1
|
Szangolies L, Gallagher CA, Jeltsch F. Individual energetics scale up to community coexistence: Movement, metabolism and biodiversity dynamics in fragmented landscapes. J Anim Ecol 2024; 93:1065-1077. [PMID: 38932441 DOI: 10.1111/1365-2656.14134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 05/29/2024] [Indexed: 06/28/2024]
Abstract
Unravelling the intricate mechanisms that govern community coexistence remains a daunting challenge, particularly amidst ongoing environmental change. Individual physiology and metabolism are often studied to understand the response of individual animals to environmental change. However, this perspective is currently largely lacking in community ecology. We argue that the integration of individual metabolism into community theory can offer new insights into coexistence. We present the first individual-based metabolic community model for a terrestrial mammal community to simulate energy dynamics and home range behaviour in different environments. Using this model, we investigate how ecologically similar species coexist and maintain their energy balance under food competition. Only if individuals of different species are able to balance their incoming and outgoing energy over the long-term will they be able to coexist. After thoroughly testing and validating the model against real-world patterns such as of home range dynamics and field metabolic rates, we applied it as a case study to scenarios of habitat fragmentation - a widely discussed topic in biodiversity research. First, comparing single-species simulations with community simulations, we find that the effect of habitat fragmentation on populations is strongly context-dependent. While populations of species living alone in the landscape were mostly positively affected by fragmentation, the diversity of a community of species was highest under medium fragmentation scenarios. Under medium fragmentation, energy balance and reproductive investment were also most similar among species. We therefore suggest that similarity in energy balance among species promotes coexistence. We argue that energetics should be part of community ecology theory, as the relative energetic status and reproductive investment can reveal why and under what environmental conditions coexistence is likely to occur. As a result, landscapes can potentially be protected and designed to maximize coexistence. The metabolic community model presented here can be a promising tool to investigate other scenarios of environmental change or other species communities to further disentangle global change effects and preserve biodiversity.
Collapse
Affiliation(s)
- Leonna Szangolies
- Plant Ecology and Nature Conservation, University of Potsdam, Potsdam, Germany
| | - Cara A Gallagher
- Plant Ecology and Nature Conservation, University of Potsdam, Potsdam, Germany
| | - Florian Jeltsch
- Plant Ecology and Nature Conservation, University of Potsdam, Potsdam, Germany
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| |
Collapse
|
2
|
Thompson CL, Hermann EA. Behavioral thermoregulation in primates: A review of literature and future avenues. Am J Primatol 2024; 86:e23614. [PMID: 38433290 DOI: 10.1002/ajp.23614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 02/13/2024] [Accepted: 02/17/2024] [Indexed: 03/05/2024]
Abstract
Primates face severe challenges from climate change, with warming expected to increase animals' thermoregulatory demands. Primates have limited long-term options to cope with climate change, but possess a remarkable capacity for behavioral plasticity. This creates an urgency to better understand the behavioral mechanisms primates use to thermoregulate. While considerable information exists on primate behavioral thermoregulation, it is often scattered in the literature in a manner that is difficult to integrate. This review evaluates the status of the available literature on primate behavioral thermoregulation to facilitate future research. We surveyed peer-reviewed publications on primate thermoregulation for N = 17 behaviors across four thermoregulatory categories: activity budgeting, microhabitat use, body positioning, and evaporative cooling. We recorded data on the primate taxa evaluated, support for a thermoregulatory function, thermal variable assessed, and naturalistic/manipulative study conditions. Behavioral thermoregulation was pervasive across primates, with N = 721 cases of thermoregulatory behaviors identified across N = 284 published studies. Most genera were known to utilize multiple behaviors (x ¯ = 4.5 ± 3.1 behaviors/genera). Activity budgeting behaviors were the most commonly encountered category in the literature (54.5% of cases), while evaporative cooling behaviors were the least represented (6.9% of cases). Behavioral thermoregulation studies were underrepresented for certain taxonomic groups, including lemurs, lorises, galagos, and Central/South American primates, and there were large within-taxa disparities in representation of genera. Support for a thermoregulatory function was consistently high across all behaviors, spanning both hot- and cold-avoidance strategies. This review reveals asymmetries in the current literature and avenues for future research. Increased knowledge of the impact thermoregulatory behaviors have on biologically relevant outcomes is needed to better assess primate responses to warming environments and develop early indicators of thermal stress.
