Journal of Thermal Biology

Climate change has altered global climatic conditions, which is affecting the reproductive strategies, offspring development, breeding biology and development of birds. We looked at the impact of different climatic variables (temperature, rainfall and wind speeds) before and during the nestling development phase on nestling development (i.e. nestling hatch weights, nestling growth rates and pre-fledging weights) in the Thorn-tailed Rayadito (Aphrastura spinicauda). We studied two populations. One is situated in a temperate rainforest on the northern border of Patagonia called Pucon which we studied in 2018 and 2019, with mild temperatures (12.5 degrees Celsius), high rainfall (636ml) and low wind speeds (6.3km/h). The other is in a sub-Antarctic old growth forest in southern Patagonia called Navarino island which we studied in 2018, 2019 and 2023, which is comparatively drier (138ml), colder (8.3 degrees Celsius) and has higher average wind speeds (16.6km/h). Embryonic development is key in ensuring individual future fitness. It is important that this is not interrupted and individuals are therefore vulnerable to damage during early development and it can have carry over effects into adulthood. Exposure to extreme climatic conditions can interrupt this development. Therefore, we expect to find that the climate during incubation to be important in predicting nestling hatch weights, growth rates and pre-fledgling weights. Climatic conditions are known to effect nestling development and extremes in climatic conditions have negative consequences on nestling development. We therefore expect that highly variable climatic conditions will have a negative effect on nestling development. We analysed populations separately because we expect populations to have developed different reaction norms to climatic factors. We found in both locations that hatching weights become lower each year, but growth rates and pre-fledging weights are unchanged. In Navarino, medium sized clutches produced the largest hatchlings whilst large and small clutches produced the smallest hatchlings and high or low rainfall during the egg laying and incubation phase produces smaller nestlings. No other climatic factors impacted hatch weights in Navarino. We also found that high or low average ambient temperatures during incubation and early nestling development in Navarino result in lower overall growth rates. Whilst in Pucon, lower rainfall and high or low wind speeds during incubation produce smaller hatchlings, but neither climatic nor biotics factors could explain growth rates in Pucon. We found pre-fledging weights could not be explained by climatic or biotics factors in either location. This is the first study of its kind to examine the environmental drivers of nestling hatch weights in birds in the wild. By better understanding how climate predicts nestling development, we can understand the potential future threats to fitness and development in birds with greater accuracy as conditions continue to change.

We examined how thermal shifts influence development time and adult body size in Drosophila melanogaster. Individual flies were exposed to alternating temperatures of 25{degrees}C (optimal) and 17{degrees}C (cold), with shifts introduced at key developmental transitions: larval hatching and pupariation. We found while larval-stage temperature is the biggest determinant of thermal plasticity of development time and adult size, the egg-stage temperature also influences the pace of development and growth throughout pre-adult duration. The effect of low-to-high and high-to-low temperature shifts on development and growth may not be symmetric. When eggs are reared at 25{degrees}C and then shifted to 17{degrees}C, larval and pupal durations undergo reduction compared to constant 17{degrees}C, but it produces slightly larger adults. A higher egg-stage temperature thus seem to exert a carryover effect that accelerates subsequent development and growth when later stages experience colder temperatures. Surprisingly, flies whose egg stage is exposed to 17{degrees}C followed by a shift to 25{degrees}C also have reduced larval duration and larger size, relative to those developing at constant 25{degrees}C. We speculate this could be either because 17{degrees}C to 25{degrees}C represents a low-to-high temperature shift or a sub-optimal-to-optimal thermal shift that results in metabolic and/or hormonal changes accelerating differentiation and growth. While pupal duration is sensitive to current and to some extent prior thermal environments, it does not contribute substantially to thermal plasticity of size. Development time is longer in males than in females, and this difference seems to start from larval stage while the pupal duration plays a bigger role in creating this sex-specific difference. Overall, employing individual fly rearing, this study helped to unravel the effect of thermal shifts on growth and development in D. melanogaster with great precision.

