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Muskellunge are a valuable sportfish species which has been stocked throughout North America. Stocking is a strategy to generate angling opportunities by introducing species to waterbodies that otherwise would not have contained the fish, such as impoundments and reservoirs. Therefore, understanding the ways fish interact with different waterbodies is critical for managers to understand. To that end, we utilized a year‐long passive telemetry study with muskellunge in a reservoir known for its muskellunge angling. Additionally, we employed temperature loggers to track lake temperatures. We found that smaller female muskellunge were more resident at sites compared to similar‐sized males, although fish did not exhibit site‐specific preferences. We also found that fish moved high distances over the course of the year without time‐specific differences. Furthermore, we found evidence that muskellunge was selected for thermal refuges in the reservoir; however, in summer, when water temperatures were elevated, fish inhabited water, which has been shown to increase incidental mortality. The results of this study indicate a need for muskellunge managers, especially in reservoirs, to consider water temperature in angling regulations. Additionally, our results highlight a need for adding habitat structure in reservoirs and altering stocking densities of fish. Collectively, these results will help inform managers on muskellunge spatial interactions within a reservoir and achieve management goals. [ABSTRACT FROM AUTHOR]

Previous studies have revealed that mixotrophs can become more heterotrophic as the temperature rises, although these studies were primarily conducted under laboratory conditions with temperature-acclimated grazers. This study investigated the short-term thermal regulation of grazing and photosynthetic performance, measured in terms of the maximum relative electron transport rate (rETRmax), of natural Karenia brevis populations on cultured Synechococcus. Bloom waters were collected in Sarasota, Florida, during the fall of 2022. Synechococcus were inoculated into K. brevis bloom waters in varying ratios and incubated at an ambient temperature and an ambient temperature ±5 °C (19, 24, and 29 °C). In general, the grazing coefficient, clearance, and ingestion rates were higher in warmer waters, although ingestion rates were significantly regulated by the prey-to-grazer ratios and, to a lesser degree, by temperatures (22 to 204 Synechococcus K. brevis−1 d−1). Overall, the rETRmax of Synechococcus controls generally increased over time with a more substantial increase at warmer temperatures, but, in the presence of grazers, the rETRmax of Synechococcus did not increase, and, remarkably, even decreased in some cases. These findings suggest that grazing on Synechococcus could directly regulate Synechococcus concentrations and indirectly reduce the photosynthetic performance of prey. Furthermore, this study demonstrates that the thermal regulation of grazing and photosynthetic performance can occur on a short-term basis. [ABSTRACT FROM AUTHOR]

Ectotherms are expected to be particularly vulnerable to climate change–driven increases in temperature. Understanding how populations adapt to novel thermal environments will be key for informing mitigation plans. We took advantage of threespine stickleback (Gasterosteus aculeatus) populations inhabiting adjacent geothermal (warm) and ambient (cold) habitats to test for adaptive evolutionary divergence using a field reciprocal transplant experiment. We found evidence for adaptive morphological divergence, as growth (length change) in non‐native habitats related to head, posterior and total body shape. Higher growth in fish transplanted to a non‐native habitat was associated with morphological shape closer to native fish. The consequences of transplantation were asymmetric with cold sourced fish transplanted to the warm habitat suffering from lower survival rates and greater parasite prevalence than warm sourced fish transplanted to the cold habitat. We also found divergent shape allometries that related to growth. Our findings suggest that wild populations can adapt quickly to thermal conditions, but immediate transitions to warmer conditions may be particularly difficult. [ABSTRACT FROM AUTHOR]

Environmental temperature fundamentally shapes insect physiology, fitness and interactions with parasites. Differential climate warming effects on host versus parasite biology could exacerbate or inhibit parasite transmission, with far-reaching implications for pollination services, biocontrol and human health. Here, we experimentally test how controlled temperatures influence multiple components of host and parasite fitness in monarch butterflies (Danaus plexippus) and their protozoan parasites Ophryocystis elektroscirrha. Using five constant-temperature treatments spanning 18–34°C, we measured monarch development, survival, size, immune function and parasite infection status and intensity. Monarch size and survival declined sharply at the hottest temperature (34°C), as did infection probability, suggesting that extreme heat decreases both host and parasite performance. The lack of infection at 34°C was not due to greater host immunity or faster host development but could instead reflect the thermal limits of parasite invasion and within-host replication. In the context of ongoing climate change, temperature increases above current thermal maxima could reduce the fitness of both monarchs and their parasites, with lower infection rates potentially balancing negative impacts of extreme heat on future monarch abundance and distribution. [ABSTRACT FROM AUTHOR]

Organismal thermal limits affect a wide range of biogeographical and ecological processes. Copepods are some of the most abundant animals on the planet and play key roles in aquatic habitats. Despite their abundance and ecological importance, there is limited data on the factors that affect copepod thermal limits, impeding our ability to predict how aquatic ecosystems will be affected by anthropogenic climate change. In a warming ocean, one factor that may have particularly important effects on thermal limits is the availability of food. A recently proposed feedback loop known as "metabolic meltdown" suggests that starvation and exposure to high temperatures interact to drastically reduce organismal thermal limits, increasing vulnerability to warming. To investigate one component of this feedback loop, we examined how starvation affects thermal limits (critical thermal maxima: CTmax) of Acartia tonsa, a widespread estuarine copepod. We found that there was no effect of short‐duration exposure to starvation (up to 2 days). However, after 3 days, there was a significant decrease in the CTmax of starved copepods relative to the fed controls. Our results provide empirical evidence that extended periods of starvation reduce thermal limits, potentially initiating "metabolic meltdown" in this key species of coastal copepod. This suggests that changes in food availability may increase the vulnerability of copepods to increasing temperatures, amplifying the effects of climate change on coastal systems. [ABSTRACT FROM AUTHOR]

It is difficult to determine what a given I Q i SB 10 sb value measures without comparison to I Q i SB 10 sb values across comparable temperatures, provided the value is an extrapolation from any two temperatures. Although intuitive at first glance, I Q i SB 10 sb values are limited to measuring effects at two temperatures, must be assessed with similar I Q i SB 10 sb values across related temperature ranges to be comparable, and treat temperature effects as piecemeal. It is possible to average I Q i SB 10 sb values to get an overall effect (with values weighted proportional to the squared differences in temperature for non-equidistant temperatures), but this does not justify the use of pairwise I Q i SB 10 sb values to begin with. Moving away from Q 10 values Limits of measuring two temperatures Although I Q i SB 10 sb values extrapolate to 10°C, only considering two temperatures is less reliable, and less accurate, than accounting for more than two temperatures. [Extracted from the article]

Ectothermic species are dependent on temperature, which drives many aspects of their physiology, including locomotion. The distribution of the native populations of Xenopus laevis is characterized by an exceptional range in latitude and altitude. Along altitudinal gradients, thermal environments change, and populations experience different temperatures. In this study, we compared critical thermal limits and thermal performance curves of populations from the native range across an altitudinal gradient to test whether optimal temperatures for exertion differ depending on altitude. Data on exertion capacity were collected at six different temperatures (8°C, 12°C, 16°C, 19°C, 23°C, and 27°C) for four populations spanning an altitudinal gradient (60, 1,016, 1,948, and 3,197 m asl). Results show that the thermal performance optimum differs among populations. Populations from cold environments at high altitudes exhibit a lower optimal performance temperature than populations from warmer environments at lower altitudes. The ability of this species to change its optimal temperature for locomotor exertion across extremely different climatic environments within the native range may help explain its exceptional invasive potential. These results suggest that ectothermic species capable of adapting to broad altitudinal ranges may be particularly good at invading novel climatic areas, given their ability to cope with a wide range of variation in environmental temperatures. [ABSTRACT FROM AUTHOR]