Collapse
Affiliation(s)
- Cynthia L Thompson
- Department of Biomedical Sciences, Grand Valley State University, Allendale, Michigan, USA
| | - Emily A Hermann
- Department of Biomedical Sciences, Grand Valley State University, Allendale, Michigan, USA
| |
Collapse
|
3
|
Gębczyński AK, Sadowska J, Konarzewski M. Differences in the range of thermoneutral zone between mouse strains: potential effects on translational research. Am J Physiol Regul Integr Comp Physiol 2024; 326:R91-R99. [PMID: 38009211 DOI: 10.1152/ajpregu.00154.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 10/27/2023] [Accepted: 11/20/2023] [Indexed: 11/28/2023]
Abstract
Laboratory mice are commonly used for studies emulating human metabolism. To render human energetics, their ratio of daily (DEE) to basal (BMR) energy expenditure of 1.7-1.8 should be maintained. However, the DEE/BMR ratio strongly depends on whether a given study using a mouse model is carried out above, or below the lower critical temperature (LCT) of the thermoneutral zone, which is rarely considered in translational research. Here, we used mice artificially selected for high or low rates of BMR along with literature data to analyze the effect of ambient temperature on possible systematic bias in DEE/BMR. We demonstrated that the estimated LCTs of mice from the high and low BMR lines differ by more than 7°C. Furthermore, the range of variation of LCTs of mouse strains used in translational research spans from 23 to 33°C. Differences between LCTs in our selected mice and other mouse strains are mirrored by differences in their DEE-to-BMR ratio, on average increasing it at the rate of 0.172°C-1 at temperatures below LCT. Given the wide range of LCTs in different mouse strains, we conclude that the energetic cost of thermoregulation may differ greatly for different mouse strains with a potentially large impact on translational outcomes. Thus, the LCT of a given mouse strain is an important factor that must be considered in designing translational studies.
Collapse
Affiliation(s)
| | - Julita Sadowska
- Faculty of Biology, University of Białystok, Białystok, Poland
| | | |
Collapse
|
4
|
Levesque DL, Breit AM, Brown E, Nowack J, Welman S. Non-Torpid Heterothermy in Mammals: Another Category along the Homeothermy-Hibernation Continuum. Integr Comp Biol 2023; 63:1039-1048. [PMID: 37407285 DOI: 10.1093/icb/icad094] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 06/14/2023] [Accepted: 06/29/2023] [Indexed: 07/07/2023] Open
Abstract
Variability in body temperature is now recognized to be widespread among whole-body endotherms with homeothermy being the exception rather than the norm. A wide range of body temperature patterns exists in extant endotherms, spanning from strict homeothermy, to occasional use of torpor, to deep seasonal hibernation with many points in between. What is often lost in discussions of heterothermy in endotherms are the benefits of variations in body temperature outside of torpor. Endotherms that do not use torpor can still obtain extensive energy and water savings from varying levels of flexibility in normothermic body temperature regulation. Flexibility at higher temperatures (heat storage or facultative hyperthermia) can provide significant water savings, while decreases at cooler temperatures, even outside of torpor, can lower the energetic costs of thermoregulation during rest. We discuss the varying uses of the terms heterothermy, thermolability, and torpor to describe differences in the amplitude of body temperature cycles and advocate for a broader use of the term "heterothermy" to include non-torpid variations in body temperature.
Collapse
Affiliation(s)
| | - Ana M Breit
- School of Biology and Ecology, University of Maine, 04469 Orono, ME, USA
| | - Eric Brown
- School of Biology and Ecology, University of Maine, 04469 Orono, ME, USA
| | - Julia Nowack
- School of Biological and Environmental Sciences, Liverpool John Moores University, L3 3AF Liverpool, UK
| | - Shaun Welman
- Department of Zoology, Nelson Mandela University, Gqeberha 6031, South Africa
| |
Collapse
|
5
|
Keith SA, Drury JP, McGill BJ, Grether GF. Macrobehaviour: behavioural variation across space, time, and taxa. Trends Ecol Evol 2023; 38:1177-1188. [PMID: 37661519 DOI: 10.1016/j.tree.2023.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/02/2023] [Accepted: 08/10/2023] [Indexed: 09/05/2023]
Abstract
We explore how integrating behavioural ecology and macroecology can provide fundamental new insight into both fields, with particular relevance for understanding ecological responses to rapid environmental change. We outline the field of macrobehaviour, which aims to unite these disciplines explicitly, and highlight examples of research in this space. Macrobehaviour can be envisaged as a spectrum, where behavioural ecologists and macroecologists use new data and borrow tools and approaches from one another. At the heart of this spectrum, interdisciplinary research considers how selection in the context of large-scale factors can lead to systematic patterns in behavioural variation across space, time, and taxa, and in turn, influence macroecological patterns and processes. Macrobehaviour has the potential to enhance forecasts of future biodiversity change.
Collapse
Affiliation(s)
- Sally A Keith
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.
| | - Jonathan P Drury
- Department of Biosciences, Durham University, Durham, DH1 3LE, UK
| | - Brian J McGill
- School of Biology and Ecology and Mitchell Center for Sustainability Solutions, University of Maine, Orono, ME 04469, USA
| | - Gregory F Grether
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| |
Collapse
|
6
|
Maloney CM, Careau V. Individual variation in heat substitution: is activity in the cold energetically cheaper for some individuals than others? J Exp Biol 2022; 225:276466. [PMID: 36036801 DOI: 10.1242/jeb.244186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 08/25/2022] [Indexed: 11/20/2022]
Abstract
In many endotherms, a potentially important yet often overlooked mechanism to save energy is the use of the heat generated by active skeletal muscles to replace heat that would have been generated by thermogenesis (i.e., "activity-thermoregulatory heat substitution"). While substitution has been documented numerous times, the extent of individual variation in substitution has never been quantified. Here, we used a home-cage respirometry system to repeatedly measure substitution through the concomitant monitoring of metabolic rate (MR) and locomotor activity in 46 female white-footed mice (Peromyscus leucopus). A total of 117 measures of substitution were taken by quantifying the difference in the slope of the relationship between MR and locomotor activity speed at two different ambient temperatures. Consistency repeatability (±se) of substitution was 0.313±0.131 - hence, about a third of the variation in substitution occurs at the among-individual level. Body length and heart mass were positively correlated with substitution whereas surface area was negatively correlated with substitution. These two sub-organismal traits accounted for the majority of the among-individual variation (i.e., individual differences in substitution were not significant after accounting for these traits). Overall, our results imply that the energetic cost of activity below the thermoneutral zone is consistently cheaper from some individuals than others, and that the energy saved from substitution might be available to invest in fitness-enhancing activities.
