The potential for behavioral thermoregulation to buffer "cold-blooded" animals against climate warming

The gut-liver axis plays a limited role in mediating the liver's heat susceptibility of Chinese giant salamander

The Chinese giant salamander (CGS, Andrias davidianus), a flagship amphibian species, is highly vulnerable to high temperatures, posing a significant threat under future climate change. Previous research linked this susceptibility to liver energy deficiency, accompanied by shifts in gut microbiota and reduced food conversion rates, raising questions about the role of the gut-liver axis in mediating heat sensitivity. This study investigated the responses of Chinese giant salamander larvae to a temperature gradient (10-30 °C), assessing physiological changes alongside histological, gut metagenomic, and tissue transcriptomic analyses. Temperatures above 20 °C led to mortality, which resulted in delayed growth. Histological and transcriptomic data revealed metabolic exhaustion and liver fibrosis in heat-stressed salamanders, underscoring the liver's critical role in heat sensitivity. While heat stress altered the gut microbiota's community structure, their functional profiles, especially in nutrient absorption and transformation, remained stable. Both gut and liver showed temperature-dependent transcriptional changes, sharing some common variations in actins, heat shock proteins, and genes related to transcription and translation. However, their energy metabolism exhibited opposite trends: it was downregulated in the liver but upregulated in the gut, with the gut showing increased activity in the pentose phosphate pathway and oxidative phosphorylation, potentially countering metabolic exhaustion. Our findings reveal that the liver of the larvae exhibits greater thermal sensitivity than the gut, and the gut-liver axis plays a limited role in mediating thermal intolerance. This study enhances mechanistic understanding of CGS heat susceptibility, providing a foundation for targeted conservation strategies in the face of climate change.

The ultimate challenge to climate change: Endurance of a thermophilic reptile to the harsh temperatures on an extremely hot island

Herbivorous ectotherms are especially vulnerable to climate change and those inhabiting hot environments may already live near their maximum physiological limits. Insular species are particularly susceptible to changing thermal conditions because they cannot relocate. This proves a very poor prognostic for the survival of herbivorous reptiles living on islands. The piebald chuckwalla, Sauromalus varius, is a large iguana endemic to San Esteban Island, located in the Gulf of California, encompassed by the Sonoran Desert, one of the hottest areas on earth. We investigated the thermal ecology of this iguana during the hottest month of the year coinciding with the fruiting of its most important food source, the giant cardon. We measured field body temperature (Tbfield), voluntary maximum body temperature, the onset of thermal stress responses, and critical maximum temperature, and compared these with the thermal landscape. We found that Tbfield was 37.2±1.3°C (average±SD) and iguanas sought shade at a body temperature of 39.2±1.4°C. Iguanas started panting at 42.4±2.0°C, a cooling strategy at the expense of precious body water, and often defecated, at 43.2±1.9°C, with concomitant loss of water. We determined that these iguanas can maintain activity at body temperatures of 47.2±2.2°C, however they use various mechanical and behavioral mechanism to avoid these extremes. On the island, ground temperatures reached up to 62.4°C. Shade of plants can provide thermal shelter during part of the day. However, even in some caves temperatures could reach 41.5°C and under rocks 48.0°C, which is higher than these animals voluntarily tolerate. Our results indicated that although these chuckwallas can support high temperatures, their strategy incurs substantial water loss, a resource only available for the iguana through cacti consumption. Environmental temperature that increases with climate change will likely lead to an ever-increasing use of shelters, perhaps even resulting in complete inactivity during the cacti fruiting period.

A zinc finger protein shapes the temperature adaptability of a cosmopolitan pest

Global climate change is characterized by increased extreme temperatures affecting insects at all trophic levels. Zinc finger proteins (ZFPs) are key regulators of gene expression and cell differentiation in eukaryotes, essential for stress resistance in both animals and plants. Using CRISPR/Cas9 for gene deletion, this study predicted and examined the structure of ZFP320 in the diamondback moth (Plutella xylostella) and investigated its function in temperature stress response through a comprehensive age-stage, two-sex life table analysis. We found ZFP320 encodes a 387 amino acid protein (43 kDa) with no transmembrane domains, featuring a ZnF-C2H2 domain. Quantitative fluorescence analysis showed that ZFP320 expression increased under high temperatures. ZFP320 knockout altered antioxidant gene expression, resulting in higher levels of superoxide dismutase and catalase in mutant strains compared with wild-type strain. Life table analysis revealed that the mutant strains had shorter fecundity and oviposition periods under both normal and high temperatures. Additionally, mutant strains exhibited lower parameters (r, λ, R0), as well as reduced survival rates and critical thermal maxima. Notably, PxZFP320 plays a crucial role in temperature adaptation, paving the way for future investigations on the significance of ZFPs in P. xylostella's temperature tolerance.

Chasing the Niche: Escaping Climate Change Threats in Place, Time, and Space

Climate change is creating mismatches between species' current environments and their historical niches. Locations that once had the abiotic and biotic conditions to support the persistence of a species may now be too warm, too dry, or simply too different, to meet their niche requirements. Changes in behaviors, altered phenology, and range shifts are common responses to climate change. Though these responses are often studied in isolation by scientists from disparate subfields of ecology, they all represent variants of the same solution-strategies to realign the conditions populations experience with their niche. Here, we aim to (1) identify the physiological and ecological effects, and potential alignment, of these three ecological responses: shifts in behavior, phenology, or ranges, (2) determine the circumstances under which each type of response may be more or less effective at mitigating the effects of climate change, and (3) consider how these strategies might interact with each other. Each response has been previously reviewed, but efforts to consider relationships between ecological (or with evolutionary) responses have been limited. A synthetic perspective that considers the similarities among ecological responses and how they interact with each other and with evolutionary responses offers a more robust view on species' resilience to climate change.

Hydrothermal physiology and vulnerability to climatic change: insight from European vipers

Clarifying physiological adaptations is crucial to understand species distribution and predict vulnerability to changing climatic conditions. Considering energy and water constraints jointly is necessary because these facets are intertwined in ectotherms. The genus Vipera is a diversified group of Palearctic snakes with parapatric distributions and contrasted climatic affinities. These species are active thermoregulators relying on basking to maintain their body temperature. While some species such as V. berus and V. seoanei are adapted to cold and wet environments, other species have intermediate (temperate-oceanic) affinities (V. aspis), and some such as V. latastei and V. ammodytes inhabit warm and semi-arid climates. We studied physiological traits related to energy and water balance in these five species to better understand species' vulnerability to climate change. First, using open-flow respirometry we quantified standard metabolic rate (SMR) and evaporative water loss (TEWL) at three temperatures (15 °C, 25 °C and 33 °C). Cold- and wet-adapted species exhibited higher metabolic rates and evaporative water loss, reflecting adaptations to colder, wetter environments, while warm- and dry-adapted species showed lower rates. Second, we used these data to investigate their physiological responses to extreme climatic events (ECE). Simulated responses to summer heat spells revealed a major increase in energy expenditure and water loss rates across species. However, the effect was more prominent in cold- and wet-adapted species. This study underscores the physiological constraints that cold and wet-adapted species face during extreme climate events, providing insights into the vulnerabilities of ectotherms to ongoing environmental changes.

Latitude shapes diel patterns in insect biodiversity

The writings of naturalists from two centuries past are brimming with accounts of the stark differences in the kinds and numbers of organisms encountered during the day and night as well as between the tropical and temperate zones. However, only recently have ecologists begun to systematically explore the geographic variation in the diel activity patterns of species on Earth. Examining data from 60 insect communities distributed globally, I find that the proportion of nocturnal species in a community declines from a peak of 36% at the equator to 8% at 60° latitude, while the proportion of diurnal species shows no significant trend. By contrast, the proportion of cathemeral (day- and night-active) species in a community increases poleward from 18% to 68% along the same gradient. These latitudinal trends in the partitioning of diel activity time among co-occurring insect species in communities broadly reflect previously documented biogeographic patterns in the global distributions of vertebrate species occupying different temporal niches. Since diel activity patterns shape insect community dynamics, uncovering their mechanistic basis and the roles of factors such as temperature, light and biotic interactions is vital for curbing insect declines in the Anthropocene.

