Temperature, Demography, and Ectotherm Fitness

Huey,; Berrigan, None

doi:10.2307/3079165

Cited by 70 publications

(79 citation statements)

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“…Therefore, a full demographic model will be necessary to evaluate the overall effects of warming. However, because thermal fitness curves are asymmetric (Gilchrist 1995;Huey & Berrigan 2001), being 'too hot' is likely to be much worse physiologically than being 'too cold'.…”

Section: Resultsmentioning

confidence: 99%

Why tropical forest lizards are vulnerable to climate warming

et al. 2009

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Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied. We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto Rican Anolis and Sphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low.

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Section: Resultsmentioning

confidence: 99%

Why tropical forest lizards are vulnerable to climate warming

et al. 2009

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“…7). Moreover, differences in E may reflect the nature of the traits themselves: for example, indices of population growth (intrinsic rate of population growth vs. net reproductive rate) have different temperature sensitivities, even when calculated from the exact same demographic data (19). Other potential sources of variability in E will no doubt open for exploration in this rich, diverse dataset.…”

Section: Perspective and Conclusionmentioning

confidence: 99%

Variation in universal temperature dependence of biological rates

Huey

Kingsolver

2011

Proc. Natl. Acad. Sci. U.S.A.

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F or more than a century, biologists have known that body temperature strongly affects the capacities and rates of organisms and thus is a key determinant of organismal performance and Darwinian fitness (1-3). Although rate/temperature (RT) relationships have been quantified for many traits and taxa, interest in RT studies is being revitalized because RT relationships are relevant to predicting biological responses to climate warming (4), as well as to testing the metabolic theory of ecology (MTE), a thermodynamic model of the impacts of body size, temperature, and metabolism on broad-scale biological patterns (5, 6). In PNAS, Dell et al. (7) present a massive compilation of RT data, evaluate quantitative predictions of MTE, and analyze systematic patterns of variation in temperature sensitivity. Their findings both support and challenge MTE, and their analyses will prompt new insights into systematic variation in temperature sensitivity of biological traits. Thermodynamics and Organismal RatesOne of the first quantitative studies of thermal sensitivity was published in PNAS in 1920 by the legendary astronomer Harlow Shapley (8). He showed that walking speed of ants increased directly and predictably with temperature, at least to some "optimal" or maximum-activity temperature. In fact, he could predict air temperature to within 1°C, merely by measuring ant walking speed! He noted (8) that ant activity should be governed by the same physical processes (e.g., temperature) that control chemical and metabolic interactions. Then, in a second PNAS article on ant "thermokinetics" (9), he found that ant thermal sensitivity was consistent with thermodynamic [i.e., BoltzmannArrhenius (BA)] expectations. Thus, a thermodynamic basis of organismal RT relationships is longstanding. Interestingly, Shapley (10) later commented, "One of the most interesting points I have gathered in my scientific career is the speed at which one particular kind of ant will run with a rising temperature."Fast forward to the 21st century, when proponents of MTE began formalizing the thermodynamic bases for RT relationships (5, 6). They argued (5, 6) the thermal sensitivity of diverse activities can be described by simple BA kinetics (equation 1 in ref. 7), in which the log of a rate is linearly related to the inverse of absolute temperature with slope E ("activation energy"). Their empirical studies showed an E value of approximately 0.65 eV in several interspecific comparisons, suggesting that E had a universal thermal dependence (UTD) for many biological rates of diverse organisms. Nevertheless, other interspecific and intraspecific comparisons have challenged UTD on empirical and conceptual grounds (3,(11)(12)(13). In the aforementioned new study in PNAS, Dell et al. (7) substantially advance this debate by synthesizing and analyzing data on 1,072 thermal sensitivities (on a within-species basis) of diverse physiological and ecological traits (n = 112) in 309 species (plants, microbes, animals) from land, sea, and air.For RT relationships, Dell...

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“…This is especially true for ectotherms like desert tortoises that need to self-regulate their body temperature behaviorally and in response to environmental conditions (Zimmerman et al 1994). As a result, they and other ectotherms, are particularly sensitive to climatic variation (Barrows 2011) due possibly to fitness consequences imposed by varying environmental temperatures (Huey & Berrigan 2001). Phenology is the study of the timing and environmental causes, both biotic and abiotic, of recurring biological events in life cycles (Mitchell 1979, Stenseth & Mysterud 2002, and perhaps the simplest indicator of ecological responses to climate change (Walther et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Climatic variation affects clutch phenology in Agassiz’s desert tortoise Gopherus agassizii

Lovich¹,

Agha²,

Meulblok³

et al. 2012

Endang. Species. Res.

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There is concern about how climate change might affect Agassiz's desert tortoise Gopherus agassizii, a threatened species. We studied the effects of climatic variation on clutch phenology of a population at a wind energy generation facility for 7 field seasons between 1997 and 2011. Using X-radiography, we quantified the following phenophases based on the number of calendar days to each event from 1 January: appearance and disappearance of 65 first and 53 second clutches, and inter-clutch intervals between first and second clutches. Although third clutches were rare (n = 8), they were observed in 5 of 7 yr and were produced by 8 different females, all of which produced a third clutch only once during the study. Shelled eggs were visible from as early as 11 April to as late as 28 July, and the overall time span that eggs were visible differed among years. After controlling for maternal effects, we observed statistically significant inter-annual variation in all phenophases except for inter-clutch interval. Clutch appearance was late in cool years relative to warm years and especially late after 2 consecutive cool years. Using degree day (DD) methodology, we calculated DD accumulation during the post-hibernation and nesting season for each year. We then used DD estimates for mean date of first clutch appearance to predict the mean date of first clutch appearance in subsequent years with 1 to 10 d accuracy for all but 1 yr (1998) with El Niño conditions. Clutch phenology appears to be correlated with inter-annual variation in climate and may be influenced by climatic events in previous years.

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Temperature, Demography, and Ectotherm Fitness

Cited by 70 publications

References 1 publication

Why tropical forest lizards are vulnerable to climate warming

Why tropical forest lizards are vulnerable to climate warming

Variation in universal temperature dependence of biological rates

Climatic variation affects clutch phenology in Agassiz’s desert tortoise Gopherus agassizii

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