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Bacteria use several means to survive under stress conditions such as nutrient depletion. One such response is the formation of hibernating 100S ribosomes, which are translationally inactive 70S dimers. In Gammaproteobacteria (Enterobacterales), 100S ribosome formation requires ribosome modulation factor (RMF) and short hibernation promoting factor (HPF), whereas it is mediated by only long HPF in the majority of bacteria. Here, we investigated the role of HPFs of Comamonas testosteroni, which belongs to the Betaproteobacteria with common ancestor to the Gammaproteobacteria. C. testosteroni has two genes of HPF homologs of differing length (CtHPF‐125 and CtHPF‐119). CtHPF‐125 was induced in the stationary phase, whereas CtHPF‐119 conserved in many other Betaproteobacteria was not expressed in the culture conditions used here. Unlike short HPF and RMF, and long HPF, CtHPF‐125 could not form 100S ribosome. We first constructed the deletion mutant of Cthpf‐125 gene. When the deletion mutant grows in the stationary phase, 70S particles were degraded faster than in the wild strain. CtHPF‐125 contributes to stabilizing the 70S ribosome. CtHPF‐125 and CtHPF‐119 both inhibited protein synthesis by transcription‐translation in vitro. Our findings suggest that CtHPF‐125 binds to ribosome, and stabilizes 70S ribosomes, inhibits translation without forming 100S ribosomes and supports prolonging life. [ABSTRACT FROM AUTHOR]

Hibernation is a key adaptation for coping with unfavorable climatic conditions and low food availability in areas with severe winter conditions. While understanding the physiology and phenology of this adaptation has received considerable attention, comparatively little information is available on how hibernation will be affected by changing climate conditions. We used GPS telemetry data from 20 free‐ranging brown bears monitored over 31 winters between 2007 and 2022, to identify behavioral strategies of bears during winter. We applied behavioral change point analysis to quantify brown bears' hibernation phenology in a population close to the bear's southern latitudinal range limit in Europe where supplementary food is available to bears year‐round. We observed winter behavior patterns that varied across age and reproductive classes but also within individuals between winters. Among 31 winter events, we registered six cases in which bears exhibited a single hibernation/stationary period and 19 events where hibernation was split into up to five stationary periods. Moreover, six winter events did not show behaviors consistent with hibernation and individuals remained partly or completely active throughout winter. The movement of these active bears decreased with increasing snow depth. In addition, these winter‐active bears showed higher fidelity to supplementary feeding sites during the winter period compared to the rest of the year. Our data suggest that an abundance of human‐provided food resources during winter may facilitate the emergence of different wintering strategies in brown bears. Furthermore, supplemental feeding sites in combination with predicted mild winters and prolonged natural food availability suggest that the use of hibernation as an energy‐saving strategy to overcome severe environmental conditions may decrease in the future. [ABSTRACT FROM AUTHOR]

Use of dens during winter is an important strategy for American black bears (Ursus americanus) for both energy conservation and reproduction; and occupancy of suitable den sites has implications for reproductive fitness. Denning strategies may change as a result of changing climatic conditions and habitat loss. Black bears occupy arid environments in the eastern Sierra Nevada and the western ranges of the Great Basin Ecosystem. Our objectives were to identify: (1) which physical characteristics of habitat influenced selection of den sites at multiple spatial scales and (2) which environmental factors influenced timing of entrance and exit of dens by females and males. We evaluated selection of den sites by black bears at three spatial scales (300, 1000, and 4000 m) from 2011 to 2022. Terrain ruggedness was important for selection of den sites at all spatial scales. Within a 300‐m buffer from the den, bears selected den sites with rugged terrain, lower horizontal visibility, and greater canopy cover, resulting in more concealment and protection than that of the surrounding environment. Within 1000‐ and 4000‐m buffers around each den, bears selected den sites with rugged terrain, northern aspects, and steep slopes. At the 4000‐m scale, we observed interactions between sex with slope and distance to roads; females selected den sites on steeper slopes and closer to roads than did males. Females remained in the dens longer than males by entering earlier in the autumn and exiting later in the spring. Male bears exited their dens earlier with increasing consecutive days above freezing temperatures, but that relationship was weak for females. Knowing what characteristics are important for selection of den sites, and influence timing of denning, will be important for understanding how shifting climatic patterns will affect bears, particularly in arid environments that may be prone to wider fluctuations in climatic drivers of denning in the future. [ABSTRACT FROM AUTHOR]

Hibernation is a life history strategy for conservation of energy during adverse conditions, primarily of temperature or resource availability. Whilst energy conservation is beneficial in itself, it is less clear whether hibernation confers wider conservation benefits or mitigates or exacerbates a wide range of threats.We briefly review how hibernation manifests in mammalian biology, primarily through energy budgets, activity levels and resource requirements, but then ask how these interact with existing pressures to affect conservation risk. We also explore conservation actions that could alleviate the negative relations between some pressures and hibernation biology and review the available evidence for these measures.Hibernation can convey some protection from disease and predation, though there are notable exceptions, for example white‐nose syndrome. There is well‐established evidence that hibernators are prone to hazards of disturbance during hibernation, necessitating careful mitigation. Hibernators exhibit diverse responses to the pressures related to climate change, including temperature variability and phenological and range mismatches. Yet for each aspect, there are examples of species and populations responding negatively, such as with reduced survival, which suggests that hibernation could exacerbate the negative consequences of climate change.Though there are times when hibernators do not respond as expected, we find several positive conservation actions, such as modern grilles and regulations reducing the disturbance of cave‐hibernating bat species. Understanding and working with hibernation biology can, therefore, successfully mitigate the additional risks it confers. [ABSTRACT FROM AUTHOR]

Dormancy or hibernation is a non‐proliferative state of cells with low metabolic activity and gene expression. Dormant cells sequester ribosomes in a translationally inactive state, called dormant/hibernating ribosomes. These dormant ribosomes are important for the preservation of ribosomes and translation shut‐off. While recent studies attempted to elucidate their modes of formation, the regulation and roles of the diverse dormant ribosomal populations are still largely understudied. The mechanistic details of the formation of dormant ribosomes in stress and especially their disassembly during recovery remain elusive. In this review, we discuss the roles of dormant ribosomes and their potential regulatory mechanisms. Furthermore, we highlight the paradigms that need to be answered in the field of ribosomal dormancy. [ABSTRACT FROM AUTHOR]

The intestinal microbiota help regulate hibernation in vertebrates. However, it needs to be established how hibernation modulates the gut microbiome and intestinal metabolism. In the present study, we used an artificial hibernation model to examine the responses of the gut microbiota of the Strauchbufo raddei to the environmental changes associated with this behavior. Hibernation significantly lowered the diversity of the microbiota and altered the microbial community of the gut. Proteobacteria, Firmicutes, and Bacteroidota were the major bacterial phyla in the intestines of S. raddei. However, Firmicutes and Proteobacteria predominated in the gut of active and hibernating S. raddei, respectively. Certain bacterial genera such as Pseudomonas, Vibrio, Ralstonia, and Rhodococcus could serve as biomarkers distinguishing hibernating and non‐hibernating S. raddei. The gut microbiota was more resistant to environmental stress in hibernating than active S. raddei. Moreover, metabolomics revealed that metabolites implicated in fatty acid biosynthesis were highly upregulated in the intestines of hibernating S. raddei. The metabolites that were enriched during hibernation enabled S. raddei to adapt to the low temperatures and the lack of exogenous food that are characteristic of hibernation. A correlation analysis of the intestinal microbiota and their metabolites revealed that the gut microbiota might participate in the metabolic regulation of hibernating S. raddei. The present study clarified the modifications that occur in the intestinal bacteria and their symbiotic relationship with their host during hibernation. These findings are indicative of the adaptive changes in the metabolism of amphibians under different environmental conditions. [ABSTRACT FROM AUTHOR]

