Thermal Ecology, Environments, Communities, and Global Change: Energy Intake and Expenditure in Endotherms

Kronfeld‐Schor, Noga; Dayan, Tamar

doi:10.1146/annurev-ecolsys-110512-135917

Cited by 48 publications

(36 citation statements)

References 117 publications

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“…Our understanding of the functional significance of hibernation has tended to focus on its direct effects on energetics, with less attention on how prolonged dormancy – a behaviour contrasting with the high state of activity characteristic of small endothermic animals – might affect other ecological traits (Kronfeld‐Schor & Dayan ) and the evolution of life‐history strategies among mammals. Mortality risk of small mammals while hibernating is five times lower on average compared to the active season (Turbill, Bieber & Ruf ).…”

Section: Introductionmentioning

confidence: 99%

Thermal climate‐linked variation in annual survival rate of hibernating rodents: shorter winter dormancy and lower survival in warmer climates

Turbill

Prior

2016

Functional Ecology

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1. In seasonal climates, many animals, including a wide range of small mammals, are physiologically capable of prolonged dormancy (~hibernation), when foraging-related activity ceases entirely for part the year. Low metabolic rates while dormant minimise energy and water requirements, but the behavioural state of inactivity also reduces exposure to mortality risks, especially predation. 2. Thermal effects on activity underlie spatial patterns in annual survival rate of ectothermic animals. We hypothesised that, because local thermal conditions affect the duration of mammalian hibernation, positive effects of dormancy on survival could also underlie a negative relationship between spatial variation in thermal climate and annual survival rate among populations of hibernating rodents. 3. We applied mixed models to test for effects of local thermal climate on collated data of hibernation duration and annual survival rate among populations of hibernating and a representative sample of non-hibernating rodent species. 4. Our analyses revealed strong negative effects of mean annual temperature on hibernation duration and adult annual survival rate within hibernating species (b: À8Á6 day and À5Á1% per 1°C) but no effect in non-hibernating rodent species. This thermal climate-linked pattern in annual survival rate seems to be unique among mammals. A parsimonious explanation lies in the large increase in monthly survival rates during hibernation compared to activity. 5. The current spatial pattern suggests ongoing climate warming might reduce annual survival rates of hibernating rodents by shortening their hibernation season. Decreased annual survival because of increased activity in warmer climates with shorter winter seasons is an unappreciated mechanism leading to impacts of global warming on animal populations in temperate climates.

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Section: Introductionmentioning

confidence: 99%

Thermal climate‐linked variation in annual survival rate of hibernating rodents: shorter winter dormancy and lower survival in warmer climates

Turbill

Prior

2016

Functional Ecology

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“…Social dynamics within hibernacula, timing of immergence (i.e., juvenile typically enter estivation 2–3 weeks after older age classes; Knopf, ) and hibernacula depth (Knopf & Balph, ) could also explain observed differences in juvenile survival when compared to older age classes. On the other hand, colder temperatures could benefit adults/yearling UGS as they can reduce the energetic output necessary during hibernation (Kronfeld‐Schor & Dayan, ) and allow UGS to remain in hibernation longer (Turbill & Prior, ).…”

