Journal of Thermal Biology

Long-term winter dormancy in ectotherms (brumation) defines the annual cycle of many temperate-zone reptiles, yet the transcriptional regulation that supports survival across months of cold and aphagy remains poorly understood. We generated time-resolved transcriptomic profiles of liver and testis from male red-sided garter snakes (Thamnophis sirtalis parietalis) at five timepoints spanning the eight-month brumation cycle: pre-brumation, early, mid-, and late brumation, and post-arousal under continued aphagy. Time-course negative-binomial regression (maSigPro) followed by gene-set enrichment analysis identified 3,715 transcripts in liver and 5,828 in testis with significant temporal expression structure organized into five overarching temporal patterns: sustained downregulation, downregulation with post-arousal recovery, sustained upregulation, brumation-specific upregulation and cyclic modulation. Liver showed coordinated upregulation of fatty acid mobilization enzymes (ATGL, FOXO1, PPAR, CPT1A) and gluconeogenic regulators (CREBBP, PCK1) coincident with sustained low temperatures. Additionally, low temperature transcriptional activity was suggestive of a shift toward hepatic lipid mobilization and alanine-supported gluconeogenesis. Testis showed sustained suppression of meiosis, reproduction, and DNA-metabolism gene sets that did not fully recover at arousal consistent with this species dissociated reproductive pattern. Both tissues showed coordinated upregulation of stress-response pathways involving heat-shock proteins, HIF1 and a glutathione-based antioxidant defense. Interestingly, three vitellogenin transcripts and 17{beta}-hydroxysteroid dehydrogenases associated with estradiol-favoring steroid metabolism were upregulated in male liver during late brumation, which is not expected during natural physiology in adult males. Together these data support a framework in which temperature- and starvation-associated transcriptional programs contribute to survival of one of the longest, coldest brumations documented in a squamate. Summary statementA time-resolved transcriptomic analysis of liver and testis spanning eight months of winter brumation in Thamnophis sirtalis parietalis reveals gene expression patterns consistent with a temperature-associated shift toward hepatic lipid mobilization, sustained reproductive suppression, and vitellogenin response in males.

Climate change-induced heatwaves threaten ectotherms, whose physiology is tightly coupled to ambient temperature. Vulnerability assessments often rely on data from one or a few populations, implicitly assuming uniform thermal sensitivity across species genetic diversity. Quantifying such variation is especially important for traits with wider ecological consequences; our focus here is on immune function, which shapes disease dynamics. We addressed this knowledge gap using ten clonal lineages of the New Zealand snail Potamopyrgus antipodarum exposed to ambient (17{degrees}C) or heatwave conditions (27{degrees}C) for 4 or 8 days. We measured two complementary innate immune traits: general phenoloxidase-like (PO-like) activity, which integrates the activity of multiple phenoloxidase enzymes, and laccase activity, which targets a specific PO enzyme subclass important in mollusc immunity. Heat exposure suppressed both traits, but patterns differed across clones. While PO-like activity declined uniformly, laccase activity showed substantial among-clone variation in heatwave responses at day 4, though these differences converged by day 8. Heat-induced immune suppression is thus trait-specific, depends on genetic background, and varies with exposure duration. Together, these results demonstrate that studies limited to a single genotype, population, or timepoint risk miscalculating species-level vulnerability.