Critical thermal maxima methodology (CTM) has been used to infer acute upper thermal tolerance in fishes since the 1950s, yet its ecological relevance remains debated. In this study, the authors synthesize evidence to identify methodological concerns and common misconceptions that have limited the interpretation of critical thermal maximum (CTmax; value for an individual fish during one trial) in ecological and evolutionary studies of fishes. They identified limitations of, and opportunities for, using CTmax as a metric in experiments, focusing on rates of thermal ramping, acclimation regimes, thermal safety margins, methodological endpoints, links to performance traits and repeatability. Care must be taken when interpreting CTM in ecological contexts, because the protocol was originally designed for ecotoxicological research with standardized methods to facilitate comparisons within study individuals, across species and contexts. CTM can, however, be used in ecological contexts to predict impacts of environmental warming, but only if parameters influencing thermal limits, such as acclimation temperature or rate of thermal ramping, are taken into account. Applications can include mitigating the effects of climate change, informing infrastructure planning or modelling species distribution, adaptation and/or performance in response to climate‐related temperature change. The authors' synthesis points to several key directions for future research that will further aid the application and interpretation of CTM data in ecological contexts. [ABSTRACT FROM AUTHOR]

Mating behaviors are sensitive to novel or stressful thermal conditions, particularly for ectothermic organisms. An organism's sensitivity to temperature, which may manifest in altered mating outcomes, can be shaped in part by temperatures experienced during development. Here, we tested how developmental temperature shapes the expression of adult mating-related behaviors across different ambient conditions, with a focus on courtship behavior, mating rates, and mating signals and preferences. To do so, we reared treehoppers under two temperature regimes and then tested the expression of male and female mating behaviors across a range of ambient temperatures. We found that developmental temperature affects the thermal sensitivity of courtship behavior and mating signals for males. However, developmental temperature did not affect the thermal sensitivity of courtship or mate preferences in females. This sex-specific plasticity did not alter the likelihood of mating across ambient temperatures, but it did disrupt how closely mating signals and preferences matched each other at higher ambient temperatures. As a result, developmental temperature could alter sexual selection through signal–preference de-coupling. We further discuss how adult age may drive sex-specific results, and the potential for mismatches between developmental and mating thermal environments under future climate change predictions. [ABSTRACT FROM AUTHOR]

In tree canopies, incoming solar radiation interacts with leaves and branches to generate temperature differences within and among leaves, presenting thermal opportunities and risks for leaf‐dwelling ectotherms. Although leaf biophysics and insect thermal ecology are well understood, few studies have examined them together in single systems. We examined temperature variability in aspen canopies, Populus tremuloides, and its consequences for a common herbivore, the leaf‐mining caterpillar Phyllocnistis populiella. We shaded leaves in the field and measured effects on leaf temperature and larval growth and survival. We also estimated larval thermal performance curves for feeding and growth and measured upper lethal temperatures. Sunlit leaves directly facing the incoming rays reached the highest temperatures, typically 3–8°C above ambient air temperature. Irradiance‐driven increases in temperature, however, were transient enough that they did not alter observed growth rates of leaf miners. Incubator and ramping experiments suggested that larval performance peaks between 25 and 32°C and declines to zero between 35 and 40°C, depending on the duration of temperature exposure. Upper lethal temperatures during 1‐h heat shocks were 42–43°C. When larvae were active in early spring, temperatures generally were low enough to depress rates of feeding and growth below their maxima, and only rarely did estimated mine temperatures rise beyond optimal temperatures. Observed leaf or mine temperatures never approached larval upper lethal temperatures. At this site during our experiments, larvae thus appeared to have a significant thermal safety margin; the more pressing problem was inadequate heat. Detailed information on mine temperatures and larval performance curves, however, allowed us to leverage long‐term data sets on air temperature to estimate potential future shifts in performance and longer‐term risks to larvae from lethally high temperatures. This analysis suggests that, in the past 20 years, larval performance has often been limited by cold and that the risk of heat stress has been low. Future warming will raise mean rates of feeding and growth but also the risk of exposure to injuriously or lethally high temperatures. [ABSTRACT FROM AUTHOR]

Surface temperatures are mechanistically linked to vegetation biophysical and physiological processes. Although remote sensing in the thermal infrared (TIR) domain can offer novel insights into the impacts of changing surface temperatures on vegetation, the transformative potential of remote sensing for plant ecology has not yet been realized.Remotely sensed surface temperatures can be used to derive stomatal behaviour and identify stressful environmental conditions in near‐real time. Plant species, traits and structural characteristics can be evaluated with high spectral resolution TIR emissivity.Beyond canopy scales, thermal remote sensing can enhance the inferences obtained from manipulative experiments and empirical evidence, providing unique insight into shifts in species ranges and phenology with changing climate conditions.Scaling leaf traits, canopy structure and regional patterns require an integrated understanding of both process and technology. Theory linking surface temperatures to vegetation dynamics is summarized from an energy balance perspective. We outline scaling considerations including the impacts of morphology on leaf energy balance, canopy structure influences on convective heat exchange and potential confounding impacts of non‐vegetated surfaces.Synthesis. We introduce a unifying framework to link leaf to globe through thermal remote sensing. Recent and emerging advances in sensors, data availability and analytics, together with synergies between TIR remote sensing and other data sources, present a timely opportunity for ecologists to advance our understanding of plant physiology, ecology and biogeography with thermal remote sensing. [ABSTRACT FROM AUTHOR]

Understanding the ecological processes that underpin the dynamics of community turnover in response to environmental change is critical to predicting how warming will influence ecosystem functioning. Here, we quantify the effect of changing temperature on community composition and ecosystem functioning via the action of ecological selection on population-level thermal traits. To achieve this, we use microbes isolated from a network of geothermal streams in Iceland where in situ temperatures span 8–38°C within a single catchment. We first quantified variability in thermal tolerance between taxa, and then assembled synthetic communities along a broad thermal gradient to explore how temperature-driven selection on thermal tolerance traits shaped the emergent community structures and functions. We found marked changes in community structure and composition with temperature, such that communities exposed to extreme temperatures (10, 35°C) had highly asymmetric biomass distributions and low taxonomic richness. Thermal optima were a good predictor of the presence and relative abundance of taxa in the hightemperature treatments. We also found that the evenness of the abundance distribution was related to ecosystem production, such that communities with more equitable abundance distribution were also the most productive. Our results highlight the utility of using a multi-level approach that links populationlevel traits with community structure and ecosystem functioning to better understand how ecological communities will respond to global warming. [ABSTRACT FROM AUTHOR]

Beneficial microorganisms shape the evolutionary trajectories of their hosts, facilitating or constraining the colonization of new ecological niches. One convincing example entails the responses of insect–microbe associations to rising temperatures. Indeed, insect resilience to stressful high temperatures depends on the genetic identity of the obligate symbiont and the presence of heat-protective facultative symbionts. As extensively studied organisms, aphids and their endosymbiotic bacteria represent valuable models to address eco-evolutionary questions about the thermal ecology of insect–microbe partnerships, with broad relevance to various biological systems and insect models. This meta-analysis aims to quantify the context-dependent impacts of symbionts on host phenotype in benign or stressful heat conditions, across fitness traits, types of heat stress and symbiont species. We found that warming lowered the benefits (resistance to parasitoids) and costs (development, fecundity) of infection by facultative symbionts, which was overall mostly beneficial to the hosts under short-term heat stress (heat shock) rather than extended warming. Heat-tolerant genotypes of the obligate symbiont Buchnera aphidicola and some facultative symbionts (Rickettsia sp., Serratia symbiotica) improved or maintained aphid fitness under heat stress. We discuss the implications of these findings for the general understanding of the cost–benefit balance of insect–microbe associations across multiple traits and their eco-evolutionary dynamics faced with climate change. [ABSTRACT FROM AUTHOR]

