The thermal limits to life on Earth

Clarke, Andrew

doi:10.1017/s1473550413000438

Cited by 117 publications

(86 citation statements)

References 120 publications

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“…A more biologically sound approach would be to measure the thermal thresholds at which cell, membrane or protein damage occurs by means of molecular biomarkers, and to validate how the former relate to the wide variety of metrics of heat and cold tolerance, among which CT max and CT min are just one option (Clusella-Trullas & Chown, 2014;Sinclair et al, 2016). These developments are occurring in the fields of comparative physiology (Somero, 2011) and extremophile biology (Clarke, 2014) and await incorporation in (macro)ecological and physiological research integrating the molecular, cellular and whole-organism levels of biological organization (Pörtner et al, 2006). Overall, those efforts could shed light on a conceptually fundamental question that has been surprisingly poorly tested when it comes to correlating behaviour, physiology and life history (Montiglio, Dammhahn, Dubuc Messier, & Réale, 2018): are thermal tolerances truly individual, population and/or species traits?…”

Section: Discussionmentioning

confidence: 99%

Heat tolerance is more variable than cold tolerance across species of Iberian lizards after controlling for intraspecific variation

et al. 2020

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The widespread observation that heat tolerance is less variable than cold tolerance (‘cold‐tolerance asymmetry’) leads to the prediction that species exposed to temperatures near their thermal maxima should have reduced evolutionary potential for adapting to climate warming. However, the prediction is largely supported by species‐level global studies based on single estimates of both physiological metrics per taxon. We ask whether cold‐tolerance asymmetry holds for Iberian lizards after accounting for intraspecific variation in critical thermal maxima (CTmax) and minima (CTmin). To do so, we quantified CTmax and CTmin for 58 populations of 15 Iberian lizard species (299 individuals). Then, we randomly selected one population from each study species (population sample = 15 CTmax and CTmin values), tested for differences between the variance of both thermal metrics across species, and repeated the test for thousands of population samples as if we had undertaken the same study thousands of times, each time sampling one different population per species (as implemented in global studies). The ratio of variances in CTmax to CTmin across species varied up to 16‐fold depending on the populations chosen. Variance ratios show how much CTmax departs from the cross‐species mean compared to CTmin, with a unitary ratio indicating equal variance of both thermal limits. Sampling one population per species was six times more likely to result in the observation of greater CTmax variance (‘heat‐tolerance asymmetry’) than cold‐tolerance asymmetry. The probability of obtaining the data (given the null hypothesis of equal variance being true) was twice as likely for cases of cold‐tolerance asymmetry than for the opposite scenario. Range‐wide, population‐level studies that quantify heat and cold tolerance of individual species are urgently needed to ascertain the global prevalence of cold‐tolerance asymmetry. While broad latitudinal clines of cold tolerance have been strongly supported, heat tolerance might respond to smaller‐scale climatic and habitat factors hence go unnoticed in global studies. Studies investigating physiological responses to climate change should incorporate the extent to which thermal traits are characteristic of individuals, populations and/or species. A free Plain Language Summary can be found within the Supporting Information of this article.

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Section: Discussionmentioning

confidence: 99%

Heat tolerance is more variable than cold tolerance across species of Iberian lizards after controlling for intraspecific variation

et al. 2020

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“…(iii) Active metabolism We make a distinction between life with active metabolism and organisms that can survive without growth and reproduction (e.g., Stan-Lotter 2007). We restrict our attention to environments that allow organisms to have an active metabolism and to complete their life cycle (Clarke 2014). An active metabolism is required to create the chemical disequilibrium that defines atmospheric biosignatures.…”

Section: (I) Surface Habitabilitymentioning

confidence: 99%

“…However, the experimental data on the temperature limits for the completion of the life cycle, T L , are not particularly abundant, especially for complex life, and are spread in a large number of papers (see, e.g., Precht 1973). Here we use a recent review work by Clarke (2014) as the main reference for such data. In discussing the thermal limits we should always keep in mind that temperature is only one of the ambient factors that affect life.…”

Section: Thermal Limits Of Terrestrial Lifementioning

confidence: 99%

“…Lower limits for invertebrates and ectothermic vertebrates lie between ~ 2 o C and ~0 o C (Clarke 2014). A general figure adopted as the high temperature limit of ectothermic metazoans is 47 o C (Pörtner 2002).…”

Section: Thermal Limits For Multicellular Poikilothermsmentioning

confidence: 99%

“…A general figure adopted as the high temperature limit of ectothermic metazoans is 47 o C (Pörtner 2002). For instance, the average upper limit for insects is evaluated as 47.4 o C (Addo-Bediaco et al 2000) and the limit for freshwater invertebrates at ~46 o C (Clarke 2014). Also terrestrial and marine invertebrates generally conform to these limits.…”

Section: Thermal Limits For Multicellular Poikilothermsmentioning

confidence: 99%

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From climate models to planetary habitability: temperature constraints for complex life

Silva

Vladilo

Schulte

et al. 2016

International Journal of Astrobiology

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In an effort to derive temperature based criteria of habitability for multicellular life, we investigated the thermal limits of terrestrial poikilotherms, i.e. organisms whose body temperature and the functioning of all vital processes is directly affected by the ambient temperature. Multicellular poikilotherms are the most common and evolutionarily ancient form of complex life on earth. The thermal limits for the active metabolism and reproduction of multicellular poikilotherms on earth are approximately bracketed by the temperature interval 0 o C  T  50 o C. The same interval applies to the photosynthetic production of oxygen, an essential ingredient of complex life, and for the generation of atmospheric biosignatures observable in exoplanets. Analysis of the main mechanisms responsible for the thermal thresholds of terrestrial life suggests that the same mechanisms would apply to other forms of chemical life. We therefore propose a habitability index for complex life, h 050 , representing the mean orbital fraction of planetary surface that satisfies the temperature limits 0 o C  T  50 o C. With the aid of a climate model tailored for the calculation of the surface temperature of Earth-like planets (ESTM), we calculated h 050 as a function of planet insolation, S, and atmospheric columnar mass, N atm , for a few earth-like atmospheric compositions with trace levels of CO 2 . By displaying h 050 as a function of S and N atm , we built up an atmospheric mass habitable zone (AMHZ) for complex life. At variance with the classic habitable zone, the inner edge of the complex life habitable zone is not affected by the uncertainties inherent to the calculation of the runaway greenhouse limit. The complex life habitable zone is significantly narrower than the habitable zone of dry planets. Our calculations illustrate how changes in ambient conditions dependent on S and N atm , such as temperature excursions and surface dose of secondary particles of cosmic rays, may influence the type of life potentially present at different epochs of planetary evolution inside the AMHZ.

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