Climate-induced shifts in crocodile body temperature impact behavior and performance

The increase of energy in the climate system caused by anthropogenic climate change is expected to disrupt predictable weather patterns and result in greater temperature extremes.1,2 As a result of these climate shifts, El-Niño Southern Oscillation (ENSO), which drives predictable periods of hot/dry and cool/wet across the Pacific, is expected to increase in variability and magnitude.3 These changes will significantly impact ectotherms, whose performance across a range of behaviors is dependent on local environmental temperatures.4 As such, we must understand the way individuals experience climate conditions and how changes in their body temperature (Tb), whether through climate or modification of their thermoregulatory mechanisms,5 affect their performance. Laboratory studies have shown that estuarine crocodile (Crocodylus porosus) diving and swimming performance is reduced above 32°C-33°C,6,7,8 temperatures commonly exceeded across their natural range. By monitoring Tb and diving activity in 203 free-ranging estuarine crocodiles over 15 years, we show that the Tb of crocodiles has increased alongside rising air temperatures since 2008, reflecting the climatic shifts caused by the ENSO cycle. As ambient temperatures rose, crocodiles experienced more days close to critical thermal limits (32°C-33°C), at which temperatures the duration of dives was reduced and the prevalence of active cooling behavior was elevated. This study demonstrates that crocodiles are susceptible to multi-year fluctuations in ambient temperature, which requires them to undertake concomitant changes in behavior. They are already close to their physiological thermal limit, but the impact of future predicted rises in temperature remains unknown.

How Air Temperature and Solar Radiation Impact Life History Traits in a Wild Insect

Ectotherms are essential components of all ecosystems. They rely on external heat sources like air temperature and solar radiation to regulate their body temperature and optimise life history traits. Climate change, by altering air temperature and cloud cover, will likely impact these processes. To examine how air temperature and shade influence terrestrial insects, we reared nymphs of the field cricket (Gryllus campestris) at high (mean air temperature 13.4°C) and low (mean air temperature 9.6°C) sites in northern Spain, with partially shaded and unshaded treatments at each site. We tested for local adaptation to these climate variables by rearing nymphs from high and low altitude genetic lineages in all treatment combinations. Development time was significantly longer (on average 10 days) at low air temperature but was unaffected by a 40% increase in shade, suggesting crickets compensate for reduced sun exposure in shaded environments and may forgo some opportunities to gain energy from the sun in unshaded environments. Adult mass was affected by an interaction between shade and air temperature. At low air temperature, shaded crickets had higher mass (on average + 0.06 g) than unshaded crickets, whereas at high air temperature, shaded crickets had lower mass than unshaded crickets (on average - 0.08 g). This indicates that changes in cloud cover will impact insects differently in warmer and cooler parts of their range. We found no evidence for local adaptation in either development time or mass, suggesting these traits are not strongly differentiated between populations from high and low altitude environments. Our findings highlight the importance of considering both air temperature and solar radiation when predicting climate change impacts on insects. Shifts in temperature and cloud cover may have complex and region-specific effects on these vital ecosystem components.

Using dynamic foodscape models to assess bottom-up constraints on population performance of herbivores

Resource heterogeneity governs a multitude of ecological processes, but the mechanisms by which heterogeneity influences population performance are not fully resolved. Because optimizing behavior is challenging in heterogeneous landscapes, individual variation in foraging and movement strategies is common, and understanding the consequences of that variation is one of the most pressing challenges in modern ecology. In theory, such consequences should be modulated at least in part by nutrition, which directly influences discretionary energy available for growth and reproduction. We developed a series of linked dynamic models for predicting (1) spatiotemporal variation in the foodscapes available to seven distinct populations of elk (Cervus canadensis) in Idaho, USA, and (2) variation in pregnancy rates among those populations as a function of foodscape use and availability. Foodscape models, which predicted variation in suitable forage biomass (biomass of forage that met or exceeded requirements of female elk at peak lactation), generally performed well, with adjusted R2 values ranging from 0.34 to 0.51. Patterns of foodscape use differed among populations and years, with some populations showing selection for the foodscape and others exhibiting indifference or even avoidance of high-quality forage resources. Pregnancy rates ranged from 66% to 100%, and our top model relating pregnancy to metrics of forage availability explained 41% of the variation among 20 elk population-years. Our top model relating pregnancy to foodscape use by elk explained 57% of the variation in pregnancy rates among 12 population-years. Pregnancy rates were influenced more strongly by heterogeneity in foodscape use and availability than by differences in mean or maximum suitable biomass among populations. Our results suggest that population performance of elk was modulated both by the availability of high-quality forage and by factors that constrained use of the foodscape by elk. The dynamic modeling approach we developed for linking nutritional resources to herbivore performance is generalizable to many other species and systems and can be used by wildlife managers to assess whether herbivore populations might be limited by bottom-up factors.

Vulnerability of amphibians to global warming

Amphibians are the most threatened vertebrates, yet their resilience to rising temperatures remains poorly understood1,2. This is primarily because knowledge of thermal tolerance is taxonomically and geographically biased3, compromising global climate vulnerability assessments. Here we used a phylogenetically informed data-imputation approach to predict the heat tolerance of 60% of amphibian species and assessed their vulnerability to daily temperature variations in thermal refugia. We found that 104 out of 5,203 species (2%) are currently exposed to overheating events in shaded terrestrial conditions. Despite accounting for heat-tolerance plasticity, a 4 °C global temperature increase would create a step change in impact severity, pushing 7.5% of species beyond their physiological limits. In the Southern Hemisphere, tropical species encounter disproportionally more overheating events, while non-tropical species are more susceptible in the Northern Hemisphere. These findings challenge evidence for a general latitudinal gradient in overheating risk4-6 and underscore the importance of considering climatic variability in vulnerability assessments. We provide conservative estimates assuming access to cool shaded microenvironments. Thus, the impacts of global warming will probably exceed our projections. Our microclimate-explicit analyses demonstrate that vegetation and water bodies are critical in buffering amphibians during heat waves. Immediate action is needed to preserve and manage these microhabitat features.

Contrasting effects of climate warming on hosts and parasitoids: insights from Rocky Mountain aspen leaf miners and their parasitoids

Because temperature has pervasive effects on biological rates, climate warming may alter the outcomes of interactions between insect hosts and their parasitoids, which, for many host species, constitute the single largest source of mortality. Despite growing interest in parasitoid-host responses to climate change, there are few empirical tests of thermal tolerance differences between non-model lepidopteran hosts and their parasitoids and almost none from mountain ecosystems where warming is occurring more rapidly. We examined the thermal ecology of a host-parasitoid interaction in the Rocky Mountains using wild populations of the aspen leaf miner (Phyllocnistis populiella) and a set of previously unknown eulophid parasitoids that attack them. Host and parasitoid development rates were differentially sensitive to temperature. In addition, upper thermal limits of adult parasitoids were lower than those of host caterpillars, and in choice experiments, parasitoids reared at different temperatures showed no plasticity in preferred temperatures. However, when coupled to simulations of leaf microclimates in aspen canopies, these observations suggest, contrary to expectations, that climate warming may potentially benefit parasitoids.

Effects of Temperature on the Thermal Biology and Locomotor Performance of Two Sympatric Extreme Desert Lizards

Lizards are ideal models for investigating animal adaptations to climate change, given their sensitivity to temperature and their significance in physiological ecology. In this study, the effects of temperature on the thermal biology and locomotor performance of two sympatric desert lizards, Eremias roborowskii and Phrynocephalus axillaris, were examined. We analyzed morphological differences, the relationship between environmental temperatures (Te) and selected body temperatures (Tsel), and locomotor performance across varying Te. We also assessed the critical thermal maximum (CTmax) and active body temperature (Tb) to evaluate current thermal conditions. Our results indicate that E. roborowskii's Tsel line intersected isotherm at 27.37 °C is higher than P. axillaris (27.04 °C), and the difference in correlation coefficients between the Tsel line and isotherm indicates that P. axillaris exhibits a superior physiological thermoregulatory capacity, exhibiting less dependence on Te. Locomotor performance assessments showed P. axillaris and E. roborowskii displayed distinct strengths in sprint speed, number of pauses, and maximum distance movement. Eremias roborowskii demonstrated better endurance with fewer pauses and a more consistent length of continuous movement at higher Te, while P. axillaris exhibited a faster sprint speed (0.8355 vs. 0.8157 m/s at 30 °C) and greater movement distance (78.53 vs. 89.82 cm at 32 °C). These differences may be attributable to variations in body size and ecological strategies, as E. roborowskii is an ambush lizard, whereas P. axillaris is an active striking type, which suggests that there is a balanced relationship between endurance and speed. Our study provides critical insights into the convergent evolution and ecological adaptation of two sympatric lizard species in extreme desert ecosystems.

