Behavioural and physiological adaptations to low-temperature environments in the common frog, Rana temporaria
Abstract and Figures
Background
Extreme environments can impose strong ecological and evolutionary pressures at a local level. Ectotherms are particularly sensitive to low-temperature environments, which can result in a reduced activity period, slowed physiological processes and increased exposure to sub-zero temperatures. The aim of this study was to assess the behavioural and physiological responses that facilitate survival in low-temperature environments. In particular, we asked: 1) do high-altitude common frog (Rana temporaria) adults extend the time available for larval growth by breeding at lower temperatures than low-altitude individuals?; and 2) do tadpoles sampled from high-altitude sites differ physiologically from those from low-altitude sites, in terms of routine metabolic rate (RMR) and freeze tolerance? Breeding date was assessed as the first day of spawn observation and local temperature recorded for five, paired high- and low-altitude R. temporaria breeding sites in Scotland. Spawn was collected and tadpoles raised in a common laboratory environment, where RMR was measured as oxygen consumed using a closed respiratory tube system. Freeze tolerance was measured as survival following slow cooling to the point when all container water had frozen.
Results
We found that breeding did not occur below 5°C at any site and there was no significant relationship between breeding temperature and altitude, leading to a delay in spawning of five days for every 100 m increase in altitude. The relationship between altitude and RMR varied by mountain but was lower for individuals sampled from high- than low-altitude sites within the three mountains with the highest high-altitude sites (≥900 m). In contrast, individuals sampled from low-altitudes survived freezing significantly better than those from high-altitudes, across all mountains.
Conclusions
Our results suggest that adults at high-altitude do not show behavioural adaptations in terms of breeding at lower temperatures. However, tadpoles appear to have the potential to adapt physiologically to surviving at high-altitude via reduced RMR but without an increase in freeze tolerance. Therefore, survival at high-altitude may be facilitated by physiological mechanisms that permit faster growth rates, allowing completion of larval development within a shorter time period, alleviating the need for adaptations that extend the time available for larval growth.
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... In mountain environments, species living at high elevation face strong constraints such as seasonal snow cover and low temperatures during the breeding season (Körner, 2007). Species must grow, reproduce and acquire resources during a shorter and colder growing season than at low elevations (Ryser, 1996;McCaffery and Maxell, 2010;Muir et al., 2014). In addition, for amphibian species, their full development is highly dependent on water availability in wetland pools, which itself depends on climate parameters as well as potential water storage in snowpack and glaciers (Carlson et al., 2020). ...
... It can also be negative (Reading, 2007;Tomaševic et al., 2007;Blaustein et al., 2010;Todd et al., 2010;Garner et al., 2011;Wassens et al., 2013;Carter et al., 2018;Fitzpatrick et al., 2020), for instance if earlier breeding phenology increases the risk of exposure of embryos to cold air temperatures or drought (Loman, 2009;Benard, 2015). Hence, with the documented earlier onset of snowmelt occurring in response to warmer winter and spring temperatures in documented in the European Alps (Beniston, 2012;Hall et al., 2015;Klein et al., 2016), surface pond embryos may be exposed to a greater risk of frost, which in turn would influence embryonic survival (Beattie, 1987;Frisbie et al., 2000;Muir et al., 2014) and population dynamics. This phenomenon has been observed for plants (Inouye, 2008), where the change in last spring frost timing is slower than the shift in plant phenology, leading to higher plant mortality Pardee et al., 2019; but see Klein et al., 2018 for evidence of consistent advances in snowmelt timing and last spring frost, leading to unchanged plant exposure to frost frequency and intensity). ...
... In order to determine whether temperature influenced mean spawning date after snowmelt, we calculated mean air temperature at 2 m for the 30 days after snowmelt, for each year and elevation (30 days corresponded to the median duration between snowmelt date and spawning date). Maximum temperature, minimum temperature and growing degree days (above 5 • C as in Muir et al., 2014) were also tested and gave the same conclusions as mean air temperature. Finally, to compare the risk of wetland drying during the larval development, we calculated the average summer air temperature at 2 m (June, July, and August) at both stations (1,340 and 1,970 m asl) for each year. ...