O_LIChill-susceptible insects such as Drosophila are vulnerable to progressive disruption of ion and water homeostasis during cold stress, and low temperature exposure is a key factor affecting their physiology and distribution. Comparative studies of cold tolerance traditionally use simple or single-condition assays for interspecific comparisons, but the emergence of thermal death time (TDT) models offers a comprehensive framework to assess cold tolerance across different stress intensities and durations. C_LIO_LIHere we construct TDT curves for six Drosophila species, spanning boreal to tropical habitats, using Lt50 estimates across a range of stressful low temperatures (Lt50 ranging from [~] 20 min to 2 days). For all species, the TDT curves provided good fits to the log(Lt50) vs. temperature data (R2 = 0.87 - 0.99). C_LIO_LITDT curves from all species had steep slopes demonstrating that cold injury rate has a high thermal sensitivity such that small changes in temperature have profound effects on survival duration. The interspecific similarity of TDT slopes indicates that a conserved physiological dysfunction underlies cold injury across species. Further, additive accumulation of cold-induced injury in split-dose experiments suggests that acute and moderate cold damage represent the same underlying physiological dysfunction occurring at different rates. C_LIO_LIThe TDT curve intercepts (species-specific tolerance thresholds) differed markedly between boreal, temperate, and tropical species and correlated strongly with their habitat temperature. Data from the present study and meta-analysis of published data find that the inherent species cold tolerance decreases by [~] 0.45 {degrees}C for each {degrees}C colder the winter environment of the species is. When also considering the cold acclimation cues in cold climates we argue the experienced level of cold stress intensity is similar across environments inhabited by the Drosophila genus. This suggests that cold tolerance is important in shaping the fundamental niche of both boreal and tropical species. C_LIO_LIOverall, the TDT analysis of Drosophila at low temperature provides a powerful and predictive tool for quantifying insect cold tolerance. This approach enables detailed cross-species comparisons that allows for both ecological and physiological inference. Thus, TDT curves offer relevant approximations of insect cold resistance that could help predict insect responses to climatic change. C_LI

Heat tolerance is critical for ectotherms facing environmental temperature variability, yet how it varies across life stages, and whether trade-offs occur between temperature-induced developmental plasticity and heat tolerance, remain unclear, particularly in organisms undergoing metamorphosis which represent 95% of all animal species. We examined how early-life thermal conditions shape growth, development, survival, acclimation capacity, heat tolerance, and energy allocation across ontogeny in the African clawed frog (Xenopus laevis), reared at six constant temperatures (17-32{degrees}C). We tested whether higher developmental temperatures generate trade-offs between accelerated growth and heat tolerance, and the consequences for post-metamorphic resilience to extreme heat. Rearing at 32{degrees}C was lethal before metamorphosis. At non-lethal warm temperatures (17-29{degrees}C), larvae and juveniles simultaneously accelerated development, maintained growth, and enhanced heat tolerance. However, juveniles reared at 29{degrees}C showed reduced survival, elevated corticosterone responses to acute stress, and diminished acclimation capacity, indicating increased energetic demands and constrained metabolic flexibility. These findings show that amphibians can integrate developmental plasticity with plastic adjustments in heat tolerance, but that such strategies incur cumulative physiological costs. By adopting an across-life-stage approach, our study highlights energy-allocation constraints that may limit population persistence under climate warming in species with complex life cycles.

The seasonal forms of the temperate butterfly Araschnia levana (Nymphalidae: Nymphalinae) differ in morphology (weight, wing area, and wing loading) and colouration. Spring individuals are predominantly orange with higher weight per wing area, (i.e. wing loading) while summer individuals are black with a white stripe and have lower wing loading. However, it remains unclear if and how these seasonal differences affect heating and cooling dynamics. We compared thermal responses of seasonal forms, focusing on the roles of morphology and colouration. Further, we assessed whether live butterflies heat and cool differently from dead individuals to detect the presence of active thermoregulation. Morphology and colouration influenced the thermal dynamics of the thorax and wings as expected from heat-transfer principles, but we found no evidence of active thermoregulation on the thorax. Based on aligned temperature curves, seasonal forms showed similar thermal dynamics. This similarity was driven by morphology and colouration, with larger wing area accelerating thermal change and higher body weight (or wing loading) reducing it, thereby masking underlying form-specific patterns. After accounting for significant morphological differences between forms, the thorax of spring individuals heated and cooled faster than that of summer ones. This trend suggests form-specific optimisation of thermal performance, likely as a response to temperate climates. Thermal responses differ between forms in ways not directly explained by the polyphenism itself, potentially reflecting a broader trait of multivoltine ectotherms to cope with seasonal temperature changes.

