1
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Fu C, Zhou KY, Hu Y, Zhang YF, Fu SJ. The effects of the predictability of acclimatory temperature on the growth and thermal tolerance of juvenile Spinibarbus sinensis. Comp Biochem Physiol A Mol Integr Physiol 2024; 295:111652. [PMID: 38703990 DOI: 10.1016/j.cbpa.2024.111652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 05/01/2024] [Accepted: 05/01/2024] [Indexed: 05/06/2024]
Abstract
Heated effluent injection, cold hypolimnetic water inputs from dams, and extreme weather events can lead to unpredictable temperature fluctuations in natural waters, impacting fish performance and fitness. We hypothesized that fish exposed to such unpredictable fluctuations would exhibit weaker growth and enhanced thermal tolerance compared to predictable conditions. Qingbo (Spinibarbus sinensis) was selected as the experimental subject in this study. The qingbo were divided into a constant temperature group (C, 22 ± 0.5 °C), a predictable temperature fluctuation group (PF, 22 ± 4 °C, first warming, then cooling within a day) and an unpredictable temperature fluctuation group (UF, 22 ± 4 °C, the order of warming or cooling is random). After 40 days of temperature acclimation, the growth, metabolic rate, spontaneous activity, thermal tolerance, plasma cortisol concentration and liver hsp70 level of the fish were measured. Unexpectedly, neither the PF nor the UF group showed decreased growth compared to the C group. This could be attributed to the fact that temperature variation did not lead to a substantial increase in basic energy expenditure. Furthermore, feeding rates increased due to temperature fluctuations, although the difference was not significant. Both the PF and UF groups exhibited increased upper thermal tolerance, but only the UF group exhibited improved lower thermal tolerance and higher liver hsp70 levels compared to the C group. The qingbo that experienced unpredictable temperature fluctuations had the best thermal tolerance among the 3 groups, which might have occurred because they had the highest level of hsp70 expression. This may safeguard fish against the potential lethal consequences of extreme temperatures in the future. These findings suggested that qingbo exhibited excellent adaptability to both predictable and unpredictable temperature fluctuations, which may be associated with frequent temperature fluctuations in its natural habitat.
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Affiliation(s)
- Cheng Fu
- Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Conservation and Utilization of Freshwater Fishes, Animal Biology Key Laboratory of Chongqing Education Commission, Chongqing Normal University, Chongqing 401331, China
| | - Ke-Ying Zhou
- Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Conservation and Utilization of Freshwater Fishes, Animal Biology Key Laboratory of Chongqing Education Commission, Chongqing Normal University, Chongqing 401331, China
| | - Yue Hu
- Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Conservation and Utilization of Freshwater Fishes, Animal Biology Key Laboratory of Chongqing Education Commission, Chongqing Normal University, Chongqing 401331, China
| | - Yong-Fei Zhang
- Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Conservation and Utilization of Freshwater Fishes, Animal Biology Key Laboratory of Chongqing Education Commission, Chongqing Normal University, Chongqing 401331, China
| | - Shi-Jian Fu
- Laboratory of Evolutionary Physiology and Behavior, Chongqing Key Laboratory of Conservation and Utilization of Freshwater Fishes, Animal Biology Key Laboratory of Chongqing Education Commission, Chongqing Normal University, Chongqing 401331, China.
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2
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Stocker CW, Bamford SM, Jahn M, Mazué GPF, Pettersen AK, Ritchie D, Rubin AM, Noble DWA, Seebacher F. The Effect of Temperature Variability on Biological Responses of Ectothermic Animals-A Meta-Analysis. Ecol Lett 2024; 27:e14511. [PMID: 39354891 DOI: 10.1111/ele.14511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 08/19/2024] [Accepted: 08/20/2024] [Indexed: 10/03/2024]
Abstract
Climate change is altering temperature means and variation, and both need to be considered in predictions underpinning conservation. However, there is no consensus in the literature regarding the effects of temperature fluctuations on biological functions. Fluctuations may affect biological responses because of inequalities from non-linear responses, endocrine regulation or exposure to damaging temperatures. Here we establish the current state of knowledge of how temperature fluctuations impact biological responses within individuals and populations compared to constant temperatures with the same mean. We conducted a meta-analysis of 143 studies on ectothermic animals (1492 effect sizes, 118 species). In this study, 89% of effect sizes were derived from diel cycles, but there were no significant differences between diel cycles and shorter (<8 h) or longer (>48 h) cycles in their effect on biological responses. We show that temperature fluctuations have little effect overall on trait mean and variance. Nonetheless, temperature fluctuations can be stressful: fluctuations increased 'gene expression' in aquatic animals, which was driven mainly by increased hsp70. Fluctuating temperatures also decreased longevity, and increased amplitudes had negative effects on population responses in aquatic organisms. We conclude that mean temperatures and extreme events such as heat waves are important to consider, but regular (particularly diel) temperature fluctuations are less so.