Reliable estimates of population trends are important for prioritizing and implementing wildlife management actions. Abundance estimates are the most informative metric of population status but are difficult and costly to achieve for rare or elusive species. For bat species that are highly mobile and nocturnal, abundance estimates are usually only possible at their roosts. Although they are relatively easy to census in individual roosts, it is often unclear whether observed trends are representative of broader populations trends. Dual‐frame sampling is useful for monitoring wildlife populations that exhibit site fidelity and are highly visible but where the proportion of the population in known sites is unknown. We adapted a dual‐frame sampling approach to estimate abundance of Townsend's big‐eared bats (Corynorhinus townsendii) hibernating in a system of >800 caves at Lava Beds National Monument (LBNM) in northern California, USA, in 2013–2022. Beginning with a list of opportunistically discovered hibernacula, we expanded inference to the entire system by randomly selecting sites and stratifying survey effort according to number of bats observed during previous counts. Following 4 years of surveys, we began substituting survey‐informed estimates for some site types to improve efficiency of the monitoring effort. We estimated that a mean of 2,216 ± 112 (SE) bats hibernated at the study site annually and observed fluctuations of up to 22% around the mean population estimate and as much as 21% from the previous year. Despite annual fluctuations, we did not detect a trend in the number of hibernating bats at LBNM over the study period, underlining the challenges of detecting population trends in long‐lived species not exposed to pronounced stressors. Because our analytical approach generates reliable estimates of trend while accommodating annual variability in survey effort among years, it should be attractive to wildlife managers faced with shifting priorities and resources. [ABSTRACT FROM AUTHOR]

Summary: A 1‐year systematic diary was kept by an anonymous diarist in Hamburg in the year 1755–1756. Sleep, activities, food intake, urine volume, and meteorological data were documented daily. The systematic recording of sleep and naps, with an accuracy of a quarter of an hour allowed analysis of the placement, duration, and consistency of sleep. The mean (range) night sleep duration was 6 (3–9) h. The distribution of sleep interruptions showed two peaks, short (≤30 min) and long (≥45 min) interruptions. The latter indicted nights with segmented sleep. Time in bed was subject to strong seasonal variations. Bedtime and rise time were earlier in summer than in winter and sleep latency was shorter in summer than in winter. However, sleep duration displayed a large spread in all seasons and did not differ substantially between summer and winter. Seasonal variations of sleep timing were related to the varying daylight hours during the year. Finally, the results of this individual case may prompt a more detailed investigation of the variability of sleep behaviour in the pre‐industrial period. [ABSTRACT FROM AUTHOR]

Extended school nonattendance has been identified across previous literature as problematic for autistic pupils and prevalence rates are considerably higher for this cohort than their neurotypical peers. The neurodiversity paradigm calls for a shift towards qualitative and participatory research methodologies, which was identified as a suitable approach for the current study to understand autistic young people's lived experiences. This participatory inquiry adopted a flexible and reflective approach with two autistic adolescents who had extended school nonattendance and aimed to explore how Kas and Z experienced this and described effective support to meet their needs. Adolescents' perspectives were supported by three parental viewpoints. The participatory design allowed participants to identify key themes of effective support: a nuanced relationship with time; internal processes of control and motivation; relationships and safe environments; perspectives around their diagnosis of autism. A thematic map was developed to highlight the interaction between adolescents' perspectives and parental viewpoints and the superordinate, researcher‐identified theme of Understanding and Acceptance of Individual Lived Experience of Autism. The methodology and themes suggest considerations for professionals to develop practice to support autistic pupils who experience extended school nonattendance. Implications for future research are discussed. [ABSTRACT FROM AUTHOR]

Many animals routinely make energetic trade‐offs to adjust to environmental demands and these trade‐offs often have significant implications for survival. For example, environmental hypoxia is commonly experienced by many organisms and is an energetically challenging condition because reduced oxygen availability constrains aerobic energy production, which can be lethal. Many hypoxia‐tolerant species downregulate metabolic demands when oxygen is limited; however, certain physiological functions are obligatory and must be maintained despite the need to conserve energy in hypoxia. Of particular interest is immunity (including both constitutive and induced immune functions) because mounting an immune response is among the most energetically expensive physiological processes but maintaining immune function is critical for survival in most environments. Intriguingly, physiological responses to hypoxia and pathogens share key molecular regulators such as hypoxia‐inducible factor‐1α, through which hypoxia can directly activate an immune response. This raises an interesting question: do hypoxia‐tolerant species mount an immune response during periods of hypoxia‐induced hypometabolism? Unfortunately, surprisingly few studies have examined interactions between immunity and hypometabolism in such species. Therefore, in this review, we consider mechanistic interactions between metabolism and immunity, as well as energetic trade‐offs between these two systems, in hypoxia‐tolerant animals but also in other models of hypometabolism, including neonates and hibernators. Specifically, we explore the hypothesis that such species have blunted immune responses in hypometabolic conditions and/or use alternative immune pathways when in a hypometabolic state. Evidence to date suggests that hypoxia‐tolerant animals do maintain immunity in low oxygen conditions, but that the sensitivity of immune responses may be blunted. [ABSTRACT FROM AUTHOR]

Hibernation, a survival strategy in mammals for extreme climates, induces physiological phenomena such as ischemia–reperfusion and metabolic shifts that hold great potential for advancements in modern medicine. Despite this, the molecular mechanisms underpinning hibernation remain largely unclear. This study used RNA‐seq and Iso‐seq techniques to investigate the changes in liver transcriptome expression of Rhinolophus pusillus during hibernation and active periods, as well as under different microhabitat temperatures. We identified 11 457 differentially expressed genes during hibernation and active periods, of which 395 showed significant differential expression. Genes associated with fatty acid catabolism were significantly upregulated during hibernation, whereas genes related to carbohydrate metabolism and glycogen synthesis were downregulated. Conversely, immune‐related genes displayed differential expression patterns: genes tied to innate immunity were significantly upregulated, while those linked to adaptive immunity and inflammatory response were downregulated. The analysis of transcriptomic data obtained from different microhabitat temperatures revealed that R. pusillus exhibited an upregulation of genes associated with lipid metabolism in lower microhabitat temperature. This upregulation facilitated an enhanced utilization rate of triglyceride, ultimately resulting in increased energy provision for the organism. Additionally, R. pusillus upregulated gluconeogenesis‐related genes regardless of the microhabitat temperature, demonstrating the importance of maintaining blood glucose levels during hibernation. Our transcriptomic data reveal that these changes in liver gene expression optimize energy allocation during hibernation, suggesting that liver tissue adaptively responds to the inherent stress of its function during hibernation. This study sheds light on the role of differential gene expression in promoting more efficient energy allocation during hibernation. It contributes to our understanding of how liver tissue adapts to the stressors associated with this state. [ABSTRACT FROM AUTHOR]

In winter, many reptiles have a period of inactivity (“brumation”). During brumation there is no energetic intake, therefore there would be an advantage to reducing energetic expenditure. The size of energetically costly organs, a major determinant of metabolic rate, is known to be flexible in many tetrapods. Seasonal plasticity of organ size could serve as both an energy‐saving mechanism and a source of nutrients for brumating reptiles. We studied a population of an invasive gecko, Tarentola annularis, to test for seasonal changes in activity, metabolic rate, and mass of various organs. The observed period of inactivity was December–February. Standard metabolic rates during the activity season were 1.85 times higher than in brumating individuals. This may be attributed to decreased organ mass during winter: heart mass decreased by 37%, stomach mass by 25%, and liver mass by 69%. Interestingly, testes mass increased by 100% during winter, likely in preparation for the breeding season, suggesting that males prioritize breeding over other functions upon return to activity. The size of the kidneys and lungs remained constant. Organ atrophy occurred only after geckos reduced their activity, so we hypothesize that organ mass changes in response to (rather than in anticipation of) cold winter temperatures and the associated fasting. Degradation of visceral organs can maintain energy demands in times of low supply, and catabolism of the protein from these organs can serve as a source of both energy and water during brumation. These findings bring us closer to a mechanistic understanding of reptiles’ physiological adaptations to environmental changes. [ABSTRACT FROM AUTHOR]