Environmental temperature is a crucial abiotic factor that influences the success of ectothermic organisms, including hosts and pathogens in disease systems. One example is the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), which has led to widespread amphibian population declines. Understanding its thermal ecology is essential to effectively predict outbreaks. Studies that examine the impact of temperature on hosts and pathogens often do so in controlled constant temperatures. Although varying temperature experiments are becoming increasingly common, it is unrealistic to test every temperature scenario. Thus, reliable methods that use constant temperature data to predict performance in varying temperatures are needed. In this study, we tested whether we could accurately predict Bd growth in three varying temperature regimes, using a Bayesian hierarchical model fit with constant temperature Bd growth data. We fit the Bayesian hierarchical model five times, each time changing the thermal performance curve (TPC) used to constrain the logistic growth rate to determine how TPCs influence the predictions. We then validated the model predictions using Bd growth data collected from the three tested varying temperature regimes. Although all TPCs overpredicted Bd growth in the varying temperature regimes, some functional forms performed better than others. Varying temperature impacts on disease systems are still not well understood and improving our understanding and methodologies to predict these effects could provide insights into disease systems and help conservation efforts. [ABSTRACT FROM AUTHOR]

Aim: There is ongoing debate regarding the extent to which body size is selected by the environment. To address this issue, we assessed how thermo-oxygenic conditions select body size of rotifer species composing a regional species pool. Location: Approximately 600 different water bodies in Sweden. Taxon: Rotifers (188 species). Methods: Data were acquired from previously published studies. For the environmental parameters, we conducted principal component analysis (PCA) to recognize the pattern among the species-specific thermal and oxygenic preferences of rotifers of different ecology. We assigned a standard body length to each species. We performed phylogenetically correlated analyses to evaluate the relationships between body length and the parameters that were selected as PCA drivers. Results: Thermal and oxygenic tolerance ranges, designated by the differences between the minimum and maximum of species occurrence, were grouped separately from the optima designated by the conditions referring to the highest species abundance, according to PC1 versus PC2. The parameters representing temperature and oxygen occupied opposite positions on the PC2 axis. Body size selection was driven by both temperature and oxygen, but the cues for this selection differed; species with higher thermal optima were smaller, while species with wider oxygen tolerance ranges were larger. Main conclusion: The body sizes of rotifer species are filtered by both thermal and oxygenic conditions. Selection is driven by tolerance ranges and optima. Oxygenic conditions are as important as thermal conditions in body size selection within a species assemblage. [ABSTRACT FROM AUTHOR]

Adaptive evolution is key in mediating responses to global warming and may sometimes be the only solution for species to survive. Such evolution will expectedly lead to changes in the populations' thermal reaction norm and improve their ability to cope with stressful conditions. Conversely, evolutionary constraints might limit the adaptive response. Here, we test these expectations by performing a real‐time evolution experiment in historically differentiated Drosophila subobscura populations. We address the phenotypic change after nine generations of evolution in a daily fluctuating environment with average constant temperature, or in a warming environment with increasing average and amplitude temperature across generations. Our results showed that (1) evolution under a global warming scenario does not lead to a noticeable change in the thermal response; (2) historical background appears to be affecting responses under the warming environment, particularly at higher temperatures; and (3) thermal reaction norms are trait dependent: although lifelong exposure to low temperature decreases fecundity and productivity but not viability, high temperature causes negative transgenerational effects on productivity and viability, even with high fecundity. These findings in such an emblematic organism for thermal adaptation studies raise concerns about the short‐term efficiency of adaptive responses to the current rising temperatures. [ABSTRACT FROM AUTHOR]

The impact of global warming on mountain ecosystems is predicted to be high, and particularly in the tropical region. Geothermal streams have provided comprehensive evidence about how aquatic biodiversity changes across natural thermal gradients, but current knowledge is restricted to arctic and temperate zones. Thermal tolerances are different in tropical biological communities, resulting in high thermal sensitivity and low capacity to endure change in their thermal environments. This feature can change the response of aquatic organisms to warming, yet there is little empirical evidence to support this assumption.In this study, we address this issue by evaluating how water temperature affects biodiversity, and the structure of primary and secondary producers of a high‐elevation geothermal stream system (4,500 m above sea level) in the Bolivian Andes. We analysed multi‐taxa responses to increased water temperature using benthic macroinvertebrate families, benthic algae and cyanobacteria, fishes, and macrophytes as study organisms. Different models were run to assess the response of aquatic biota to temperature. In addition, threshold indicator taxa analysis (TITAN) was used to identify changes in macroinvertebrate taxa distributions along the thermal gradient.We found that macroinvertebrate richness decreased at 24–25°C due to the different taxon‐specific responses to temperature. Threshold indicator taxa analysis identified 17 temperature thresholds for each family of macroinvertebrates. Changes in macroinvertebrate community composition were significantly associated with changes in water temperature. Similarly, changes in macrophytes were associated with temperature differences, and high macrophyte richness was found at 19–20°C. Chlorophyll‐a concentration of green algae and diatoms was higher at intermediate temperatures 20–22°C, macroinvertebrates density peaked at 27°C, and fish body size reduced linearly with temperature.Temperature increase in the geothermal stream resulted in a reduction of aquatic diversity and primary and secondary producers by simplifying the community structure to a few warm‐adapted taxa and reduced body size. These patterns differed from those obtained in temperate/arctic geothermal streams, but are similar to other studies at high‐elevation. In a context of increasing warming, the ecological structure of high‐elevation streams might lose cold‐adapted taxa, and change to smaller populations. Additional studies based on ecosystem functioning of geothermal streams could lead to a better understanding on how warming affects high‐elevation streams. [ABSTRACT FROM AUTHOR]

Temperature has long been understood as a fundamental condition that influences ecological patterns and processes. Heterogeneity in landscapes that is structured by ultimate (climate) and proximate (vegetation, topography, disturbance events, and land use) forces serve to shape thermal patterns across multiple spatio‐temporal scales. Thermal landscapes of grasslands are likely shifting as woody encroachment fragments these ecosystems and studies quantifying thermal fragmentation in grassland systems resulting from woody encroachment are lacking. We utilized the August 21st, 2017, solar eclipse to mimic a rapid sunrise/sunset event across a landscape characterized as a grassland to experimentally manipulate levels of solar radiation in the system. We then quantified changes in near‐surface temperatures resulting from changes in solar radiation levels during the eclipse. Temperatures were monitored across three grassland pastures in central Oklahoma that were characterized by different densities (low, medium, and high) of Juniperus virginiana to understand the impact of woody encroachment on diurnal temperature patterns and thermal heterogeneity in a grassland's thermal landscape. The largest temperature range across sites that occurred during the eclipse was in the mixed grass vegetation. Similarly, the largest change in thermal heterogeneity occurred in the grassland with the lowest amount of woody encroachment. Thermal heterogeneity was lowest in the highly encroached grassland, which also experienced the lowest overall change in thermal heterogeneity during the eclipse. Time series models suggested that solar radiation was the most influential factor in predicting changes in thermal heterogeneity as opposed to ambient temperature alone. These results suggest that highly encroached grasslands may experience lower diurnal variability of temperatures at the cost of a decrease in the overall thermal heterogeneity of that landscape. It appears that fine‐scale spatio‐temporal thermal variation is largely driven by solar radiation, which can be influenced by vegetation heterogeneity inherent within a landscape. [ABSTRACT FROM AUTHOR]