Identifying how and why species vary in their ability to adjust to rapidly changing climates is a key challenge in ecology. While phenological shifts are well documented for birds and often studied in the context of tracking resource availability, less is known about the extent to which adjustments in phenology allow populations to track a consistent thermal niche. In particular, there has been little examination of how the extent of phenological thermal niche tracking compares over time versus space; a comparison that has the potential to inform on the underlying mechanisms. Here, we use data on breeding phenology derived from BTO Nest Record Scheme data, to examine the extent to which 13 passerine bird species track a consistent incubation thermal niche across years (both interannually and a year gradient) and along latitudinal and elevational gradients, and whether migrant and resident species differ in their tracking ability. Overall, we found support across species for partial tracking, with all species showing trends consistent with partial tracking across one or more axis, though for one species we could not reject the null hypothesis of no tracking. When we looked at average trends across species, we found significant tracking across interannual variation, latitude, and elevation, but not across a year trend. However, we found no evidence that tracking differs between residents and migrants, and for only a few species did we found evidence that species incubation thermal niche impacts on fitness. Taken together, our findings highlight the extent to which shifts in phenology can allow birds to track a thermal niche in a changing climate. The timing of a thermal niche provides a useful and widely-applicable yardstick to examine how changes in climate will impact on the abiotic conditions that populations experience.

Climate change is altering breeding phenology in birds worldwide, yet tropical systems remain understudied despite harbouring the greatest avian diversity. We drew upon 26 years (1998-2024) of breeding phenology and reproductive success data on three sympatric Asian hornbill species (Great Hornbill Buceros bicornis, Wreathed Hornbill Rhyticeros undulatus, Oriental Pied Hornbill Anthracoceros albirostris) from a tropical forest in northeast India to examine whether trends in long-term breeding parameters reflect directional climate change or interannual variability. Over the study period, we found no significant directional trends in nest entry timing, occupancy, or breeding success over 26 years, despite modest regional warming. However, breeding parameters showed sensitivity to interannual temperature variation, with pre-breeding temperature (January-February) explaining 36-70% of variance in nest timing. Temperature sensitivity differed among species, with Wreathed Hornbill showing the strongest response (-15.9 days/{degrees}C), followed by Great Hornbill (-9.8 days/{degrees}C), and Oriental Pied Hornbill showing the weakest (-4.8 days/{degrees}C), consistent with predictions that larger, frugivorous species with extended breeding cycles would exhibit greater climatic sensitivity. The underlying mechanism appears related to a body size-phenology-thermal exposure interaction: Oriental Pied Hornbills nest later (mid-April) with shorter breeding cycles ([~]90 days), completing reproduction before peak monsoon heat (June), whereas both larger species nest earlier (mid-February) but endure thermal stress throughout extended breeding cycles ([~]130+ days) into August. Notably, annual occupancy and breeding success remained stable across years despite strong phenological responses to temperature, suggesting that phenological plasticity may help maintain reproductive performance under current climatic variation. These findings indicate that tropical cavity-nesting frugivores exhibit phenological plasticity coupled with demographic stability, though the mechanisms underlying this apparent buffering remain incompletely understood, and body size-dependent differences in thermal exposure suggest heterogeneous vulnerabilities to future warming scenarios.

Environmental warming is generally expected to increase metabolic demand in ectotherms. However, facultatively endothermic insects such as bumblebees regulate body temperature and may reduce thermogenic investment under warm conditions, potentially altering physiological performance and responses to climate change. We combined flow-through respirometry and infrared thermography to test how elevated ambient temperature (25 vs 35{degrees}C) affects feeding energetics and postprandial metabolism in the bumblebee Bombus terrestris. Bees maintained substantially lower thoracic temperature excess at 35{degrees}C than at 25{degrees}C, both before and during feeding. Feeding metabolic rate was also lower at 35{degrees}C and was strongly positively associated with thoracic temperature excess, indicating that feeding energetics were primarily explained by thermoregulatory state rather than ambient temperature alone. Elevated temperature reduced both the probability and energetic magnitude of specific dynamic action (SDA), including total SDA expenditure, early postprandial metabolism, and peak metabolic amplitude. In contrast, SDA duration and time to peak response showed little temperature dependence. Our results demonstrate that warming can suppress energetic expenditure in facultatively endothermic pollinators by limiting thermogenic investment and postprandial metabolic responses, potentially constraining the energetic flexibility underpinning foraging performance under climate warming.