Ecologists have studied the role of interspecific competition in structuring ecological communities for decades. Differential weather effects on animal competitors may be a particularly important factor contributing to the outcome of competitive interactions, though few studies have tested this hypothesis in free‐ranging animals. Specifically, weather might influence competitive dynamics by altering competitor densities and/or per‐capita competitive effects on demographic vital rates. We used a 9‐year data set of marked individuals to test for direct and interactive effects of weather and competitor density on survival probability in two coexisting mammalian congeners: Columbian ground squirrels (Urocitellus columbianus) and northern Idaho ground squirrels (Urocitellus brunneus). Ambient temperature and precipitation influenced survival probability in both species, but the effects of weather differed between the two species. Moreover, density of the larger Columbian ground squirrel negatively impacted survival probability in the smaller northern Idaho ground squirrel (but not vice versa), and the strength of the negative effect was exacerbated by precipitation. That is, cooler, wetter conditions benefited the larger competitor to the detriment of the smaller species. Our results suggest weather‐driven environmental variation influences the competitive equilibrium between ecologically similar mammals of differential body size. Whether future climate change leads to the competitive exclusion of either species will likely depend on the mechanism(s) explaining the coexistence of these competing species. Divergent body size and, hence, differences in thermal tolerance and giving up densities offer potential explanations for the weather‐dependent competitive asymmetry we documented, especially if the larger species competitively excludes the smaller species from habitat patches of shared preference via interference. [ABSTRACT FROM AUTHOR]

Torpor or heterothermy is an energy‐saving mechanism used by endotherms to overcome harsh environmental conditions. During winter, the garden dormouse (Eliomys quercinus) hibernates with multiday torpor bouts and body temperatures of a few degrees Celsius, interrupted by brief euthermic phases. This study investigates gene expression within the hypothalamus, the key brain area controlling energy balance, adding information on differential gene expression potentially relevant to orchestrate torpor. A de novo assembled transcriptome of the hypothalamus was generated from garden dormice hibernating under constant darkness without food and water at 5 °C. Samples were collected during early torpor, late torpor, and interbout arousal. During early torpor, 765 genes were differentially expressed as compared with interbout arousal. Twenty‐seven pathways were over‐represented, including pathways related to hemostasis, extracellular matrix organization, and signaling of small molecules. Only 82 genes were found to be differentially expressed between early and late torpor, and no pathways were over‐represented. During late torpor, 924 genes were differentially expressed relative to interbout arousal. Despite the high number of differentially expressed genes, only 10 pathways were over‐represented. Of these, eight were also observed to be over‐represented when comparing early torpor and interbout arousal. Our results are largely consistent with previous findings in other heterotherms. The addition of a transcriptome of a novel species may help to identify species‐specific and overarching torpor mechanisms through future species comparisons. [ABSTRACT FROM AUTHOR]

To investigate the impact of short summers and long summer solar periods at high latitudes on the behavior of a nocturnal, hibernating mammal, we recorded the phenology of Myotis lucifugus (little brown myotis) at 60° N in the Northwest Territories (NWT), Canada. In particular, we assessed the timing of spring emergence from, and autumn entry into, hibernation, reproduction, and seasonal mass fluctuations. We used a combination of acoustic monitoring and capture surveys at two hibernacula and two maternity roosts during 2011 and 2012. Myotis spp. were active at the hibernacula from late April to late September/early October, suggesting that the "active" season length is similar to that of populations farther south. At maternity colonies, we detected M. lucifugus activity from early May to early October, with peaks during mid‐July in both years. Lactation, fledging, and weaning all occurred later in the NWT than at more southern locations, and reproductive rates were significantly lower than rates observed farther south. The average mass of individuals fluctuated throughout the season, with an initial decline immediately following emergence from hibernation likely reflecting increased energy expenditure due to flight and decreased use of torpor, coupled with relatively low prey intake due to low prey abundance associated with cool temperatures. Females did not appear to have lower pre‐hibernation masses than those in more southern populations, suggesting that despite the cool spring and autumn temperatures, and short summer nights, bats are able to obtain enough energy for reproduction and mass accumulation for hibernation. However, the lower reproductive rates may indicate that there are limitations to life at the northern limits of the species' range. [ABSTRACT FROM AUTHOR]

Fire is a vital management tool for maintaining prairie ecosystems. Prescribed burns control invasive species, regulate succession, stimulate plant growth, and are a cheap and effective method for removing excess biomass; however, fire can also inadvertently cause wildlife mortality, placing land managers in a challenging situation. Turtles are especially at risk of mortality from fire because of their low mobility and population sensitivity to reductions in adult survival. We studied ornate box turtles (Terrapene ornata) at 3 sites in Illinois, USA, from 2019–2022 to determine the best predictors of above‐ground activity so land managers can conduct prescribed burns when turtles are underground. We used turtle shell temperature, air temperature, soil temperature, and precipitation data to develop a predictive model of above‐ground activity. The best model for predicting above‐ground activity included an interaction between day of year and current air temperature. Earlier in spring and later in fall, above‐ground activity is more likely at higher air temperatures compared to later in spring and earlier in fall when the same likelihood of above‐ground activity is predicted at lower air temperatures. In spring, we recommend burning in Illinois ornate box turtle habitat before 1 April when air temperature is <10°C and in fall after 1 November when air temperature is <15°C. Above these temperature thresholds, there is a >5% likelihood that turtles in northern populations are above ground. [ABSTRACT FROM AUTHOR]

Populations wax and wane over time in response to an organism's interactions with abiotic and biotic forces. Numerous studies demonstrate that fluctuations in local populations can lead to shifts in relative population densities across the geographic range of a species over time. Fewer studies attempt to disentangle the causes of such shifts. Over four decades (1983–2022), we monitored populations of hibernating Indiana bats (Myotis sodalis) in two areas separated by ~110 km. The number of bats hibernating in the northern area increased from 1983 to 2011, while populations in the southern area remained relatively constant. We used simulation models and long‐term weather data to demonstrate the duration of time bats must rely on stored fat during hibernation has decreased in both areas over that period, but at a faster rate in the northern area. Likewise, increasing autumn and spring temperatures shortened the periods of sporadic prey (flying insect) availability at the beginning and end of hibernation. Climate change thus increased the viability of northern hibernacula for an increasing number of bats by decreasing energetic costs of hibernation. Then in 2011, white‐nose syndrome (WNS), a disease of hibernating bats that increases energetic costs of hibernation, was detected in the area. From 2011 to 2022, the population rapidly decreased in the northern area and increased in the southern area, completely reversing the northerly shift in population densities associated with climate change. Energy balance during hibernation is the singular link explaining the northerly shift under a changing climate and the southerly shift in response to a novel disease. Continued population persistence suggests that bats may mitigate many impacts of WNS by hibernating farther south, where insects are available longer each year. [ABSTRACT FROM AUTHOR]

Background: As with many non‐traditional companion animals, husbandry is a crucial part of maintaining the health of captive tortoises. Husbandry deficiencies are a common factor in the development of clinical disease, and awareness of the species‐specific requirements and common consequences of husbandry failings, are critical in managing these patients in practice. Aim of the article: This article outlines basic husbandry requirements and husbandry‐related conditions for the more common tortoise species that may present to first‐opinion practice. Descriptions to assist in species identification are included, as these become relevant when assessing hibernation suitability of individual animals. Hibernation‐related health concerns are also discussed. [ABSTRACT FROM AUTHOR]

Freshwater turtles are important consumers in Australian freshwater ecosystems. They serve as scavengers, nutrient regulators, and as food sources and Totems for Traditional Owners throughout Australia. Despite their importance, most Australian freshwater turtle species are declining. The impact of winter wetland drying on turtle populations remains unknown, and winter exposure of hibernating turtles may be an important additional source of mortality. We aimed to examine turtle responses to seasonal and episodic wetland drying in wetlands using acoustic telemetry and active trapping. Wetlands were chosen that spanned a range of hydrological connectivity to the adjacent Edward/Kolety‐Wakool River. We found that tagged Emydura macquarii typically exit wetlands disconnected from the adjacent permanent river prior to winter, and overwinter in the river. Female E. macquarii rapidly re‐entered 'home' wetlands (wetlands in which they were initially tagged) the following spring, whereas males tended to leave the study area, returning occasionally. Although we were not able to evaluate a winter drying event, one of the wetlands experienced partial summer drying. All three local turtle species (E. macquarii, Chelodina expansa, C. longicollis) exited the wetland long before winter drying would have become a potential threat. Our results suggest that turtles in this system may be protected from winter wetland drying because they move to the adjacent permanent river prior to winter. Spending the winter in the river channel reduces the risks of being trapped in a drying wetland as temperatures drop in winter. [ABSTRACT FROM AUTHOR]