Collapse
Affiliation(s)
- Caroline M Maloney
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Vincent Careau
- Department of Biology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| |
Collapse
|
7
|
Ruperto EF, Taraborelli PA, Menéndez J, Sassi PL. Behavioral plasticity in two endemic rodents from the Andes Mountains: strategies for thermal and energetic balance. Mamm Biol 2022. [DOI: 10.1007/s42991-022-00263-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
8
|
Rubalcaba JG, Gouveia SF, Villalobos F, Cruz-Neto AP, Castro MG, Amado TF, Martinez PA, Navas CA, Dobrovolski R, Diniz-Filho JAF, Olalla-Tárraga MÁ. Physical constraints on thermoregulation and flight drive morphological evolution in bats. Proc Natl Acad Sci U S A 2022; 119:e2103745119. [PMID: 35377801 PMCID: PMC9169619 DOI: 10.1073/pnas.2103745119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 02/01/2022] [Indexed: 11/22/2022] Open
Abstract
Body size and shape fundamentally determine organismal energy requirements by modulating heat and mass exchange with the environment and the costs of locomotion, thermoregulation, and maintenance. Ecologists have long used the physical linkage between morphology and energy balance to explain why the body size and shape of many organisms vary across climatic gradients, e.g., why larger endotherms are more common in colder regions. However, few modeling exercises have aimed at investigating this link from first principles. Body size evolution in bats contrasts with the patterns observed in other endotherms, probably because physical constraints on flight limit morphological adaptations. Here, we develop a biophysical model based on heat transfer and aerodynamic principles to investigate energy constraints on morphological evolution in bats. Our biophysical model predicts that the energy costs of thermoregulation and flight, respectively, impose upper and lower limits on the relationship of wing surface area to body mass (S-MR), giving rise to an optimal S-MR at which both energy costs are minimized. A comparative analysis of 278 species of bats supports the model’s prediction that S-MR evolves toward an optimal shape and that the strength of selection is higher among species experiencing greater energy demands for thermoregulation in cold climates. Our study suggests that energy costs modulate the mode of morphological evolution in bats—hence shedding light on a long-standing debate over bats’ conformity to ecogeographical patterns observed in other mammals—and offers a procedure for investigating complex macroecological patterns from first principles.
Collapse
Affiliation(s)
- Juan G. Rubalcaba
- Department of Biology, McGill University, Montreal, QC H3A 1B1, Canada
- Departamento de Biología y Geología, Física y Química Inorgánica, Universidad Rey Juan Carlos, 28933 Madrid, Spain
| | - Sidney F. Gouveia
- Departamento de Ecologia, Universidade Federal de Sergipe, 49100-000 Sergipe, Brazil
| | | | - Ariovaldo P. Cruz-Neto
- Departamento de Biodiversidade, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, 13506‐900 São Paulo, Brazil
| | - Mario G. Castro
- Departamento de Biología y Geología, Física y Química Inorgánica, Universidad Rey Juan Carlos, 28933 Madrid, Spain
| | - Talita F. Amado
- Departamento de Biología y Geología, Física y Química Inorgánica, Universidad Rey Juan Carlos, 28933 Madrid, Spain
| | - Pablo A. Martinez
- Departamento de Biologia, Universidade Federal de Sergipe, 49100-000 Sergipe, Brazil
| | - Carlos A. Navas
- Departamento de Fisiologia, Instituto de Biociência, Universidade de São Paulo, 05508-090 São Paulo, Brazil
| | - Ricardo Dobrovolski
- Instituto de Biologia, Universidade Federal da Bahia, 40170-115 Salvador, BA, Brazil
| | | | - Miguel Á. Olalla-Tárraga
- Departamento de Biología y Geología, Física y Química Inorgánica, Universidad Rey Juan Carlos, 28933 Madrid, Spain
| |
Collapse
|
9
|
Levesque DL, Nowack J, Boyles JG. Body Temperature Frequency Distributions: A Tool for Assessing Thermal Performance in Endotherms? Front Physiol 2021; 12:760797. [PMID: 34721082 PMCID: PMC8551754 DOI: 10.3389/fphys.2021.760797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 09/07/2021] [Indexed: 12/25/2022] Open
Abstract
There is increasing recognition that rather than being fully homeothermic, most endotherms display some degree of flexibility in body temperature. However, the degree to which this occurs varies widely from the relatively strict homeothermy in species, such as humans to the dramatic seasonal hibernation seen in Holarctic ground squirrels, to many points in between. To date, attempts to analyse this variability within the framework generated by the study of thermal performance curves have been lacking. We tested if frequency distribution histograms of continuous body temperature measurements could provide a useful analogue to a thermal performance curve in endotherms. We provide examples from mammals displaying a range of thermoregulatory phenotypes, break down continuous core body temperature traces into various components (active and rest phase modes, spreads and skew) and compare these components to hypothetical performance curves. We did not find analogous patterns to ectotherm thermal performance curves, in either full datasets or by breaking body temperature values into more biologically relevant components. Most species had either bimodal or right-skewed (or both) distributions for both active and rest phase body temperatures, indicating a greater capacity for mammals to tolerate body temperatures elevated above the optimal temperatures than commonly assumed. We suggest that while core body temperature distributions may prove useful in generating optimal body temperatures for thermal performance studies and in various ecological applications, they may not be a good means of assessing the shape and breath of thermal performance in endotherms. We also urge researchers to move beyond only using mean body temperatures and to embrace the full variability in both active and resting temperatures in endotherms.