Investigating the distribution of hydrogen-producing bacteria (HPB) is of great significance to understanding the source of biological hydrogen production in geothermal environments. Here, we explored the compositions of HPB populations in the sediments of hot springs from the Daggyai, Quzhuomu, Quseyongba, and Moluojiang geothermal zones on the Tibetan Plateau, with the use of Illumina MiSeq high-throughput sequencing of 16S rRNA genes and hydA genes. In the present study, the hydA genes were successfully amplified from the hot springs with a temperature of 46–87°C. The hydA gene phylogenetic analysis showed that the top three phyla of the HPB populations were Bacteroidetes (14.48%), Spirochaetes (14.12%), and Thermotogae (10.45%), while Proteobacteria were absent in the top 10 of the HPB populations, although Proteobacteria were dominant in the 16S rRNA gene sequences. Canonical correspondence analysis results indicate that the HPB community structure in the studied Tibetan hot springs was correlated with various environmental factors, such as temperature, pH, and elevation. The HPB community structure also showed a spatial distribution pattern; samples from the same area showed similar community structures. Furthermore, one HPB isolate affiliated with Firmicutes was obtained and demonstrated the capacity of hydrogen production. These results are important for us to understand the distribution and function of HPB in hot springs. [ABSTRACT FROM AUTHOR]

Climate change is predicted to dramatically alter biological diversity and distributions, driving extirpations, extinctions, and extensive range shifts across the globe. Warming can also, however, lead to phenotypic or behavioural plasticity, as species adapt to new conditions. Recent genomic research indicates that some species are capable of rapid evolution as selection favours adaptive responses to environmental change and altered or novel niche spaces. New advances are providing mechanistic insights into how temperature might accelerate evolution in the Anthropocene. These discoveries highlight intriguing new research directions – such as using geothermal and polar systems combined with powerful genomic tools – that will help us to understand the processes underpinning adaptive evolution and better project how ecosystems will change in a warming world. Much of the impact of increasing temperature on biodiversity is predicted to be widespread and adverse; however, rapid evolutionary responses to a warming world may be beneficial for some species. Genomic research is revealing that some species are capable of rapid adaptive evolution in the face of environmental change associated with rising temperatures, providing mechanistic insights into how temperature might accelerate evolution in the Anthropocene. The main mechanisms by which temperature drives adaptive organismal responses include accelerated mutation rates, increased genetic diversity, and enhanced plasticity. New understanding of the processes underpinning adaptive evolution are a critical aspect of the projection of ecosystem changes in a warming world. [ABSTRACT FROM AUTHOR]

Intra- and interspecific variability can both ensure ecosystem functions. Generalizing the effects of individual and species assemblages requires understanding how much within and between species trait variation is genetically based or results from phenotypic plasticity. Phenotypic plasticity can indeed lead to rapid and important changes of trait distributions, and in turn community functionality, depending on environmental conditions, which raises a crucial question: could phenotypic plasticity modify the relative importance of intra- and interspecific variability along environmental gradients? We quantified the fundamental niche of five genotypes in monocultures for each of five ciliate species along a wide thermal gradient in standardized conditions to assess the importance of phenotypic plasticity for the level of intraspecific variability compared to differences between species. We showed that phenotypic plasticity strongly influences trait variability and reverses the relative extent of intra- and interspecific variability along the thermal gradient. Our results show that phenotypic plasticity may lead to either increase or decrease of functional trait variability along environmental gradients, making intra- and interspecific variability highly dynamic components of ecological systems. [ABSTRACT FROM AUTHOR]

Background: Terrestrial hot spring settings span a broad spectrum of physicochemistries. Physicochemical parameters, such as pH and temperature, are key factors influencing differences in microbial composition across diverse geothermal areas. Nonetheless, analysis of hot spring pools from the Taupo Volcanic Zone (TVZ), New Zealand, revealed that some members of the bacterial genus, Acidithiobacillus, are prevalent across wide ranges of hot spring pHs and temperatures. To determine the genomic attributes of Acidithiobacillus that inhabit such diverse conditions, we assembled the genomes of 19 uncultivated hot spring Acidithiobacillus strains from six geothermal areas and compared these to 37 publicly available Acidithiobacillus genomes from various habitats. Results: Analysis of 16S rRNA gene amplicons from 138 samples revealed that Acidithiobacillus comprised on average 11.4 ± 16.8% of hot spring prokaryotic communities, with three Acidithiobacillus amplicon sequence variants (ASVs) (TVZ_G1, TVZ_G2, TVZ_G3) accounting for > 90% of Acidithiobacillus in terms of relative abundance, and occurring in 126 out of 138 samples across wide ranges of temperature (17.5–92.9 °C) and pH (1.0–7.5). We recovered 19 environmental genomes belonging to each of these three ASVs, as well as a fourth related group (TVZ_G4). Based on genome average nucleotide identities, the four groups (TVZ_G1-TVZ_G4) constitute distinct species (ANI < 96.5%) of which three are novel Acidithiobacillus species (TVZ_G2-TVZ_G4) and one belongs to Acidithiobacillus caldus (TVZ_G1). All four TVZ Acidithiobacillus groups were found in hot springs with temperatures above the previously known limit for the genus (up to 40 °C higher), likely due to significantly higher proline and GC contents than other Acidithiobacillus species, which are known to increase thermostability. Results also indicate hot spring-associated Acidithiobacillus have undergone genome streamlining, likely due to thermal adaptation. Moreover, our data suggest that Acidithiobacillus prevalence across varied hot spring pHs is supported by distinct strategies, whereby TVZ_G2-TVZ_G4 regulate pH homeostasis mostly through Na+/H+ antiporters and proton-efflux ATPases, whereas TVZ_G1 mainly relies on amino acid decarboxylases. Conclusions: This study provides insights into the distribution of Acidithiobacillus species across diverse hot spring physichochemistries and determines genomic features and adaptations that potentially enable Acidithiobacillus species to colonize a broad range of temperatures and pHs in geothermal environments. BoTSrZ5f8ypScVzkmXt8zF Video Abstract [ABSTRACT FROM AUTHOR]

Aim: Temperature is fundamental to the physiological and ecological performance of marine organisms, but its role in modulating the magnitude of ecological impacts by exotic species remains unresolved. Here, we examine the relationship between thermal regimes in the range of origin of marine exotic species and sites of measured impact, after human‐induced introduction. We compare this relationship with the magnitude of impact exerted by exotic species on native ecosystems. Location: Global. Time period: 1977–2017 (meta‐analysis). Major taxa studied: Marine exotic species. Methods: Quantitative impacts of exotic species in marine ecosystems were obtained from a global database. The native range of origin of exotic species was used to estimate the realized thermal niche for each species and compared with the latitude and climatic conditions in recipient sites of recorded impact of exotic species. The difference in median temperatures between recipient sites and the thermal range of origin (i.e., thermal midpoint anomaly) was compared with the magnitude of effect sizes by exotic species on native species, communities and ecosystems. Results: Recorded impacts occurred predominantly within the thermal niche of origin of exotic species, albeit with a tendency toward higher latitudes and slightly cooler conditions. The severity of impacts by exotic species on abundance of native taxa displayed a hump‐shaped relationship with temperature. Peak impacts were recorded in recipient sites that were 2.2°C cooler than the thermal midpoint of the range of origin of exotic species, and impacts decreased in magnitude toward higher and lower thermal anomalies. Main conclusions: Our findings highlight how temperature and climatic context influence ecological impacts by exotic species in marine ecosystems and the implications for existing and novel species interactions under climate change. [ABSTRACT FROM AUTHOR]

Tetranychus ludeni Zacher is a spider mite that has invaded all continents except Antarctica and become an economically important pest around the world. Understanding the plasticity of its life history traits as a response to temperatures provides critical information for its risk analysis and management. Here we tested its response to temperatures ranging from 15 to 30°C over two generations. We found that there was no difference in the egg hatch rate and immature survival rate across temperatures in the first generation. However, the egg hatch rate was lower and immature survival rate was higher at 30°C in the second generation. The sex ratio (proportion of females) of resultant adults was consistent under all test temperatures in both generations except for 30°C in the second generation which was lower. Higher temperature accelerated development in both generations but the development at the lower temperatures was faster in the second generation. Adult body size in both generations generally decreased with the increase of temperature, with females being more likely than males to adjust body size in response to temperature changes they first experienced. Temperature-dependent body size was not translated into fecundity, but larger adults lived longer. The thermal threshold was lower and degree days (DD) were greater in the second generation than in the first generation. Our findings indicate that life history traits of T. ludeni are highly flexible and adaptive to dynamic thermal environment in successive generations. Furthermore, increasing temperature elevated the intrinsic rate of increase (rm) but shortened the generation time (T) and the time to double the population size (Dt). The net population growth rate (R0) was higher at 20 and 25°C as compared to lower and higher temperatures. [ABSTRACT FROM AUTHOR]