Hibernating mammals are natural models of resistance to ischemia, hypoxia‐reperfusion injury, and hypothermia. Daurian ground squirrels (spermophilus dauricus) can adapt to endure multiple torpor‐arousal cycles without sustaining cardiac damage. However, the molecular regulatory mechanisms that underlie this adaptive response are not yet fully understood. This study investigates morphological, functional, genetic, and metabolic changes that occur in the heart of ground squirrels in three groups: summer active (SA), late torpor (LT), and interbout arousal (IBA). Morphological and functional changes in the heart were measured using hematoxylin‐eosin (HE) staining, Masson staining, echocardiography, and enzyme‐linked immunosorbent assay (ELISA). Results showed significant changes in cardiac function in the LT group as compared with SA or IBA groups, but no irreversible damage occurred. To understand the molecular mechanisms underlying these phenotypic changes, transcriptomic and metabolomic analyses were conducted to assess differential changes in gene expression and metabolite levels in the three groups of ground squirrels, with a focus on GO and KEGG pathway analysis. Transcriptomic analysis showed that differentially expressed genes were involved in the remodeling of cytoskeletal proteins, reduction in protein synthesis, and downregulation of the ubiquitin‐proteasome pathway during hibernation (including LT and IBA groups), as compared with the SA group. Metabolomic analysis revealed increased free amino acids, activation of the glutathione antioxidant system, altered cardiac fatty acid metabolic preferences, and enhanced pentose phosphate pathway activity during hibernation as compared with the SA group. Combining the transcriptomic and metabolomic data, active mitochondrial oxidative phosphorylation and creatine‐phosphocreatine energy shuttle systems were observed, as well as inhibition of ferroptosis signaling pathways during hibernation as compared with the SA group. In conclusion, these results provide new insights into cardio‐protection in hibernators from the perspective of gene and metabolite changes and deepen our understanding of adaptive cardio‐protection mechanisms in mammalian hibernators. [ABSTRACT FROM AUTHOR]

The reptilian form of hibernation (brumation) is much less studied than its mammalian and insect equivalents. Hibernation and brumation share some basic features but may differ in others. Evidence for hypometabolism in brumating reptiles beyond the effect of temperature is sporadic and often ignored.We calculated the standard metabolic rates (SMR, oxygen uptake during inactivity), in winter and/or summer, of 156 individuals representing 59 species of Israeli squamates across all 17 local families. For 32 species, we measured the same individuals during both seasons. We measured gas exchange continuously in a dark metabolic chamber, under the average January high and low temperatures (20°C and 12°C), during daytime and nighttime. We examined how SMR changes with season, biome, body size, temperature and time of day, using phylogenetic mixed models.Metabolic rates increased at sunrise in the diurnal species, despite no light or other external cues, while in nocturnal species the metabolic rates did not increase. Cathemeral species shifted from a diurnal‐like diel pattern in winter to a nocturnal‐like pattern in summer. Regardless of season, Mediterranean species SMRs were 30% higher than similar‐sized desert species. Summer SMR of all species together scaled with body size with an exponent of 0.84 but dropped to 0.71 during brumation. Individuals measured during both seasons decreased their SMR between summer and winter by a 47%, on average, at 20°C and by 70% at 12°C. Q10 was 1.75 times higher in winter than in summer, possibly indicating an active suppression of metabolic processes under cold temperatures.Our results challenge the commonly held perception that squamate physiology is mainly shaped by temperature, with little role for intrinsic metabolic regulation. The patterns we describe indicate that seasonal, diel and geographic factors can trigger remarkable shifts in metabolism across squamate species. [ABSTRACT FROM AUTHOR]

Hibernation is often associated with high mortality, especially during early life stages, and losses can be exacerbated by unusual winter conditions or if animals enter hibernation carrying a disease. Here, we examined how overwintering amphibians may be affected by the combined effects of mild winters, which are projected to increase in frequency due to climate change, and of chytridiomycosis, a disease that has contributed to the decline of hundreds of species worldwide. We exposed juvenile agile frogs Rana dalmatina to Batrachochytrium dendrobatidis (Bd), the causative agent of chytridiomycosis, and subsequently subjected them to either a long, cold winter (1.5°C for 91 days) or a short, mild winter (4.5°C for 61 days) under laboratory conditions. Agile frogs proved to be highly resistant to Bd as only 37% of Bd‐exposed individuals became infected as determined before hibernation, and prevalence further decreased to 8% by the end of hibernation, with individuals showing very low infection intensity values. We observed lack of mortality in control and Bd‐exposed groups also, in both types of winter. The two types of winter we simulated did not result in differing body mass loss either alone or in combination with experimental infection. In the Bd‐exposed group, the two types of winter also did not cause differences in prevalence and infection intensity. However, among Bd‐exposed frogs, individuals that were Bd negative when entering hibernation lost more body mass than their conspecifics that carried the fungus at the onset of overwintering. Based on our results, warming winter climate conditions, with or without Bd infection, do not decrease body mass and survival rate of hibernating agile frogs, and do not increase susceptibility of individuals to chytridiomycosis. It remains to be seen to what extent the relatively weak effects of milder winters can be generalized to other amphibians of the temperate climate zone. [ABSTRACT FROM AUTHOR]

The marsupial Monito del monte (Dromiciops gliroides) utilizes both daily and seasonal bouts of torpor to preserve energy and prolong survival during periods of cold and unpredictable food availability. Torpor involves changes in cellular metabolism, including specific changes to gene expression that is coordinated in part, by the posttranscriptional gene silencing activity of microRNAs (miRNA). Previously, differential miRNA expression has been identified in D. gliroides liver and skeletal muscle; however, miRNAs in the heart of Monito del monte remained unstudied. In this study, the expression of 82 miRNAs was assessed in the hearts of active and torpid D. gliroides, finding that 14 were significantly differentially expressed during torpor. These 14 miRNAs were then used in bioinformatic analyses to identify Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that were predicted to be most affected by these differentially expressed miRNAs. Overexpressed miRNAs were predicted to primarily regulate glycosaminoglycan biosynthesis, along with various signaling pathways such as Phosphoinositide‐3‐kinase/protein kinase B and transforming growth factor‐β. Similarly, signaling pathways including phosphatidylinositol and Hippo were predicted to be regulated by the underexpression of miRNAs during torpor. Together, these results suggest potential molecular adaptations that protect against irreversible tissue damage and enable continued cardiac and vascular function despite hypothermia and limited organ perfusion during torpor. [ABSTRACT FROM AUTHOR]

Skin microbiota play an important role in protecting bat hosts from the fungal pathogen Pseudogymnoascus destructans, which has caused dramatic bat population declines and extinctions. Recent studies have provided insights into the bacterial communities of bat skin, but variation in skin bacterial community structure in the context of the seasonal dynamics of fungal invasion, as well as the processes that drive such variation, remain largely unexplored. In this study, we characterized bat skin microbiota over the course of the bat hibernation and active season stages and used a neutral model of community ecology to determine the relative roles of neutral and selective processes in driving microbial community variation. Our results showed significant seasonal shifts in skin community structure, as well as less diverse microbiota in hibernation than in the active season. Skin microbiota were influenced by the environmental bacterial reservoir. During both the hibernation and active season stages, more than 78% of ASVs in bat skin microbiota were consistent with neutral distribution, implying that neutral processes, that is, dispersal or ecological drift contributing the most to shifts in skin microbiota. In addition, the neutral model showed that some ASVs were actively selected by the bats from the environmental bacterial reservoir, accounting for approximately 20% and 31% of the total community during hibernation and active season stages, respectively. Overall, this research provides insights into the assemblage of bat‐associated bacterial communities and will aid in the development of conservation strategies against fungal disease. [ABSTRACT FROM AUTHOR]

