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opencc-zeroApr 2023View details →

Linking critical thermal maximum to mortality from thermal stress in a cold-water frog

Estimates of organismal thermal tolerance are frequently used to assess physiological risk from warming, yet the assumption that these estimates are predictive of mortality has been called into question. We tested this assumption in the cold water-specialist frog, Ascaphus montanus. For seven populations, we used dynamic experimental assays to measure tadpole critical thermal maximum (CTmax) and measured mortality from chronic thermal stress for three days at different temperatures. We tested the relationship between previously–estimated population CTmax and observed mortality, as well as the strength of CTmax as a predictor of mortality compared to local stream temperatures capturing varying timescales. Populations with higher CTmax experienced significantly less mortality in the warmest temperature treatment (25℃). We also found that population CTmax outperformed stream temperature metrics as the top predictor of observed mortality. These results demonstrate a clear link between CTmax and mortality from thermal stress, contributing evidence that CTmax is a relevant metric for physiological vulnerability assessments.

publicFeb 2024View details →

Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum

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publicFeb 2021View details →

Morphometric materials for analyzing Eulipotyphlans across the Paleocene-Eocene-Thermal Maximum

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publicMay 2023View details →

Linking critical thermal maximum to mortality from thermal stress in a cold-water frog

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opencc-zeroDec 2014View details →

Data from: The extended Price equation quantifies species selection on mammalian body size across the Palaeocene/Eocene Thermal Maximum

Species selection, covariation of species' traits with their net diversification rates, is an important component of macroevolution. Most studies have relied on indirect evidence for its operation and have not quantified its strength relative to other macroevolutionary forces. We use an extension of the Price equation to quantify the mechanisms of body size macroevolution in mammals from the latest Palaeocene and earliest Eocene of the Bighorn and Clarks Fork Basins of Wyoming. Dwarfing of mammalian taxa across the Palaeocene/Eocene Thermal Maximum (PETM), an intense, brief warming event that occurred at approximately 56 Ma, has been suggested to reflect anagenetic change and the immigration of small bodied-mammals, but might also be attributable to species selection. Using previously reconstructed ancestor–descendant relationships, we partitioned change in mean mammalian body size into three distinct mechanisms: species selection operating on resident mammals, anagenetic change within resident mammalian lineages and change due to immigrants. The remarkable decrease in mean body size across the warming event occurred through anagenetic change and immigration. Species selection also was strong across the PETM but, intriguingly, favoured larger-bodied species, implying some unknown mechanism(s) by which warming events affect macroevolution.

opencc-zeroMay 2022View details →

Testing the reliability and ecological implications of ramping rates in the measurement of Critical Thermal maximum

Critical Thermal maximum (CTmax) is often used to characterize the upper thermal limits of organisms and represents a key trait for evaluating the fitness of ectotherms. The lack of standardization in CTmax assays has, however, introduced methodological problems in its measurement, which can lead to questionable estimates of species' upper thermal limits. Focusing on ants, which are model organisms for research on thermal ecology, we aim to obtain a reliable ramping rate that will yield the most rigorous measures of CTmax for the most species. After identifying three commonly used ramping rates (i.e., 0.2, 0.5 and 1.0 °C min-1) in the literature, we experimentally determine their effects on the CTmax values of 27 species measured using dynamic assays. Next, we use static assays to evaluate the accuracy of these values in function of the time of exposure. Finally, we use field observations of species' foraging activities across a wide range of ground temperatures to identify the most biologically relevant CTmax values and to develop a standardized method. Our results demonstrate that the use of a 1 °C min-1 ramping rate in dynamic assays yields the most reliable CTmax values for comparing ant species' upper thermal limits, which are further validated in static assays and field observations. We further illustrate how methodological biases in physiological trait measurements can affect subsequent analyses and conclusions on community comparisons between strata and habitats, and the detection of phylogenetic signal (Pagel's λ and Bloomberg's K). Overall, our study presents a methodological framework for identifying a reliable and standardized ramping rate to measure CTmax in ants, which can be applied to other ectotherms. Particular attention should be given to CTmax values obtained with less suitable ramping rates, and the potential biases they may introduce to trait-based research on global warming and habitat conversion, as well as inferences about phylogenetic conservatism.

Figure 4 in Voluntary thermal maximum of grassland vipers (Vipera spp.): environmental drivers and local adaptation

Figure 4. Mitochondrial phylogeny of grassland vipers and their predicted (pVTmax) upper thermal tolerance. Pale circles indicate pVT max at presence localities and large dots and error bars show mean ± SE of pVT max.