Understanding the maintenance of among‐individual behavioral variation in populations and predicting its consequences are key challenges in behavioral ecology. Studying the association between repeatable behaviors and other traits under selection may shed light on the underlying selective pressures. We used the model snail Cepaea nemoralis to examine whether individual behavior is associated with shell morph, a key trait that has been extensively studied in the context of thermal tolerance and predator avoidance, and which is known to be under strict genetic control in this species. We quantified proxies of boldness and exploration in snails of three morphs coming from two habitats with different thermal contexts. We show that both behaviors were repeatable at the among‐individual level (within‐state Rboldness = 0.22 [95% credible interval: 0.15; 0.29]; Rexploration = 0.20 [0.15; 0.25]). Behavior was associated with shell morph, with the darker morph (five‐banded) being consistently shyer and slower to explore. There was no evidence that thermal environment of origin influenced behavior. Snails became faster when test temperature increased; we found no evidence morphs differed in their thermal response. Boldness and exploration were correlated among individuals, forming a syndrome (r = 0.28 [0.10; 0.46]). The link we find between morph and boldness is compatible with visual selection by avian predators, assuming a positive association between boldness and morphological defense (phenotypic compensation hypothesis). The fact morph‐behaviors associations are consistent across environments, despite selection on morph, hint to a possible underlying genetic origin. Finally, we discuss how our findings combined with decades of evolutionary research make C. nemoralis a very valuable model to study the evolution of behavior in response to environmental changes. [ABSTRACT FROM AUTHOR]

Constructing burrows is energetically expensive, yet is a common trait across a broad spectrum of animals. The benefits of using burrows must therefore outweigh the costs of constructing burrows, which may reduce the risk of predation and/or ease the need for active thermoregulation. We examined the use of burrows in Butterfly Lizards (Leiolepis belliana), a common Southeast Asian lizard that constructs burrows in open, sandy plains. We used radiotelemetry to track the activity patterns and measured the thermal environment of 12 individuals across 14 d of sampling. We found that L. belliana had high site fidelity, using the same burrows across the sampling period. There were significant differences between substrate temperatures inside and outside the burrow across the whole sampling period. However, the lower internal burrow temperature still exceeded the upper thermal tolerance of a similar sized lizard species during midday, and this probably explains why we did not observe lizards in their burrows during the middle of the day. Burrows were constructed in a shallow, Y-shaped, concave shape, with each of the three branches of the Y ending in a surface opening, a design that allows for easy escape if threatened by a predator. Due to burrow temperatures exceeding lethal body temperatures for much of the day, and the Y-shape structure of the burrows, we propose that the major function of burrows for this species is as a predator escape mechanism. [ABSTRACT FROM AUTHOR]

Predation is a key ecological interaction affecting populations and communities. Climate warming can modify this interaction both directly by the kinetic effects of temperature on biological rates and indirectly through integrated behavioural and physiological responses of the predators and prey. Temperature dependence of predation rates can further be altered by predator‐induced plasticity of prey locomotor activity, but empirical data about this effect are lacking.We propose a general framework to understand the influence of predator‐induced developmental plasticity on behavioural thermal reaction norms in prey and their consequences for predator–prey dynamics. Using a mesocosm experiment with dragonfly larvae (predator) and newt larvae (prey), we tested if the predator‐induced plasticity alters the elevation or the slope of the thermal reaction norms for locomotor activity metrics in prey. We also estimated the joint predator–prey thermal response in mean locomotor speed, which determines prey encounter rate, and modelled the effect of both phenomena on predator–prey population dynamics.Thermal reaction norms for locomotor activity in prey were affected by predation risk cues but with minor influence on the joint predator–prey behavioural response. We found that predation risk cues significantly decreased the intercept of thermal reaction norm for total activity rate (i.e. all body movements) but not the other locomotor activity metrics in the prey, and that prey locomotor activity rate and locomotor speed increased with prey density.Temperature had opposite effects on the mean relative speed of predator and prey as individual speed increased with temperature in predators but decreased in prey. This led to a negligible effect of body temperature on predicted prey encounter rates and predator–prey dynamics. The behavioural component of predator–prey interaction varied much more between individuals than with temperature and the presence of predation risk cues in our system.We conclude that within‐population variation in locomotor activity can buffer the influence of body temperature and predation risk cues on predator–prey interactions, and further research should focus on the magnitude and sources of behavioural variation in interacting species to predict the impact of climate change on predator–prey interactions and food web dynamics. [ABSTRACT FROM AUTHOR]

Research on the thermal ecology and physiology of free‐living organisms is accelerating as scientists and managers recognize the urgency of the global biodiversity crisis brought on by climate change. As ectotherms, temperature fundamentally affects most aspects of the lives of amphibians and reptiles, making them excellent models for studying how animals are impacted by changing temperatures. As research on this group of organisms accelerates, it is essential to maintain consistent and optimal methodology so that results can be compared across groups and over time. This review addresses the utility of reptiles and amphibians as model organisms for thermal studies by reviewing the best practices for research on their thermal ecology and physiology, and by highlighting key studies that have advanced the field with new and improved methods. We end by presenting several areas where reptiles and amphibians show great promise for further advancing our understanding of how temperature relations between organisms and their environments are impacted by global climate change. Highlights: we provide a useful "how to" guide for studying the thermal ecology of reptiles and amphibians.We highlight key studies on reptiles and amphibians that help us understand the impacts of the climate crisis on biodiversity. [ABSTRACT FROM AUTHOR]

Environments experienced during development have long‐lasting consequences for adult performance and fitness. The "environmental matching" hypothesis predicts that individuals perform best when adult and developmental environments match whereas the "silver spoon" hypothesis expects that fitness is higher in individuals developed under favorable environments regardless of adult environments. Temperature and nutrition are the two most influential determinants of environmental quality, but it remains to be elucidated which of these hypotheses better explains the long‐term effects of thermal and nutritional histories on adult fitness traits. Here we compared how the temperature and nutrition of larval environment would affect adult survivorship and reproductive success in the fruit fly, Drosophila melanogaster. The aspect of nutrition focused on in this study was the dietary protein‐to‐carbohydrate (P:C) ratio. The impact of low developmental and adult temperature was to improve adult survivorship. High P:C diet had a negative effect on adult survivorship when ingested during the adult stage, but had a positive effect when ingested during development. No matter whether adult and developmental environments matched or not, females raised in warm and protein‐enriched environments produced more eggs than those raised in cool and protein‐limiting environments, suggesting the presence of a significant silver spoon effect of larval temperature and nutrition. The effect of larval temperature on adult egg production was weak but persisted across the early adult stage whereas that of larval nutrition was initially strong but diminished rapidly after day 5 posteclosion. Egg production after day 5 was strongly influenced by the P:C ratio of the adult diet, indicating that the diet contributing mainly to reproduction had shifted from larval to adult diet. Our results highlight the importance of thermal and nutritional histories in shaping organismal performance and fitness and also demonstrate how the silver spoon effects of these aspects of environmental histories differ fundamentally in their nature, strength, and persistence. [ABSTRACT FROM AUTHOR]

