Validating measurements of acclimation for climate change adaptation

Terblanche, John S.; Hoffmann, Ary A.

doi:10.1016/j.cois.2020.04.005

Cited by 46 publications

(53 citation statements)

References 71 publications

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“…Critical limits are a widely used metric for assessing the vulnerability of organisms to climate change. Yet, methodology strongly affects outcomes; for example, fast ramping rates or high start temperatures can result in higher CT max estimates [47]. Our study highlights the importance of flow in influencing thermal limits and suggests that higher flows may raise estimated values of CT max .…”

Section: Discussionmentioning

confidence: 86%

Flow increases tolerance of heat and hypoxia of an aquatic insect

et al. 2021

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Recent experiments support the idea that upper thermal limits of aquatic insects arise, at least in part, from a lack of sufficient oxygen: rising temperatures typically stimulate metabolic demand for oxygen more than they increase rates of oxygen supply from the environment. Consequently, factors influencing oxygen supply, like water flow, should also affect thermal and hypoxia tolerance. We tested this hypothesis by measuring the effects of experimentally manipulated flows on the heat and hypoxia tolerance of aquatic nymphs of the giant salmonfly (Plecoptera: Pteronarcys californica ), a common stonefly in western North America. As predicted, stoneflies in flowing water (10 cm s −1 ) tolerated water that was approximately 4°C warmer and that contained approximately 15% less oxygen than did those in standing water. Our results imply that the impacts of climate change on streamflow, such as changes in patterns of precipitation and decreased snowpack, will magnify the threats to aquatic insects from warmer water temperatures and lower oxygen levels.

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Section: Discussionmentioning

confidence: 86%

Flow increases tolerance of heat and hypoxia of an aquatic insect

et al. 2021

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“…Acclimation and other kinds of physiological plasticity are likely to play an important role in reducing the short-and long-term effects, thereby increasing species resilience towards urbanisation. Despite the high interest in plasticity, studies of urban physiology (like most urban ecology studies) mainly use effect size analyses and summary statistics between urban and non-urban sites, which obscure the potential to explore the underlying variance across different contexts (see Terblanche and Hoffmann, 2020). Cross-fostering, common garden and translocation studies would also be useful for understanding both the capacities for plasticity across naïve and pre-exposed individuals and populations, and the underlying mechanism(s) behind the variation (i.e.…”

Section: Physiological Plasticity: Chronic and Acute Responsesmentioning

confidence: 99%

Urban ecophysiology: beyond costs, stress and biomarkers

Isaksson

2020

Journal of Experimental Biology

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Natural habitats are rapidly declining due to urbanisation, with a concomitant decline in biodiversity in highly urbanised areas. Yet thousands of different species have colonised urban environments. These organisms are exposed to novel urban conditions, which are sometimes beneficial, but most often challenging, such as increased ambient temperature, chemicals, noise and light pollution, dietary alterations and disturbance by humans. Given the fundamental role of physiological responses in coping with such conditions, certain physiological systems such as the redox system, metabolism and hormones are thought to specifically influence organisms’ ability to persist and cope with urbanisation. However, these physiological systems often show mixed responses to urbanisation. Does this mean that some individuals, populations or species are resilient to the urban environmental challenges? Or is something missing from our analyses, leading us to erroneous conclusions regarding the impact of urbanisation? To understand the impact of urbanisation, I argue that a more integrated mechanistic and ecological approach is needed, along with experiments, in order to fully understand the physiological responses; without knowledge of their ecological and evolutionary context, physiological measures alone can be misinterpreted. Furthermore, we need to further investigate the causes of and capacity for individual plasticity in order to understand not only the impact of urbanisation, but also species resilience. I argue that abiotic and biotic urban factors can interact (e.g. pollution with micro- and macronutrients) to either constrain or relax individual physiological responses – and, thereby, plasticity – on a temporal and/or spatial scale, which can lead to erroneous conclusions regarding the impact of urbanisation.

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“…of 0.25 • C/min, a rate that is thought to be more ecologically relevant than a higher rate although still faster than diurnal rates of air temperature change (Chown et al, 2009;Nyamukondiwa and Terblanche, 2010), with frequent checking for the onset of spasms and the loss of righting response (no response to stimuli), using the latter for the comparative analysis. The start temperature was set at 22.5 • C for 10 mins (intermediate between the two acclimation temperatures of 20 • C and 26 • C) so that the ramping rate was exactly the same between individuals acclimated at different temperatures and avoiding the confounding effect of starting from a different baseline condition that might artificially elevate measures of the plastic response (Terblanche and Hoffmann, 2020). Typically we used 9-10 individuals per acclimation temperature and critical thermal measured (or more when possible), even though for one population of C. hottentotus we could only obtain 5-6 individuals for each measurement (Table 2).…”

Section: Thermal Baths and Critical Thermal Limitsmentioning

confidence: 99%

“…For example, it is well established that the thermal limit assay endpoints (e.g. choice of behavioural metric, like heat coma or muscle spasms), and variation in assay methods such as ramping rate and start conditions, can readily influence tolerance estimates and the magnitude of plasticity (reviewed recently in Terblanche and Hoffmann, 2020).…”

Section: Tablementioning

confidence: 99%

Geographic variation in acclimation responses of thermal tolerance in South African diving beetles (Dytiscidae: Coleoptera)

Hidalgo‐Galiana

Ribera

Terblanche

2021

Comparative Biochemistry and Physiology Part A: Molecular &

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Understanding sources of variation in animal thermal limits is critical to forecasting ecological responses to climate change. Here, we estimated upper and lower thermal limits, and their capacity to respond to thermal acclimation, in several species and populations of diving beetles (Dytiscidae) from diverse geographic regions representative of variable climate within South Africa. We also considered ecoregions and latitudinal ranges as potential predictors of thermal limits and the plasticity thereof. For upper thermal limits, species showed significant variation and limited acclimation-related plasticity. Lower thermal limits responded to acclimation in some cases and showed marked variation among species that could be explained by taxonomic affiliation and ecoregion. Limited acclimation ability in the species included in this study suggest plasticity of thermal limits will not be a likely buffer for coping with climate change. From the present results for the Dytiscidae of the region, it appears the group may be particularly susceptible to heat and/or drought and may thus serve as useful indicator species of ecosystem change. Understanding how these climate-related impacts play out at different spatial and temporal scales will have profound implications for conservation management and functional responses, especially important in a region already showing a trend for warming and drying.

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Validating measurements of acclimation for climate change adaptation

Cited by 46 publications

References 71 publications

Flow increases tolerance of heat and hypoxia of an aquatic insect

Flow increases tolerance of heat and hypoxia of an aquatic insect

Urban ecophysiology: beyond costs, stress and biomarkers

Geographic variation in acclimation responses of thermal tolerance in South African diving beetles (Dytiscidae: Coleoptera)

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