Altitudinal variation in thermal vulnerability of Qinghai-Tibetan Plateau lizards under climate warming

The survival of ectotherms worldwide is threatened by climate change. Whether increasing temperatures increase the vulnerability of ectotherms inhabiting temperate plateau areas remains unclear. To understand altitudinal variation in the vulnerability of plateau ectotherms to climate warming, Qinghai toad-headed lizards (Phrynocephalus vlangalii) were subjected to semi-natural enclosure experiments with simulated warming at high (2,600 m) and superhigh (3,600 m) elevations of the Dangjin Mountain, China. Our results revealed that the thermoregulatory effectiveness and warming tolerance (WT) of the toad-headed lizards were significantly affected by climate warming at both elevations, but their thermal sensitivity remained unchanged. After warming, the thermoregulatory effectiveness of lizards at superhigh elevations decreased because of the improved environmental thermal quality, whereas that of lizards at high-elevation conditions increased. Although the body temperature selected by high-elevation lizards was also significantly increased, the proportion of their active body temperature falling within the set-point temperature range decreased. This indicates that it is difficult for high-elevation lizards to adjust their body temperatures within a comfortable range under climate warming. Variations in the WT and thermal safety margin (TSM) under climate warming revealed that lizards at the superhigh elevation benefited from improved environmental thermal quality, whereas those at the high elevation originally on the edge of the TSM faced more severe threats and became more vulnerable. Our study highlights the importance of thermal biological traits in evaluating the vulnerability of ectotherms in temperate plateau regions.

Climate change and the cost-of-living squeeze in desert lizards

Climate warming can induce a cost-of-living "squeeze" in ectotherms by increasing energetic expenditures while reducing foraging gains. We used biophysical models (validated by 2685 field observations) to test this hypothesis for 10 ecologically diverse lizards in African and Australian deserts. Historical warming (1950-2020) has been more intense in Africa than in Australia, translating to an energetic squeeze for African diurnal species. Although no net impact on Australian diurnal species was observed, warming generated an energetic "relief" (by increasing foraging time) for nocturnal species. Future warming impacts will be more severe in Africa than in Australia, requiring increased rates of food intake (+10% per hour active for diurnal species). The effects of climate warming on desert lizard energy budgets will thus be species-specific but potentially predictable.

Forecasting Range Shifts in Terrestrial Alpine Insects Under Global Warming

Anthropogenic planetary heating is disrupting global alpine systems, but our ability to empirically measure and predict responses in alpine species distributions is impaired by a lack of comprehensive data and technical limitations. We conducted a comprehensive, semi-quantitative review of empirical studies on contemporary range shifts in alpine insects driven by climate heating, drawing attention to methodological issues and potential biotic and abiotic factors influencing variation in responses. We highlight case studies showing how range dynamics may affect standing genetic variation and adaptive potential, and discuss how data integration frameworks can improve forecasts. Although biotic and abiotic factors influence individual species responses, most alpine insects studied so far are shifting to higher elevations. Upslope shifts are often accompanied by range contractions that are expected to diminish species genetic variation and adaptive potential, increasing extinction risk. Endemic species on islands are predicted to be especially vulnerable. Inferences drawn from the responses of alpine insects, also have relevance to species in other montane habitats. Correlative niche modelling is a keystone tool to predict range responses to planetary heating, but its limited ability to consider biological processes underpinning species' responses complicates interpretation. Alpine insects exhibit some potential to respond to rising temperatures via genetic change or phenotypic plasticity. Thus, future efforts should incorporate biological processes by using flexible hybrid niche modelling approaches to enhance the biological realism of predictions. Boosting scientific capability to envisage the future of alpine environments and their associated biota is imperative given that the speed and intensity of heating on high-mountain ecosystems can surpass our ability to collect the empirical data required to guide effective conservation planning and management decisions.

Solar radiation alters heat balance and thermoregulation in a flying desert bee

Solar radiation is an important environmental variable for terrestrial animals, but its impact on the heat balance of large flying insects has been poorly studied. Desert bees are critical to ecosystem function through their pollination services, and are exposed to high radiant loads. We assessed the role of solar radiation in the heat balance of flying desert Centris pallida bees by calculating heat budgets for individuals in a respirometer in shaded versus sunny conditions from 16 to 37°C air temperatures, comparing the large and small male morphs and females. Solar radiation was responsible for 43 to 54% of mean total heat gain. Bees flying in the sun had thorax temperatures 1.7°C warmer than bees flying in the shade, storing a very small fraction of incident radiation in body tissues. In most cases, flight metabolic rate was not suppressed for bees flying in the sun, but evaporative water loss rates more than doubled. The most dramatic response to solar radiation was an increase in convection, mediated by a more than doubling of convective conductance, allowing thermoregulation while conserving body water. In large morph males and females, the increased convective conductance in the sun was mediated by increased heat transfer from the thorax to abdomen. Because convection is limited as body temperatures approach air temperatures, solar radiation combined with warming air temperatures may cause endothermic flying bees to reach a tipping point at which increases in non-sustainable evaporation are necessary for survival.

New insights into the neurophysiological effects of heat stress on the Chinese mitten crab (Eriocheir sinensis)

Climate warming and frequent incidents of extreme high temperatures are serious global concerns. Heat stress induced by high temperature has many adverse effects on animal physiology, especially in aquatic poikilotherms. Chinese mitten crab (Eriocheir sinensis) is sensitive to high temperatures, this study evaluated the harmful effects of heat stress on the neurotoxicity, intestinal health, microbial diversity, and metabolite profiles. The results showed that heat stress caused histopathological damages and altered the ultrastructure of lesions in the cranial ganglia. Heat stress significantly upregulated the mRNA expression of apoptosis-related genes, and significantly altered the expression of neurotransmitter receptors. In addition, heat stress induced significant intestinal damages that mainly manifested as a significant increase in the activity of diamine oxidase in the serum and contents of histamine in the intestine. The diversity and abundance of intestinal microbiota altered abnormally in E. sinensis exposed to heat stress, and the bacteria that exhibited significant variations in abundance were closely related to the production of neurotransmitters and neuromodulators. Heat stress caused significant changes in the intestinal metabolite profiles, which mainly involved the amino acid and lipid metabolism pathways. Analysis of the correlation showed that the abnormal changes in metabolites were closely related to differences in the abundance of intestinal microbiota. Therefore, this study showed that heat stress could cause neurophysiological toxic effects, which may be related to intestinal ecological imbalance.

How Much Warming Can Mosquito Vectors Tolerate?

Climate warming is expected to substantially impact the global landscape of mosquito-borne disease, but these impacts will vary across disease systems and regions. Understanding which diseases, and where within their distributions, these impacts are most likely to occur is critical for preparing public health interventions. While research has centered on potential warming-driven expansions in vector transmission, less is known about the potential for vectors to experience warming-driven stress or even local extirpations. In conservation biology, species risk from climate warming is often quantified through vulnerability indices such as thermal safety margins-the difference between an organism's upper thermal limit and its habitat temperature. Here, we estimated thermal safety margins for 8 mosquito species that are the vectors of malaria, dengue, chikungunya, Zika, West Nile and other major arboviruses, across their known ranges to investigate which mosquitoes and regions are most and least vulnerable to climate warming. We find that several of the most medically important mosquito vector species, including Ae. aegypti and An. gambiae, have positive thermal safety margins across the majority of their ranges when realistic assumptions of mosquito behavioral thermoregulation are incorporated. On average, the lowest climate vulnerability, in terms of both the magnitude and duration of thermal safety, was just south of the equator and at northern temperate range edges, and the highest climate vulnerability was in the subtropics. Mosquitoes living in regions including the Middle East, the western Sahara, and southeastern Australia, which are largely comprised of desert and xeric shrubland biomes, have the highest climate vulnerability across vector species.