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Affiliation(s)
- Clayton W Stocker
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, New South Wales, Australia
| | - Stephanie M Bamford
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, New South Wales, Australia
| | - Miki Jahn
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, New South Wales, Australia
| | - Geoffrey P F Mazué
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, New South Wales, Australia
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Amanda K Pettersen
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, New South Wales, Australia
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Daniel Ritchie
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, New South Wales, Australia
| | - Alexander M Rubin
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, New South Wales, Australia
| | - Daniel W A Noble
- Division of Ecology and Evolution, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Frank Seebacher
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, New South Wales, Australia
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3
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Spence-Jones HC, Pein CM, Shama LNS. Intergenerational effects of ocean temperature variation: Early life benefits are short-lived in threespine stickleback. PLoS One 2024; 19:e0307030. [PMID: 39093894 PMCID: PMC11296643 DOI: 10.1371/journal.pone.0307030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 06/27/2024] [Indexed: 08/04/2024] Open
Abstract
Current climate change models predict an increase in temperature variability and extreme events such as heatwaves, and organisms need to cope with consequent changes to environmental variation. Non-genetic inheritance mechanisms can enable parental generations to prime their offspring's abilities to acclimate to environmental change-but they may also be deleterious. When parents are exposed to predictable environments, intergenerational plasticity can lead to better offspring trait performance in matching environments. Alternatively, parents exposed to variable or unpredictable environments may use plastic bet-hedging strategies to adjust the phenotypic variance among offspring. Here, we used a model species, the threespine stickleback (Gasterosteus aculeatus), to test whether putatively adaptive intergenerational effects can occur in response to shifts in environmental variation as well as to shifts in environmental mean, and whether parents employ plastic bet-hedging strategies in response to increasing environmental variation. We used a full-factorial, split-clutch experiment with parents and offspring exposed to three temperature regimes: constant, natural variation, and increased variation. We show that within-generation exposure to increased temperature variation reduces growth of offspring, but having parents that were exposed to natural temperature variation during gametogenesis may offset some early-life negative growth effects. However, these mitigating intergenerational effects do not appear to persist later in life. We found no indication that stickleback mothers plastically altered offspring phenotypic variance (egg size or clutch size) in response to temperature variation. However, lower inter-individual variance of juvenile fish morphology in offspring of increased variation parents may imply the presence of conservative bet-hedging strategies in natural populations. Overall, in our experiment, parental exposure to temperature variation had limited effects on offspring fitness-related traits. Natural levels of environmental variation promoted a potentially adaptive intergenerational response in early life development, but under more challenging conditions associated with increased environmental variation, the effect was lost.
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Affiliation(s)
- Helen Clare Spence-Jones
- Coastal Ecology Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, List, Germany
| | - Carla M. Pein
- Coastal Ecology Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, List, Germany
| | - Lisa N. S. Shama
- Coastal Ecology Section, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, List, Germany
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4
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Jacob S, Dupont L, Haegeman B, Thierry M, Campana JLM, Legrand D, Cote J, Raffard A. Phenotypic plasticity and the effects of thermal fluctuations on specialists and generalists. Proc Biol Sci 2024; 291:20240256. [PMID: 38889786 DOI: 10.1098/rspb.2024.0256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 04/17/2024] [Indexed: 06/20/2024] Open
Abstract
Classical theories predict that relatively constant environments should generally favour specialists, while fluctuating environments should be selected for generalists. However, theoretical and empirical results have pointed out that generalist organisms might, on the contrary, perform poorly under fluctuations. In particular, if generalism is underlaid by phenotypic plasticity, performance of generalists should be modulated by the temporal characteristics of environmental fluctuations. Here, we used experiments in microcosms of Tetrahymena thermophila ciliates and a mathematical model to test whether the period or autocorrelation of thermal fluctuations mediate links between the level of generalism and the performance of organisms under fluctuations. In the experiment, thermal fluctuations consistently impeded performance compared with constant conditions. However, the intensity of this effect depended on the level of generalism: while the more specialist strains performed better under fast or negatively autocorrelated fluctuations, plastic generalists performed better under slow or positively autocorrelated fluctuations. Our model suggests that these effects of fluctuations on organisms' performance may result from a time delay in the expression of plasticity, restricting its benefits to slow enough fluctuations. This study points out the need to further investigate the temporal dynamics of phenotypic plasticity to better predict its fitness consequences under environmental fluctuations.