O_LILocal environmental conditions during the breeding season can limit bird populations. Identifying which variables, when, and how they affect key biological traits such as body condition is crucial for understanding long-term population trends under ongoing climate change. C_LIO_LIWe analysed the relationships between environmental variables and body condition during the breeding season in European robins (Erithacus rubecula), aiming to uncover links between short-term environmental influences and long-term trends in body condition in the context of local climate change. C_LIO_LIUsing data from a robin population monitored between 2007 and 2021, we applied weather sliding-window analyses to identify periods when temperature, soil moisture, and vegetation productivity best predicted individual body condition. For each variable, we identified critical time windows (CTWs) influencing (1) body condition across the season and (2) individual changes within two weeks. Juveniles and adults were analysed separately, with adult males and females distinguished during pre- and post-fledging periods. We also assessed long-term trends in environmental variables and body condition, and examined how body condition was correlated with apparent survival. C_LIO_LIBody condition variation across the season was explained by different environmental variables depending on age, sex, and period. Body condition declined with increasing minimum temperatures in adult males and juveniles, and with low soil moisture in adults of both sexes. We did not identify reliable CTWs explaining short-term within-individual changes in body condition. Across 2007-2021, body condition in adult males during the post-fledging period declined with rising minimum temperatures, while fledging dates advanced. Apparent survival was positively associated with body condition only in juvenile robins. C_LIO_LIOur results reveal multiple seasonal environmental influences that may contribute to short- and long-term declines in body condition in European robins, with effects particularly strong (or most detectable) in adult males. Reduced body condition may have demographic consequences by lowering juvenile survival, although shifts in breeding phenology could mitigate this impact. Overall, these findings highlight how environmental effects on body condition can shape long-term population trends and species vulnerability to climate change. C_LI

Climate-driven warming is challenging the physiological limits of aquatic ectotherms, with cardiac performance emerging as one of the key determinants of thermal tolerance. Cardiac function relies on mitochondrial ATP production, and mitochondrial dysfunction has been linked to cardiac failure at critical temperatures. However, mitochondria are plastic and may represent a target for interventions aimed at improving thermal tolerance in fish. Exercise training improves whole-animal performance in fish, including cardiac thermal performance, and improves mitochondrial function in other taxa. However, its effects on the thermal sensitivity of cardiac mitochondria remain unknown. This study investigated whether exercise-training alters cardiac mitochondrial performance at optimal and critical temperatures in rainbow trout Oncorhynchus mykiss. Farmed rainbow trout were subjected to a four-week exercise training regime, while control fish remained under standard rearing conditions. Cardiac mitochondrial respiration was assessed in permeabilised heart fibres at 16{degrees}C (optimal growth temperature) and 26{degrees}C (temperature associated with cardiac arrhythmia) and several biochemical and nuclear indicators were measured. No significant differences were detected between treatments for any measured variable. However, trained fish generally exhibited higher maximal respiratory capacities and respiratory control ratios, particularly at the elevated temperature, suggesting subtle improvements in mitochondrial function despite considerable inter-individual variation. Temperature influenced mitochondrial performance, increasing proton leak and reducing coupling efficiency. These findings demonstrate that cardiac mitochondrial function is thermally sensitive and represents a potential targeted for improving thermal resilience in aquaculture species.