Rapid changes to weather caused by climate change have a negative effect on much of the worlds animal populations and species. Some populations are more vulnerable than others to the effects of climate change, and individuals are particularly vulnerable during early development. Good embryonic development is important for vertebrate species because this can dictate their breeding success and survival rates, and disruptions to this phase can have far reaching fitness effects that can last into adulthood and beyond. We looked at the impact of weather (ambient temperature, rainfall and wind speed) on the embryonic development of thorn-tailed Rayadito (Aphrastura spinicauda) at two different latitudes in Patagonia, Chile. We measured the heart rate of embryos just before hatching using an egg buddy machine to determine embryonic development. Optimum development of nestlings is important for fledging, so it is essential that embryonic development is successful. We studied two populations. One is situated in a temperate rainforest on the northern border of Patagonia called Pucon which we studied in 2018 and 2019, with mild temperatures (12 degrees Celsius), high rainfall (636ml) and low wind speeds (6.3km/h). The other is in a sub-Antarctic old growth forest in southern Patagonia called Navarino island which we studied in 2018, 2019 and 2023, which is comparatively drier (138ml), colder (8.3 degrees Celsius) and has higher average wind speeds (16.6km/h). We found that embryonic development was better in the south compared to the north, indicated by higher embryo heart rates near hatching in the south. Development of embryos in the northern site was slower when conditions were cold and windy. Development of embryos in the southern site was unaffected by temperature, rainfall or wind speeds. In northern Patagonia, when minimum temperatures were low and wind speeds high during the period encompassing clutch completion, initiation of full incubation and during incubation, have a negative impact on embryonic development. In contrast, when Rayaditos in the southern population experience slow embryonic development, they extend the incubation period allowing embryos more time to develop before hatching. Our study shows that in the north of Patagonia embryonic development declines over years and that Rayaditos seem not to have adapted to dealing with climate change. On the other hand, in the south of Patagonia, embryonic development is unaffected by climatic factors, suggesting that Rayaditos are adapting to climate change through extending their incubation periods, allowing embryos to fully develop before hatching. It appears that Rayaditos in the northern population are not extending their incubation periods and are not adapting to the threats posed by climate change. To our knowledge, this is the first study of its kind to examine embryonic development in the field and to associate this to changing weather patterns whilst highlighting specific days on which development is influenced.

BackgroundHumidity ramp protocols are widely used to assess human heat tolerance limits, but the impact of ramp temporal structure (e.g., step duration) on estimated critical environmental limits (CELs) remains unclear. This study integrated theoretical modeling and empirical testing to assess these effects on apparent core temperature (Tcr) inflection points. MethodsA first-order thermal model described Tcr dynamics during stepwise humidity changes at fixed dry-bulb temperature (Tdb), with analytical solutions for increments of duration {Delta}t and sensitivity analyses across relevant time constants ({tau}). Twenty-six healthy young adults (14 males, 12 females) completed randomized trials at Tdb=42 {degrees}C: (1) slow-ramp (4-hour equilibration at 40% RH, then +6% RH/hour for 2 hours followed by +3% RH/hour; RH range: 40-61%) and (2) aggressive-ramp (30 min equilibration, then +2% RH every 5 min; RH range: 28-88%). Rectal and skin temperatures, heart rate, and perceptual ratings were monitored continuously. ResultsWhen {Delta}t/{tau} <<1, thermal disequilibrium accelerated Tcr rises, yielding prematurely low CELs; dwell times [&ge;] 60 min/step permitted near-equilibrium and higher thresholds. Aggressive-ramp CELs were significantly lower than slow-ramp (males: 29.9{+/-}1.6 {degrees}C vs. 33.4{+/-}0.5 {degrees}C; females: 30.3{+/-}0.9 {degrees}C vs. 33.8{+/-}0.5 {degrees}C), with downward shifts of 3.4{+/-}1.9 {degrees}C and 3.5{+/-}0.9 {degrees}C, respectively. ConclusionRapid humidity increments systematically underestimate heat tolerance due to thermal lag. Accurate CEL determination requires prolonged stable exposures (gold standard) or slow ramps ensuring sufficient equilibration ({Delta}t [&ge;] 60 min/step). Our findings reveal a core limitation of aggressive-ramp protocols and offer a framework for improved assessment of human environmental compensability. NEW & NOTEWORTHYThis study reveals how ramp temporal structure affects heat tolerance assessment. Rapid humidity increments in aggressive-ramp protocols cause premature underestimation of critical environmental limits (CELs) due to thermal disequilibrium. In contrast, prolonged dwell times ([&ge;] 60 min/step) in slow ramps allow near-equilibrium conditions, resulting in higher and more accurate CELs. These findings emphasize the importance of equilibration time in defining heat tolerance and provide a more reliable approach for assessing heat stress in extreme environments.

