Exploring key issues of aerobic scope interpretation in ectotherms: absolute versus factorial

Halsey, Lewis G.; Killen, Shaun S.; Clark, Timothy D.; Norin, Tommy

doi:10.1007/s11160-018-9516-3

Cited by 62 publications

(54 citation statements)

References 54 publications

(73 reference statements)

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“…All model assumptions were tested and verified, and the statistical results reported below are the values from the full models including all interactions. Our results for AAS (Table 2, Figure 2C) versus FAS (Supplementary Table 3, Supplementary Figure 1) are largely similar, and we only present the results for AAS, which is considered to be more informative and robust (Halsey et al 2018).…”

Section: Discussionsupporting

confidence: 52%

Multigenerational exposure to elevated temperatures leads to a reduction in standard metabolic rate in the wild

Pilakouta

Killen

Kristjánsson

et al. 2019

Preprint

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1. In light of global climate change, there is a pressing need to understand and predict the capacity of populations to respond to rising temperatures. Metabolic rate is a key trait that is likely to influence the ability to cope with climate change. Yet, empirical and theoretical work on metabolic rate responses to temperature changes has so far produced mixed results and conflicting predictions.2. Our study addresses this issue using a novel approach of comparing fish populations in geothermally warmed lakes and adjacent ambient-temperature lakes in Iceland. This unique 'natural experiment' provides repeated and independent examples of populationsexperiencing contrasting thermal environments for many generations over a small geographic scale, thereby avoiding the confounding factors associated with latitudinal or elevational comparisons. Using Icelandic sticklebacks from three warm and three cold habitats, we measured individual metabolic rates across a range of acclimation temperatures to obtain reaction norms for each population.3. We found a general pattern for a lower standard metabolic rate in sticklebacks from warm habitats when measured at a common temperature, as predicted by Krogh's rule.Metabolic rate differences between warm-and cold-habitat sticklebacks were more pronounced at more extreme acclimation temperatures, suggesting the release of cryptic genetic variation upon exposure to novel conditions, which can reveal hidden evolutionary potential. We also found a stronger divergence in metabolic rate between thermal habitats in allopatry than sympatry, indicating that gene flow may constrain physiological adaptation when dispersal between warm and cold habitats is possible. 3 4. In sum, our study suggests that fish may diverge toward a lower standard metabolic rate in a warming world, but this might depend on connectivity and gene flow between different thermal habitats.

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Section: Discussionsupporting

confidence: 52%

Multigenerational exposure to elevated temperatures leads to a reduction in standard metabolic rate in the wild

Pilakouta

Killen

Kristjánsson

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…All model assumptions were tested and verified, and the statistical results reported below are the values from the full models including all interactions. Our results for AAS (Table ; Figure c) versus FAS (Table S3; Figure S1) are largely similar, and we only present the results for AAS, which is considered to be more informative and robust (Halsey, Killen, Clark, & Norin, ).…”

Section: Methodsmentioning

confidence: 54%

Multigenerational exposure to elevated temperatures leads to a reduction in standard metabolic rate in the wild

et al. 2020

Self Cite

View full text Add to dashboard Cite

1. In light of global climate change, there is a pressing need to understand and predict the capacity of populations to respond to rising temperatures. Metabolic rate is a key trait that is likely to influence the ability to cope with climate change.Yet, empirical and theoretical work on metabolic rate responses to temperature changes has so far produced mixed results and conflicting predictions.2. Our study addresses this issue using a novel approach of comparing fish populations in geothermally warmed lakes and adjacent ambient-temperature lakes in Iceland. This unique 'natural experiment' provides repeated and independent examples of populations experiencing contrasting thermal environments for many generations over a small geographic scale, thereby avoiding the confounding factors associated with latitudinal or elevational comparisons. Using Icelandic sticklebacks from three warm and three cold habitats, we measured individual metabolic rates across a range of acclimation temperatures to obtain reaction norms for each population.3. We found a general pattern for a lower standard metabolic rate (SMR) in sticklebacks from warm habitats when measured at a common temperature, as predicted by Krogh's rule. Metabolic rate differences between warm-and cold-habitat sticklebacks were more pronounced at more extreme acclimation temperatures, suggesting the release of cryptic genetic variation upon exposure to novel conditions, which can reveal hidden evolutionary potential. We also found a stronger divergence in metabolic rate between thermal habitats in allopatry than sympatry, indicating that gene flow may constrain physiological adaptation when dispersal between warm and cold habitats is possible. 4. In sum, our study suggests that fish may diverge toward a lower SMR in a warming world, but this might depend on connectivity and gene flow between different thermal habitats. K E Y W O R D S climate change, countergradient variation, Gasterosteus aculeatus, Krogh's rule, metabolic cold adaptation, physiology, threespine stickleback 1206 | Functional Ecology PILAKOUTA eT AL.

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“…Conversely, increased maintenance metabolism costs would necessitate increased foraging success, which is already quite low in the study population 33 and an increased demand could lead to starvation 34 . Interestingly, supposed changes in ṀO 2Min were not reflected in absolute or factorial aerobic scope, possibly owing to variability in ṀO 2Min and ṀO 2Max and because FAS and AAS estimates were low relative to other fishes 35 . Whilst a lack of correlation between ṀO 2Min and ṀO 2Max across individuals is possible 36 , its absence suggests the possibility of measurement error, likely in ṀO 2Max for which best practice has not been established in sharks 37 .…”

Section: Discussionmentioning

confidence: 93%

The power struggle: assessing interacting global change stressors via experimental studies on sharks

Bouyoucos

Watson

Planes

et al. 2020

Sci Rep

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Ocean warming and acidification act concurrently on marine ectotherms with the potential for detrimental, synergistic effects; yet, effects of these stressors remain understudied in large predatory fishes, including sharks. We tested for behavioural and physiological responses of blacktip reef shark (Carcharhinus melanopterus) neonates to climate change relevant changes in temperature (28 and 31 °C) and carbon dioxide partial pressures (pCO2; 650 and 1050 µatm) using a fully factorial design. Behavioural assays (lateralisation, activity level) were conducted upon 7–13 days of acclimation, and physiological assays (hypoxia tolerance, oxygen uptake rates, acid–base and haematological status) were conducted upon 14–17 days of acclimation. Haematocrit was higher in sharks acclimated to 31 °C than to 28 °C. Significant treatment effects were also detected for blood lactate and minimum oxygen uptake rate; although, these observations were not supported by adequate statistical power. Inter-individual variability was considerable for all measured traits, except for haematocrit. Moving forward, studies on similarly ‘hard-to-study’ species may account for large inter-individual variability by increasing replication, testing larger, yet ecologically relevant, differences in temperature and pCO2, and reducing measurement error. Robust experimental studies on elasmobranchs are critical to meaningfully assess the threat of global change stressors in these data-deficient species.

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Exploring key issues of aerobic scope interpretation in ectotherms: absolute versus factorial

Cited by 62 publications

References 54 publications

Multigenerational exposure to elevated temperatures leads to a reduction in standard metabolic rate in the wild

Multigenerational exposure to elevated temperatures leads to a reduction in standard metabolic rate in the wild

Multigenerational exposure to elevated temperatures leads to a reduction in standard metabolic rate in the wild

The power struggle: assessing interacting global change stressors via experimental studies on sharks

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