The alarming decline of amphibians around the world calls for complementary studies to better understand their responses to climate change. In mountain environments, water resources linked to snowmelt play a major role in allowing amphibians to complete tadpole metamorphosis. As snow cover duration has significantly decreased since the 1970s, amphibian populations could be strongly impacted by climate warming, and even more in high elevation sites where air temperatures are increasing at a higher rate than at low elevation. In this context, we investigated common frog ( Rana temporaria ) breeding phenology at two different elevations and explored the threats that this species faces in a climate change context. Our objectives were to understand how environmental variables influence the timing of breeding phenology of the common frog, and explore the threats that amphibians face in the context of climate change in mountain areas. To address these questions, we collected 11 years (2009–2019) of data on egg-spawning date, tadpole development stages, snowmelt date, air temperature, rainfall and drying up of wetland pools at ∼1,300 and ∼1,900 m a.s.l. in the French Alps. We found an advancement of the egg-spawning date and snowmelt date at low elevation but a delay at high elevations for both variables. Our results demonstrated a strong positive relationship between egg-spawning date and snowmelt date at both elevations. We also observed that the risk of frost exposure increased faster at high elevation as egg-spawning date advanced than at low elevation, and that drying up of wetland pools led to tadpole mortality at the high elevation site. Within the context of climate change, egg-spawning date is expected to happen earlier in the future and eggs and tadpoles of common frogs may face higher risk of frost exposure, while wetland drying may lead to higher larval mortality. However, population dynamics studies are needed to test these hypotheses and to assess impacts at the population level. Our results highlight climate-related threats to common frog populations in mountain environments, but additional research should be conducted to forecast how climate change may benefit or harm amphibian populations, and inform conservation and land management plans in the future.
... Previous studies identified a strong relationship between snowmelt dates and spawning dates (Terhivuo, 1988;Corn & Muths, 2002;Corn, 2003;Bison et al., 2021), thereby confirming a high degree of plasticity in terms of breeding timing (Muir, Biek & Mable, 2014). Bison et al. (2021) observe in R. temporaria a relationship with the DOY of snowmelt and DOY of middle spawning activity. ...
The Montseny massif shelters the southernmost western populations of common frogs (Rana temporaria) that live in a Mediterranean climate, one which poses a challenge for the species' persistence in a scenario of rising temperatures. We evaluated the effect of climate change at three levels. First, we analysed if there has been an advancement in the onset of spawning period due to the increase in temperatures. Second, we analysed the impact of climatic variables on the onset of the spawning period and, third, how the distribution of this species could vary according to the predictions with regard to rising temperatures for the end of this century. From 2009 to 2021, we found there had been an increase in temperatures of 0.439 C/decade, more than the 0.1 C indicated by estimates for the second half of the previous century. We found an advancement in the onset of the reproduction process of 26 days/decade for the period 2009-2022, a change that has been even more marked during the last eight years, when data were annually recorded. Minimum temperatures and the absence of frost days in the week prior to the onset of the spawning period determine the start of reproduction. Predictions on habitat availability for spawning provided by climatic niche analysis for the period 2021-2100 show a potential contraction of the species range in the Montseny and, remarkably, much isolation from the neighbouring populations.
... Fast and progressive temperature change could minimize acclimation phenomena (Burleson and Silva, 2011) and involved in a shift of thermal tolerant threshold (Frederich and Pörtner, 2000). The common frog (Rana temporaria) for instance did not show any behavioral adaptations in terms of breeding at lower temperatures (below 5 • C) (Muir et al., 2014). ...
Climatic change (global warming) not only limited to the terrestrial environmental variations but also transforming the aquatic environments. Recent studies have reported that both coastal and freshwater bodies have experienced the progressive warming and will intensify (giant leap) during this century. Same time the bewildering array of thermal stresses poses serious threats to the aquatic organisms. Although, there is a growing body of literature and scientific consensus regarding the effects of temperature to the aquatic biota. Hitherto, the extent to which the thermo-chemical stress on aquatic organisms intensifying is not fully elaborated. We have summarized following declarations:
• Temperature variations induce a range of physiological and biological responses in aquatic organisms including corticosteroid response, metabolic response, immune responses, heat shock proteins, and wavering in haemolymph parameters.