Sea turtles exhibit environmental sex determination and face risks of over-feminization, heat-induced embryonic failure, and hatchling mortality due to rising global temperatures. Mitigating these impacts of climate change may necessitate interventions to reduce sand temperature. One proposed strategy is to irrigate nests with seawater, but uncertainties exist regarding turtle egg tolerance to saline nest sand. To test the hypothesis that sea turtle embryos can tolerate a regimen of irrigation with seawater at a management-relevant scale, we investigated the impact of two levels of large-scale irrigation using cooled seawater on green turtle nests and embryos, assessing the effects on important nest environmental factors and developmental success. Irrigation which simulated 200 mm of rain reduced the temperature in clutches by up to 5.6 {degrees}C (1.34 {+/-} 0.10 mean {+/-} SD) without adversely affecting clutch oxygen levels, sand water potential, or sand moisture content, but our irrigation regimens resulted in very low hatching success (1.5%). However, late-stage embryonic mortality predominated, suggesting that early embryos may have an unexpected tolerance to saline sand and increasing our understanding of sea turtle resilience to seawater irrigation. The observation that younger embryos may be less susceptible to seawater-associated mortality than mature embryos near hatching further informs the limitations and potential applications of seawater irrigation as a management strategy.

O_LIPhenological shifts are a major ecological consequence of climate change, yet studies often focus on single life stages meaning that the potential for carryover effects between life stages remains poorly understood. Failing to account for these effects may lead to inaccurate estimates of phenological shifts, with consequences for predicted synchrony among interacting species. This is especially relevant for temperate systems where climate warming is occurring unevenly across the year. C_LIO_LIHere, we investigated how temperature experienced the previous autumn and winter (during the pupal and egg stage) influences spring phenology in the winter moth (Operophtera brumata), a herbivorous insect with distinct life stages. Using 50 years of local climate data to create five experimental temperature regimes, we first quantified phenotypic plasticity in the duration and temporal variability of pupal and egg development. We then examined how timing of adult moth emergence affects timing of offspring hatching. C_LIO_LIWe found divergent effects of temperature on different life stages; pupal development time was shortest at intermediate temperatures while egg development time decreased linearly with increasing temperature. Furthermore, phenological shifts due to the conditions experienced by the mother were carried over to influence the phenology of her offspring. While this carryover effect was partially compensated during subsequent stages, compensation decreased under warming conditions. C_LIO_LIThese results refine our understanding of the sensitivity of the annual cycle of winter moth phenology to variation in temperature with potential implications for population dynamics and interspecific interactions. Overall, our findings highlight the need to consider the impacts of warming across multiple life stages so that carryover effects can be properly accounted for. Doing so will improve predictions of phenological shifts under future climates. C_LI

O_LIEctotherms in thermally variable environments mediate energy expenditure through both physiological and behavioural responses. However, many studies focus on constant temperature acclimation, and few consider behaviour and physiology in unison. It is unclear how acclimation to thermal variability affects locomotory choices, activity timing, and performance across daily thermal cycles. C_LIO_LIWe investigated the effects of thermal variability in the temperate dung beetle Onthophagus taurus. Following acclimation to a low amplitude (22{degrees}C {+/-} 2{degrees}C) or a high amplitude (22{degrees}C {+/-} 10{degrees}C) temperature regime, we measured behaviour and metabolic rate across temperatures. We hypothesised that O. taurus adjusts its locomotive strategy and search window when kept in high amplitude fluctuating temperatures to reduce energy loss associated with high temperature exposure. C_LIO_LIWe found that differences in energy expenditure were determined by propensity for flight which differed between acclimation treatments, particularly at intermediate temperatures. We also found that, following acclimation to a high amplitude of thermal variability, O. taurus exhibited a greater intensity of activity over a narrower window of time, and O. taurus acclimated to a low amplitude of thermal variability showed nocturnal activity. C_LIO_LIWe then used the data to model activity through the growing season over five years. Biophysical models were built using NicheMapR Microclimate and Ectotherm functions to test the length of potential searching time across seasons, the temperatures individuals are exposed, and locomotive strategy. Model outputs showed that acclimation to higher amplitudes of thermal variability increased accumulated degree-hours of activity relative to the low variability acclimation group. Individuals acclimated to higher amplitudes of thermal variability showed greater accumulated degree-hours in spring and fall, but exhibited shorter periods of activity during summer, with the model predicting increased opportunities for flight. Comparatively, O. taurus from the low variability acclimation treatment showed increased night activity in summer but did not fly. C_LI