Fever is a widespread and adaptive defence response that enhances immune performance through an increase in body temperature above normal values. In ectotherms, fever is expressed behaviourally through the selection of warmer microhabitats following infection, yet its magnitude and determinants vary widely across species and environments. Here, we performed a phylogenetically informed meta-analysis of behavioural fever in amphibians and reptiles to test whether its expression was shaped by climatic thermal variability, pathogen identity, and taxonomy. Specifically, we tested the hypotheses that (i) species from thermally variable environments would exhibit stronger behavioural fever than species from thermally stable environments, consistent with the climate variability hypothesis, and that (ii) reptiles would exhibit stronger fever responses than amphibians due to lower hydrothermal constraints. Across 47 studies encompassing 103 effect sizes, we found that behavioural fever is widespread but highly context-dependent. We found that evidence for behavioural fever was strongest in species from more thermally variable habitats, regardless of body size and phylogeny, suggesting that access to thermally heterogeneous landscapes and enhanced behavioural plasticity amplify the capacity to sustain febrile responses. Contrary to our hypothesis, amphibians exhibited stronger fever responses than reptiles, possibly reflecting differences in baseline thermoregulatory demands and environmental opportunity, or as a consequence of methodological artefacts. The expression of behavioural fever also varied with pathogen identity, with bacterial infections eliciting larger body temperature increases than fungal or viral challenges, although pathogen representation was uneven across studies. Together, our results support the idea that the capacity to express behavioural fever depends on access to thermally heterogeneous landscapes, and may vary according to pathogen biology. Ultimately, our study emphasises that temperature is not a background condition for host-pathogen interactions, but an active and environmentally contingent component of ectotherm immune defence in amphibians and reptiles.

Linking animal movements to environmental drivers is essential for understanding ecological processes and anticipating species responses to climate change. We investigated habitat-specific movements in a globally significant aggregation of loggerhead turtles (Caretta caretta) nesting in Cabo Verde. Satellite tags on 15 adults (12 females, 3 males) provided multi-year tracks spanning breeding, migration, and foraging habitats. Movements and phenology differed by habitat. During the breeding season, females used either coastal areas, remaining within [~]20 m depth, or undertook long looping forays up to 360 km. Males showed two strategies: two remained resident in Cabo Verde waters, including Fra, the largest male tracked (Curved carapace length of 105 cm compared with a male mean of 90.7 {+/-} 10.3 cm), while the third migrated annually to distant foraging grounds and returned ahead of the subsequent breeding season. In foraging habitats, turtles adopted neritic or oceanic strategies: neritic turtles remained localised in warm, productive waters, whereas oceanic turtles ranged widely in deeper, less productive areas. Time- and space-shift analyses showed that oceanic foragers used intermediate sea surface temperature and chlorophyll-a conditions relative to nearby or temporally shifted alternatives, consistent with movement within a thermal-trophic trade-off. Together, these results show how sex, body size, and energy balance drive habitat-specific movement dynamics in a changing ocean.

The shift to terrestrial environments in ancestrally aquatic animals is often associated with key physiological and physical changes, including shifts in respiratory physiology and in some cases, even the evolution of completely novel respiratory structures. Examining how respiration operates across a gradient of submersion states in ancestrally aquatic terrestrial animals may shed light on how complex biological traits shift under different selective regimes. In this work, we begin exploring respiration in terrestrially-adapted land crabs that still use their gills to respire while underwater. We tested the relationship between aquatic respiratory rates, body size, and sex in red devil vampire crabs (Geosesarma hagen) at two ecologically-relevant temperatures. We found small females respire more than small males at 28{degrees}C, while large females respire more than large males at 21{degrees}C. Additionally, body size is a significant factor affecting respiratory rates of both sexes at 21{degrees}C and warmer temperatures significantly increase respiration in small crabs of both sexes. Interactions between these factors also led to emerging trends that can be explained by both physiological rules, such as reproductive investment and surface-to-volume ratios and heat transfer. We also report a temperature coefficient (Q10) of 1.52 for this species, showing an expected 52% change in respiratory and metabolic rate for every 10{degrees}C increase. This work also demonstrates the importance of understanding how and to what extent biological variables like sex and body size interact with abiotic environmental factors when measuring physiological traits in ectothermic invertebrate animals.