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Affiliation(s)
- Staffan Jacob
- Station d'Écologie Théorique et Expérimentale, UAR2029, CNRS, Moulis 09200, France
| | - Léonard Dupont
- Station d'Écologie Théorique et Expérimentale, UAR2029, CNRS, Moulis 09200, France
| | - Bart Haegeman
- CNRS/Sorbonne Université, UMR7621 Laboratoire d'Océanographie Microbienne, Banyuls-sur-Mer, France
| | - Mélanie Thierry
- Station d'Écologie Théorique et Expérimentale, UAR2029, CNRS, Moulis 09200, France
| | - Julie L M Campana
- Station d'Écologie Théorique et Expérimentale, UAR2029, CNRS, Moulis 09200, France
| | - Delphine Legrand
- Station d'Écologie Théorique et Expérimentale, UAR2029, CNRS, Moulis 09200, France
| | - Julien Cote
- Centre de Recherche sur la Biodiversité et l'Environnement (CRBE), UMR 5300, CNRS-IRD-TINP-UT3, Toulouse 31062 Cedex 9, France
| | - Allan Raffard
- Université catholique de Louvain, Earth and Life Institute, Biodiversity Research Centre, Louvain-la-Neuve, Belgium
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5
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Dupont L, Thierry M, Zinger L, Legrand D, Jacob S. Beyond reaction norms: the temporal dynamics of phenotypic plasticity. Trends Ecol Evol 2024; 39:41-51. [PMID: 37718228 DOI: 10.1016/j.tree.2023.08.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 08/21/2023] [Accepted: 08/24/2023] [Indexed: 09/19/2023]
Abstract
Phenotypic plasticity can allow organisms to cope with environmental changes. Although reaction norms are commonly used to quantify plasticity along gradients of environmental conditions, they often miss the temporal dynamics of phenotypic change, especially the speed at which it occurs. Here, we argue that studying the rate of phenotypic plasticity is a crucial step to quantify and understand its adaptiveness. Iteratively measuring plastic traits allows us to describe the actual dynamics of phenotypic changes and avoid quantifying reaction norms at times that do not truly reflect the organism's capacity for plasticity. Integrating the temporal component in how we describe, quantify, and conceptualise phenotypic plasticity can change our understanding of its diversity, evolution, and consequences.
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Affiliation(s)
- Léonard Dupont
- Station d'Ecologie Théorique et Expérimentale, UAR2029, CNRS, 09200, Moulis, France.
| | - Mélanie Thierry
- Station d'Ecologie Théorique et Expérimentale, UAR2029, CNRS, 09200, Moulis, France
| | - Lucie Zinger
- Institut de Biologie de l'ENS (IBENS), Département de Biologie, École Normale Supérieure, CNRS, INSERM, Université PSL, 75005 Paris, France; Naturalis Biodiversity Center, 2300 RA Leiden, The Netherlands
| | - Delphine Legrand
- Station d'Ecologie Théorique et Expérimentale, UAR2029, CNRS, 09200, Moulis, France
| | - Staffan Jacob
- Station d'Ecologie Théorique et Expérimentale, UAR2029, CNRS, 09200, Moulis, France
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6
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A framework to understand the role of biological time in responses to fluctuating climate drivers. Sci Rep 2022; 12:10429. [PMID: 35729311 PMCID: PMC9213464 DOI: 10.1038/s41598-022-13603-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 05/09/2022] [Indexed: 11/08/2022] Open
Abstract
Understanding biological responses to environmental fluctuations (e.g. heatwaves) is a critical goal in ecology. Biological responses (e.g. survival) are usually measured with respect to different time reference frames, i.e. at specific chronological times (e.g. at specific dates) or biological times (e.g. at reproduction). Measuring responses on the biological frame is central to understand how environmental fluctuation modifies fitness and population persistence. We use a framework, based on partial differential equations (PDEs) to explore how responses to the time scale and magnitude of fluctuations in environmental variables (= drivers) depend on the choice of reference frame. The PDEs and simulations enabled us to identify different components, responsible for the phenological and eco-physiological effects of each driver on the response. The PDEs also highlight the conditions when the choice of reference frame affects the sensitivity of the response to a driver and the type of join effect of two drivers (additive or interactive) on the response. Experiments highlighted the importance of studying how environmental fluctuations affect biological time keeping mechanisms, to develop mechanistic models. Our main result, that the effect of the environmental fluctuations on the response depends on the scale used to measure time, applies to both field and laboratory conditions. In addition, our approach, applied to experimental conditions, can helps us quantify how biological time mediates the response of organisms to environmental fluctuations.