• The observed responses due to temperature fluctuations are actually attributed to the whole organism level performances like, acclimation and adaptation, fitness, feeding and food conversion ratio, growth and development.
• Temperature dependent chemical toxicities are subjected to influence the chemical processes and underlying molecular/genetic mechanisms of aquatic organisms at individual population and community levels.
Additionally, this review outlined the series of mechanisms in aquatic organisms associated with temperature changes in single or combined with chemicals. These observations provide significant evidence that the climate change and temperature variations are critical and there is pressing need to carefully evaluate the conditions and responses at large geographical scales.
... To understand the potential response of a species to changing climates, it is necessary to characterize the thermal-dependence curves of metabolic rate across a relevant latitudinal or elevational gradient (Sears 2005;Muir et al. 2014;Bulgarella et al., 2015;Hu et al., 2019). Here, we investigated the physiological sensitivity of the endemic Pyrenean brook newt Calotriton asper through the measure of SMR across a range of ecologically relevant temperatures (5 • C-25 • C) and for individuals from populations living at elevations ranging from 250 to 2500 m a.s.l. ...
Global warming impacts biodiversity worldwide, leading to species' adaptation, migration, or extinction. The population's persistence depends on the maintenance of essential activities, which is notably driven by phenotypic adaptation to local environments. Metabolic rate – that increases with temperature in ectotherms - is a key physiological proxy for the energy available to fuel individuals' activities. Cold-adapted ectotherms can exhibit a higher resting metabolism than warm-adapted ones to maintain functionality at higher elevations or latitudes, known as the metabolic cold-adaptation hypothesis. How climate change will affect metabolism in species inhabiting contrasting climates (cold or warm) is still a debate. Therefore, it is of high interest to assess the pace of metabolic responses to global warming among populations adapted to highly different baseline climatic conditions. Here, we conducted a physiological experiment in the endemic Pyrenean brook newt (Calotriton asper). We measured a proxy of standard metabolic rate (SMR) along a temperature gradient in individuals sampled among 6 populations located from 550 to 2189 m a.s.l. We demonstrated that SMR increased with temperature, but significantly diverged depending on populations' origins. The baseline and the slope of the relationship between SMR and temperature were both higher for high-elevation populations than for low-elevation populations. We discussed the stronger metabolic response observed in high-elevation populations suggesting a drop of performance in essential life activities for these individuals under current climate change. With the increase of metabolism as the climate warms, the metabolic-cold adaptation strategy selected in the past could compromise the sustainability of cold-adapted populations if short-term evolutionary responses do not allow to offset this evolutionary legacy.
... Temperature is an important environmental factor to which anurans are ontogenically and geographically adapted through, for example, phenotypic plasticity to survive a wide range of temperatures. Oromí et al. (2015) and Muir et al. (2014) postulated that if the potential habitat of a species becomes warmer due to climate change, that species would either succumb or be displaced by more heat tolerant species depending on its capacity to adapt. In the case of the Natterjack toad however, low environmental temperatures (e.g., <18 • C) are of most concern, because they prolong the tadpoles' development period, and consequently increase predation risk. ...
All of the environmental conditions in nature act on an organism simultaneously. However, in experimental studies of the factors influencing metamorphosis, each factor needs to be examined individually in order to disentangle its specific effects. However, it is challenging to then build properly integrated models which include data on all of the different factors evaluated in different experiments. This study set out to develop a predictive model which could synthesize the results of several experiments on survival, development and growth of Nat-terjack toad (Epidalea calamita) tadpole guilds. The proposed Population Dynamic P System (PDP) model enables estimates of growth and development during the larval phase, under different environmental conditions, weather conditions, predator density, and pond characteristics and management. The architecture of the model allows the inclusion of an indefinite number of parameters and interactions, with all inputs interacting in parallel, and enables solutions to complex modeling approaches. Using the model with a range of field data, we found that the importance of predation pressure on Natterjack toad tadpole guilds exceeds the potential effects of variations in temperature and precipitation. The impact of introduced invasive predators therefore arguably poses the greatest threat to this species. This type of model holds promise as a reliable management and conservation tool for this and other species, especially where interactions between environmental factors make the impacts of individual factors difficult to predict.