O_LIMany organisms alter phenotypically plastic traits in response to environmental cues to match their phenotypes with variable environments. In larval amphibians, development and growth rates respond to spatiotemporally variable mortality risk from predation, wetland drying, or resource limitation. However, these rates are also temperature-dependent for ectotherms. Although wild animals experience these factors simultaneously (e.g., thermal regimes, predation risk, resource limitation), most studies investigate their impacts in isolation, limiting our understanding of how they interact across ecological contexts. C_LIO_LIHere we simultaneously exposed larval Plains Leopard Frogs (Lithobates blairi) to varying resource levels and predation risk treatments across a thermal regime to investigate the joint effects of these ecological drivers on growth and development rates and their consequences for size and vagility after metamorphosis. We crossed two predation treatments (waterborne cues from Procambarus gracilis fed L. blairi larvae, control water) with three food resource levels (5%, 25%, 50% of body mass) and six thermal regimes (diel {+/-} 3{degrees}C cycles of 15, 20, 22, 24, 26, 28{degrees}C), replicating each combination five times for a total of 180 individuals. We recorded growth and development rates and completion of metamorphosis, then measured juvenile body size and jumping performance. C_LIO_LIThe number of larvae completing metamorphosis was primarily determined by temperature and temperature-dependent effects of resource limitation. Percent metamorphosis peaked at intermediate temperatures when resources were high and were higher in predation-risk treatments at the warmest temperatures. Under high resources, development and growth rates showed unimodal thermal responses that were absent when resources were constrained. Higher resources increased development rates, but proportional increases in growth maintained constant body size across temperatures. Post-metamorphic body size differed only by predation treatment, with predator-exposed individuals being smaller. Juvenile jumping performance increased with body size and individuals raised with high resources without predator cues exhibited the highest performance. C_LIO_LIThe absence of temperature effects on size at metamorphosis reflected unexpected coupling of growth and development rates across treatments, producing uniform body sizes. This pattern contrasts with the temperature-size rule and suggests that plastic responses may exhibit selection for a minimum viable size at metamorphosis. C_LI

Animals often rely on cues from the environment to time reproduction with optimal conditions. However, for most species, which environmental cues are used and how their use varies across a species distribution remains poorly understood. The gray wolf (Canis lupus) is found across a broad latitudinal range (12{degrees}N to 83{degrees}N) and diverse natural habitats, making them an ideal study species to explore these questions. Using 1,261 estimated birth dates of wild and captive wolves across their global range, we investigated how environmental variables influence reproductive phenology in this widespread large carnivore. Birth dates for wild wolves ranged from November 22nd for Indian wolves (18{degrees}N) to June 15th for Arctic wolves (80{degrees}N). The best predictor of timing of birth was increasing daylength during the mating season, followed by precipitation variability during the year. The timing of birth in captive wolves was highly similar to wild wolves at same latitudes, suggesting they use similar environmental cues to time reproduction. Near the equator where photoperiod is more stable, wolves remained seasonal and likely use climatic cues to time reproduction. Our work reveals populations may use different environmental cues to time reproduction, a characteristic that likely facilitates adaptation to diverse environments.

Diapause is a critical adaptive strategy that enables temperate mosquito species to survive adverse environmental conditions and maintain population persistence across seasons. In Culex pipiens, diapause plays a key role in overwintering and influences the seasonal dynamics of arbovirus transmission. However, diapause expression is often assessed using single traits, limiting our understanding of its integrated physiological basis and variation among populations. In this study, we investigated the behavioural, morphological, and reproductive signatures of diapause across three laboratory strains of Culex pipiens (Mogden, Pirbright, and Pirbright Hybrid) reared under diapause-inducing (10 {degrees}C), cold (14 {degrees}C), and control (26-27 {degrees}C) conditions. We quantified blood-feeding behaviour, wing size as a proxy for somatic growth, and spermatheca size as an indicator of reproductive development. Diapause-inducing conditions resulted in a coordinated phenotype characterised by strong suppression of blood-feeding, increased somatic size, and marked inhibition of reproductive development. Mosquitoes reared at 10 {degrees}C exhibited near-complete feeding inhibition and significantly reduced spermatheca size, consistent with reproductive arrest, while those reared at 14 {degrees}C showed intermediate phenotypes. In contrast, control mosquitoes displayed active feeding and fully developed reproductive structures. Wing size increased progressively with decreasing temperature, with the largest individuals observed under diapause-inducing conditions. When analysed together, wing size and spermatheca development exhibited opposing responses across temperature treatments, revealing a strong negative association and indicating a trade-off between somatic growth and reproductive investment. This integrated response supports the interpretation of diapause as a coordinated life-history strategy involving resource reallocation towards survival. Additionally, diapause expression varied among strains, with the Mogden strain showing reduced sensitivity compared with Pirbright and hybrid populations, highlighting the role of genetic background in diapause plasticity. These findings demonstrate that diapause in Culex pipiens is a multi-trait, plastic phenotype with important implications for overwintering success and the seasonal dynamics of arbovirus transmission in temperate regions.