Cooling down is as important as warming up for a large-bodied tropical reptile

An ectotherm's performance and physiological function are strongly tied to environmental temperature, and many ectotherms thermoregulate behaviourally to reach optimum body temperatures. Tropical ectotherms are already living in environments matching their thermal tolerance range and may be expected to conform to environmental temperatures. We tracked the body temperatures (Tb) of 163 estuarine crocodiles across 13 years and compared Tb of 39 crocodiles to water temperature gathered using fish-borne sensors (Tw) across 3 years (2015-2018). While Tb largely conformed closely to Tw, we found inter- and intra-individual differences in relative body temperature (Tb-Tw) that depended on sex and body size as well as the time of day and year. Deviations from Tw, especially during the warm parts of the year, suggest that thermoregulatory behaviour was taking place: we found patterns of warming and cooling events that seemed to mediate this variation in Tb. Thermoregulatory behaviour was observed most frequently in larger individuals, with warming events common during winter and cooling events common during summer. By observing free-ranging animals across multiple years, we found that estuarine crocodiles show yearly patterns of active cooling and warming behaviours that modify their body temperature, highlighting their resilience in the face of recent climate warming. Our work also provides the first evidence for thermal type in large-bodied reptiles.

Metabolic regulation reduces the oxidative damage of arid lizards in response to moderate heat events

Climate warming poses a significant threat to species worldwide, particularly those inhabiting arid and semi-arid regions where extreme temperatures are increasingly prevalent. However, empirical studies investigating how moderate heat events affect the physiological processes of arid and semi-arid animals are largely scarce. To address this knowledge gap, we used an arid and semi-arid lizard species (Phrynocephalus przewalskii) as a study system. We manipulated thermal environments to simulate moderate heat events (43.5 ± 0.3°C during the heating period) for lizards and examined physiological and biochemical traits related to survival, metabolism, locomotion, oxidative stress, and telomere length. We found that the body condition and survival of the lizards were not significantly affected by moderate heat events, despite an increase in body temperature and a decrease in locomotion at high test temperatures were detected. Mechanistically, we found that the lizards exhibited down-regulated metabolic rates and enhanced activities of antioxidative enzymes, resulting in reduced oxidative damage and stable telomere length under moderate heat events. Based on these findings, which indicated a beneficial regulation of fitness by physiological and biochemical processes, we inferred that moderate heat events did not have a detrimental effect on the toad-headed agama, P. przewalskii. Overall, our research contributes to understanding the impacts of moderate heat events on arid and semi-arid species and highlights the adaptive responses and resilience exhibited by the toad-headed agama in the face of climate warming.

Altitudinal variation in reproductive investment among Gryllus campestris populations

Life history traits determine the organismal abundance within a population and are affected by the presence of trade-offs that modify relationships between traits. These relationships can vary across different environments either by local adaptation or phenotypic plasticity. Reproductive traits have direct fitness implications and therefore are suitable to study among population variation linked to environmental differences. Factors such as altitude are often related to differences in key physical factors like ambient temperature or the subsequent duration of the suitable period for annual activity. The aim of this work was to compare reproductive investment in females of the field cricket Gryllus campestris originated from different altitudes, but without identifying the components (genetic vs. phenotypic) of the analysed variables. This species has an annual cycle; after a winter diapause, adults emerge to breed by early mid spring to produce a new generation of nymphs. The study used females collected at the start of the 2021 breeding season, from 10 populations living in the Cantabrian region (Northern Spain). Five of them were located in areas under 170m a.s.l. and the other five above 1100m. Females were allowed to mate with a male from the same population and to lay eggs that we then collected to estimate egg mass and laying rate; both traits were analysed controlling for female size. We found no effect of altitude on any of the three measured traits, female size, egg mass, and laying rate, as well as on the relationships between each pair or traits. Our results suggest that this species is tolerant to environmental variation for the measured traits, showing that it has mechanisms to cope with a range of ambient temperatures.

Heat waves during egg development alter maternal care and offspring quality in the European earwig

Climate change can disrupt animal fitness by reducing survival, fertility, fecundity and altering offspring development and survival. While parental care typically helps offspring cope with harsh environmental conditions, little is known about its role in buffering extreme temperature changes, such as heat waves. In this study, we tested whether parental care mitigates the impact of cold and heat waves on eggs and juveniles in the European earwig. In this insect, mothers provide obligatory egg care for about 50 days during winter, typically at temperatures around 10 °C. We exposed mothers and their eggs to three-day thermal waves of 3 °C, 10 °C (control), 17 °C or 24 °C, both 15 and 30 days after oviposition. We then measured four maternal care behaviors, maternal weight variation, as well as eggs' developmental time, survival, and hatching rate. In the resulting juveniles, we measured weight, developmental time, thermal resistance, and the expression of six heat stress and immunity genes. We found that thermal waves reduced maternal care and induced maternal weight gain. High temperatures also decreased egg hatching success, accelerated egg and nymph development, reduced the upper thermal limit of juveniles and decreased the expression of a heat shock protein (Hsp68), while other traits remained unaffected. Overall, this study highlights that access to maternal care is not enough to alleviate the stress of exposure to non-optimal temperatures during egg development in the European earwig. It also suggests that species with maternal care do not necessarily have access to effective thermal protection and may not be better adapted to climate change.

Artificial Intelligence for Climate Change Biology: From Data Collection to Predictions

In the era of big data, ecological research is experiencing a transformative shift, yet big-data advancements in thermal ecology and the study of animal responses to climate conditions remain limited. This review discusses how big data analytics and artificial intelligence (AI) can significantly enhance our understanding of microclimates and animal behaviors under changing climatic conditions. We explore AI's potential to refine microclimate models and analyze data from advanced sensors and camera technologies, which capture detailed, high-resolution information. This integration can allow researchers to dissect complex ecological and physiological processes with unprecedented precision. We describe how AI can enhance microclimate modeling through improved bias correction and downscaling techniques, providing more accurate estimates of the conditions that animals face under various climate scenarios. Additionally, we explore AI's capabilities in tracking animal responses to these conditions, particularly through innovative classification models that utilize sensors such as accelerometers and acoustic loggers. For example, the widespread usage of camera traps can benefit from AI-driven image classification models to accurately identify thermoregulatory responses, such as shade usage and panting. AI is therefore instrumental in monitoring how animals interact with their environments, offering vital insights into their adaptive behaviors. Finally, we discuss how these advanced data-driven approaches can inform and enhance conservation strategies. In particular, detailed mapping of microhabitats essential for species survival under adverse conditions can guide the design of climate-resilient conservation and restoration programs that prioritize habitat features crucial for biodiversity resilience. In conclusion, the convergence of AI, big data, and ecological science heralds a new era of precision conservation, essential for addressing the global environmental challenges of the 21st century.

Drivers of Intraspecific Variation in Thermal Traits and Their Importance for Resilience to Global Change in Amphibians

Intraspecific variation can be as great as variation across species, but the role of intraspecific variation in driving local and large-scale patterns is often overlooked, particularly in the field of thermal biology. In amphibians, which depend on environmental conditions and behavior to regulate body temperature, recognizing intraspecific thermal trait variation is essential to comprehensively understanding how global change impacts populations. Here, we examine the drivers of micro- and macrogeographical intraspecific thermal trait variation in amphibians. At the local scale, intraspecific variation can arise via changes in ontogeny, body size, and between the sexes, and developmental plasticity, acclimation, and maternal effects may modulate predictions of amphibian performance under future climate scenarios. At the macrogeographic scale, local adaptation in thermal traits may occur along latitudinal and elevational gradients, with seasonality and range-edge dynamics likely playing important roles in patterns that may impact future persistence. We also discuss the importance of considering disease as a factor affecting intraspecific variation in thermal traits and population resilience to climate change, given the impact of pathogens on thermal preferences and critical thermal limits of hosts. Finally, we make recommendations for future work in this area. Ultimately, our goal is to demonstrate why it is important for researchers to consider intraspecific variation to determine the resilience of amphibians to global change.