... Freeze-tolerant insects tolerate low temperature through intracellular ice formation with much of the water shunted out and converted to extracellular ice (Danks, 2004;Denlinger & Lee, 2010). Regardless of compensatory modifications, when insects are exposed to low-temperature environments, this can result in reduced activity periods and slowed physiological processes (Muir et al., 2014) thereby reducing activity, development, and reproduction . ...
1. Low temperatures affect insect functioning and population dynamics. Although temperate species cope with low temperatures better than their tropical counterparts, increasing temperature variability due to climate change exposes tropical species to frequent cold stress. For keystone insect species providing important ecosystem services, low-temperature tolerances, and behavioural responses remain unknown, hampering predictions under climate change.
2. The present study examined low-temperature physiology [critical thermal minima (CTmin) and chill coma recovery time (CCRT)] of six dung beetle species across three activity times: diurnal Allogymnopleurus indigaceous (Reiche) and Euoniticellus intermedius (Reiche); crepuscular Onthophagus alexis (Klug) and Onthophagus gazella (Fabricius), and; nocturnal Copris elephenor (Klug) and Scarabaeus zambezianus (Peringuey). Further, ecological service delivery (dung removal) was examined between diurnal and nocturnal species across the temperature regimes.
3. Nocturnal species had significantly greater cold tolerance than both crepuscular and diurnal species, while CCRT was significantly shortest in diurnal than both crepuscular and nocturnal species. Dung ball production between diurnal and nocturnal species interacted with temperature, with diurnal species producing significantly fewer balls at low temperatures, while nocturnal beetles were not significantly affected. In turn, nocturnal species produced significantly larger balls than the diurnal species across temperatures. Effects of temperature regime shifts were intertwined with the foraging ecology of individual species.
4. Future research should quantify species' functional responses toward different amounts of dung masses as stressful temperatures increase.
5. Results are significant for determination of species thermal ranges and predicting costs of low-temperature stress through reduced ecological services under shifting thermal environments.
... Although several studies on tadpoles found no CnGV pattern of metabolic rates (e.g. Rana temporaria; Lindgren and Laurila 2009;Muir et al. 2014), it is arguable that metabolic rate at terrestrial adult stages of amphibians along the altitudinal gradient may largely differ from early aquatic stages due to the increased number of energetic trade-offs over ontogeny (Montiglio et al. 2018). Essentially, the MCA hypothesis as well as its reproductive pattern-dependence are based on the increased-intake model where variation in maintenance MR reflects variation in the size of organs that mobilize energy (e.g., digestive organs, muscle). ...
The metabolic cold adaptation (MCA) hypothesis predicts an increase in metabolic rate and thermal sensitivity of poikilotherms from cold environments as compared to those from warm environments, when measured under standardized conditions. This compensatory response is also expected to evolve in life history and behavioral traits if the reductions in these phenotypic traits at low temperature involves in a reduction in itness. We investigated the extent to which the level of energy intake (measured as feeding rate), energy turnover (measured as standard metabolic rate, SMR) and the energy budget (energy allocation to growth and physical activity) are infuenced by climatic conditions in three populations of the Asiatic toad (Bufo gargarizans) distributed across an altitudinal gradient of 1350 m in the Qionglai Mountains of Western China.
We found a similar thermal reaction norm of SMR at both population and individual levels; therefore, the data did not support the MCA hypothesis. However, there was a co-gradient variation (CoGV) for mass change rate in which the high and medium altitudinal populations displayed slower mass change rates than their counterparts from low altitudes. Moreover, this CoGV pattern was accompanied by a low feeding rate and high physical activity for the high- and medium-altitude populations. Our results highlight that adjustments in energy intake and energy allocation to behaviors, but not energy allocation
to metabolism of maintenance, could act as an energetic strategy to accommodate the varied growth efficiency in Asiatic toads along an altitudinal gradient.