Collapse
Affiliation(s)
- D L Levesque
- School of Biology and Ecology, University of Maine, Orono, ME, United States
| | - J Nowack
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - J G Boyles
- Cooperative Wildlife Research Laboratory, Center for Ecology, and School of Biological Sciences, Southern Illinois University, Carbondale, IL, United States
| |
Collapse
|
10
|
Brzęk P, Gębczyński A, Selewestruk P, Książek A, Sadowska J, Konarzewski M. Significance of variation in basal metabolic rate in laboratory mice for translational experiments. J Comp Physiol B 2021; 192:161-169. [PMID: 34595579 PMCID: PMC8816319 DOI: 10.1007/s00360-021-01410-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 08/24/2021] [Accepted: 09/20/2021] [Indexed: 12/03/2022]
Abstract
The basal metabolic rate (BMR) accounts for 60–70% of the daily energy expenditure (DEE) in sedentary humans and at least 50% of the DEE in laboratory mice in the thermoneutral zone. Surprisingly, however, the significance of the variation in the BMR is largely overlooked in translational research using such indices as physical activity level (PAL), i.e., the ratio of DEE/BMR. In particular, it is unclear whether emulation of human PAL in mouse models should be carried out within or below the thermoneutral zone. It is also unclear whether physical activity within the thermoneutral zone is limited by the capacity to dissipate heat generated by exercise and obligatory metabolic processes contributing to BMR. We measured PAL and spontaneous physical activity (SPA) in laboratory mice from two lines, divergently selected towards either high or low level of BMR, and acclimated to 30 °C (i.e., the thermoneutral zone), 23 or 4 °C. The mean PAL did not differ between both lines in the mice acclimated to 30 °C but became significantly higher in the low BMR mouse line at the lower ambient temperatures. Acclimation to 30 °C reduced the mean locomotor activity but did not affect the significant difference observed between the selected lines. We conclude that carrying out experiments within the thermoneutral zone can increase the consistency of translational studies aimed at the emulation of human energetics, without affecting the variation in physical activity correlated with BMR.
Collapse
Affiliation(s)
- Paweł Brzęk
- Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245, Białystok, Poland.
| | - Andrzej Gębczyński
- Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245, Białystok, Poland
| | - Piotr Selewestruk
- Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245, Białystok, Poland
| | - Aneta Książek
- Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245, Białystok, Poland
| | - Julita Sadowska
- Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245, Białystok, Poland
| | - Marek Konarzewski
- Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245, Białystok, Poland
| |
Collapse
|
11
|
Morales JO, Walker N, Warne RW, Boyles JG. Heterothermy as a mechanism to offset energetic costs of environmental and homeostatic perturbations. Sci Rep 2021; 11:19038. [PMID: 34561468 PMCID: PMC8463709 DOI: 10.1038/s41598-021-96828-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/05/2021] [Indexed: 11/30/2022] Open
Abstract
Environmental and biotic pressures impose homeostatic costs on all organisms. The energetic costs of maintaining high body temperatures (Tb) render endotherms sensitive to pressures that increase foraging costs. In response, some mammals become more heterothermic to conserve energy. We measured Tb in banner-tailed kangaroo rats (Dipodomys spectabilis) to test and disentangle the effects of air temperature and moonlight (a proxy for predation risk) on thermoregulatory homeostasis. We further perturbed homeostasis in some animals with chronic corticosterone (CORT) via silastic implants. Heterothermy increased across summer, consistent with the predicted effect of lunar illumination (and predation), and in the direction opposite to the predicted effect of environmental temperatures. The effect of lunar illumination was also evident within nights as animals maintained low Tb when the moon was above the horizon. The pattern was accentuated in CORT-treated animals, suggesting they adopted an even further heightened risk-avoidance strategy that might impose reduced foraging and energy intake. Still, CORT-treatment did not affect body condition over the entire study, indicating kangaroo rats offset decreases in energy intake through energy savings associated with heterothermy. Environmental conditions receive the most attention in studies of thermoregulatory homeostasis, but we demonstrated here that biotic factors can be more important and should be considered in future studies.
Collapse
Affiliation(s)
- Javier Omar Morales
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, 62901, USA.