Figure 3 in Voluntary thermal maximum of grassland vipers (Vipera spp.): environmental drivers and local adaptation

Figure 3. Observed (VTmax) and predicted (pVTmax) upper thermal tolerance of grassland vipers (mean ± SE). The pVTmax is the prediction of the random forest model fitted using environmental variables. Error bars show SE and the dashed line indicates 1:1 line.

Figure 2 in Voluntary thermal maximum of grassland vipers (Vipera spp.): environmental drivers and local adaptation

Figure 2. Phylogenetic relationship of the studied taxa and the corresponding distribution of VT max. Black vertical lines indicate peak value (eVTmax).

Figure 1 in Voluntary thermal maximum of grassland vipers (Vipera spp.): environmental drivers and local adaptation

Figure 1. Distribution records of grassland vipers used in the study (white dots) and approximate distribution of their range (polygons) according to the taxonomy in Freitas et al. (2020). Numbered points and taxon names in yellow letters indicate populations measured for VT max and white dots indicate locations used to extract environmental data and estimate pVT max. Photos by E. Mizsei.

opencc-by-4.0Jan 2023View details →

Early Triassic Thermal Maximum and its ecological impact on conodonts

Supporting Information for Early Triassic Thermal Maximum and its ecological impact on conodonts

publicJul 2015View details →

Data from: The extended Price equation quantifies species selection on mammalian body size across the Palaeocene/Eocene Thermal Maximum

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publicJun 2022View details →

Testing the reliability and ecological implications of ramping rates in the measurement of Critical Thermal maximum

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publicJun 2025View details →

Evidence for increased animal pollination during the Paleocene-Eocene Thermal Maximum

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publicAug 2013View details →

Data from: Calcareous nannoplankton ecology and community change across the Paleocene-Eocene Thermal Maximum

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opencc-zeroAug 2020View details →

Dataset for Body size impacts critical thermal maximum measurements in lizards

Understanding the mechanisms behind critical thermal maxima (CTmax, the high body temperature at which neuromuscular coordination is lost) of organisms is central to understanding ectotherm thermal tolerance. Body size is an often overlooked variable that may affect interpretation of CTmax, and consequently, how CTmax is used to evaluate mechanistic hypotheses of thermal tolerance. We tested the hypothesis that body size affects CTmax and its interpretation in two experimental contexts. First, in four Sceloporus species, we examined how inter- and intra-specific variation in body size affected CTmax at normoxic and experimentally-induced hypoxic conditions, and cloacal heating rate under normoxic conditions. Negative relationships between body size and CTmax were exaggerated in larger species, and hypoxia-related reductions in CTmax were unaffected by body size. Smaller individuals had faster cloacal heating rates and higher CTmax, and variation in cloacal heating rate affected CTmax in the largest species. Second, we examined how body size interacted with the location of body temperature measurements (i.e., cloaca versus brain) in Sceloporus occidentalis, then compared this in living and deceased lizards. Brain temperatures were consistently lower than cloacal temperatures. Smaller lizards had larger brain-cloacal temperature differences than larger lizards, due to a slower cloacal heating rate in large lizards. Both live and dead lizards had lower brain than cloacal temperatures, suggesting living lizards do not actively maintain lower brain temperatures when they cannot pant. Thermal inertia influences CTmax data in complex ways, and body size should therefore be considered in studies involving CTmax data on species with variable sizes.

opencc-zeroDec 2016View details →

Data from: Effects of warming rate, acclimation temperature and ontogeny on the critical thermal maximum of temperate marine fish larvae

Most of the thermal tolerance studies on fish have been performed on juveniles and adults, whereas limited information is available for larvae, a stage which may have a particularly narrow range in tolerable temperatures. Moreover, previous studies on thermal limits for marine and freshwater fish larvae (53 studies reviewed here) applied a wide range of methodologies (e.g. the static or dynamic method, different exposure times), making it challenging to compare across taxa. We measured the Critical Thermal Maximum (CTmax) of Atlantic herring (Clupea harengus) and European seabass (Dicentrarchus labrax) larvae using the dynamic method (ramping assay) and assessed the effect of warming rate (0.5 to 9°C h-1) and acclimation temperature. The larvae of herring had a lower CTmax (lowest and highest values among 222 individual larvae, 13.1 – 27.0 °C) than seabass (lowest and highest values among 90 individual larvae, 24.2 – 34.3 °C). At faster rates of warming, larval CTmax significantly increased in herring, whereas no effect was observed in seabass. Higher acclimation temperatures led to higher CTmax in herring larvae (2.7 ± 0.9°C increase) with increases more pronounced at lower warming rates. Pre-trials testing the effects of warming rate are recommended. Our results for these two temperate marine fishes suggest using a warming rate of 3 - 6 °C h-1: CTmax is highest in trials of relatively short duration, as has been suggested for larger fish. Additionally, time-dependent thermal tolerance was observed in herring larvae, where a difference of up to 8°C was observed in the upper thermal limit between a 0.5- or 24-h exposure to temperatures >18°C. The present study constitutes a first step towards a standard protocol for measuring thermal tolerance in larval fish.

