Chill coma onset and recovery fail to reveal true variation in thermal performance among populations of Drosophila melanogaster

Davis, Hannah E.; Cheslock, Alexandra; MacMillan, Heath A.

doi:10.1038/s41598-021-90401-5

Cited by 15 publications

(9 citation statements)

References 51 publications

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“…[10,15,16,21]; table 1). Because different cold tolerance traits have different underlying mechanisms and vary in different ways among and within populations and lineages of Drosophila [3,7,33,34], we carried out our experiment twice using different metrics of thermotolerance: CCO and CCRT (figure 1).…”

Section: Introductionmentioning

confidence: 99%

A lack of repeatability creates the illusion of a trade-off between basal and plastic cold tolerance

2021

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The thermotolerance–plasticity trade-off hypothesis predicts that ectotherms with greater basal thermal tolerance have a lower acclimation capacity. This hypothesis has been tested at both high and low temperatures but the results often conflict. If basal tolerance constrains plasticity (e.g. through shared mechanisms that create physiological constraints), it should be evident at the level of the individual, provided the trait measured is repeatable. Here, we used chill-coma onset temperature and chill-coma recovery time (CCO and CCRT; non-lethal thermal limits) to quantify cold tolerance of Drosophila melanogaster across two trials (pre- and post-acclimation). Cold acclimation improved cold tolerance, as expected, but individual measurements of CCO and CCRT in non-acclimated flies were not (or only slightly) repeatable. Surprisingly, however, there was still a strong correlation between basal tolerance and plasticity in cold-acclimated flies. We argue that this relationship is a statistical artefact (specifically, a manifestation of regression to the mean; RTM) and does not reflect a true trade-off or physiological constraint. Thermal tolerance trade-off patterns in previous studies that used similar methodology are thus likely to be impacted by RTM. Moving forward, controlling and/or correcting for RTM effects is critical to determining whether such a trade-off or physiological constraint exists.

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Section: Introductionmentioning

confidence: 99%

A lack of repeatability creates the illusion of a trade-off between basal and plastic cold tolerance

2021

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“…[11,16,17,22]; Table 1). Because different cold tolerance traits have different underlying mechanisms and vary in different ways among and within populations and lineages of Drosophila [3,8,34,35], we carried out our experiment twice using different metrics of thermotolerance: chill-coma onset (CCO) and chill-coma recovery time (CCRT; Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

A lack of repeatability creates the illusion of a trade-off between basal and plastic cold tolerance

O’Neill

Davis

MacMillan

2021

Preprint

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The thermotolerance-plasticity trade-off hypothesis predicts that ectotherms with greater basal thermal tolerance have a lower acclimation capacity. This hypothesis has been tested at both high and low temperatures but the results often conflict. If basal tolerance constrains plasticity (e.g. through shared mechanisms that create physiological constraints), it should be evident at the level of the individual, provided the trait measured is repeatable. Here, we used chill-coma onset temperature and chill-coma recovery time (CCO and CCRT; non-lethal thermal limits) to quantify cold tolerance of [I]Drosophila melanogaster[/I] across two trials (pre- and post-acclimation). Cold acclimation improved cold tolerance, as expected, but individual measurements of CCO and CCRT in non-acclimated flies were not (or only slightly) repeatable. Surprisingly, however, there was still a strong correlation between basal tolerance and plasticity in cold-acclimated flies. We argue that this relationship is a statistical artefact (specifically, a manifestation of regression to the mean; RTM) and does not reflect a true trade-off or physiological constraint. Thermal tolerance trade-off patterns in previous studies that used similar methodology are thus likely to be impacted by RTM. Moving forward, controlling and/or correcting for RTM effects is critical to determining whether such a trade-off or physiological constraint truly exists.

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“…While data from the survival assays assists in determining the effects of cholesterol on D. melanogaster cold tolerance, measuring CCO and CCRT provides additional insight. Employing multiple cold tolerance metrics is useful as variation in one metric is not always associated with variation in others (Davis et al, 2021). We found no effect of a high cholesterol diet on either CCO or CCRT in D. melanogaster (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The mechanisms underlying different chill tolerance traits are related, but distinct, meaning these traits can vary independently (Davis et al, 2021). While CCO is caused by the silencing of neuromuscular signaling from temperature effects on ionoregulation in the central nervous system (Andersen and Overgaard, 2019), CCRT relates to recovery of this local ion balance as well as restoration of systemic ion homeostasis via the renal system (MacMillan et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Effects of a high cholesterol diet onDrosophilachill tolerance are highly context-dependent

Allen,

Ritchie,

El-Saadi

et al. 2023

Preprint

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Chill susceptible insects are thought to be injured through different mechanisms depending on the duration and severity of chilling. While chronic chilling causes “indirect” injury through disruption of metabolic and ion homeostasis, acute chilling is suspected to cause “direct” injury, in part through phase transitions of cell membrane lipids. Dietary supplementation of cholesterol can reduce acute chilling injury inDrosophila melanogaster, but the generality of this effect and the mechanisms underlying it remain unclear. To better understand how and why cholesterol has this effect, we assessed how a high cholesterol diet and thermal acclimation independently and interactively impact several measures of chill tolerance in both male and female flies. Cholesterol supplementation positively affected tolerance to acute chilling in warm-acclimated flies (as reported previously). Conversely, feeding on the high-cholesterol diet negatively affected tolerance to chronic chilling in both cold and warm acclimated flies, as well as tolerance to acute chilling in cold acclimated flies. Cholesterol had no effect on the ability of flies to remain active in the cold or recover movement after a cold stress. Our findings support the idea that dietary cholesterol reduces mechanical injury to membranes caused by direct chilling injury, and that acute and chronic chilling are associated with distinct mechanisms of injury. Feeding on a high-cholesterol diet may interfere with mechanisms involved in cold acclimation, leaving cholesterol augmented flies more susceptible to chilling injury under some conditions.HighlightsCholesterol improves cold shock tolerance of warm-acclimated fliesCold acclimation and chronic cold instead lead to negative effects of cholesterol on chill toleranceCholesterol did not affect the ability of flies to remain active in the coldBoth sexes were similarly affected by a high cholesterol diet

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Chill coma onset and recovery fail to reveal true variation in thermal performance among populations of Drosophila melanogaster

Cited by 15 publications

References 51 publications

A lack of repeatability creates the illusion of a trade-off between basal and plastic cold tolerance

A lack of repeatability creates the illusion of a trade-off between basal and plastic cold tolerance

A lack of repeatability creates the illusion of a trade-off between basal and plastic cold tolerance

Effects of a high cholesterol diet onDrosophilachill tolerance are highly context-dependent

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