Hibernation is a remarkable behaviour deployed by a diverse array of endotherms within many clades that greatly reduces metabolic need, but also has somatic costs. Hibernation in modern endotherms is often assumed to be an adaptation allowing animals to avoid extreme thermal conditions or food shortages in seasonal environments. However, many animals hibernate when foraging conditions are energetically profitable, suggesting other causal factors influence hibernation behaviour.Understanding the selection pressures responsible for intraspecific variation in the timing and duration of hibernation can help elucidate the relative evolutionary influences of the ultimate ecological causes of hibernation. We tested four previously proposed mechanistic hypotheses to explain intraspecific variation in hibernation phenology in the federally threatened northern Idaho ground squirrel (Urocitellus brunneus): (1) thermal tolerance, (2) food limitation, (3) predation avoidance and (4) sexual selection.The predation avoidance and sexual selection hypotheses received the most support, although we also found some support for the thermal tolerance and food limitation hypotheses. Heavy squirrels increased hibernation duration regardless of environmental conditions, as predicted solely by the predation avoidance hypothesis. Reproductive males emerged from hibernation earlier in spring than other sex–age classes, a pattern predicted by the sexual selection hypothesis. Temperature and food availability explained a much smaller amount of the variation in hibernation behaviour, only partially supporting predictions of the thermal tolerance and food limitation hypotheses.Our results indicate that animals navigate life‐history trade‐offs between energetic allocation to survival and reproduction via state‐dependent optimization of hibernation phenology. Consequently, any future environmental changes that influence body condition will have implications for population ecology and life‐history evolution of hibernating animals due to stark differences in daily survival probability between hibernation and the active season. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

In order to assess the consequences of climate change and evaluate its impacts on wildlife, it is essential to do so on a species‐specific level. It is assumed that changes in the ambient temperature influence energy consumption as well as food availability and thus foraging behavior, reproduction, survival, and therefore population dynamics in bats. Based on this assumption, the present study aims to gain insights into the roosting and breeding behavior of the greater mouse‐eared bat (Myotis myotis) in relation to changes of the ambient temperature. For this purpose, we investigated the effect of ambient temperature on the phenology of the greater mouse‐eared bat by using activity data of the bats collected using light barriers at the maternity roosts. The light barrier used in this study is a system that detects the interruption of two light beams, for example, by a flying bat, and displays it as an electrical signal. The investigations have shown that the higher the winter temperatures, the earlier the greater mouse‐eared bats returned to the roosts to form the maternity colony; however, this was only true for ambient temperatures below 0.5°C,birth season started earlier at higher spring temperatures,the dissolution of maternity roosts occurred earlier with earlier birth season and at higher ambient temperatures during lactation. The results revealed that ambient temperature has an influence on the phenology of the greater mouse‐eared bat. Depending on the respective life history stage, an increase in ambient temperature can have a positive or negative effect on the fitness of the animals. In recent years, mild winters have been recorded more frequently, which can have an influence on the behavior of bats. Warm winters within certain limits seem to lead to an earlier formation of the maternity colony, which can be positive or negative for the bats depending on persistent weather conditions and thus insect availability. In the course of climate change, we can also expect earlier spring events and an increase in spring temperature, as well as hot spells in summer. These warm springs and summers seem to lead to an earlier beginning of births, a faster development of the juveniles and an earlier dissolution of the maternity roost. An advance of reproductive activities can be assumed to increase the chance to survive the following winter in both mothers and their young, as they have more time to build up sufficient energy reserves for hibernation before winter starts. Due to the climatic changes, phenological changes of the bats be expected. This study highlights that in order to understand the impact of climate change on biodiversity, it is necessary to investigate in detail effects on a species‐specific level and also to consider direct and indirect effects of ambient temperature on different life history stages. [ABSTRACT FROM AUTHOR]

Torpor and hibernation are energy‐saving heterothermic strategies widespread among mammals, and bats have reports of hibernation in North America, Europe, Asia, Oceania, and Africa. However, to date, there was no evidence of hibernation by bats in South America. We tagged four individuals of Eptesicus brasiliensis and one remained torpid for 13 consecutive days in a tree cavity roost in southern Brazil, showing evidence that bats can hibernate in South America. [ABSTRACT FROM AUTHOR]

Hibernation is a widespread adaptation in animals to seasonally changing environmental conditions. In the face of global anthropogenic change, information about plastic adjustments to environmental conditions and associated mortality costs are urgently needed to assess population persistence of hibernating species. Here, we used a five‐year data set of 1047 RFID‐tagged individuals from two bat species, Myotis nattereri and Myotis daubentonii that were automatically recorded each time they entered or left a hibernaculum. Because the two species differ in foraging strategy and activity pattern during winter, we expected species–specific responses in the timing of hibernation relative to environmental conditions, as well as different mortality costs of early departure from the hibernaculum in spring. Applying mixed‐effects modelling, we disentangled population‐level and individual‐level plasticity in the timing of departure. To estimate mortality costs of early departure, we used both a capture mark recapture analysis and a novel approach that takes into account individual exposure times to mortality outside the hibernaculum. We found that the timing of departure varied between species as well as among and within individuals, and was plastically adjusted to large‐scale weather conditions as measured by the NAO (North Atlantic Oscillation) index. Individuals of M. nattereri, which can exploit milder temperatures for foraging during winter, tuned departure more closely to the NAO index than individuals of M. daubentonii, which do not hunt during winter. Both analytical approaches used to estimate mortality costs showed that early departing individuals were less likely to survive until the subsequent hibernation period than individuals that departed later. Overall, our study demonstrates that individuals of long‐lived hibernating bat species have the potential to plastically adjust to changing climatic conditions, although the potential for adjustment differs between species. [ABSTRACT FROM AUTHOR]

Animals can respond to climate change through changes in behaviour, morphology or life‐history traits. Changes in life‐history traits do not occur independently, as they trade off or co‐evolve with other traits.Hibernation is a life‐history trait used to cope with periods of low resource availability. The energetic and survival benefits of hibernation depend on environmental conditions. Climate change‐induced changes in hibernation patterns are therefore likely to affect other life‐history traits through trade‐offs.We systematically reviewed the literature to: 1) identify studies testing for associations between climatic variables and life‐history traits in mammalian hibernators; and 2) assess variation in responses between species.Air temperature was the most commonly measured climatic variable, and phenology of hibernation emergence was the most commonly studied life‐history trait. In most studies and species, emergence date became earlier, litter size increased and the number of interbout arousals increased with increasing air temperature.Despite being considered key life‐history traits due to their potential to influence population dynamics, our search returned no studies on the effects of climatic variables on the age of primiparity or on the age distribution of reproduction.Directions of associations between climatic variables and life‐history traits often differed between species, and both species‐ and sex‐specific variations occurred in response to climatic variables for some traits.We highlight the importance of long‐term, species‐specific research, and the need for further studies on indirect effects of climatic cues on co‐adapted traits to understand the potential for mammalian hibernators to respond to ongoing and future climate change. [ABSTRACT FROM AUTHOR]

Vancouver Island marmots (Marmota vancouverensis) (VIMs) are a critically endangered species of fat‐storing hibernators, endemic to Vancouver Island, British Columbia, Canada. In addition to in‐situ conservation efforts, a captive breeding program has been ongoing since 1997. The captive diet is mostly pellet‐based and rich in n−6 polyunsaturated fatty acids (PUFAs). In captivity, overall length of hibernation is shortened, and marmots have higher adipose tissue reserves compared to their wild‐born counterparts, which may be a risk factor for cardiovascular disease, the leading cause of mortality in captive marmots. To investigate differences in lipid metabolism between wild and captive populations of VIMs, blood vitamin E, fatty acid (FA) profiles and leptin, and white adipose tissue (WAT) FA profiles were compared during the active season (May to September 2019). Gas chromatography, high‐performance liquid chromatography, and multiplex kits were used to obtain FA profiles, α‐tocopherol, and leptin values, respectively. In both plasma and WAT, the concentration of the sum of all FA in the total lipids was significantly increased in captive VIMs. The n−6/n−3 ratio, saturated FAs, and n−6 PUFAS were higher in captive marmots, whereas n−3 PUFAs and the HUFA score were higher in wild marmots. Serum concentrations of α‐tocopherol were greater by an average of 45% in captive marmots, whereas leptin concentrations did not differ. Results from this study may be applied to improve the diet and implement weight management to possibly enhance the quality of hibernation and decrease the risk of cardiovascular and metabolic diseases of captive VIMs. [ABSTRACT FROM AUTHOR]