Climate warming alters the thermal environment experienced by ectotherms, whose physiological performance and fitness are constrained by temperature. Early life stages are often the temperature-sensitive phases of the life cycle, with potential consequences for population persistence, particularly in freshwater stenotherms such as the Arctic charr (Salvelinus alpinus). The persistence of populations will partly depend on the adaptive potential of critical life stages to environmental changes. In this study, we used a common garden approach to compare the response and phenotypic plasticity of four charr populations to warmer conditions. These populations inhabit thermally contrasted lakes and differ in origin (native/introduced) and management history. We reared embryos at either an optimal (5{degrees}C) temperature for larval development or a warmer but realistic (8.5 {degrees}C) temperature. We tested adaptive divergence among populations in four traits (survival, incubation duration, body length and yolk sac volume), using Qst - Fst comparisons. We report negative effects of temperature on body size, survival and earlier hatching. Thermal reaction norms differed among populations, indicating adaptive divergence. Contrary to expectations, populations originating from warmer environments did not consistently exhibit higher trait values under elevated temperatures. In contrast, the unmanaged and colder high-altitude population exhibited higher survival rates and lower yolk reserves for a given size under heat stress than the other populations. Our results suggested that evolutionary trajectories specific to each population are shaped by factors related to the populations history, including introductions, demographic fluctuations and long-term repopulation practices, which can jointly influence the potential for adaptation to heat stress.

Sexual size dimorphism (SSD), the difference in body size between males and females, typically conforms to Renschs rule across species: SSD increases with body size when males are larger but decreases when females are larger. Although this macroevolutionary pattern has been extensively documented, intraspecific analyses remain rare, yet they are essential for understanding the proximate mechanisms underlying the origin and maintenance of sexual dimorphism. In particular, it remains unclear whether within-species variation in SSD is driven primarily by sex-specific differences in growth rate or in development time. Here, we addressed this question by examining SSD scaling in inbred lines of Drosophila melanogaster from the well-established Drosophila melanogaster Genetic Reference Panel (DGRP) reared under two thermal environments (25 {degrees}C and 28 {degrees}C). Females were consistently larger than males, resulting in pronounced female-biased SSD across different lines of this model insect. Moreover, SSD increased with overall body size, representing a reversal of Renschs rule at the intraspecific level. This scaling pattern was largely explained by higher female growth rates rather than sexual differences in development time. Elevated temperature reduced SSD by decreasing female growth rate while slightly enhancing that of males. Together, our results demonstrate that Renschs rule does not universally apply at intraspecific level and underscore the critical role of growth rate and environmental sensitivity in shaping SSD at the intraspecific level.

Kissing bugs are the primary vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Kissing bugs are exposed to thermal variability, including short periods of heat stress, which can induce mortality or exert sublethal effects. This study investigated Rhodnius prolixus following brief periods of high thermal stress with respect to survival, blood feeding, developmental processes, and T. cruzi infection, with a focus on sublethal effects. Our results demonstrated a significant decrease in survival for R. prolixus at 42 {degrees}C for 8 hours. When exposed to sub-lethal thermal stress (40{degrees}C for 8 hours), blood ingestion (amount and proportion) was reduced after 24 hours of recovery from thermal stress. Among the bugs that fed after 24 hours, molting was not impacted by temperature exposure. The infection rate decreased after heat exposure, likely due to reduced blood volume ingested when feeding 24 hours after heat stress. A week of recovery after exposure to higher temperatures improved feeding and increased infection rates to levels comparable to those of kissing bugs not exposed to thermal stress. Our findings offer insights into how extreme temperature events may influence Chagas disease. Specifically, these studies highlight the need to clarify how temperature, particularly at sublethal levels, interacts with vector biology to alter parasite transmission.