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, 62901, USA.
| | - Nikki Walker
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, 62901, USA
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, 62901, USA
| | - Robin W Warne
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, 62901, USA
| | - Justin G Boyles
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, 62901, USA
- Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois, 62901, USA
| |
Collapse
|
12
|
Smith LL. The Central Role of Hypothermia and Hyperactivity in Anorexia Nervosa: A Hypothesis. Front Behav Neurosci 2021; 15:700645. [PMID: 34421554 PMCID: PMC8377352 DOI: 10.3389/fnbeh.2021.700645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/24/2021] [Indexed: 12/24/2022] Open
Abstract
Typically, the development of anorexia nervosa (AN) is attributed to psycho-social causes. Several researchers have recently challenged this view and suggested that hypothermia and hyperactivity (HyAc) are central to AN. The following hypothesis will attempt to clarify their role in AN. Anorexia nervosa patients (ANs) have significantly lower core temperatures (Tcore) compared to healthy controls (HCs). This reduced temperature represents a reset Tcore that needs to be maintained. However, ANs cannot maintain this Tcore due primarily to a reduced basal metabolic rate (BMR); BMR usually supplies heat to sustain Tcore. Therefore, to generate the requisite heat, ANs revert to the behavioral-thermoregulatory strategy of HyAc. The majority of ANs (~89%) are reportedly HyAc. Surprisingly, engagement in HyAc is not motivated by a conscious awareness of low Tcore, but rather by the innocuous sensation of "cold- hands" frequently reported by ANs. That is, local hand-thermoreceptors signal the brain to initiate HyAc, which boosts perfusion of the hands and alters the sensation of "cold-discomfort" to one of "comfort." This "rewarding" consequence encourages repetition/habit formation. Simultaneously, hyperactivity increases the availability of heat to assist with the preservation of Tcore. Additionally, HyAc induces the synthesis of specific brain neuromodulators that suppress food intake and further promote HyAc; this outcome helps preserve low weight and perpetuates this vicious cycle. Based on this hypothesis and supported by rodent research, external heat availability should reduce the compulsion to be HyAc to thermoregulate. A reduction in HyAc should decrease the production of brain neuromodulators that suppress appetite. If verified, hopefully, this hypothesis will assist with the development of novel treatments to aid in the resolution of this intractable condition.
Collapse
Affiliation(s)
- Lucille Lakier Smith
- Human Performance Laboratory, Department of Kinesiology, School of Health Sciences, East Carolina University, Greenville, NC, United States
| |
Collapse
|
13
|
Abstract
Temperature is an important environmental factor governing the ability of organisms to grow, survive and reproduce. Thermal performance curves (TPCs), with some caveats, are useful for charting the relationship between body temperature and some measure of performance in ectotherms, and provide a standardized set of characteristics for interspecific comparisons. Endotherms, however, have a more complicated relationship with environmental temperature, as endothermy leads to a decoupling of body temperature from external temperature through use of metabolic heat production, large changes in insulation and variable rates of evaporative heat loss. This has impeded our ability to model endothermic performance in relation to environmental temperature as well as to readily compare performance between species. In this Commentary, we compare the strengths and weaknesses of potential TPC analogues (including other useful proxies for linking performance to temperature) in endotherms and suggest several ways forward in the comparative ecophysiology of endotherms. Our goal is to provide a common language with which ecologists and physiologists can evaluate the effects of temperature on performance. Key directions for improving our understanding of endotherm thermoregulatory physiology include a comparative approach to the study of the level and precision of body temperature, measuring performance directly over a range of body temperatures and building comprehensive mechanistic models of endotherm responses to environmental temperatures. We believe the answer to the question posed in the title could be 'yes', but only if 'performance' is well defined and understood in relation to body temperature variation, and the costs and benefits of endothermy are specifically modelled.
Collapse
Affiliation(s)
| | - Katie E Marshall
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
| |
Collapse
|
14
|
van der Meer J. Production efficiency differences between poikilotherms and homeotherms have little to do with metabolic rate. Ecol Lett 2021; 24:219-226. [PMID: 33166039 PMCID: PMC7821020 DOI: 10.1111/ele.13633] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/02/2020] [Accepted: 09/29/2020] [Indexed: 11/29/2022]
Abstract
The idea that homeothermic populations have a much lower production efficiency than poikilothermic populations, because warm-blooded individuals exhibit a higher metabolic rate per gram of body weight, is widespread. Using Dynamic Energy Budget (DEB) theory, in combination with a modelling exercise based on empirical data for over 1000 different species, I show that this idea is wrong. Production efficiency of homeothermic individuals can be as high or even higher than that of poikilotherms. Differences observed are merely the result of different energy allocation and life-history strategies. Birds, for example have evolved to invest a large proportion of the assimilated energy in somatic growth and maintenance and to mature at a relatively large size. Therefore, their production efficiency as an adult is low. This low reproduction efficiency combined with a low mortality rate causes the low production efficiency of bird (and other homeothermic) populations.