zenodo28/100

Northern Hemisphere vegetation change drives a Holocene thermal maximum

In this data directory are netCDF data needed to evaluate the CESM1.2 results from the referenced publication. There are four categories for separate groupings of data. They are as follows: CAM The “CAM” category contains surface temperature (“TREFHT”) and dust aerosol optical depth (“AODDUST1” and “AODDUST2”) data for all 13 simulations presented in this publication. A separate netCDF file exists for each individual simulation, entitled “[SIMULATION_NAME]_CAM_timeseries.nc”, and each file contains monthly output for the 50 years of model data used in the publication. SST The “SST” category contains sea surface temperature (“TEMP”) data for five of the simulations presented in this publication. A separate netCDF file exists for each individual simulation, entitled “[SIMULATION_NAME]_SST_timeseries.nc”, and each file contains monthly output for the 50 years of model data used in the publication. The simulations for which SST data are present are: PICONTROL 6kaPI_VEG 6kaGS 6kaGS+ARC 6ka FSURDAT The “FSURDAT” category contains plant functional type percentage (“PCT_PFT”) and monthly leaf area index (“MONTHLY_LAI”) boundary condition data that was used to initialize each simulation presented in this publication. A separate netCDF file exists for each individual simulation, entitled “[SIMULATION_NAME]_FSURDAT.nc”. RADIATION The “RADIATION” category contains radiation, cloud, surface temperature, and land fraction data from five of the simulations presented in this publication. This data can be used to recreate the APRP results among other radiative calculations. A separate netCDF file exists for each individual simulation, entitled “[SIMULATION_NAME]_RADIATION_climatology.nc”, and each file contains a monthly climatology (January to December) averaged from the 50 years of model data used in the publication.

opencc-by-4.0Feb 2022View details →

opencc-zeroJul 2022View details →

Pollen records of Miocene thermal maximum

In order to identify the northern latitudinal limit between mangroves composed of Avicennia only and diversified mangroves during the Cenozoic thermal maxima, a special attention was paid to the Middle Miocene Climatic Optimum (MMCO: 17–14 Ma) in the Mediterranean s.l. region, including the Mediterranean Basin s.s. and its former brackish appendix, the Paratethys (Popescu et al., accepted, Journ. Biogeogr.). Pollen data come from forty-five biostratigraphically well-dated marine samples from 8 locations belonging to the MMCO. Information on the age and stratigraphy of some of the locations can be found in the following papers: Jiménez-Moreno et al., 2008, Journ. Biogeogr., 35, 1638-1649 (Göllenrsdorf); Jiménez-Moreno & Suc, 2005, Palaeogeogr. Palaeoclimatol. Palaeoecol., 253, 224-241 (Alboran A1, Estagel, Bayanne, La Rierussa); Besson et al., 2005, C.R. Geoscience, 337, 1045-1054 (Châteauredon). The data have been performed and interpreted using a robust botanical background for identification of pollen grains and their representativeness in marine coastal sediments. Pollen grains have been botanically identified by comparison with large modern pollen collections developed from sampling of flowers in herbariums, especially on the basis of an accurate morphological examination of the pollen grains. Pollen counts are at least of 100 to 150 pollen grains per sample, the most abundant taxon, usually Pinus in the Mediterranean marine sediments, being excluded. These data have been already used for reconstruction of vegetation and climate history in the Mediterranean region, particularly for past-climate quantification, establishment of the thermal palaeo-gradient in Europe during the Miocene and estimate of palaeo-elevation of the nearby mountains (e.g., see: Fauquette et al., 2007, The Micropalaeontological Soc., Spec. Publ.,The Geological Soc., 481-502; Fauquette et al., 2015, Earth Planet. Sci. Lett., 412, 220-234). They can be reused for any synthesis on the Miocene vegetation and climate reconstruction.