Temperatures in aquatic ecosystems have been affected by anthropogenic activities such as agricultural and industrial water use, and climate change caused by greenhouse gas emissions. Changes in water temperature directly affect the cellular and organismal physiology of fishes because most fishes are ectotherms. These effects can take different forms, such as increased cellular stress and reactive oxygen species (ROS) production. However, the type and magnitude of response depend on the duration and the frequency of the exposure to elevated water temperature. In this study, we investigated the long-term effects of exposure to daily thermal fluctuations occurring during early-life stages of zebrafish, Danio rerio, on gene expression and CTmax in later developmental stages. To do so, wild-type zebrafish were exposed daily to a + 5{degrees}C fluctuation in temperature from ambient (28 {degrees}C) to 33 {degrees}C over the first 30 days post fertilization (dpf), before being held until 90 dpf at ambient temperature. The fish that experienced daily thermal fluctuation were compared to a control group that was kept at 28 {degrees}C throughout the experiment and sampled at the same timepoints. Samples were collected at 18 (larval), 30, 60 (juvenile), and 90 (adult) dpf to study the expression of heat shock proteins and oxidative stress genes. The thermotolerance of fish was tested using CTmax trials at 60 and 90 dpf. Daily thermal fluctuation over the first 30 dpf led to a significant increase in the expression of hsp47, gstp1a, sod1, and sod2 genes at 60 dpf, and hsp47, hsp90aa1, hsp90ab1, cat, glulb, gstp1a, sod1, and sod2 genes at 90 dpf. The only significant increase detected during the larval stage was glulb at 18 dpf. Fish that experienced thermal fluctuation also had a higher CTmax at 60 dpf, but this increased thermotolerance significantly decreased from 60 to 90 dpf, where it was not different between treatments. Overall, our study demonstrates that early-life thermal stress increased cellular stress responses and thermotolerance in zebrafish into later ontological stages.

Thermal extremes are among the most immediate environmental challenges faced by animals. Coping with these conditions across life is complex because growth changes body size, heat exchange and thermoregulatory demands. Consequently, adaptive responses in young, small individuals may be maladaptive, or require adjustment, later in life. However, in endotherms we know very little about how thermoregulatory responses to hot and cold temperatures change during development, or about the molecular mechanisms regulating responses. We examined the molecular responses to acute heat (40{degrees}C), cold (12{degrees}C) and control (23{degrees}C) conditions in 1- and 8-week-old ostrich chicks (Struthio camelus), a rapidly growing species exposed to strong daily and seasonal temperature variation. We found that in 1-week-old chicks, 32% of temperature-related genes were involved in both heat and cold responses, indicating that responses to opposing temperatures involve overlapping molecular pathways. However, the response of 75% of these genes changed during development. For example, some genes that increased with heat when young decreased with heat later in development, and vice versa. Such opposing selection pressures may maintain genetic variation in thermoregulatory pathways. Consistent with this prediction, comparisons between ostrich subspecies adapted to different thermal environments revealed patterns of genomic variation compatible with balancing selection in differentially expressed genes. Our results show that hot and cold temperatures trigger overlapping molecular responses that change during development, which shape genetic variation in the thermoregulatory system.