Collapse
Affiliation(s)
- Jaap van der Meer
- Wageningen Marine ResearchP.O. Box 57Den Helder1780 ABThe Netherlands
- Department of Ecological ScienceVrije Universiteit AmsterdamAmsterdamThe Netherlands
- Department of Coastal SystemsNIOZ Royal Netherlands Institute for Sea ResearchDen BurgThe Netherlands
| |
Collapse
|
15
|
Roussel D, Le Coadic M, Rouanet JL, Duchamp C. Skeletal muscle metabolism in sea-acclimatized king penguins. I. Thermogenic mechanisms. J Exp Biol 2020; 223:jeb233668. [PMID: 32968000 DOI: 10.1242/jeb.233668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/10/2020] [Indexed: 12/25/2022]
Abstract
At fledging, king penguin juveniles undergo a major energetic challenge to overcome the intense and prolonged energy demands for thermoregulation and locomotion imposed by life in cold seas. Among other responses, sea acclimatization triggers fuel selection in skeletal muscle metabolism towards lipid oxidation in vitro, which is reflected by a drastic increase in lipid-induced thermogenesis in vivo However, the exact nature of skeletal muscle thermogenic mechanisms (shivering and/or non-shivering thermogenesis) remains undefined. The aim of the present study was to determine in vivo whether the capacity for non-shivering thermogenesis was enhanced by sea acclimatization. We measured body temperature, metabolic rate, heart rate and shivering activity in fully immersed king penguins (Aptenodytes patagonicus) exposed to water temperatures ranging from 12 to 29°C. Results from terrestrial pre-fledging juveniles were compared with those from sea-acclimatized immature penguins (hereafter 'immatures'). The capacity for thermogenesis in water was as effective in juveniles as in immatures, while the capacity for non-shivering thermogenesis was not reinforced by sea acclimatization. This result suggests that king penguins mainly rely on skeletal muscle contraction (shivering or locomotor activity) to maintain endothermy at sea. Sea-acclimatized immature penguins also exhibited higher shivering efficiency and oxygen pulse (amount of oxygen consumed or energy expended per heartbeat) than pre-fledging juvenile birds. Such increase in shivering and cardiovascular efficiency may favor a more efficient activity-thermoregulatory heat substitution providing penguins with the aptitude to survive the tremendous energetic challenge imposed by marine life in cold circumpolar oceans.
Collapse
Affiliation(s)
- Damien Roussel
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Marion Le Coadic
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Jean-Louis Rouanet
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| | - Claude Duchamp
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69622 Villeurbanne, France
| |
Collapse
|
16
|
Crowell MM, Shoemaker KT, Matocq MD. Ideal conditions for increased trapping success of pygmy rabbits (Brachylagus idahoensis) across the Great Basin. J Mammal 2020. [DOI: 10.1093/jmammal/gyaa114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Sagebrush-steppe ecosystems are one of the most imperiled ecosystems in North America and many of the species that rely on these habitats are of great conservation concern. Pygmy rabbits (Brachylagus idahoensis) are one of these species. They rely on sagebrush year-round for food and cover, and are understudied across their range in the intermountain west due in part to their recalcitrance to standard capture techniques. Identifying an efficient and minimally biased trapping method therefore is a critical first step in learning more about this species. We assessed how trap orientation and weather characteristics influenced trap success for Tomahawk traps placed in and around pygmy rabbit burrows by carrying out trapping surveys at 16 occupied pygmy rabbit sites across the Great Basin from 2016 to 2018. We found that pygmy rabbits had a greater probability of being captured in traps with the open end facing away from burrow entrances. Pygmy rabbits also were more likely to be captured on clear days (0–5% cloud cover) and during periods of cooler temperatures during summer months (June–August). We found no evidence that sex or age ratios differed, or that individuals differed meaningfully, in their preference for certain trap orientations. To increase trap success for pygmy rabbits, we suggest maximizing trapping effort during summer months, at dawn, and maximizing the proportion of Tomahawk traps facing away from burrow entrances. We anticipate that our monitoring protocol will enable more effective research into the ecology and conservation of this cryptic and potentially imperiled species.
Collapse
Affiliation(s)
- M M Crowell
- Department of Natural Resources and Environmental Science, University of Nevada, Reno, NV, USA
| | - K T Shoemaker
- Department of Natural Resources and Environmental Science, University of Nevada, Reno, NV, USA
| | - M D Matocq
- Department of Natural Resources and Environmental Science, University of Nevada, Reno, NV, USA
| |
Collapse
|
17
|
Kozłowski J, Konarzewski M, Czarnoleski M. Coevolution of body size and metabolic rate in vertebrates: a life-history perspective. Biol Rev Camb Philos Soc 2020; 95:1393-1417. [PMID: 32524739 PMCID: PMC7540708 DOI: 10.1111/brv.12615] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 05/05/2020] [Accepted: 05/07/2020] [Indexed: 12/30/2022]
Abstract
Despite many decades of research, the allometric scaling of metabolic rates (MRs) remains poorly understood. Here, we argue that scaling exponents of these allometries do not themselves mirror one universal law of nature but instead statistically approximate the non-linearity of the relationship between MR and body mass. This 'statistical' view must be replaced with the life-history perspective that 'allows' organisms to evolve myriad different life strategies with distinct physiological features. We posit that the hypoallometric allometry of MRs (mass scaling with an exponent smaller than 1) is an indirect outcome of the selective pressure of ecological mortality on allocation 'decisions' that divide resources among growth, reproduction, and the basic metabolic costs of repair and maintenance reflected in the standard or basal metabolic rate (SMR or BMR), which are customarily subjected to allometric analyses. Those 'decisions' form a wealth of life-history variation that can be defined based on the axis dictated by ecological mortality and the axis governed by the efficiency of energy use. We link this variation as well as hypoallometric scaling to the mechanistic determinants of MR, such as metabolically inert component proportions, internal organ relative size and activity, cell size and cell membrane composition, and muscle contributions to dramatic metabolic shifts between the resting and active states. The multitude of mechanisms determining MR leads us to conclude that the quest for a single-cause explanation of the mass scaling of MRs is futile. We argue that an explanation based on the theory of life-history evolution is the best way forward.