Hibernation, a hypometabolic state associated with low body temperature and reduced metabolic and activity rates, represents one adaptation to harsh seasonal environmental conditions. As a consequence of hypometabolism, energetically costly neuronal processes also ought to be reduced. Since active neuronal pathways are prerequisites for learning and memory, and because previous studies revealed variable patterns, it remains unclear whether and how hibernating animals retain memories, however. Here, we investigated the effect of seasonally reduced activity on memory retention in 36 wild grey mouse lemurs (Microcebus murinus). Data from activity loggers confirmed that female grey mouse lemurs entered hibernation during the cool dry season, whereas males exhibited episodic bursts of activity throughout the austral winter. Thus, compared to males, we predicted females to show lower memory retention of visual and spatial stimulus–reward associations learned before hibernation. In contrast to our prediction, all individuals performed worse in the post‐hibernation testing session in both types of tests, compared to the pre‐hibernation learning session, and males (N = 11) performed even worse than females (N = 14) in the post‐hibernation testing session. Although females (N = 9) equipped with activity loggers tended to be less active than males (N = 4), sex‐specific activity levels were unrelated to interindividual differences in memory retention. Hence, the post‐hibernation decrease in performance of grey mouse lemurs may reflect a more general disability to retain stimulus–reward associations than a lack of memory retention due to seasonal hypometabolism, as suggested for some species of bats or squirrels. [ABSTRACT FROM AUTHOR]

The brown bear Ursus arctos undergoes exceptional physiological adaptions during annual hibernation that minimize energy consumption, including profound decrease in heart rate, cardiac output, and respiratory rate. These changes are completely reversible after the bears reenter into the active state in spring. In this case report, we show episodes of sinus arrest in a hibernating Scandinavian brown bear and in humans, recorded by implantable loop recorders and discuss the possible underlying mechanisms. Lessons learned from cardiac adaptations in hibernating bears might prove useful in the treatment of patients with sinus node dysfunction. [ABSTRACT FROM AUTHOR]

Bats arouse from hibernation both naturally and in response to disturbances. Frequent bat arousals can decrease survival due to increased energetic costs. An active sand mine in west‐central Wisconsin hosted over 52,000 hibernating bats of 4 species in inactive tunnels, and regularly blasted with explosives to remove sand. We collected environmental and acoustic data at this mine during two hibernation seasons (November 1 through February 28 in 2013–2014 and 2014–2015) to examine the effect of blasting on echolocation calls (bat activity), a measure of bat arousal from hibernation. We used total bat activity recorded 7 h before and 7 h after blast time as the response variable, assigned it to a binary category and used that as a fixed effect. We used explosive charge per delay (kg), number of blasts per day, number of consecutive blast days, barometric pressure, temperature, and hibernation season as fixed effects. We used generalized linear mixed models with a negative binomial distribution and Bayesian information criterion (BIC) for model selection. The BIC‐optimal model did not include any of the variables associated with blasting, but included activity timing, temperature, barometric pressure, and season as fixed effects, of which all were significant. Blasting did not influence bat activity significantly in this mine. [ABSTRACT FROM AUTHOR]

A noteworthy limitation among existing studies on the use of online technologies by political parties is the focus on elections. This study extends the frontiers by examining the extent to which Nigeria's political parties use their websites, as well as Facebook and Twitter platforms to communicate and mobilise citizens during and beyond elections. Using web assessment survey, data collected from the online platforms of registered political parties in February 2015 and February 2017 were analysed—to see trends in online activities during (2015 elections) and outside of elections (2017). The study reveals that the parties are caught in the web of the contradictory possibilities of digital engagement. On the one hand, is an online quiescence in the period between elections, which is premised on poor party institutionalisation. On the other hand, the parties are largely unable to reverse elements of institutionalisation challenges by leveraging digital tools to develop roots in the society and boost their public image. This quandary helps to demonstrate where the Nigerian party system fits in the equalisation versus normalisation debate on the utility of digital tools. [ABSTRACT FROM AUTHOR]

Glycerol and aquaporin 9 (aquaglyceroporin) are known to be involved in freeze tolerance in the Japanese tree frog Hyla japonica. However, the regulatory mechanisms of freeze tolerance in this species have not been fully elucidated. In the present study, we focused on the inter‐ and intracellular dynamics of glucose to analyze the role of glucose and glucose‐related proteins such as transporter and metabolic enzymes in freeze tolerance. Serum glucose concentrations were compared among the frogs that were nonhibernating, hibernating, and thawed after freezing at −4°C for 6 hr. Serum concentrations of glucose in thawed frogs were significantly higher than those in hibernating and nonhibernating, active frogs. Periodic acid–Schiff staining showed that the accumulation of glycogen in the hepatocytes increased before hibernation and decreased after freezing and thawing. Quantitative RT‐PCR analysis using the liver showed that, compared with active frogs, the type 2 glucose transporter gene (glut2) was upregulated in frozen frogs, the liver glycogen phosphorylase gene (pygl) was upregulated in frozen or thawed frogs, and the type 2 glycogen synthase gene (gys2) was upregulated in hibernating frogs. Immunohistochemistry of liver sections showed that, compared with nonhibernating frogs, Glut2 proteins were clearly increased most likely on the plasma membrane of hepatocytes in hibernating frogs and further increased by freezing, then decreased after thawing. These results suggest the possibility that glucose acts as a cryoprotectant in H. japonica. [ABSTRACT FROM AUTHOR]

Metabolic rate depression during prolonged bouts of torpor is characteristic of mammalian hibernation, reducing energy expenditures over the winter. Cell cycle arrest is observed in quiescent cells during dormancy, partly due to the retinoblastoma (Rb) protein at G1/S, given cell division and proliferation are metabolic‐costly processes. Rb binds to E2F transcription factors and recruits corepressors (e.g., SUV39H1) to E2F target genes, blocking their transcription and cell cycle passage. Phosphorylation by cyclin‐CDK complexes at S780 or S795 abolishes Rb‐mediated repression, allowing transition into S phase. The present study compares Rb‐E2F1 responses between euthermic and torpid states in five organs (brain, heart, kidney, liver, skeletal muscle) of 13‐lined ground squirrels (Ictidomys tridecemlineatus). Immunoblotting assessed the expression of Rb, pRb (S780, S795), E2F1, and SUV39H1. Our findings demonstrate multi‐tissue upregulation of Rb and SUV39H1 during torpor, with tissue‐specific changes to E2F1 and pRb (S780), suggesting Rb‐E2F1 contributes to cell cycle control in hibernation. Highlights: Tissue‐specific regulation of the Rb‐E2F1 pathway in 13‐lined ground squirrel.Rb repress E2F1, and Suv39H1 can act as additional factor in cell cycle repression in brain, kidney and liver.Possibility of alternate of roles of E2F1 in the heart and liver during hibernation. [ABSTRACT FROM AUTHOR]

Animals are expected to adjust their behavioral patterns to improve fitness outcomes, such as fecundity or offspring survival. For long‐lived hibernators, decisions made in each annual cycle may reflect considerations not just for concurrent survival and reproduction but also the pressure to maximize overwinter survival and future reproductive success. We examined how these elements manifest themselves in the body mass variation patterns of North American northern latitude temperate bats, whose size and roosting habits present considerable monitoring challenges. We characterized and compared the summer and fall mass variation patterns of little brown myotis (Myotis lucifugus) and northern myotis (M. septentrionalis) from a historic dataset. In summer, the estimated date of parturition was strongly associated with spring foraging conditions (low wind, low precipitation, and warm temperatures), and mass gain associated with female reproduction conferred considerable differentiation between the mass variation patterns of females and males. In fall, differences were most apparent among species, although adults exhibited a greater capacity for rapid mass gain than juveniles. These results demonstrate how reproductive constraints and interannual survival have important influences on the behavior of temperate bats. Future work should seek to quantify the fitness benefits of patterns identified in this study, such as the rate of prehibernation mass gain. [ABSTRACT FROM AUTHOR]