Heterogeneity has a critical influence on biodiversity and ecosystem processes. While the influence of heterogeneity on species diversity and abundance is well documented, how heterogeneity influences the distribution and arrangement of necessary resources across a landscape is still unclear. Heterogeneity in vegetation structure and composition is often cited as an important factor in the nearground thermal environment; however, because of a paucity of comparative studies across landscapes that differ in their degree of vegetation heterogeneity, researchers lack knowledge of the underlying mechanisms that influence variation in the thermal environment. Particularly, we do not have a clear understanding of the relative contribution of structural and compositional vegetation heterogeneity to thermal patterns. Therefore, we assessed the thermal environment in nine grassland landscapes that differed in their degree of structural and compositional heterogeneity. At the landscape level, we used a variance partitioning approach with linear mixed models to measure the link between four metrics of vegetation heterogeneity and temperature variability. At the microsite level, we used piecewise structural equation models to assess the fine-scale drivers of temperature in these landscapes and develop a causal model describing the relationship between vegetation variables and temperature. We found that temperature variance at the landscape scale was strongly related to the diversity of plant functional groups, heterogeneity in plant species composition, and variation in vegetation height. At finer scales, species richness, vegetation height, and overhead obstruction were the best predictors of temperature once weather was accounted for. Vegetation composition variables indirectly influenced fine-scale temperature variation through their effects on vegetation structure. These results suggest that scale has a strong influence on the observed relationship between temperature variance and different metrics of vegetation heterogeneity. Our results provide support for the role of landscape heterogeneity in shaping the thermal landscape and offer insights into the possible impacts of habitat homogenization on the thermal environment. [ABSTRACT FROM AUTHOR]

A broader understanding of how landscape resistance influences climate change vulnerability for many species is needed, as is an understanding of how barriers to dispersal may impact vulnerability. Freshwater biodiversity is at particular risk, but previous studies have focused on popular cold‐water fishes (e.g., salmon, trout, and char) with relatively large body sizes and mobility. Those fishes may be able to track habitat change more adeptly than less mobile species. Smaller, less mobile fishes are rarely represented in studies demonstrating effects of climate change, but depending on their thermal tolerance, they may be particularly vulnerable to environmental change. By revisiting 280 sites over a 20 year interval throughout a warming riverscape, we described changes in occupancy (i.e., site extirpation and colonization probabilities) and assessed the environmental conditions associated with those changes for four fishes spanning a range of body sizes, thermal and habitat preferences. Two larger‐bodied trout species exhibited small changes in site occupancy, with bull trout experiencing a 9.2% (95% CI = 8.3%–10.1%) reduction, mostly in warmer stream reaches, and westslope cutthroat trout experiencing a nonsignificant 1% increase. The small‐bodied cool water slimy sculpin was originally distributed broadly throughout the network and experienced a 48.0% (95% CI = 42.0%–54.0%) reduction in site occupancy with declines common in warmer stream reaches and areas subject to wildfire disturbances. The small‐bodied comparatively warmer water longnose dace primarily occupied larger streams and increased its occurrence in the lower portions of connected tributaries during the study period. Distribution shifts for sculpin and dace were significantly constrained by barriers, which included anthropogenic water diversions, natural step‐pools and cascades in steeper upstream reaches. Our results suggest that aquatic communities exhibit a range of responses to climate change, and that improving passage and fluvial connectivity will be important climate adaptation tactics for conserving aquatic biodiversity. [ABSTRACT FROM AUTHOR]

Life history strategies shape many aspects of species' ecological importance and population demographics. For ectotherms, life history strategies are highly dependent on temperature, among other environmental conditions. With projected increases in global temperatures, understanding the success of organisms under warmer conditions is critical. Due to the difficulty of establishing long-term heating studies on whole lake systems, there is little empirical evidence addressing the potential changes in life history strategies of fish in situ in response to future climate warming predictions. Here, we study early growth rates, size-at-maturation, maximum adult size, and lifespan of bluegill sunfish in three lakes in Illinois from 2013 to 2017 that experience above-ambient temperatures year-round due to artificial heating by electrical power plant cooling systems and compare these to populations in three nearby ambient lakes. Temperature changes in the heated lakes are within the range of temperature increases predicted by the year 2100. We find evidence that life history strategies and population demographics are substantially affected by warmer environments. Heated populations showed 22% faster first-year growth, 23% shorter lifespans, greater rates of maturation at small body sizes, and over a 4-fold reduction in the relative number of individuals that reach large sizes. Changes in life history strategies, including lifespan and maximum sizes, will be evident across many fish species under warmer conditions in the future and further research should aim to address how these changes will affect trophic interactions. [ABSTRACT FROM AUTHOR]

Aim: In ectotherms, gradients of environmental temperature can regulate metabolism, development and ultimately fitness. The thermal adaptation hypothesis assumes that thermoregulation is costly and predicts that more thermally variable environments favour organisms with wider thermal ranges and thermal limits (i.e., critical thermal minima and maxima, CTmin and CTmax) which track environmental temperatures. We test the thermal adaptation hypothesis at two biological levels of organization, the community and species level. Location: Continental USA. Time period: May–August 2016 and May–August 2017. Major taxa studied: Ants (Hymenoptera:Formicidae). Methods: We used ramping assays to measure CTmax and CTmin for 132 species of North American ants across 31 communities spanning 15.7° of latitude. Results: Ants were cold tolerant in cooler environments particularly at the community level where CTmin was positively correlated with the maximum monthly temperature (CTmin = 0.24Tmax − 0.4; R2 =.39, p <.001). In contrast, most ant communities included some highly thermophilic species, with the result that CTmax did not covary with environmental temperature means or extremes. Consequently, we found no evidence that thermally variable environments supported ant communities with broader thermal ranges. We found a strong phylogenetic signal in CTmax but not CTmin. Species level responses paralleled community data, where maximum monthly temperatures positively correlated with species CTmin but not CTmax, which was significantly lower in subterranean species. Main conclusions: Our results suggest a large fraction of continental trait diversity in CTmax and CTmin can be found in a given ant community, with species with high CTmax widely distributed regardless of environmental temperature. Species level analyses found the importance of local microclimate and seasonality in explaining thermal tolerances. Frequent invariance in CTmax of insects at a large scale might be caused by (a) local adaptations to a site's microclimates and (b) species acclimation potential, both of which cannot be accounted for with mean annual temperatures. [ABSTRACT FROM AUTHOR]

It is unclear how historical adaptation versus maladaptation in a prior environment affects population evolvability in a novel habitat. Prior work showed that vesicular stomatitis virus (VSV) populations evolved at constant 37°C improved in cellular infection at both 29°C and 37°C; in contrast, those evolved under random changing temperatures between 29°C and 37°C failed to improve. Here, we tested whether prior evolution affected the rate of adaptation at the thermal‐niche edge: 40°C. After 40 virus generations in the new environment, we observed that populations historically evolved at random temperatures showed greater adaptability. Deep sequencing revealed that most of the newly evolved mutations were de novo. Also, two novel evolved mutations in the VSV glycoprotein and replicase genes tended to co‐occur in the populations previously evolved at constant 37°C, whereas this parallelism was not seen in populations with prior random temperature evolution. These results suggest that prior adaptation under constant versus random temperatures constrained the mutation landscape that could improve fitness in the novel 40°C environment, perhaps owing to differing epistatic effects of new mutations entering genetic architectures that earlier diverged. We concluded that RNA viruses maladapted to their previous environment could "leapfrog" over counterparts of higher fitness, to achieve faster adaptability in a novel environment. [ABSTRACT FROM AUTHOR]

An analytical model is proposed to analyze the vibration and buckling problem of partially cracked thin orthotropic microplate in the presence of thermal environment. The differential governing equation for the cracked plate is derived using the classical plate theory in conjunction with the strain gradient theory of elasticity. The crack is modeled using appropriate crack compliance coefficients based on the simplified line spring model. The influence of thermal environment is incorporated in governing equation in form thermal moments and in-plane compressive forces. The governing equation for cracked plate has been solved analytically to get fundamental frequency and central deflection of plate. To demonstrate the accuracy of the present model, few comparison studies are carried out with the published literature. The stability and dynamic characteristics of the cracked plate are studied considering various parameters such as crack length, plate thickness, change in temperature, and internal length scale of microstructure. It has been concluded that the frequency and deflection are affected by crack length, temperature, and internal length scale of microstructure. Furthermore, to study the buckling behavior of cracked plate, the classical relations for critical buckling load and critical buckling temperature is also proposed considering the effect of crack length, temperature, and internal length scale of microstructure. [ABSTRACT FROM AUTHOR]