O_LIThe frequency and intensity of heat events is increasing across marine and terrestrial ecosystems. Within the same ecological community, the relative exposure and sensitivity to heat stress may vary considerably among interacting species, like predators and prey. This can be especially true for species that interact at the aquatic-terrestrial interface, as well as for interactions between primarily nocturnal and diurnal species, making it difficult to predict how such communities will respond to habitat warming. C_LIO_LIThermal limit metrics such as CTmax are often assumed to equate with ecological death because such temperatures impair behavioral activity and/or physiological functioning. Prey that are diurnally active can be more frequently exposed to temperatures that approach CTmax compared to their nocturnal predators, which may use thermal refuges during the day. Yet the impacts of daytime heat exposure on nighttime predation risk remain unknown. C_LIO_LIHere, we compared the thermal environment, performance, and heat tolerance between the predatory blue crab, Callinectus sapidus and one of its prey species, the mangrove periwinkle Littoraria anguilifera in a tropical mangrove ecosystem. We examined how exposing prey to heat stress at and below their CTmax affected their capacity to avoid predation in the field at night when predation risk is highest. C_LIO_LIWe found that acute exposure to temperatures near CTmax during the day increased the prey species susceptibility to predation during recovery at night. Although both interacting predator and prey have high thermal tolerance, prey are exposed to conditions that already reach CTmax, suggesting that current extremes in temperatures may already be influencing vulnerability to predation in this ecosystem. C_LIO_LIOur results suggest that differential exposure to sublethal heat stress in diurnal prey relative to their predator, along with the subsequent impact of these exposures on predation risk, will play a role in shaping these interacting as climate warms. C_LI

Phenological shifts under climate change often arise through phenotypic plasticity and, where this is insufficient to track shifts in optimum timing, genetic adaptation may also play a role. Understanding the contributions of these two processes is critical for predicting species persistence in a changing climate. While many species show phenological plasticity, we know surprisingly little about the contributions that genetic adaptation of the plasticity reaction norm elevation (timing in the mean environment) and slope (shift in timing as a response to temperature) make to phenological shifts. With the aim of disentangling plasticity from adaptation in temperature-phenology reaction norms, we applied a statistical approach to long-term first egg-laying data from 44 Finnish bird species represented by 69 populations spanning six decades. Applying phylogenetic meta-analysis to parameter estimates obtained from the individual time series, we estimated average plasticity and adaptation effect sizes and tested whether migratory strategy, generation length, and mean laying-date explained among-species variation. Egg-laying phenology was strongly plastic, advancing by 2.5 days {degrees}C{square}{superscript 1}. We found no evidence for a steeper reaction norm between 5-year periods versus within them, consistent with no adaptation of the reaction norm elevation. However, we detected a significant steepening of slopes over time (-0.04 days {degrees}C{square}{superscript 1} year{square}{superscript 1}), consistent with plasticity across the whole study area increasing from -2.5 to -5.1 days {degrees}C{square}{superscript 1} and in the northernmost area (-0.07 days {degrees}C{square}{superscript 1} year{square}{superscript 1}) from -2 to -6.5 days {degrees}C{square}{superscript 1} over the 64-year study period. Trait analyses revealed no significant effect of migratory strategy, generation length, nor mean phenology on adaptation. We show that plasticity enables substantial short-term tracking of warming accompanied by noteworthy evidence consistent with widespread evolution of. Our approach demonstrates how observational data can help reveal evolutionary signals, offering a tool for improved understanding of the processes that underpin phenological responses.