Collapse
Affiliation(s)
- Jan Kozłowski
- Institute of Environmental SciencesJagiellonian UniversityGronostajowa7, 30‐387KrakówPoland
| | - Marek Konarzewski
- Institute of BiologyUniversity of BiałystokCiołkowskiego 1J, 15‐245, BiałystokPoland
| | - Marcin Czarnoleski
- Institute of Environmental SciencesJagiellonian UniversityGronostajowa7, 30‐387KrakówPoland
| |
Collapse
|
18
|
Favilla AB, Costa DP. Thermoregulatory Strategies of Diving Air-Breathing Marine Vertebrates: A Review. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.555509] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
19
|
Menzies AK, Studd EK, Majchrzak YN, Peers MJL, Boutin S, Dantzer B, Lane JE, McAdam AG, Humphries MM. Body temperature, heart rate, and activity patterns of two boreal homeotherms in winter: Homeostasis, allostasis, and ecological coexistence. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13640] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Allyson K. Menzies
- Department of Natural Resource Sciences McGill University Ste‐Anne‐de‐Bellevue QC Canada
| | - Emily K. Studd
- Department of Natural Resource Sciences McGill University Ste‐Anne‐de‐Bellevue QC Canada
- Department of Biological Sciences University of Alberta Edmonton AB Canada
| | | | | | - Stan Boutin
- Department of Biological Sciences University of Alberta Edmonton AB Canada
| | - Ben Dantzer
- Department of Psychology University of Michigan Ann Arbor MI USA
- Department of Ecology and Evolutionary Biology University of Michigan Ann Arbor MI USA
| | - Jeffrey E. Lane
- Department of Biology University of Saskatchewan Saskatoon SK Canada
| | - Andrew G. McAdam
- Department of Ecology and Evolutionary Biology University of Colorado Boulder CO USA
| | - Murray M. Humphries
- Department of Natural Resource Sciences McGill University Ste‐Anne‐de‐Bellevue QC Canada
| |
Collapse
|
20
|
Bonebrake TC, Rezende EL, Bozinovic F. Climate Change and Thermoregulatory Consequences of Activity Time in Mammals. Am Nat 2020; 196:45-56. [PMID: 32552099 DOI: 10.1086/709010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Activity times structure the thermal environments experienced by organisms. In mammals, species shift from being nocturnal to diurnal and vice versa, but the thermal consequences of variable activity patterns remain largely unexplored. Here we used theoretical thermoregulatory polygons bounded by estimates of basal metabolic rates (BMR), maximum metabolic rates (MMR), and thermal conductance (C) in small mammals to explore the metabolic consequences of exposure to global-scale daytime and nighttime temperatures. Model predictions indicated higher metabolic scope for activity for nocturnal species at low latitudes and that reduced minimum C and larger body size increased the geographic range in which nocturnality was advantageous. Consistent with predictions, within rodents nocturnal species have low C. However, nocturnal mammals tend to be smaller than diurnal species, likely reflecting the importance of additional factors driving body size. Projections of warming impacts on small mammals suggest that diurnal species could lose habitable space globally. Conversely, warming could lift cool temperature constraints on nocturnal species and increase habitable space, suggesting that a shift toward nocturnal niches might be favored in a warming world. Taken together, these findings demonstrate the importance of energetic considerations for endotherms in managing global change impacts on nocturnal and diurnal species.
Collapse
|
21
|
Schaeffer PJ, O'Mara MT, Breiholz J, Keicher L, Lázaro J, Muturi M, Dechmann DKN. Metabolic rate in common shrews is unaffected by temperature, leading to lower energetic costs through seasonal size reduction. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191989. [PMID: 32431881 PMCID: PMC7211839 DOI: 10.1098/rsos.191989] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 03/31/2020] [Indexed: 06/01/2023]
Abstract
Small endothermic mammals have high metabolisms, particularly at cold temperatures. In the light of this, some species have evolved a seemingly illogical strategy: they reduce the size of the brain and several organs to become even smaller in winter. To test how this morphological strategy affects energy consumption across seasonally shifting ambient temperatures, we measured oxygen consumption and behaviour in the three seasonal phenotypes of the common shrew (Sorex araneus), which differ in size by about 20%. Body mass was the main driver of oxygen consumption, not the reduction of metabolically expensive brain mass. Against our expectations, we found no change in relative oxygen consumption with low ambient temperature. Thus, smaller body size in winter resulted in significant absolute energy savings. This finding could only partly be explained by an increase of lower cost behaviours in the activity budgets. Our findings highlight that these shrews manage to avoid one of the most fundamental and intuitive rules of ecology, allowing them to subsist with lower resource availability and successfully survive the harsh conditions of winter.