The Shape of Water: Physiological Adaptations to Habitat Aridity in the Ornate Tree Lizard (Urosaurus ornatus)

Deserts have always amazed researchers due to their high diversity of habitats, where plant and animal species have been able to adapt and diversify, even when these areas impose several constraints on an organism's activity patterns. In particular, deserts support several lizard species adapted to the thermal and water restrictions found in such biomes. Although several studies have attempted to understand how lizard species might respond to water deficits or droughts in deserts, few have addressed how these responses might vary along a latitudinal gradient. This raises the question of whether physiological buffering of the organism or the climatic environment affects water loss in lizards. Here, we used six populations of Urosaurus ornatus to test whether water loss is influenced more by the intrinsic physiology of the lizard or by the climatic niche. We found that water loss is primarily influenced by the climatic niche of the lizard. However, future studies should focus on how microclimatic variables can influence water loss in organisms found across large latitudinal gradients.

Behavioural Thermoregulation of Flowers via Petal Movement

Widely documented in animals, behavioural thermoregulation mitigates negative impacts of climate change. Plants experience especially strong thermal variability but evidence for plant behavioural thermoregulation is limited. Along a montane elevation gradient, Argentina anserina flowers warm more in alpine populations than at lower elevation. We linked floral temperature with phenotypes to identify warming mechanisms and documented petal movement and pollinator visitation using time-lapse cameras. High elevation flowers were more cupped, focused light deeper within flowers and were more responsive to air temperature than low; cupping when cold and flattening when warm. At high elevation, a 20° increase in petal angle resulted in a 0.46°C increase in warming. Warming increased pollinator visitation, especially under cooler high elevation temperatures. A plasticity study revealed constitutive elevational differences in petal cupping and stronger temperature-induced floral plasticity in high elevation populations. Thus, plant populations have evolved different behavioural responses to temperature driving differences in thermoregulatory capacity.

Leveraging camera traps and artificial intelligence to explore thermoregulation behaviour

Behavioural thermoregulation has critical ecological and physiological consequences that profoundly influence individual fitness and species distributions, particularly in the context of climate change. However, field monitoring of this behaviour remains labour-intensive and time-consuming. With the rise of camera-based surveys and artificial intelligence (AI) approaches in computer vision, we should try to build better tools for characterizing animals' behavioural thermoregulation. In this study, we developed a deep learning framework to automate the detection and classification of thermoregulation behaviour. We used lizards, the Rough-tail rock agama (Laudakia vulgaris), as a model animal for thermoregulation. We colour-marked the lizards and curated a diverse dataset of images captured by trail cameras under semi-natural conditions. Subsequently, we trained an object-detection model to identify lizards and image classification models to determine their microclimate usage (activity in sun or shade), which may indicate thermoregulation preferences. We then evaluated the performance of each model and analysed how the classification of thermoregulating lizards performed under different solar conditions (sun or shade), times of day and marking colours. Our framework's models achieved high scores in several performance metrics. The behavioural thermoregulation classification model performed significantly better on sun-basking lizards, achieving the highest classification accuracy with white-marked lizards. Moreover, the hours of activity and the microclimate choices (sun vs shade-seeking behaviour) of lizards, generated by our framework, are closely aligned with manually annotated data. Our study underscores the potential of AI in effectively tracking behavioural thermoregulation, offering a promising new direction for camera trap studies. This approach can potentially reduce the labour and time associated with ecological data collection and analysis and help gain a deeper understanding of species' thermal preferences and risks of climate change on species behaviour.

A frog in hot water: the effect of temperature elevation on the adrenal stress response of an African amphibian

Amphibians, with their unique physiology and habitat requirements, are especially vulnerable to changes in environmental temperatures. While the activation of the physiological stress response can help to mitigate the impact of such habitat alteration, chronic production of elevated glucocorticoid levels can be deleterious in nature. There is no empirical evidence indicating the physiological response of African amphibians to temperature changes, where individuals are unable to emigrate away from potential stressors. To rectify this, we used the edible bullfrog (Pyxicephalus edulis) as a model species to determine the effect of elevated temperature on the adrenocortical response of the species using a recently established matrix. While a control group was kept at a constant temperature (25 °C) throughout the study period, an experimental group was exposed to control (25 °C) and elevated temperatures (30 °C). Mucous swabs were collected throughout the study period to determine dermal glucocorticoid (dGC) concentrations, as a proxy for physiological stress. In addition to this, individual body mass measurements were collected. The results showed that individuals within the experimental group who experienced increased temperatures had significantly elevated dGC levels compared to the control animals. Furthermore, there was a significant difference in the percentage mass change between experimental and control animals . These findings indicate the physiological sensitivity of the edible bullfrog to a thermal stressor in captivity. While this study shows the importance of proper amphibian management within the captive environment, it also highlights the coming danger of global climate change to this and similar amphibian species.

Collective effects of rising average temperatures and heat events on oviparous embryos

Survival of the immobile embryo in response to rising temperature is important to determine a species' vulnerability to climate change. However, the collective effects of 2 key thermal characteristics associated with climate change (i.e., rising average temperature and acute heat events) on embryonic survival remain largely unexplored. We used empirical measurements and niche modeling to investigate how chronic and acute heat stress independently and collectively influence the embryonic survival of lizards across latitudes. We collected and bred lizards from 5 latitudes and incubated their eggs across a range of temperatures to quantify population-specific responses to chronic and acute heat stress. Using an embryonic development model parameterized with measured embryonic heat tolerances, we further identified a collective impact of embryonic chronic and acute heat tolerances on embryonic survival. We also incorporated embryonic chronic and acute heat tolerance in hybrid species distribution models to determine species' range shifts under climate change. Embryos' tolerance of chronic heat (T-chronic) remained consistent across latitudes, whereas their tolerance of acute heat (T-acute) was higher at high latitudes than at low latitudes. Tolerance of acute heat exerted a more pronounced influence than tolerance of chronic heat. In species distribution models, climate change led to the most significant habitat loss for each population and species in its low-latitude distribution. Consequently, habitat for populations across all latitudes will shift toward high latitudes. Our study also highlights the importance of considering embryonic survival under chronic and acute heat stresses to predict species' vulnerability to climate change.

Thermal Tolerance and Preferred Temperature in the Critical Endangered Montseny Brook Newt (Calotriton arnoldi)

Climate change, driven by increased human greenhouse gas emissions since the beginning of the industrial revolution up to the present day, is considered one of the major threats to biodiversity in the twenty-first century. One of the most affected groups is the ectotherms due to their direct dependence on environmental temperatures. In recent years, several studies have analysed the effects of temperature and thermal tolerance on several species of ectotherms. However, there are species whose thermal tolerances are still unknown. Such is the case of the critically endangered species, the Montseny Brook Newt (Calotriton arnoldi), endemic to the Montseny massif in Spain and whose thermal biology is unknown. Its critical situation makes it essential to know its tolerance to cooling, warming and thermopreferendum in water environments where the newt lives. Three experimental procedures were conducted from the western and eastern subspecies of C. arnoldi, considering four classes separately (males, females, juveniles and larvae). The results obtained showed that the CTmax of the species exceeded 31 °C, with a significant difference between the two subspecies. We found that the species tolerates low temperatures (<1 °C) well because the genera Calotriton is adapted to live in cold waters with temperatures below 15 °C. Although the thermopreference of the species was expected to trend to cold temperatures, some individuals chose relatively high temperatures, obtaining a range of 11.7 °C to 21.6 °C. The results presented in this study are an advance in the knowledge of the thermal physiology of this species and support the importance of the temperature of the torrent on its survival. Knowing their thermal limits and their preferred temperature range will help to propose management measures that promote the conservation of streams and riparian forest cover to mitigate temperature increases due to climate change.

Effects of thermophily-relevant temperature variation and sex on digestive performance in pythons

Different physiological performances are often optimized at slightly varying temperatures, which can lead to ectotherms selecting higher body temperatures during certain physiological efforts (e.g., digestion, reproduction). Such thermophilic responses can lead to temperature-based tradeoffs between two physiological activities with differing optimal temperatures or between optimizing a physiological activity and water balance, as water loss is elevated at higher temperatures. For example, ectotherms will often select a higher body temperature after consuming a meal, but the extent to which body temperature is elevated after eating is affected by its hydric state. Despite this known hydration state-based suppression of thermophily associated with digestion, the impact of this reduced body temperature on digestion performance is unknown. Accordingly, we determined whether small, thermophily-relevant changes in body temperature impact digestive efficiency or passage time and whether sex influenced the extent of the effect. Eighteen (9 female and 9 male) Children's pythons (Antaresia childreni) each consumed a meal at three temperatures (29 °C, 30 °C, and 31 °C), and gut passage time and digestive efficiency were determined. We found that neither metric was affected by temperature over the range tested. However, digestive efficiency was significantly impacted by the interaction between sex and temperature with males having significantly lower digestive efficiency than females at 31 °C, but not 29 °C or 30 °C. Our results provide insight into the effects of temperature on digestive physiology across narrow temperature ranges as well as demonstrate a sex-based difference in digestive physiology.