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7
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Gurgel-Lourenço RC, de S Rodrigues-Filho CA, de Oliveira Araújo PV, Sánchez-Botero JI. Phenotypic variation among silverside populations (Atherinopsidae: Atherinella brasiliensis) from distinct environments in Northeastern Brazil. ZOOLOGY 2021; 150:125981. [PMID: 34814095 DOI: 10.1016/j.zool.2021.125981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 10/31/2021] [Accepted: 11/09/2021] [Indexed: 11/16/2022]
Abstract
The successful adaptation of populations to a wide range of environments is a central topic in ecology. Based on the assumption that body shape may affect survival, we evaluated to what extent biotic and abiotic factors are capable of inducing morphological changes in Brazilian silverside populations (Atherinella brasiliensis). To reach this goal, we compared 18 morphological traits of specimens from five ecosystems representing three types of environment (estuary, coastal lagoon, reservoir). Populations from estuaries displayed greater anal fin area and greater caudal fin aspect ratio and area. Populations from coastal lagoons had more compressed bodies, larger heads, and slightly broader caudal peduncles. The fish from estuaries and coastal lagoons had longer caudal peduncles, larger pelvic fins and larger eye area. Population from reservoir had more depressed bodies and greater oral protrusion. Food availability explained 31% of the observed ecomorphological patterns. Overall, the morphology of the respective populations was consistent with each type of environment, making it possible to associate phenotypic variation with habitat and feeding patterns, although abiotic factors were more significant than biotic factors. In conclusion, landlocked populations of A. brasiliensis are sustainable and add to current knowledge of phenotypical variability in a species widely distributed along the Western Atlantic coast.
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Affiliation(s)
- Ronaldo C Gurgel-Lourenço
- Pós-graduação em Ciências Marinhas Tropicais, Instituto de Ciências do Mar - Labomar, Universidade Federal do Ceará - UFC, Av. da Abolição 3207, 60165-081, Fortaleza, CE, Brazil.
| | - Carlos A de S Rodrigues-Filho
- Pós-graduação em Ecologia, Conservação e Manejo da Vida Silvestre, Departamento de Genética, Ecologia e Evolução, Universidade Federal de Minas Gerais - UFMG, Av. Presidente Antônio Carlos 6627, 31270-910, Belo Horizonte, MG, Brazil.
| | | | - Jorge I Sánchez-Botero
- Departamento de Biologia, Campus do Pici, Universidade Federal do Ceará - UFC, 60440-900, Fortaleza, CE, Brazil.
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8
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March-Salas M, Fandos G, Fitze PS. Effects of intrinsic environmental predictability on intra-individual and intra-population variability of plant reproductive traits and eco-evolutionary consequences. ANNALS OF BOTANY 2021; 127:413-423. [PMID: 32421780 PMCID: PMC7988524 DOI: 10.1093/aob/mcaa096] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 05/14/2020] [Indexed: 05/22/2023]
Abstract
BACKGROUND AND AIMS It is widely accepted that changes in the environment affect mean trait expression, but little is known about how the environment shapes intra-individual and intra-population variance. Theory suggests that intra-individual variance might be plastic and under natural selection, rather than reflecting developmental noise, but evidence for this hypothesis is scarce. Here, we experimentally tested whether differences in intrinsic environmental predictability affect intra-individual and intra-population variability of different reproductive traits, and whether intra-individual variability is under selection. METHODS Under field conditions, we subjected Onobrychis viciifolia to more and less predictable precipitation over 4 generations and 4 years. We analysed effects on the coefficient of intra-individual variation (CVi-i) and the coefficient of intra-population variation (CVi-p), assessed whether the coefficients of intra-individual variation (CsVi-i) are under natural selection and tested for transgenerational responses (ancestor environmental effects on offspring). KEY RESULTS Less predictable precipitation led to higher CsVi-i and CsVi-p, consistent with plastic responses. The CsVi-i of all studied traits were under consistent stabilizing selection, and precipitation predictability affected the strength of selection and the location of the optimal CVi-i of a single trait. All CsVi-i differed from the optimal CVi-i and the maternal and offspring CsVi-i were positively correlated, showing that there was scope for change. Nevertheless, no consistent transgenerational effects were found in any of the three descendant generations, which contrasts with recent studies that detected rapid transgenerational responses in the trait means of different plant species. This suggests that changes in intra-individual variability take longer to evolve than changes in trait means, which may explain why high intra-individual variability is maintained, despite the stabilizing selection. CONCLUSIONS The results indicate that plastic changes of intra-individual variability are an important determinant of whether plants will be able to cope with changes in environmental predictability induced by the currently observed climatic change.