Studies of ecomorphology reveal fascinating examples of how natural selection can mold intra- and interspecific variation in morphology–habitat associations. Despite a growing appreciation for the influence of other factors on these associations (e.g., sexual selection), our understanding of the consequences of spatial variation in their expression remains limited. Given the known ties between habitat selection and thermoregulation, one outcome of such variation might be concomitant divergence in a species' thermal ecological traits. We capitalize on morphology, habitat use, and thermal data collected on adult Sagebrush Lizards (Sceloporus graciosus) from eight populations distributed throughout the species' geographic range to address this limitation. In terms of their morphology, we detected no overall sexual dimorphism in body size, but there was consistent male-biased dimorphism in limb lengths and head width. Although head width and jaw length variation was unrelated to habitat use, larger lizards and lizards with longer legs exploited more open habitats compared to smaller individuals. These ecomorphological patterns were associated with concomitant variation in thermal traits: specifically, substrate temperatures varied geographically, and jointly these temperatures and habitat configuration predicted parallel variation in lizard body temperature. In general, lizards exploiting warmer perches and more heterogeneous habitats attained higher body temperatures. Overall, these findings provide some evidence that lability in thermal traits might be an underappreciated outcome of geographic variation in ecomorphology, possibly providing an important buffer against variable environmental conditions throughout a species' range. [ABSTRACT FROM AUTHOR]

Fish distribution is strongly influenced by temperature, with populations predicted to respond to ongoing changes in ocean climate by adapting distribution to maintain preferred thermal habitats. Over the last several decades, the Northwest Atlantic off Newfoundland, Canada has experienced wide variation in temperature and significant changes in the structure of the marine community. A period of particularly cold ocean conditions from the mid-1980s to mid-1990s saw Greenland halibut occupying deeper waters, and moving farther offshore and southward. Distributional shifts across periods of varying thermal conditions were most pronounced in the youngest ages. While no specific nursery areas were evident, these young fish typically occurred in shallower waters where temperatures were more variable, moving deeper with age. Sensitivity to changing ocean climate may vary with age. This adaptation to shifting temperatures suggests that this species is likely to alter its distribution in the face of continued changes in ocean climate. Age-specific differences in response to changing temperature have potential implications for ecosystem interactions and fisheries management. [ABSTRACT FROM AUTHOR]

Thermal ecology theory predicts that transmission of infectious diseases should respond unimodally to temperature, that is be maximized at intermediate temperatures and constrained at extreme low and high temperatures. However, empirical evidence linking hot temperatures to decreased transmission in nature remains limited.We tested the hypothesis that hot temperatures constrain transmission in a zooplankton–fungus (Daphnia dentifera–Metschnikowia bicuspidata) disease system where autumnal epidemics typically start after lakes cool from their peak summer temperatures. This pattern suggested that maximally hot summer temperatures could be inhibiting disease spread.Using a series of laboratory experiments, we examined the effects of high temperatures on five mechanistic components of transmission. We found that (a) high temperatures increased exposure to parasites by speeding up foraging rate but (b) did not alter infection success post‐exposure. (c) High temperatures lowered parasite production (due to faster host death and an inferred delay in parasite growth). (d) Parasites made in hot conditions were less infectious to the next host (instilling a parasite 'rearing' or 'trans‐host' effect of temperature during the prior infection). (e) High temperatures in the free‐living stage also reduce parasite infectivity, either by killing or harming parasites.We then assembled the five mechanisms into an index of disease spread. The resulting unimodal thermal response was most strongly driven by the rearing effect. Transmission peaked at intermediate hot temperatures (25–26°C) and then decreased at maximally hot temperatures (30–32°C). However, transmission at these maximally hot temperatures only trended slightly lower than the baseline control (20°C), which easily sustains epidemics in laboratory conditions and in nature. Overall, we conclude that while exposure to hot epilimnetic temperatures does somewhat constrain disease, we lack evidence that this effect fully explains the lack of summer epidemics in this natural system. This work demonstrates the importance of experimentally testing hypothesized mechanisms of thermal constraints on disease transmission. Furthermore, it cautions against drawing conclusions based on field patterns and theory alone. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Western Anatolia hosts many low‐to‐moderate and high‐temperature geothermal sources in which active faults play a dominant role to control the recharge and the discharge of geothermal fluid. In this study, we used the two‐dimensional geoelectric structure of Kütahya Hisarcık geothermal field, and created a conceptual hydrogeophysical model that includes faults, real topographical variations and geological units. The temperature distribution and fluid flow pattern are also investigated. The depth extension of Hisarcık Fault, electrical basement and low resistivity anomalies related to the presence of geothermal fluid are determined by using resistivity studies in the area. Numerical simulations suggest that Hisarcık fault functioning as a fluid conduit primarily enables hot fluid to be transported from depth to the surface. It is shown that the locations of predicted outflow vents coincide with those of hot springs in the area. [ABSTRACT FROM AUTHOR]

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We reviewed the literature pertaining to Brook Charr thermal habitat, one of Fry's original species used in developing his scope for activity, to determine what guidance may be established for defining thermal habitat from the literature. The literature was surprisingly large, with 53 publications estimating Brook Charr thermal habitat. The laboratory-based optimal temperature estimates varied widely but were far more consistent when only acclimation-controlled studies were considered. Acclimation-controlled estimates of optimal temperature matched the peak of the aerobic scope curve published nearly 70 years ago. Confidence in defining optimal thermal habitat is strengthened for Brook Charr based on this match because the peak in aerobic scope has strong mechanistic links between physiology and thermal ecology. However, laboratory-based studies used only sub-adult Brook Charr and may underrepresent Brook Charr thermal habitat in nature due to ontogenetic differences in thermal preference. Optimal temperature estimates from aerobic scope or acclimation-controlled studies should be used to define thermal habitat boundaries for fish but should be treated with caution if based on sub adults. Population level sampling is needed to determine the generality of these literature-derived boundaries among Brook Charr populations. [ABSTRACT FROM AUTHOR]

Soil thermal properties are needed in specific engineering applications, such as the design of high-level radioactive waste disposal, buried power transmission cables and geothermal systems. The propagation of the heat flow in a soil exposed to a temperature gradient is based on three main soil thermal properties: the thermal conductivity (λ), the thermal capacity (C) and the thermal diffusivity (α = λ/C). The temperature variations affect the physical properties of soil, inducing changes in its thermal properties. In this study, the evolution of thermal properties of different compacted soils exposed to cyclic temperature variations were investigated through laboratory tests. The results showed that at 20 °C, the thermal conductivity of the compacted soils increased on the dry side of the compaction curve until it reached a maximum near the optimum water content. Variation of λ in a temperature range of 1–20 °C was not shown, but a slight increase of λ was measured in the range of 20–40 °C, which was clearly confirmed in the range of 40–70 °C. The application of cyclic temperature variations to the samples showed partially reversible evolution of thermal conductivity and totally reversible evolution of volumetric heat capacity. [ABSTRACT FROM AUTHOR]

Background Obtaining an optimal flower temperature can be crucial for plant reproduction because temperature mediates flower growth and development, pollen and ovule viability, and influences pollinator visitation. The thermal ecology of flowers is an exciting, yet understudied field of plant biology. Scope This review focuses on several attributes that modify exogenous heat absorption and retention in flowers. We discuss how flower shape, orientation, heliotropic movements, pubescence, coloration, opening–closing movements and endogenous heating contribute to the thermal balance of flowers. Whenever the data are available, we provide quantitative estimates of how these floral attributes contribute to heating of the flower, and ultimately plant fitness. Outlook Future research should establish form–function relationships between floral phenotypes and temperature, determine the fitness effects of the floral microclimate, and identify broad ecological correlates with heat capture mechanisms. [ABSTRACT FROM AUTHOR]