Anthropogenic, environmental and temporal associations with vertebrate road mortality in a wildland-urban interface of a biodiverse desert ecoregion

Road mortality adversely affects wildlife populations. As urbanization and infrastructure densities expand, transportation and wildlife management aim to mitigate wildlife-vehicle conflicts while conserving biodiversity. Roadways in aridland ecosystems can invariably and adversely impact wildlife differently from temperate and other biomes, yet these rapidly urbanizing regions are understudied as are urban-rural gradients. We conducted road-cruise surveys (n = 204; 2018-2023) to assess anthropogenic, environmental, and temporal factors associated with vertebrate roadkill across the wildland-urban interface of Arizona's biodiverse Sonoran Desert ecoregion-already subjected to increased human development and climate change. Of n = 2019 vertebrates observed, 28.5% were roadkill. Increasing urbanization levels were associated with reduced vertebrate abundance on roads and increased road-killed endothermic vertebrates. Traffic volume was strongly associated with reduced vertebrate abundance and increased roadkill; additive effects on roadkill began at approximately 20 vehicles. Daily low temperature and/or relative humidity were also associated with roadkill across vertebrate groups. We provide empirical evidence to understand wildlife-roadkill associations across expanding wildland-urban interfaces to inform effective roadkill mitigation and wildlife conservation management strategies in biodiverse aridland regions. We recommend that managers mitigate or avoid development in rural areas that possess high biodiversity, valuable waterways or migration corridors, and populations of vulnerable species.

Ocean warming and acidification adjust inter- and intra-specific variability in the functional trait expression of polar invertebrates

Climate change is known to affect the distribution and composition of species, but concomitant alterations to functionally important aspects of behaviour and species-environment relations are poorly constrained. Here, we examine the ecosystem ramifications of changes in sediment-dwelling invertebrate bioturbation behaviour-a key process mediating nutrient cycling-associated with near-future environmental conditions (+ 1.5 °C, 550 ppm [pCO2]) for species from polar regions experiencing rapid rates of climate change. We find that responses to warming and acidification vary between species and lead to a reduction in intra-specific variability in behavioural trait expression that adjusts the magnitude and direction of nutrient concentrations. Our analyses also indicate that species behaviour is not predetermined, but can be dependent on local variations in environmental history that set population capacities for phenotypic plasticity. We provide evidence that certain, but subtle, aspects of inter- and intra-specific variation in behavioural trait expression, rather than the presence or proportional representation of species per se, is an important and under-appreciated determinant of benthic biogeochemical responses to climate change. Such changes in species behaviour may act as an early warning for impending ecological transitions associated with progressive climate forcing.

Comparative life-history responses of lacewings to changes in temperature

Insects play a crucial role in all ecosystems, and are increasingly exposed to higher in temperature extremes under climate change, which can have substantial effects on their abundances. However, the effects of temperature on changes in abundances or population fitness are filtered through differential responses of life-history components, such as survival, reproduction, and development, to their environment. Such differential responses, or trade-offs, have been widely studied in birds and mammals, but comparative studies on insects are largely lacking, limiting our understanding of key mechanisms that may buffer or exacerbate climate-change effects across insect species. Here, we performed a systematic literature review of the ecological studies of lacewings (Neuroptera), predatory insects that play a crucial role in ecosystem pest regulation, to investigate the impact of temperature on life cycle dynamics across species. We found quantitative information, linking stage-specific survival, development, and reproduction to temperature variation, for 62 species from 39 locations. We then performed a metanalysis calculating sensitives to temperature across life-history processes for all publications. We found that developmental times consistently decreased with temperature for all species. Survival and reproduction however showed a weaker response to temperature, and temperature sensitivities varied substantially among species. After controlling for the effect of temperature on life-history processes, the latter covaried consistently across two main axes of variation related to instar and pupae development, suggesting the presence of life-history trade-offs. Our work provides new information that can help generalize life-history responses of insects to temperature, which can then expand comparative demographic and climate-change research. We also discuss important remaining knowledge gaps, such as a better assessment of adult survival and diapause.

Temperature, not net primary productivity, drives continental-scale variation in insect flight activity

The amount of energy available in a system constrains large-scale patterns of abundance. Here, we test the role of temperature and net primary productivity as drivers of flying insect abundance using a novel continental-scale data source: weather surveillance radar. We use the United States NEXRAD weather radar network to generate a near-daily dataset of insect flight activity across a gradient of temperature and productivity. Insect flight activity was positively correlated with mean annual temperature, explaining 38% of variation across sites. By contrast, net primary productivity did not explain additional variation. Grassland, forest and arid-xeric shrubland biomes differed in their insect flight activity, with the greatest abundance in subtropical and temperate grasslands. The relationship between insect flight abundance and temperature varied across biome types. In arid-xeric shrublands and in forest biomes the temperature-abundance relationship was indirectly (through net primary productivity) or directly (in the form of precipitation) mediated by water availability. These results suggest that temperature constraints on metabolism, development, or flight activity shape macroecological patterns in ectotherm abundance. Assessing the drivers of continental-scale patterns in insect abundance and their variation across biomes is particularly important to predict insect community response to warming conditions. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Flexibility in thermal requirements: a comparative analysis of the wide-spread lizard genus Sceloporus

Adaptation or acclimation of thermal requirements to environmental conditions can reduce thermoregulation costs and increase fitness, especially in ectotherms, which rely heavily on environmental temperatures for thermoregulation. Insight into how thermal niches have shaped thermal requirements across evolutionary history may help predict the survival of species during climate change. The lizard genus Sceloporus has a widespread distribution and inhabits an ample variety of habitats. We evaluated the effects of geographical gradients (i.e. elevation and latitude) and local environmental temperatures on thermal requirements (i.e. preferred body temperature, active body temperature in the field, and critical thermal limits) of Sceloporus species using published and field-collected data and performing phylogenetic comparative analyses. To contrast macro- and micro-evolutional patterns, we also performed intra-specific analyses when sufficient reports existed for a species. We found that preferred body temperature increased with elevation, whereas body temperature in the field decreased with elevation and increased with local environmental temperatures. Critical thermal limits were not related to the geographic gradient or environmental temperatures. The apparent lack of relation of thermal requirements to geographic gradient may increase vulnerability to extinction due to climate change. However, local and temporal variations in thermal landscape determine thermoregulation opportunities and may not be well represented by geographic gradient and mean environmental temperatures. Results showed that Sceloporus lizards are excellent thermoregulators, have wide thermal tolerance ranges, and the preferred temperature was labile. Our results suggest that Sceloporus lizards can adjust to different thermal landscapes, highlighting opportunities for continuous survival in changing thermal environments.

Predicting organismal response to marine heatwaves using dynamic thermal tolerance landscape models

Marine heatwaves (MHWs) can cause thermal stress in marine organisms, experienced as extreme 'pulses' against the gradual trend of anthropogenic warming. When thermal stress exceeds organismal capacity to maintain homeostasis, organism survival becomes time-limited and can result in mass mortality events. Current methods of detecting and categorizing MHWs rely on statistical analysis of historic climatology and do not consider biological effects as a basis of MHW severity. The re-emergence of ectotherm thermal tolerance landscape models provides a physiological framework for assessing the lethal effects of MHWs by accounting for both the magnitude and duration of extreme heat events. Here, we used a simulation approach to understand the effects of a suite of MHW profiles on organism survival probability across (1) three thermal tolerance adaptive strategies, (2) interannual temperature variation and (3) seasonal timing of MHWs. We identified survival isoclines across MHW magnitude and duration where acute (short duration-high magnitude) and chronic (long duration-low magnitude) events had equivalent lethal effects on marine organisms. While most research attention has focused on chronic MHW events, we show similar lethal effects can be experienced by more common but neglected acute marine heat spikes. Critically, a statistical definition of MHWs does not accurately categorize biological mortality. By letting organism responses define the extremeness of a MHW event, we can build a mechanistic understanding of MHW effects from a physiological basis. Organism responses can then be transferred across scales of ecological organization and better predict marine ecosystem shifts to MHWs.