Workers of the ant Cardiocondyla elegans drop female sexuals into the nest entrance of other colonies to promote outbreeding with unrelated, wingless males. Corroborating the results from previous years, we document that carrier and carried female sexuals are typically related and that the transfer initially occurs mostly from their joint natal colonies to unrelated colonies. Female sexuals mate multiply with up to seven genetically distinguishable males. Contrary to our expectation, the colony growth rate of multiple‐mated and outbred female sexuals was lower than that of inbred or single‐mated females, leading to the question of why female sexuals mate multiply at all. Despite the obvious costs, multiple mating might be a way for female sexuals to "pay rent" for hibernation in an alien nest. We argue that in addition to evade inbreeding depression from regular sibling mating over many generations, assisted dispersal might also be a strategy for minimizing the risk of losing all reproductive investment when nests are flooded in winter. [ABSTRACT FROM AUTHOR]

Prior to the introduction of white‐nose syndrome (WNS) to North America, temperate bats were thought to remain within hibernacula throughout most of the winter. However, recent research has shown that bats in the southeastern United States emerge regularly from hibernation and are active on the landscape, regardless of their WNS status. The relationship between winter activity and susceptibility to WNS has yet to be explored but warrants attention, as it may enable managers to implement targeted management for WNS‐affected species. We investigated this relationship by implanting 1346 passive integrated transponder (PIT) tags in four species that vary in their susceptibility to WNS. Based on PIT‐tag detections, three species entered hibernation from late October to early November. Bats were active at hibernacula entrances on days when midpoint temperatures ranged from −1.94 to 22.78°C (mean midpoint temperature = 8.70 ± 0.33°C). Eastern small‐footed bats (Myotis leibii), a species with low susceptibility to WNS, were active throughout winter, with a significant decrease in activity in mid‐hibernation (December 16 to February 15). Tricolored bats (Perimyotis subflavus), a species that is highly susceptible to WNS, exhibited an increase in activity beginning in mid‐hibernation and extending through late hibernation (February 16 to March 31). Indiana bats (M. sodalis), a species determined to have a medium–high susceptibility to WNS, remained on the landscape into early hibernation (November 1 to December 15), after which we did not record any again until the latter portion of mid‐hibernation. Finally, gray bats (M. grisescens), another species with low susceptibility to WNS, maintained low but regular levels of activity throughout winter. Given these results, we determined that emergence activity from hibernacula during winter is highly variable among bat species and our data will assist wildlife managers to make informed decisions regarding the timing of implementation of species‐specific conservation actions. [ABSTRACT FROM AUTHOR]

Hibernation is one of the fundamental strategies in response to cold environmental temperatures. During hibernation, the endocrine and circadian systems ensure minimal expenditure of energy for survival. The circadian rhythms of key hormones, melatonin (MT), corticosterone (CORT), triiodothyronine (T3), and thyroxine (T4), and the underlying molecular regulatory mechanisms of hibernation have been well determined in mammals but not in ectotherms. Here, a terrestrial hibernating species, Asiatic toad (Bufo gargarizans), was employed to investigate the plasma CORT, MT, T3, and T4; and the retina, brain, and liver mRNA expression of the core clock genes, including circadian locomotor output cycles kaput (Clock), brain and muscle ARNT‐like 1 (Bmal1), cryptochrome (Cry) 1 and 2, and period (Per) 1 and 2, at 7‐time points over a 24‐h period under acute cold (1 day at 4°C), and hibernation (45 days at 4°C). Our results showed that the circadian rhythms of the core clock genes were rather unaffected by acute cold exposure in the retina, unlike the brain and liver. In contrast, during hibernation, the liver clock genes displayed significant circadian oscillations, while those in the retina and brain stopped ticking. Furthermore, plasma CORT expressed circadian oscillations in both groups, and T3 in acute cold exposure group, whereas T4 and MT did not. Our results reveal that the plasma CORT and the liver sustain rhythmicity when the brain was not, indicating that the liver clock along with the adrenal clock synergistically maintains the metabolic requirements to ensure basic survival in hibernating Asiatic toads. [ABSTRACT FROM AUTHOR]

Ischemic stroke is a common cerebral disease. However, the treatment for the disease is limited. Daurian ground squirrel (GS; Spermophilus dauricus), a hibernating mammalian species, is highly tolerant to ischemia. In the present study, GS neurons in a non‐hibernating state were found to be more resistant to oxygen–glucose deprivation (OGD), an ischemic model in vitro. We leveraged the differences in the endurance capacity of GS and rats to investigate the mechanisms of resistance to ischemia in GS neurons. We first identified glutamate–aspartate transporter 1 (GLAST) as a cytoprotective factor that contributed to tolerance against OGD injury of GS neurons. The expression of GLAST in GS neurons was much higher than that in rat neurons. Overexpression of GLAST rescued viability in rat neurons, and GS neurons exhibited decreased viability following GLAST knockdown under OGD conditions. Mechanistically, more glutamate was transported into neurons after GLAST overexpression and served as substrates for ATP production. Furthermore, eukaryotic transcription initiation factor 4E binding protein 1 was downregulated by GLAST to rescue neuronal viability. Our findings not only revealed an important molecular mechanism underlying the survival of hibernating mammals but also suggested that neuronal GLAST may be a potential target for ischemic stroke therapy. [ABSTRACT FROM AUTHOR]

Climatic shifts to warmer and often drier conditions are challenging terrestrial species worldwide. These shifts are occurring more rapidly at higher elevations and latitudes, likely causing disproportionate effects to mammalian hibernators there. While there is some information about how these species' ranges are responding to climatic shifts, we lack an understanding of how climate components are affecting species' life history variation, which is key to individual success and population‐level resilience. We reviewed the literature to identify the direction of life history responses to climate change in mammalian hibernators along three axes: latitudinal, elevational and temporal. We found 39 studies involving 27 species that reported climate effects on our four target life history traits – phenology, body mass/condition and growth, reproduction and survival. We found warmer temperatures are advancing hibernator phenology and increasing reproductive success. By contrast, warming and drying trends are having uncertain effects on body condition, and complex effects on survival – depending on season, age class, latitude and elevation. We found no pattern of significant climate‐trait outcomes by duration or decade of study. More research on drought conditions – particularly in relation to resource availability – would help inform hibernator susceptibility to increased drying trends expected to intensify globally. Notably, our results are highly biased towards small mammal hibernators in Northern Hemisphere alpine/mountain ecosystems, with few long‐term studies conducted on Southern Hemisphere hibernators. This review highlights that phenological shifts constitute one of the most obvious consequences of climate change, yet, the timing of life history events (e.g. timing of migration, reproduction, hibernation) remains poorly understood. Further integration of insights from physiologists, evolutionary biologists and population ecologists working on wild populations will improve our collective understanding of the effects of seasonal climatic shifts on mammalian hibernator life history traits, key drivers of their population‐level persistence. [ABSTRACT FROM AUTHOR]

Alpine mammals are highly vulnerable to current and projected climate change because they are confined to a certain elevation range. Physiological and behavioural adaptations in burrowing species, such as finding shelter in burrows when the summer conditions are unfavorable and hibernating in winter during the stressful period of resource shortage, could partly buffer the negative impacts of these forecasted changes. We studied the links between environmental factors and annual variations in adult mass and survival over 14 years in hoary marmots. We hypothesized that annual variation in seasonal environmental factors determines individual mass and survival through direct effects on food quality and availability, expecting greater survival when marmots reach higher mass before hibernation. We found that harsh winters decreased mass at emergence from hibernation by 47% compared with mild winters. Nonetheless, adult marmots had a greater mass gain in summers following harsh winters and reached a similar mass at the end of the summer compared with summers following mild winters. This suggests individuals can adopt a resource allocation strategy that allows maximizing summer mass gain to survive hibernation. Earlier springs also increased summer mass gain by 15 g day−1, and tended to increase apparent adult survival by 23%, compared with late springs. While these findings suggest a warming climate could have positive effects on summer mass gain and survival, survival also tended to decrease by 24% in summers with more precipitation. This suggests the forecasted changes in precipitation extremes could also trigger considerable negative effects on the demography of burrowing species in the long term. Our study shows that, although burrowing and hibernating behaviours could buffer responses to environmental changes, these behaviours are not an indefectible shield against climate change. [ABSTRACT FROM AUTHOR]