Current climate change leads to longer frequencies and reduced predictability of climatic parameters. Recent studies have highlighted the importance of considering multiple environmental factors, but experimental evidence on how species respond to their combined effect remains scarce. Here, we experimentally manipulated precipitation frequency and predictability and tested how they affect body size, growth, and survival using the common lizard (Zootoca vivipara) as a model species. Longer precipitation frequency negatively affected adult growth and male survival. Predictability influenced body size-dependent survival of yearlings and adults in certain frequency treatments. In yearlings, treatment-induced growth differences compensated for treatment-induced differences in size-dependent survival, resulting in no size differences during reproduction. In adults, treatment-induced differences in size-dependent survival were not compensated for, resulting in body size differences during reproduction among treatments. Consequently, precipitation frequency and predictability had a joint effect on life-history traits. Our results demonstrate that, even without water shortage, small differences in the frequency and predictability of precipitation affect population demography and life-history traits. This indicates that integrating the interactive action of different climatic parameters will be key to understanding and better anticipating future impacts of climate change on species.

Carausius morosus, the Indian stick insect, is a slender twig-like insect endemic to India. Though widely introduced through captivity around the world and commonly used in laboratories or kept as a household pet, standardized animal husbandry laboratory protocols are lacking. Here we report detailed laboratory culture conditions for C. morosus. We maintain stocks at 23 {degrees}C, 70% relative humidity, and a 12:12 hour light-dark photoperiod. This culture has been successfully sustained under these conditions for over two years, with standardized protocols in place for dietary and cage setup conditions. We also report methods for egg and hatchling care to support ongoing experiments with C. morosus. These standardized methods improve reproducibility and accessibility, enabling the broader use of C. morosus as a laboratory model system for developmental, behavioral, and physiological studies. SummaryThis paper outlines detailed protocols for maintaining a Carausius morosus laboratory colony, including key procedures for animal husbandry, egg and hatchling care, and an overview of the species lifespan and biological characteristics.

Dauer larvae are a dormant developmental stage in nematodes that is induced by a range of environmental cues. The molecular mechanisms that transduce these cues to regulate dauer entry have been well characterized in Caenorhabditis elegans, whereas those in other nematode species remain unclear. The closest known sibling species of C. elegans, Caenorhabditis inopinata, occupies a distinct ecological niche and shows an extremely low frequency of dauer formation by starvation in laboratory conditions, suggesting that it could serve as a useful comparative model for analyzing dauer-inducing mechanisms. To support such analysis, we generated a fluorescent dauer reporter, Cin-col-183p::mCherry, in C. inopinata based on a previously reported dauer-specific reporter in C. elegans. This reporter showed fluorescence specifically in the pre-dauer and dauer stages, but not in other developmental stages, indicating that it functions as a dauer-specific marker in C. inopinata. Using these marker strains, we compared the responses to high temperature and RNAi-mediated knockdown of insulin/IGF-1 pathway genes (daf-2, age-1, and pdk-1), and found that dauer induction differs mechanistically between C. elegans and C. inopinata. This dauer-specific fluorescent strain will be a useful tool for investigating the diversity of dauer-inducing mechanisms across nematode species. Article SummaryDauer is a dormant developmental stage in nematodes induced by environmental stress. Although its regulation is well studied in Caenorhabditis elegans, the mechanisms in other species remain unclear. Here, we developed a fluorescent dauer reporter, Cin-col-183p::mCherry, in Caenorhabditis inopinata, a close relative of C. elegans. The reporter was specifically expressed in pre-dauer and dauer stages, confirming its usefulness as a dauer marker. Using this strain, we found that responses to high temperature and insulin/IGF-1 pathway gene knockdown differ between C. elegans and C. inopinata. This reporter will help reveal diversity in dauer-inducing mechanisms across nematode species.

Local temperatures can shape the ability of introduced species to flourish and disrupt novel environments. The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive beetle that threatens ash trees in North America and Europe. To assess the role of temperature on EAB reproduction, we reared groups of adult beetles at one of four temperatures (12, 15, 18, and 21 {degrees}C) and measured reproductive success (laying fertilized eggs and egg hatching). There was no effect of rearing temperature on EAB female lifespans but no eggs laid at 15 or 18 {degrees}C hatched, suggesting these temperatures disrupt the reproductive process of EAB. Females reared at 21 {degrees}C, however, consistently laid eggs that hatched. We then used these results to assess the likelihood of reproductive success over the previous ten years in eight cities in Canada that host EAB. All locations experienced temperatures of [&ge;] 21 {degrees}C, but the number of hours and the number of days above this critical temperature were highly variable. There were ample opportunities in all locations for EAB to reproduce, but EAB in cooler cities would experience thermal limitations thus slowing the spread of EAB populations.