Pesticides are one of the main drivers of the worldwide amphibian decline. Their actual toxicity depends on a number of factors, like the species in focus or the developmental stage of exposed individuals. As ectothermic species, the metabolism of amphibians is influenced by ambient temperature. Therefore, temperature also affects metabolic rates and thus processes that might enhance or reduce toxic effects. Studies about the interactive effect of temperature and toxicity on amphibians are rare and deliver contrasting results. To investigate the temperature-dependent pesticide sensitivity of larvae of two European species we conducted acute toxicity tests for the viticultural fungicide Folpan® 500 SC with the active ingredient folpet at different temperatures (6°C, 11°C, 16°C, 21°C, 26°C). Sensitivity of Rana temporaria and Bufotes viridis was highly affected by temperature: early larvae (Gosner stage 20) were about twice more sensitive to Folpan® 500 SC at 6°C compared to 21°C. Next to temperature, species and developmental stage of larvae had an effect on sensitivity. The most sensitive individuals (early stages of R . temporaria at 6°C) were 14.5 times more sensitive than the least sensitive ones (early stages of B . viridis at 26°C). Our results raise concerns about typical ecotoxicological studies with amphibians that are often conducted at temperatures between 15°C and 20°C. We suggest that future test designs should be performed at temperatures that reflect the temperature range amphibians are exposed to in their natural habitats. Variations in the sensitivity due to temperature should also be considered as an uncertainty factor in upcoming environmental risk assessments for amphibians.
The Xizang plateau frog, Nanorana parkeri (Anura: Dicroglossidae), enters a dormant state in the winter in response to seasonal cold and lack of food. To investigate the physiological and ecological characteristics of overwintering in this species, we measured habitat conditions (hibernacula temperatures, body temperature, and water quality variables), morphology, metabolite concentrations, total antioxidant capacity (T-AOC), and bacteria-killing ability (BKA) of plasma during summer and winter. We found that N. parkeri hibernates underwater at the bottom of ponds (10-20-cm depth). Dissolved oxygen content in the water decreases significantly (by 12%) in the winter compared with summer, suggesting that overwintering N. parkeri may experience hypoxia. Body mass, body mass index, hepatosomatic index, and hepatic glycogen concentration all increased significantly in winter-collected frogs as compared to summer-collected individuals, indicating that overwintering N. parkeri accumulates high fuel/energy reserves to support prolonged periods of hibernation. A significant reduction in glucose, urea, and lactate concentrations in most organs may be closely related to metabolic depression in overwintering N. parkeri. Liver lactate concentration rose significantly in winter-collected frogs, suggesting that anaerobic metabolism dominates when this species overwinters. The T-AOC of plasma showed a significant reduction in winter, suggesting a reduced need for antioxidant defenses. Oppositely, the BKA of plasma increased significantly in winter versus summer, indicating that innate immunity was enhanced during overwintering. In summary, these behavioral (migrating to caves), physiological, and biochemical adjustments may be key for the successful overwintering of this high-altitude frog.
The red tree frog Litoria rubella from Australia has been studied for several decades showing that their dorsal skin glands secrete a number of small peptides containing a Pro–Trp sequence, known as tryptophyllin L peptides. Although peptides from many genera of Australian frogs have been reported to possess a variety of biological activities, the bioactivities of this peptide family have remained to be discovered. In this study, we investigated the antioxidant potency of a number of tryptophyllin L peptides for the first time using a joint statistical and experimental approach in which predictions based on Gaussian three‐dimensional quantitative structure–activity relationship (3D‐QSAR) models were employed to guide an in vitro experimental investigation. Two tryptophyllin tripeptides P–W–L (OH) and P–W–L (NH2) were predicted to have the Trolox equivalent antioxidant capacity (TEAC) values of 0.80 and 0.87 μM Trolox/μM peptide, respectively. With those promising results, antioxidant capabilities of five tryptophyllin L peptides with the common core Pro–Trp–Leu were synthesized and subjected to 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH), ferric reducing ability of plasma (FRAP) and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) radical cation (ABTS˙⁺) radical scavenging assays. The tests indicated that all the tested tryptophyllin L peptides, noticeably S–P–W–L (OH) and F–P–W–L (NH2), are strong ABTS˙⁺ radical scavengers and moderate scavengers in the other two assays. The results, thus, suggested that the tryptophyllin L peptides are likely to be a part of the skin antioxidant system helping the frog to cope with drastic change in oxygen exposure and humidity, as they inhabit over a large area of Australia with a wide climate variation.