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Affiliation(s)
- Martí March-Salas
- Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutiérrez Abascal, Madrid, Spain
- Department of Biodiversity and Ecologic Restoration, Instituto Pirenaico de Ecología (IPE-CSIC), Avda. Nuestra Señora de la Victoria, Jaca, Spain
- For correspondence. E-mail or
| | - Guillermo Fandos
- Department of Geography, Humboldt-Universität zu Berlin, Rudower Chaussee, Berlin, Germany
| | - Patrick S Fitze
- Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales (MNCN-CSIC), José Gutiérrez Abascal, Madrid, Spain
- Department of Biodiversity and Ecologic Restoration, Instituto Pirenaico de Ecología (IPE-CSIC), Avda. Nuestra Señora de la Victoria, Jaca, Spain
- For correspondence. E-mail or
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Burton T, Einum S. The old and the large may suffer disproportionately during episodes of high temperature: evidence from a keystone zooplankton species. CONSERVATION PHYSIOLOGY 2020; 8:coaa038. [PMID: 32411372 PMCID: PMC7210711 DOI: 10.1093/conphys/coaa038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/05/2020] [Accepted: 04/15/2020] [Indexed: 06/11/2023]
Abstract
Widespread declines in the body size of aquatic ectotherms have been attributed to the poorer ability of older, larger individuals to tolerate high temperature. Here, using the thermal death time curve framework, we investigate the relationship between temperature tolerance and size/age by measuring the change in heat tolerance of the keystone zooplankton species Daphnia magna across a range of temperature intensities (and hence exposures of varying duration) among individuals that differed up to 3-fold in size and thus varied in age also. Across the gradient of exposure temperatures, younger, smaller individuals were more tolerant than older, larger individuals. This suggests that the young and the small may be better equipped to withstand temperature challenges that are both intense/brief and more moderate/prolonged. Our study generalizes results obtained from more acute tolerance assays, providing physiological evidence consistent with the observed reductions in ectotherm body size as a response to warming in aquatic systems.
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Affiliation(s)
- Tim Burton
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491 Trondheim, Norway
| | - Sigurd Einum
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491 Trondheim, Norway
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Burton T, Lakka HK, Einum S. Acclimation capacity and rate change through life in the zooplankton Daphnia. Proc Biol Sci 2020; 287:20200189. [PMID: 32228409 PMCID: PMC7209067 DOI: 10.1098/rspb.2020.0189] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 03/10/2020] [Indexed: 12/26/2022] Open
Abstract
When a change in the environment occurs, organisms can maintain an optimal phenotypic state via plastic, reversible changes to their phenotypes. These adjustments, when occurring within a generation, are described as the process of acclimation. While acclimation has been studied for more than half a century, global environmental change has stimulated renewed interest in quantifying variation in the rate and capacity with which this process occurs, particularly among ectothermic organisms. Yet, despite the likely ecological importance of acclimation capacity and rate, how these traits change throughout life among members of the same species is largely unstudied. Here we investigate these relationships by measuring the acute heat tolerance of the clonally reproducing zooplankter Daphnia magna of different size/age and acclimation status. The heat tolerance of individuals completely acclimated to relatively warm (28°C) or cool (17°C) temperatures diverged during development, indicating that older, larger individuals had a greater capacity to increase heat tolerance. However, when cool acclimated individuals were briefly exposed to the warm temperature (i.e. were 'heat-hardened'), it was younger, smaller animals with less capacity to acclimate that were able to do so more rapidly because they obtained or came closer to obtaining complete acclimation of heat tolerance. Our results illustrate that within a species, individuals can differ substantially in how rapidly and by how much they can respond to environmental change. We urge greater investigation of the intraspecific relationship between acclimation and development along with further consideration of the factors that might contribute to these enigmatic patterns of phenotypic variation.
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Affiliation(s)
- Tim Burton
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491 Trondheim, Norway
| | - Hanna-Kaisa Lakka
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491 Trondheim, Norway
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Sigurd Einum
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Realfagbygget, NO-7491 Trondheim, Norway
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