Daily temperature fluctuation interacts with the mean temperature to increase the toxicity of a pyrethroid insecticide in a moth

Climate change complicates ecotoxicology studies because species responses to pesticides depend on temperature. Classically illustrated by the effect of constant laboratory temperatures, a recent review revealed that the toxicity of pesticides is also often increased by daily temperature fluctuations. Here, we investigated the combined effects of daily temperature fluctuation and mean temperature on the toxicity of two insecticides in the moth Spodoptera littoralis. Our study tested the toxicity of chlorpyrifos and deltamethrin on larvae of six experimental groups that crossed three treatments of daily temperature fluctuations (0, 5 or 10 °C) and two treatments of mean temperatures (25 or 33 °C). We showed that daily temperature fluctuation increased larval mortality induced by chlorpyrifos and deltamethrin. However, the response differed between the organophosphorus insecticide chlorpyrifos and the pyrethroid insecticide deltamethrin. The increase in chlorpyrifos toxicity by daily temperature fluctuation did not differ between mean temperatures of 25 and 33 °C. Remarkably, the increase in deltamethrin toxicity by daily temperature fluctuation was dependent on the crossed effects of the amplitude of daily fluctuation and mean temperature. This increase in deltamethrin toxicity occurred with a daily fluctuation of only 5 °C for larvae reared at 25 °C and a daily fluctuation of 10 °C in larvae reared at 33 °C. To confidently quantify the responses of insecticide toxicity to temperature, future ecotoxicology studies will have to evaluate the generality of the interaction between the effects of daily temperature fluctuation and mean temperature.

When adaptation is slowed down: Genomic analysis of evolutionary stasis in thermal tolerance during biological invasion in a novel climate

Research conducted during the past two decades has demonstrated that biological invasions are excellent models of rapid evolution. Even so, characteristics of invasive populations such as a short time for recombination to assemble optimal combinations of alleles may occasionally limit adaptation to new environments. Here, we investigated such genetic constraints to adaptation in the invasive brown anole (Anolis sagrei)-a tropical ectotherm that was introduced to the southeastern United States, a region with a much colder climate than in its native Caribbean range. We examined thermal physiology for 30 invasive populations and tested for a climatic cline in cold tolerance. Also, we used genomics to identify mechanisms that may limit adaptation. We found no support for a climatic cline, indicating that thermal tolerance did not shift adaptively. Concomitantly, population genomic results were consistent with the occurrence of recombination cold spots that comprise more than half of the genome and maintain long-range associations among alleles in invasive populations. These genomic regions overlap with both candidate thermal tolerance loci that we identified using a standard genome-wide association test. Moreover, we found that recombination cold spots do not have a large contribution to population differentiation in the invasive range, contrary to observations in the native range. We suggest that limited recombination is constraining the contribution of large swaths of the genome to adaptation in invasive brown anoles. Our study provides an example of evolutionary stasis during invasion and highlights the possibility that reduced recombination occasionally slows down adaptation in invasive populations.

Canopy coverage, light, and moisture affect thermoregulatory trade-offs in an amphibian breeding habitat

When amphibians thermoregulate, they face a fundamental trade-off between the ability to maintain activity and an increased rate of dehydration at higher temperatures. Canopy coverage affects both the thermal and hydric conditions of the environment and can therefore influence amphibian thermoregulation. Frogs require proper conditions to thermoregulate to successfully grow, survive, and reproduce. But while we know how canopy and environmental variables typically affect operative temperature, less is known about effects on amphibian water loss rates. In this study, we measure the effect of canopy coverage on the conditions available for thermoregulation at a breeding pond of the California red-legged frog, Rana draytonii. We use agar frog models to estimate the thermal and hydric capacities frogs would experience in locations with different canopy coverage and microhabitats. At each site, we deployed models under four microhabitat treatments: wet/sun, wet/shade, dry/sun, and dry/shade. We modeled how environmental variables affected operative temperature and evaporative water loss from agar frogs. We found positive effects of air temperature, the sun treatment, and reduced canopy cover on operative temperature, and negative direct or indirect effects of these variables on evaporative water loss, consistent with the hypothesized trade-off between thermoregulatory behavior to increase temperature and the increased desiccation risk due to higher water loss. Additionally, our results indicate that the availability of wet microhabitats can allow frogs to reduce water loss, potentially mitigating the risk of desiccation when thermoregulating to achieve higher operative temperatures. Our findings suggest, that with access to proper microhabitats, amphibians can mitigate the fundamental trade-off and receive benefits of thermoregulating at high temperatures.

Physiological phenotypes differ among color morphs in introduced common wall lizards (Podarcis muralis)

Many species exhibit color polymorphisms which have distinct physiological and behavioral characteristics. However, the consistency of morph trait covariation patterns across species, time, and ecological contexts remains unclear. This trait covariation is especially relevant in the context of invasion biology and urban adaptation. Specifically, physiological traits pertaining to energy maintenance are crucial to fitness, given their immediate ties to individual reproduction, growth, and population establishment. We investigated the physiological traits of Podarcis muralis, a versatile color polymorphic species that thrives in urban environments (including invasive populations in Ohio, USA). We measured five physiological traits (plasma corticosterone and triglycerides, hematocrit, body condition, and field body temperature), which compose an integrated multivariate phenotype. We then tested variation among co-occurring color morphs in the context of establishment in an urban environment. We found that the traits describing physiological status and strategy shifted across the active season in a morph-dependent manner-the white and yellow morphs exhibited clearly different multivariate physiological phenotypes, characterized primarily by differences in plasma corticosterone. This suggests that morphs have different strategies in physiological regulation, the flexibility of which is crucial to urban adaptation. The white-yellow morph exhibited an intermediate phenotype, suggesting an intermediary energy maintenance strategy. Orange morphs also exhibited distinct phenotypes, but the low prevalence of this morph in our study populations precludes clear interpretation. Our work provides insight into how differences among stable polymorphisms exist across axes of the phenotype and how this variation may aid in establishment within novel environments.

How seasonality influences the thermal biology of lizards with different thermoregulatory strategies: a meta-analysis

Ectotherms that maintain thermal balance in the face of varying climates should be able to colonise a wide range of habitats. In lizards, thermoregulation usually appears as a variety of behaviours that buffer external influences over physiology. Basking species rely on solar radiation to raise body temperatures and usually show high thermoregulatory precision. By contrast, species that do not bask are often constrained by climatic conditions in their habitats, thus having lower thermoregulatory precision. While much focus has been given to the effects of mean habitat temperatures, relatively less is known about how seasonality affects the thermal biology of lizards on a macroecological scale. Considering the current climate crisis, assessing how lizards cope with temporal variations in environmental temperature is essential to understand better how these organisms will fare under climate change. Activity body temperatures (Tb ) represent the internal temperature of an animal measured in nature during its active period (i.e. realised thermal niche), and preferred body temperatures (Tpref ) are those selected by an animal in a laboratory thermal gradient that lacks thermoregulatory costs (i.e. fundamental thermal niche). Both traits form the bulk of thermal ecology research and are often studied in the context of seasonality. In this study, we used a meta-analysis to test how environmental temperature seasonality influences the seasonal variation in the Tb and Tpref of lizards that differ in thermoregulatory strategy (basking versus non-basking). Based on 333 effect sizes from 137 species, we found that Tb varied over a greater magnitude than Tpref across seasons. Variations in Tb were not influenced by environmental temperature seasonality; however, body size and thermoregulatory strategy mediated Tb responses. Specifically, larger species were subjected to greater seasonal variations in Tb , and basking species endured greater seasonal variations in Tb compared to non-basking species. On the other hand, the seasonal variation in Tpref increased with environmental temperature seasonality regardless of body size. Thermoregulatory strategy also influenced Tpref , suggesting that behaviour has an important role in mediating Tpref responses to seasonal variations in the thermal landscape. After controlling for phylogenetic effects, we showed that Tb and Tpref varied significantly across lizard families. Taken together, our results support the notion that the relationship between thermal biology responses and climatic parameters can be taxon and trait dependent. Our results also showcase the importance of considering ecological and behavioural aspects in macroecological studies. We further highlight current systematic, geographical, and knowledge gaps in thermal ecology research. Our work should benefit those who aim to understand more fully how seasonality shapes thermal biology in lizards, ultimately contributing to the goal of elucidating the evolution of temperature-sensitive traits in ectotherms.