Section: Discussionmentioning

confidence: 99%

Seasonal climate effects on the survival of a hibernating mammal

Falvo

Koons

Aubry

2019

Ecology and Evolution

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Global climate change and associated regional climate variability is impacting the phenology of many species, ultimately altering individual fitness and population dynamics. Yet, few studies have considered the effects of pertinent seasonal climate variability on phenology and fitness. Hibernators may be particularly susceptible to changes in seasonal climate since they have a relatively short active season in which to reproduce and gain enough mass to survive the following winter. To understand whether and how seasonal climate variability may be affecting hibernator fitness, we estimated survival from historical (1964–1968) and contemporary (2014–2017) mark–recapture data collected from the same population of Uinta ground squirrels (UGS, Urocitellus armatus ), a hibernator endemic to the western United States. Despite a locally warming climate, the phenology of UGS did not change over time, yet season‐specific climate variables were important in regulating survival rates. Specifically, older age classes experienced lower survival when winters or the following springs were warm, while juveniles benefited from warmer winter temperatures. Although metabolic costs decrease with decreasing temperature in the hibernacula, arousal costs increase with decreasing temperature. Our results suggest that this trade‐off is experienced differently by immature and mature individuals. We also observed an increase in population density during that time period, suggesting resources are less limited today than they used to be. Cheatgrass is now dominating the study site and may provide a better food source to UGS than native plants did historically.

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“…The reproductive success of an individual and its interaction with other individuals is largely determined by its use of energy (e.g., [ 1 – 3 ]). Thus, the study of changes in a host’s energy allocation in response to parasites is crucial for understanding parasite impact on both individual- and population-level processes [ 1 , 2 ].…”

Section: Introductionmentioning

confidence: 99%

Time budget, oxygen consumption and body mass responses to parasites in juvenile and adult wild rodents

et al. 2016

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BackgroundThe study of changes in a host’s energy allocation in response to parasites is crucial for understanding parasite impact on both individual- and population-level processes. Experimental studies have explored such responses mainly in a single subsample of hosts per study, primarily adult males, and have only assessed either the overall energy acquisition or expenditure, rather than their different components simultaneously, or the behavioral responses. Accordingly, two fundamental questions arise: why have multiple host strategies evolved to cope with increased energy expenditure? and, which factors determine this variation (e.g. host species, identity, age)? This study provides an important step towards addressing both questions by experimentally disentangling the short-term physiological and behavioral responses of juvenile and non-reproductive adult rodents to natural levels of flea infestation. These two cohorts represent extreme cases of the energy demand continuum, as the former, in contrast to the latter, is involved in growth - a highly energy-demanding process - and may not be able to operate far below its upper limit of energy expenditure, and thus should reduce its energy expenses upon the occurrence of extra demands (e.g. due to parasitic pressure). Accordingly, we hypothesized that the response to fleas is age-dependent and varies according to the age-specific energy requirements and constraints.MethodsWe monitored the behavior and physiology of juvenile and non-reproductive adult rodents before and after experimental flea infestation. First, we used a model selection approach to search for the factors that best explained the variability in the time budget, oxygen consumption, and body mass change in response to fleas. Then, using a path analysis approach, we quantified the different pathways connecting the important associations revealed at stage 1.ResultsCompared to their flea-free counterparts, flea-infested adults groomed longer and had a higher oxygen consumption rate, but did not lose body mass. Infested juveniles also groomed longer but grew slower and had a similar rate of oxygen consumption.ConclusionsResults suggest that both juvenile and adult rodents suffer from natural flea infestation levels. However, the comparison between the responses of juveniles and adults to experimental infestation, also suggests that juveniles may reallocate their energy expenditure from growth to maintenance, while non-reproductive adults increase their energy acquisition. Such age-dependent responses suggest that juveniles may be constrained by their higher need to rest for full functioning or by an upper limit in energy expenditure. Taken together, our study provides experimental evidence that hosts can compensate for the costs incurred by parasitism through physiological and behavioral plasticity, depending on their age, which probably determines their requirements and constraints. These compensatory responses may have important implications for the population dynamics of hosts and their parasites.

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Thermal Ecology, Environments, Communities, and Global Change: Energy Intake and Expenditure in Endotherms

Cited by 48 publications

References 117 publications

Thermal climate‐linked variation in annual survival rate of hibernating rodents: shorter winter dormancy and lower survival in warmer climates

Thermal climate‐linked variation in annual survival rate of hibernating rodents: shorter winter dormancy and lower survival in warmer climates

Seasonal climate effects on the survival of a hibernating mammal

Time budget, oxygen consumption and body mass responses to parasites in juvenile and adult wild rodents

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