One of the main threats to freshwater turtle populations is habitat destruction, which occurs as a result of human activities such as infrastructure development, forestry, aggregate extraction, and agriculture. However, the impacts of these activities on thermoregulatory opportunities for turtles are not well understood. We examined the impacts of forestry and aggregate extraction on thermal characteristics of wood turtle (Glyptemys insculpta) habitat in the Sudbury District, Ontario, by measuring the differences in absolute temperature, thermal landscape structure, and habitat thermal quality among relatively undisturbed sites (N = 2), harvested forestry sites (N = 2), and aggregate pits (N = 2) in 2015. We also tested the potential use of the thermal landscape concept as a predictor of habitat thermal quality. Undisturbed habitats were of higher thermal quality than impacted sites in terms of temperatures experienced in situ by wild wood turtles in their natural home ranges, and never reached temperatures that would be injurious to turtles (i.e., below CT MIN or above CT MAX). The undisturbed sites were of lower quality in terms of optimal temperatures (i.e., T set), and were generally cooler and their temperatures less variable than those in impacted habitats. The thermal landscape concept provided a useful predictor of habitat thermal quality when the influence of time of day was factored into the predictive model. Our data are important to the conservation and management of wood turtles because they provide a preliminary quantification of the thermal impacts of natural resource extraction on the habitat of an endangered species, and can guide the development of mitigation and rehabilitation plans by providing measures of, and targets for, thermal habitat quality. • We examined impacts of forestry and gravel extraction on thermal properties of wood turtle (Glyptemys insculpta) habitat. • Undisturbed habitats rarely reached injurious temperatures and were less variable than temperatures in impacted habitats. • Our study can guide mitigation and rehabilitation plans by providing measures of, and targets for, thermal habitat quality. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) efflux and δ13C in CO2 were measured along a natural geothermal soil temperature (Ts) gradient in upland Sitka spruce forest soil in a volcanic area in Iceland in July 2014 and 2016. The gradient that reaches from ambient soil temperature up to 40 °C warming at 10 cm depth was originally formed in May 2008, following a major earthquake. The CO2 efflux from the forest floor was measured using the static chamber method. In addition, subsurface soil CO2 concentrations and δ13C values of CO2 were studied. In summer 2014, soil surface CO2 efflux increased steadily with increasing soil temperature across a temperature gradient of 40 °C (from 260 to 3900 mg m−2 h−1). In 2016 the trend had changed; the maximum CO2 efflux (2100 mg m−2 h−1) was measured at 20 °C Ts warming and a similar nonlinear trend was observed in soil CO2 concentrations in 2016. The 13C isotope analysis of CO2 suggested that a proportion of the CO2 emitted from the warmer plots was geothermally derived. The plot with the highest geothermal source was different in 2014 and 2016, which explained the shift in the temperature dependence of the total CO2 efflux. Our study showed that a significant amount of CO2 emitted from the higher warming levels of geothermal temperature gradients can have non-biotic origin and this has to be taken into account when measuring respiration fluxes on such volcanic sites. [ABSTRACT FROM AUTHOR]

The thermal ecology of ectotherms has been studied for almost 2 centuries, but additional attention is currently being paid to it, to understand how organisms deal with the environment in a climate change context. A consensus is still far away due to the large number of factors involved and their complex interactions. In this context, 3 analyses in lacertid lizards were carried out: (i) a meta‐analysis, to test for differences between body and air temperatures from 71 populations; (ii) a meta‐analysis concerning correlations between body and air temperatures from 60 populations; and (iii) a multimodel inference of thermoregulation effectiveness indices from 45 populations. The importance of different factors, including body size, habitat, insularity, altitude, climate and season, was evaluated in all analyses to model the response variables. A strong seasonality effect was observed, with a consistent pattern of less effective thermoregulation in summer compared to other seasons. Altitude was the second most important factor, with a consistent higher thermoregulation effort in populations occurring at high elevations (>1000 m above sea level). Other factors, such as insularity or body size, can also be important, but did not exhibit a clear pattern. Finally, thermoregulation was less affected by climate and habitat type. [ABSTRACT FROM AUTHOR]

Permafrost distribution in mountains is typically more heterogeneous relative to low‐relief environments due to greater variability in the factors controlling the ground thermal regime, such as topography, snow depth, and sediment grain size (e.g., coarse blocks). Measuring and understanding the geothermal variability in high mountains remains challenging due to logistical constraints. This study presents one of the first applications of distributed temperature sensing (DTS) in periglacial environments to measure ground surface temperatures in a mountain permafrost area at much higher spatial resolution than possible with conventional methods using discrete temperature sensors. DTS measures temperature along a fibre‐optic cable at high spatial resolution (i.e., ≤ 1 m). Its use can be limited by power supply and calibration requirements, although recent methodological developments have relaxed some of these restrictions. Spatially continuous DTS measurements at a studied rock glacier provided greater resolution of geothermal variability and facilitated the interpretation of bottom temperature of snowpack data to map patchy permafrost distribution. This research highlights the potential for DTS to be a useful tool for permafrost mapping, ground thermal regime interpretation, conceptual geothermal model development, and numerical model evaluation in areas of heterogeneous mountain permafrost. [ABSTRACT FROM AUTHOR]

The thermal limit of ectotherms provides an estimate of vulnerability to climate change. It differs between contrasting microhabitats, consistent with thermal ecology predictions that a species' temperature sensitivity matches the microclimate it experiences. However, observed thermal limits may differ between ectotherms from the same environment, challenging this theory. We resolved this apparent paradox by showing that ectotherm activity generates microclimatic deviations large enough to account for differences in thermal limits between species from the same microhabitat. We studied upper lethal temperature, effect of feeding mode on plant gas exchange, and temperature of attacked leaves in a community of six arthropod species feeding on apple leaves. Thermal limits differed by up to 8 °C among the species. Species that caused an increase in leaf transpiration (+182%), thus cooling the leaf, had a lower thermal limit than those that decreased leaf transpiration (-75%), causing the leaf to warm up. Therefore, cryptic microclimatic variations at the scale of a single leaf determine the thermal limit in this community of herbivores. We investigated the consequences of these changes in plant transpiration induced by plant-insect feedbacks for species vulnerability to thermal extremes. Warming tolerance was similar between species, at ±2 °C, providing little margin for resisting increasingly frequent and intense heat waves. The thermal safety margin (the difference between thermal limit and temperature) was greatly overestimated when air temperature or intact leaf temperature was erroneously used. We conclude that feedback processes define the vulnerability of species in the phyllosphere, and beyond, to thermal extremes. [ABSTRACT FROM AUTHOR]

Abstract: Metabolism shapes the ecosystem role of organisms by dictating their energy demand and nutrient recycling potential. Metabolic theory (MTE) predicts consumer metabolic and recycling rates will rise with warming, especially if body size declines, but it ignores potential for adaptation. We measured metabolic and nutrient excretion rates of individuals from populations of a globally invasive fish that colonized sites spanning a wide temperature range (19–37°C) on two continents within the last 100 yr. Fish body size declined across our temperature gradient and MTE predicted large rises in population energy demand and nutrient recycling. However, we found that the allometry and temperature dependency of metabolism varied in a countergradient pattern with local temperature in a way that offset predictions of MTE. Scaling of nutrient excretion was more variable and did not track temperature. Our results suggest that adaptation can reduce the metabolic cost of warming, increasing the prospects for population persistence under extreme warming scenarios. [ABSTRACT FROM AUTHOR]