Ecological responses of squamate reptiles to nocturnal warming

Nocturnal temperatures are increasing at a pace exceeding diurnal temperatures in most parts of the world. The role of warmer nocturnal temperatures in animal ecology has received scant attention and most studies focus on diurnal or daily descriptors of thermal environments' temporal trends. Yet, available evidence from plant and insect studies suggests that organisms can exhibit contrasting physiological responses to diurnal and nocturnal warming. Limiting studies to diurnal trends can thus result in incomplete and misleading interpretations of the ability of species to cope with global warming. Although they are expected to be impacted by warmer nocturnal temperatures, insufficient data are available regarding the night-time ecology of vertebrate ectotherms. Here, we illustrate the complex effects of nocturnal warming on squamate reptiles, a keystone group of vertebrate ectotherms. Our review includes discussion of diurnal and nocturnal ectotherms, but we mainly focus on diurnal species for which nocturnal warming affects a period dedicated to physiological recovery, and thus may perturb activity patterns and energy balance. We first summarise the physical consequences of nocturnal warming on habitats used by squamate reptiles. Second, we describe how such changes can alter the energy balance of diurnal species. We illustrate this with empirical data from the asp viper (Vipera aspis) and common wall lizard (Podarcis muralis), two diurnal species found throughout western Europe. Third, we make use of a mechanistic approach based on an energy-balance model to draw general conclusions about the effects of nocturnal temperatures. Fourth, we examine how warmer nights may affect squamates over their lifetime, with potential consequences on individual fitness and population dynamics. We review quantitative evidence for such lifetime effects using recent data derived from a range of studies on the European common lizard (Zootoca vivipara). Finally, we consider the broader eco-evolutionary ramifications of nocturnal warming and highlight several research questions that require future attention. Our work emphasises the importance of considering the joint influence of diurnal and nocturnal warming on the responses of vertebrate ectotherms to climate warming.

How turtles keep their cool: Seasonal and diel basking patterns in a tropical turtle

Behavioural thermoregulation by ectotherms is an important mechanism for maintaining body temperatures to optimise physiological performance. Experimental studies suggest that nocturnal basking by Krefft's river turtles (Emydura macquarii krefftii) in the tropics may allow them to avoid high water temperatures, however, this hypothesis has yet to be tested in the field. In this study, we examined the influence of environmental temperature on seasonal and diel patterns of basking in E. m. krefftii in tropical north Queensland, Australia. Wildlife cameras were used to document turtle basking events for seven consecutive days and nights for each month over a year (April 2020-March 2021). Air and water temperatures were recorded simultaneously using temperature loggers. We used a negative binomial mixed effects model to compare mean basking durations (min) occurring among four environmental temperature categories based on population thermal preference (26 °C): 1) air temperature above and water temperature below preferred temperature; 2) air temperature below and water temperature above preferred temperature; 3) air and water temperatures both above preferred temperature; and 4) air and water temperatures both below preferred temperature. Basking behaviour was influenced significantly by the relationship between air and water temperature. During the day, turtles spent significantly less time basking when both air and water temperatures were above their preferred temperatures. Conversely, at night, turtles spent significantly more time basking when water temperatures were warm and air temperatures were cool relative to their preferred temperature. This study adds to the growing body of work indicating pronounced heat avoidance as a thermoregulatory strategy among tropical reptile populations.

Bringing traits back into the equation: A roadmap to understand species redistribution

Ecological and evolutionary theories have proposed that species traits should be important in mediating species responses to contemporary climate change; yet, empirical evidence has so far provided mixed evidence for the role of behavioral, life history, or ecological characteristics in facilitating or hindering species range shifts. As such, the utility of trait-based approaches to predict species redistribution under climate change has been called into question. We develop the perspective, supported by evidence, that trait variation, if used carefully can have high potential utility, but that past analyses have in many cases failed to identify an explanatory value for traits by not fully embracing the complexity of species range shifts. First, we discuss the relevant theory linking species traits to range shift processes at the leading (expansion) and trailing (contraction) edges of species distributions and highlight the need to clarify the mechanistic basis of trait-based approaches. Second, we provide a brief overview of range shift-trait studies and identify new opportunities for trait integration that consider range-specific processes and intraspecific variability. Third, we explore the circumstances under which environmental and biotic context dependencies are likely to affect our ability to identify the contribution of species traits to range shift processes. Finally, we propose that revealing the role of traits in shaping species redistribution may likely require accounting for methodological variation arising from the range shift estimation process as well as addressing existing functional, geographical, and phylogenetic biases. We provide a series of considerations for more effectively integrating traits as well as extrinsic and methodological factors into species redistribution research. Together, these analytical approaches promise stronger mechanistic and predictive understanding that can help society mitigate and adapt to the effects of climate change on biodiversity.

Japanese honey bees (Apis cerana japonica) have swarmed more often over the last two decades

The impacts of temperature increase are a concern for honey bees, which are major pollinators of crops and wild plants. Swarming is the reproductive behavior of honey bees that increases colony numbers. Honey bee colonies sometimes swarm multiple times, with each swarming termed a "swarming event" and a series of these events called a "swarming cycle." The number of swarming events per swarming cycle varies widely depending on climatic conditions and subspecies, and the recent temperature increase due to global warming might be affecting the number of swarming events per swarming cycle of native honey bees. We clarified long-term changes in the number of swarming events per swarming cycle of Japanese honey bees (Apis cerana japonica) by collecting beekeepers' swarming logbooks. The survey showed that between 2000 and 2022, Japanese honey bees swarmed 1 to 8 times per swarming cycle. Generalized linear model analysis indicated that year had a significant positive effect (coefficient, 0.03; 95% CI, 0.01-0.04); that is, the number of swarming events per swarming cycle showed a moderate increase over time. In addition, we found that colonies swarmed more often in a cycle when the swarming process began in early spring, especially in March. Considering the notably strong trend in Japan of warmer temperatures in March, the number of swarming events per swarming cycle may be increasing because reproduction is beginning earlier in the year. Further analyses are needed to verify the causal relationship of temperature increase on the number of swarming events per swarming cycle.

Thermal limits of survival and reproduction depend on stress duration: A case study of Drosophila suzukii

Studies of ectotherm responses to heat extremes often rely on assessing absolute critical limits for heat coma or death (CTmax), however, such single parameter metrics ignore the importance of stress exposure duration. Furthermore, population persistence may be affected at temperatures considerably below CTmax through decreased reproductive output. Here we investigate the relationship between tolerance duration and severity of heat stress across three ecologically relevant life-history traits (productivity, coma and mortality) using the global agricultural pest Drosophila suzukii. For the first time, we show that for sublethal reproductive traits, tolerance duration decreases exponentially with increasing temperature (R2 > 0.97), thereby extending the Thermal Death Time framework recently developed for mortality and coma. Using field micro-environmental temperatures, we show how thermal stress can lead to considerable reproductive loss at temperatures with limited heat mortality highlighting the importance of including limits to reproductive performance in ecological studies of heat stress vulnerability.

The Fall Armyworm and Larger Grain Borer Pest Invasions in Africa: Drivers, Impacts and Implications for Food Systems

Invasive alien species (IAS) are a major biosecurity threat affecting globalisation and the international trade of agricultural products and natural ecosystems. In recent decades, for example, field crop and postharvest grain insect pests have independently accounted for a significant decline in food quantity and quality. Nevertheless, how their interaction and cumulative effects along the ever-evolving field production to postharvest continuum contribute towards food insecurity remain scant in the literature. To address this within the context of Africa, we focus on the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), and the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), two of the most important field and postharvest IAS, respectively, that have invaded Africa. Both insect pests have shown high invasion success, managing to establish themselves in >50% of the African continent within a decade post-introduction. The successive and summative nature of field and postharvest damage by invasive insect pests on the same crop along its value chain results in exacerbated food losses. This systematic review assesses the drivers, impacts and management of the fall armyworm and larger grain borer and their effects on food systems in Africa. Interrogating these issues is important in early warning systems, holistic management of IAS, maintenance of integral food systems in Africa and the development of effective management strategies.