Correction for “Differences in spawning date between populations of common frog reveal local adaptation,” by Albert B. Phillimore, Jarrod D. Hadfield, Owen R. Jones, and Richard J. Smithers, which appeared in issue 18, May 4, 2010, of Proc Natl Acad Sci USA (107:8292–8297; first published April 19, 2010; 10.1073/pnas.0913792107). The authors note that on page 8296, right column, Equations 10 and 11 appeared incorrectly. See http://www.pnas.org/content/109/13/5134.3.full
Temperature adaptation is a much neglected field in the minds of climate change researchers and policy makers. However, increasing fluctuations in temperature mean that the risk of cold and heat stress will pose an increasing threat to both wild and cultivated plants and animals, with frost injury expected to cause devastating damage to crops on an increasingly large scale. Thus, improving shared knowledge of the biological mechanisms of temperature adaptation in plants and animals will help prevent major losses of crops and genetic resources in the future. This book is the first to focus on the mechanistic similarities between species in their responses to temperature in a multi-organism approach that addresses the challenges and impacts of climate change on temperature adaptation in micro-organisms (including pathogens), invertebrates, economically and scientifically important plants and vertebrates in both terrestrial and marine environments. The book concludes with a focus on the interactions between organisms, exploring common mechanisms in temperature adaptation.
Wood frogs breed in a variety of ponds and lakes in central Alaska. Dates of first appearance of frogs ranged from 24 April to 22 May. Egg laying began 4-6 days later. Egg laying was completed in a pond 4-8 days after the first egg mass appeared. Wood frogs tend to lay their egg masses at the same spot. The average number of eggs per mass was 778 with an egg diameter of 1.6 mm. Development of eggs was directly related to water temperature and occured at the same rate as that shown for wood frogs from New York. Temperature limits that permit at least 50% survival of eggs through hatching were 6@?-24@?C. Temperature tolerance of eggs and tadpoles varied with age and acclimatization. Temperature preference of tadpoles followed a normal curve and ranged from 9@? to 29@?C. Development in the field varied among different ponds and different years. Rapid growth occured once the larvae were free swimming. Average maximum weight ranged from 2.15 to 2.85 g; maximum length varied from 5.5 to 6.0 cm. Time to metamorephosis ranged from 53 to 78 days. Two periods of development are distinguished: In period I, fertilization to free-living stage, growth rate is determined by water temperature. This period occupies one-third of the development time but has a higher mortality rate than period II. The later period includes the free-swimming stage until climax metamorphosis, and development rate is determined by environmental factors such as food and population density, as well as temperature.
Everything VariesSignificanceGood and Bad HypothesesNull Hypothesesp ValuesInterpretationStatistical ModellingMaximum LikelihoodExperimental DesignThe Principle of Parsimony (Occam's Razor)Observation, Theory and ExperimentControlsReplication: It's the n's that Justify the MeansHow Many Replicates?PowerRandomizationStrong InferenceWeak InferenceHow Long to Go On?PseudoreplicationInitial ConditionsOrthogonal Designs and Non-orthogonal Observational Data
Microevolutionary responses to spatial variation in the environment seem ubiquitous, but the relative role of selection and neutral processes in driving phenotypic diversification remain often unknown. The moor frog (Rana arvalis) shows strong phenotypic divergence along an acidification gradient in Sweden. We here used correlations among population pairwise estimates of quantitative trait (P ST or Q ST from common garden estimates of embryonic acid tolerance and larval life‐history traits) and neutral genetic divergence (F ST from neutral microsatellite markers), as well as environmental differences (pond pH, predator density, and latitude), to test whether this phenotypic divergence is more likely due to divergent selection or neutral processes. We found that trait divergence was more strongly correlated with environmental differences than the neutral marker divergence, suggesting that divergent natural selection has driven phenotypic divergence along the acidification gradient. Moreover, pairwise P STs of embryonic acid tolerance and Q STs of metamorphic size were strongly correlated with breeding pond pH, whereas pairwise Q STs of larval period and growth rate were more strongly correlated with geographic distance/latitude and predator density, respectively. We suggest that incorporating measurements of environmental variation into Q ST–F ST studies can improve our inferential power about the agents of natural selection in natural populations.