and drought. In plants exposed to both UV and drought, increases in plant defense responses are less-than-additive, and so are the damage and growth retardation. Less-than-additive effects were observed across field, glasshouse and growth-chamber studies, indicating similar physiological response mechanisms. Induction of a degree of cross-resistance seems the most likely interpretation of the observed less-than-additive responses. The data show that in future climates, the impacts of increases in drought exposure may be lessened by naturally high UV regimes.
Topics: Acclimatization; Biomass; Droughts; Photosynthesis; Plant Leaves; Plant Physiological Phenomena; Plant Stomata; Plant Transpiration; Ultraviolet Rays
PubMed: 34778989
DOI: 10.1111/pce.14221 -
Neuroscience Research Sep 2023Acclimation to temperature is one of the survival strategies used by organisms to adapt to changing environmental temperatures. Caenorhabditis elegans' cold tolerance is... (Review)
Review
Acclimation to temperature is one of the survival strategies used by organisms to adapt to changing environmental temperatures. Caenorhabditis elegans' cold tolerance is altered by previous cultivation temperature, and similarly, past low-temperature induces a longer lifespan. Temperature is thought to cause a large shift in homeostasis, lipid metabolism, and reproduction in the organism because it is a direct physiological factor during chemical events. This paper will share and discuss what we know so far about the neural and molecular mechanisms that control cold tolerance and lifespan by altering lipid metabolism and physiological characteristics. We hope that this will contribute to a better understanding of how organisms respond to temperature changes.
Topics: Animals; Temperature; Caenorhabditis elegans; Cold Temperature; Acclimatization; Adaptation, Physiological
PubMed: 37086751
DOI: 10.1016/j.neures.2023.04.005 -
International Journal of Molecular... Sep 2021Drought has become a major threat to food security, because it affects crop growth and development. Drought tolerance is an important quantitative trait, which is... (Review)
Review
Drought has become a major threat to food security, because it affects crop growth and development. Drought tolerance is an important quantitative trait, which is regulated by hundreds of genes in crop plants. In recent decades, scientists have made considerable progress to uncover the genetic and molecular mechanisms of drought tolerance, especially in model plants. This review summarizes the evaluation criteria for drought tolerance, methods for gene mining, characterization of genes related to drought tolerance, and explores the approaches to enhance crop drought tolerance. Collectively, this review illustrates the application prospect of these genes in improving the drought tolerance breeding of crop plants.
Topics: Acclimatization; Crops, Agricultural; Droughts; Genes, Plant; Phenotype; Plant Breeding; Plants, Genetically Modified; Quantitative Trait Loci
PubMed: 34638606
DOI: 10.3390/ijms221910265