Cross-Fostering, i.e., the exchange of eggs or hatchlings, is a widely used technique, to disentangle genetic from environmental effects or to manipulate the clutch size. In most bird species, this manipulation is easily accepted by the social parents, leading to the conclusion that fostering has no detrimental effect. Using a dataset of four cohorts (N=298) of zebra finches (Taeniopygia castanotis), in which we fostered routinely a single egg into another nest of zebra finches, we explored potential short- and long-time effects of fostering. Noteworthy, these experiments were not designed to test this hypothesis. The objective of the egg fostering experiments was to test for parental recognition (Caspers et al. 2017) and mate choice decisions (Goluke 2018). Consequently, the aim of the present study is purely explorative. Our study confirmed previous findings that fostering has no short-term effects on the morphology and growth rates of the chicks, neither in males nor in females. However, we found that fostering has a sex-specific long-term effect. Females originating from fostered eggs had a significantly reduced lifespan compared to those from non-fostered eggs. Conversely, the lifespan of fostered males was similar to that of non-fostered males. All birds were housed in large groups, experiencing the same conditions after nutritional independence (day 35). Therefore, we can only speculate that fostering might result in early developmental stress, which may affect the individual fitness of females later in life, ultimately leading to shorter lifespans.

Nocturnal migration is a remarkable phenomenon observed in many insect species, including moths. Migratory moths are capable of maintaining precise directional orientation during migration, as demonstrated in both laboratory and field studies, suggesting that they use multiple environmental cues for orientation and navigation. Recent studies on Australian Bogong moths revealed that these animals can use stellar cues and likely the geomagnetic field (in conjunction with local visual cues) to select and maintain population-specific migratory direction. However, the underlying orientation mechanisms used by most other migratory moths are still largely unresolved. Further, it remains unclear whether migratory moths can adjust their orientation using Earths magnetic field parameters for determining their position relative to the goal (i.e. location or map information) - an ability clearly shown in some migratory birds which respond to virtual magnetic displacements by correcting their orientation (experiments when animals are exposed to magnetic cues corresponding to other geographic locations). Here, we present results from virtual magnetic displacement experiments conducted on red underwings (Catocala nupta). In addition, we tested their orientation under simulated overcast conditions and in a vertical magnetic field to get indications whether this species relies on geomagnetic or celestial cues to maintain its population-specific migratory direction. Our results show that (1) red underwings did not compensate for virtual magnetic displacement, indicating the absence of a magnetic map; (2) they remained significantly oriented in the absence of geomagnetic information, suggesting the use of a stellar compass; and (3) there was no evidence of magnetic compass orientation in absence of any visual cues.

O_LIStudying the reproduction process, which is a key determinant of individual and population fitness in endangered species, is challenging but urgently needed. The crested ibis (Nipponia nippon), a flagship endangered species recovering from an extreme population bottleneck, provides a valuable opportunity to examine how life-history strategies shape reproductive success and inform future conservation practices. C_LIO_LIWe monitored 176 breeding pairs of crested ibis over three consecutive breeding seasons and investigated the effects of three key life-history traits, namely breeding timing, clutch size, and nesting strategy (solitary versus colonial), on reproductive success (hatching and fledging success). C_LIO_LIOur analysis found that both hatching and fledging success declined significantly as breeding initiated later, and a positive association between clutch size and reproductive success in this species. These patterns were robust and repeatable across three years. Unlike other closely related species in this family, sibling competition is generally non-lethal, leading to large clutch sizes fledged in this endangered species. We consider this pattern to be a main reason underlying the rapid population recovery observed in the crested ibis. On the other hand, nesting strategy (colonial vs. solitary breeding) had no detectable effect on reproductive success. This pattern indicates the crested ibis can adopt different breeding strategies across habitats, highlighting its capacity to flexibly adjust breeding behavior in response to local environmental conditions. C_LIO_LIOur results provide an integrative assessment of how key life-history traits shape reproductive outcomes in a wild population of the crested ibis, serving as a foundation for evaluating its current status of population recovery and refining future conservation strategies for endangered avian species sharing similar life-history characteristics. C_LI