The accumulation of microplastics (MP; plastic particles 1 m - 1 mm in diameter) in the environment is an increasing global concern. Although the physiological effects of MP on organisms, including humans, are increasingly documented, their impacts on behaviour are far less understood. Further, little is known about how MP affect adaptive phenotypic plasticity - the ability of a genotype to adaptively modify its phenotype in response to environmental cues. Anuran tadpoles are key models for studying phenotypic plasticity, with well-established evidence for predator-induced behavioural adjustments. Tadpoles typically reduce their activity and risk-taking when exposed to chemical cues released by predators, which has been proven to be adaptive. We investigated whether MP exposure from the fertilised egg stage alters the behaviour of agile frog (Rana dalmatina) tadpoles, and whether it interferes with their predator-induced behavioural plasticity. Tadpoles exposed to chemical cues from dragonfly larvae showed the expected antipredator response: these larvae showed significantly reduced movement activity and risk-taking. Although exposure to MP did not influence the behaviour of tadpoles that had not been exposed to predator cues, and also did not alter predator-induced changes in movement activity, it entirely abolished the predator-induced reduction in risk-taking. These results indicate that MP can compromise antipredator behaviour, increasing the vulnerability of individuals and natural populations to predation without causing visible developmental abnormalities. We recommend that future MP research targets behavioural traits with direct relevance to survival and reproduction, and examines how adaptive phenotypic plasticity is affected.

Long-distance movement in insects has crucial impacts on agriculture, human health, and biodiversity. Although it was long assumed that only large, specialist insects had the navigation capacity to support long-distance dispersal, recent studies have demonstrated that smaller insects, such as the tiny fruit fly Drosophila melanogaster, can maintain extended, straight paths while flying or walking. This raises the question of whether other Drosophila species possess the navigation capacity to support extended dispersal. Resolving this question is particularly important for Drosophila suzukii(spotted-wing drosophila), a potent pest species that causes enormous damage worldwide to ripe fruit and berries. Spotted-wing drosophila has been thought to lack a capacity for long-distance dispersal, as prior studies have estimated maximal daily dispersal distances of less than 90 m. We developed a system to continuously track the flight trajectories of magnetically tethered D. suzukii relative to a discrete, overhead LED that mimicked the sun. We found that flies maintained remarkably straight flight headings that varied unpredictably across individuals. Male and female D. suzukii exhibited a similar navigation capacity; both sexes responded to rotation of a discrete sun stimulus with compensatory turns to maintain a stable relative heading. Our results suggest that D. suzukiihas an underappreciated capacity for rapid, radial dispersal, which could exceed 250 m in 15 min. This capacity may contribute to the pest species' invasiveness and its reliable, annual re-establishment in seasonally intolerable climates. Our findings highlight the importance of developing area-wide, regional strategies to manage the impacts of D. suzukii.

The Mount Graham red squirrel (Tamiasciurus fremonti grahamensis, MGRS) is a federally endangered subspecies endemic to southeastern Arizona. Despite the establishment of ex situ conservation programs, reproduction outside the wild has not occurred. We monitored fecal hormone metabolites (FHM) to noninvasively assess estrous cycling and reproductive hormone dynamics in ex situ-managed MGRS. We compared ex situ findings with two in situ (wild) populations. We tracked longitudinal changes in estradiol and progesterone metabolites in three ex situ managed females and evaluated whether ovulation was spontaneous or induced. We detected 22 ovulation events over two years, with timing and regularity consistent with spontaneous polyestrous cycling. Comparative hormone analyses revealed appreciably lower progesterone and corticosteroid metabolite levels in ex situ individuals, whereas estradiol levels were comparable to those of wild counterparts. These findings suggest that maintaining environmental, and social conditions, e.g., lighting, temperature, and conspecific proximity, in ex situ settings is critical and could influence reproductive success. By confirming spontaneous ovulatory cycling in MGRS and demonstrating the utility of FHM as a noninvasive reproductive assessment tool, this study advances ex situ breeding efforts and provides a framework for reproductive monitoring in other endangered taxa.