Phenological shifts associated with directional changes in climate, resulting in earlier spring activities, have been documented in several animal species. However, the extent to which species respond to overall climate change versus local climate variation is rarely studied. In addition, climate data are usually averaged over large spatial scales, even though local heterogeneity in habitats may be high, and species might be more susceptible to changes in local rather than global climate conditions. In this study, we examined the effects of spatiotemporal climate variation and climate change on the phenology of a hibernating mountain rodent, the Columbian ground squirrel (Urocitellus columbianus). Over 28 years of research (1992–2019), we studied the relationship between the microclimatic conditions experienced by adult and juvenile ground squirrels from four neighboring meadows, and their dates of emergence from hibernation. We used a microclimate model to calculate microclimate variables (local snow depth, soil temperature, air temperature, wind speed, and humidity) at an hourly scale, a 5‐m spatial resolution, and at animal height on the study sites over 28 years. Emergence dates varied with age and sex, among years, as well as among and within meadows, with some areas averaging up to 10 days earlier emergence dates from hibernation than others. While emergence dates tended to be delayed throughout the study period, long‐term temporal changes and interannual variability in emergence dates differed among meadows and depended on individual age and sex. Dates of hibernation emergence were correlated with local climate variables considered either during hibernation or during the preceding summer. Ground squirrels emerged earlier in years or at locations when/where snow melted earlier (years: all individuals excluding 2‐year‐old males, locations: yearlings and older females), and when the previous summer was less windy (≥3‐year‐old individuals) and more humid (2‐year‐old males). Two‐year‐old male ground squirrels also emerged later in locations where snow depth during winter was higher. Using a microclimate model allowed realistic predictions of phenological responses to climate, highlighting its potential for research on animal responses to abiotic change. [ABSTRACT FROM AUTHOR]

Climate change is a defining element of the current ecological landscape, with consequences ranging from global to local environments. One of the first indices of the ecological impact of the ongoing environmental changes was measurement of their effects on phenology, the seasonal timing of recurring annual events such as the beginning of the growing season, timing of flowering, and breeding seasons of animals. Research has moved beyond simple descriptions of these temporal changes to investigations of their root causes, impacts, and consequences at both ecological and evolutionary time scales. This changing landscape, environmental, ecological, and evolutionary, makes this an exciting, albeit sometimes depressing, time to be a scientist. This article is categorized under:Assessing Impacts of Climate Change > Observed Impacts of Climate ChangeClimate, Ecology, and Conservation > Observed Ecological Changes [ABSTRACT FROM AUTHOR]

The arboreal marsupial monito del monte (genus Dromiciops, with two recognized species) is a paradigmatic mammal. It is the sole living representative of the order Microbiotheria, the ancestor lineage of Australian marsupials. Also, this marsupial is the unique frugivorous mammal in the temperate rainforest, being the main seed disperser of several endemic plants of this ecosystem, thus acting as keystone species. Dromiciops is also one of the few hibernating mammals in South America, spending half of the year in a physiological dormancy where metabolism is reduced to 10% of normal levels. This capacity to reduce energy expenditure in winter contrasts with the enormous energy turnover rate they experience in spring and summer. The unique life history strategies of this living Microbiotheria, characterized by an alternation of life in the slow and fast lanes, putatively represent ancestral traits that permitted these cold‐adapted mammals to survive in this environment. Here, we describe the ecological role of this emblematic marsupial, summarizing the ecophysiology of hibernation and sociality, updated phylogeographic relationships, reproductive cycle, trophic relationships, mutualisms, conservation, and threats. This marsupial shows high densities, despite presenting slow reproductive rates, a paradox explained by the unique characteristics of its three‐dimensional habitat. We finally suggest immediate actions to protect these species that may be threatened in the near future due to habitat destruction and climate change. [ABSTRACT FROM AUTHOR]

Seasonal hibernation has provided an opportunity to study animals' phenotypic plasticity in adaptation to changing environment. In the present study focusing on the female Daurian ground squirrel (Spermophilus dauricus)—a well demonstrated seasonal hibernator—we examined their behavioral, morphological, and metabolic changes during fattening, hibernation, and emergence. Our data indicated high levels of food intake, fat deposition, and body mass increases during fattening compared to hibernation. The levels of serum glucose and triglycerides were also higher during fattening than during hibernation and emergence. Interestingly, although squirrels showed signs of obesity and elevated triglycerides in serum during fattening, triglyceride levels in the liver and skeletal muscles remained unchanged. Our data also indicated that adiponectin levels in serum and cerebrospinal fluid were different between fattening and hibernation. Levels of adiponectin receptor 1 in the skeletal muscle remained low during fattening but peaked in late hibernation. In contrast, adiponectin receptor 2 in the liver showed a steady increase during fattening, which was followed by a significant decrease at early hibernation. Our data indicate that adiponectin may play an important role in preventing heterotopic fat accumulation in a receptor‐ and organ‐specific manner, as well as in facilitating the switch from glucose metabolism to lipid metabolism during fattening and hibernation in female Daurian ground squirrels. [ABSTRACT FROM AUTHOR]

Trade-offs between specialist use of particular resources and opportunistic use of widespread materials may present different strategies for survival. Hazel dormice Muscardinus avellanarius are arboreal mammals that in Great Britain hibernate from late autumn to mid spring in nests that are specially built at ground level. Hibernation nests are rarely encountered, and little is known about the types of construction or materials used. Specifically, it is not known whether nest materials are selected opportunistically, based on their availability, or are specialised to suit local environmental conditions. We therefore conducted a study to characterise the main materials used to construct these nests, explore the distances travelled to collect materials and investigate whether regional climate and/or local microclimate have an impact on the types of nests built. Thirty-three hibernation nests were located through radio-tracking, systematic searches and incidental finds. Structurally, hibernation nests were built similarly to summer nests and were most commonly constructed with an outer layer of leaves and distinct core section made of woven material. We found no correlation between nest type and the temperature recorded at nest sites. Nests were built using a mean of two materials per nest, which were both in every case available within 3m of the nest. The most frequently used materials were bracken, hazel and beech leaves, and grasses. Dormice were flexible in their use of nest materials, using various materials harvested very locally. However, dormice travelled further to collect grasses, ferns, bracken and honeysuckle, and these materials made up most of the nests in which they were found. There were also positive correlations between material abundance and usage, and suitable materials for hibernation nest construction were therefore readily available within their home range. [ABSTRACT FROM AUTHOR]

Sex hormone‐binding globulin (SHBG) regulates the bioavailability of sex steroid hormones in the blood. Levels of SHBG increase markedly in brown bears (Ursus arctos) during hibernation, suggesting that a key regulatory role of this protein is to quench sex steroid bioavailability in hibernation physiology. To enable characterization of ursine SHBG and a cross species comparison, we established an insect cell‐based expression system for recombinant full‐length ursine and human SHBG. Compared with human SHBG, we observed markedly lower secretion levels of ursine SHBG, resulting in a 10‐fold difference in purified protein yield. Both human and ursine recombinant SHBG appeared as dimeric proteins in solution, with a single unfolding temperature of ~ 58 °C. The thermal stability of ursine and human SHBG increased 5.4 and 9.5 °C, respectively, in the presence of dihydrotestosterone (DHT), suggesting a difference in affinity. The dissociation constants for [3H]DHT were determined to 0.21 ± 0.04 nm for human and 1.32 ± 0.10 nm for ursine SHBG, confirming a lower affinity of ursine SHBG. A similarly reduced affinity, determined from competitive steroid binding, was observed for most steroids. Overall, we found that ursine SHBG had similar characteristics to human SHBG, specifically, being a homodimeric glycoprotein capable of binding steroids with high affinity. Therefore, ursine SHBG likely has similar biological functions to those known for human SHBG. The determined properties of ursine SHBG will contribute to elucidating its potential regulatory role in hibernation physiology. [ABSTRACT FROM AUTHOR]