Collapse
Affiliation(s)
| | - M. Teague O'Mara
- Department of Biological Sciences, Southeastern Louisiana University, Hammond LA 70402USA
- Department of Migration, Max Planck Institute of Animal Behavior, am Obstberg 1, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, 78462 Konstanz, Germany
| | - Japhet Breiholz
- Department of Migration, Max Planck Institute of Animal Behavior, am Obstberg 1, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, 78462 Konstanz, Germany
| | - Lara Keicher
- Department of Migration, Max Planck Institute of Animal Behavior, am Obstberg 1, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, 78462 Konstanz, Germany
| | - Javier Lázaro
- Department of Migration, Max Planck Institute of Animal Behavior, am Obstberg 1, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, 78462 Konstanz, Germany
| | - Marion Muturi
- Department of Migration, Max Planck Institute of Animal Behavior, am Obstberg 1, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, 78462 Konstanz, Germany
| | - Dina K. N. Dechmann
- Department of Migration, Max Planck Institute of Animal Behavior, am Obstberg 1, 78315 Radolfzell, Germany
- Department of Biology, University of Konstanz, 78462 Konstanz, Germany
| |
Collapse
|
22
|
Studd EK, Menzies AK, Siracusa ER, Dantzer B, Lane JE, McAdam AG, Boutin S, Humphries MM. Optimisation of energetic and reproductive gains explains behavioural responses to environmental variation across seasons and years. Ecol Lett 2020; 23:841-850. [PMID: 32189469 DOI: 10.1111/ele.13494] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/09/2019] [Accepted: 02/21/2020] [Indexed: 12/31/2022]
Abstract
Animals switch between inactive and active states, simultaneously impacting their energy intake, energy expenditure and predation risk, and collectively defining how they engage with environmental variation and trophic interactions. We assess daily activity responses to long-term variation in temperature, resources and mating opportunities to examine whether individuals choose to be active or inactive according to an optimisation of the relative energetic and reproductive gains each state offers. We show that this simplified behavioural decision approach predicts most activity variation (R2 = 0.83) expressed by free-ranging red squirrels over 4 years, as quantified through accelerometer recordings (489 deployments; 5066 squirrel-days). Recognising activity as a determinant of energetic status, the predictability of activity variation aggregated at a daily scale, and the clear signal that behaviour is environmentally forced through optimisation of gain, provides an integrated approach to examine behavioural variation as an intermediary between environmental variation and energetic, life-history and ecological outcomes.
Collapse
Affiliation(s)
- E K Studd
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Bellevue, QC, Canada.,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - A K Menzies
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Bellevue, QC, Canada
| | - E R Siracusa
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - B Dantzer
- Department of Psychology, University of Michigan, Ann Arbor, MI, USA.,Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - J E Lane
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - A G McAdam
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - S Boutin
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - M M Humphries
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, Bellevue, QC, Canada
| |
Collapse
|
23
|
Mélanie B, Caroline R, Claude D, Frédéric V, Sabrina R, Damien R, Yann V. Improved mitochondrial coupling as a response to high mass-specific metabolic rate in extremely small mammals. J Exp Biol 2020:jeb.215558. [PMID: 34005357 DOI: 10.1242/jeb.215558] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 02/04/2020] [Indexed: 02/24/2024]
Abstract
Mass-specific metabolic rate negatively co-varies with body mass from the whole-animal to the mitochondrial levels. Mitochondria are the mainly consumers of oxygen inspired by mammals to generate ATP or compensate energetic losses dissipated as the form of heat (proton leak) during oxidative phosphorylation. Consequently, ATP synthesis and proton leak thus compete for the same electrochemical gradient. Because proton leak co-varies negatively with body mass, it is unknown if extremely small mammals further decouple their mitochondria to maintain their body temperature or if they implement metabolic innovations to ensure cellular homeostasis. The present study investigates the impact of body mass variation on cellular and mitochondrial functioning in small mammals, comparing the two extremely small African pygmy mice (Mus mattheyi, approx. 5 g and Mus minutoides, approx. 7 g) with the larger house mouse (Mus musculus, approx. 22 g). Oxygen consumption rates were measured from the animal to the mitochondrial levels. We also measured mitochondrial ATP synthesis in order to appreciate the mitochondrial efficiency (ATP/O). At the whole-animal scale, mass- and surface-specific metabolic rates co-varied negatively with body mass, whereas this was not necessarily the case at cellular and mitochondrial levels. M. mattheyi had generally the lowest cellular and mitochondrial fluxes, depending on the tissue considered (liver or skeletal muscle), as well as having higher efficient muscle mitochondria than the other two species. M. mattheyi presents metabolic innovations to ensure its homeostasis, by generating more ATP per oxygen consumed.
Collapse
Affiliation(s)
- Boël Mélanie
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (UMR CNRS 5023), Université Claude Bernard Lyon1, Université de Lyon; Bd du 11 novembre 1918, Bât. Darwin C; 69622 Villeurbanne Cedex, France
| | - Romestaing Caroline
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (UMR CNRS 5023), Université Claude Bernard Lyon1, Université de Lyon; Bd du 11 novembre 1918, Bât. Darwin C; 69622 Villeurbanne Cedex, France
| | - Duchamp Claude
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (UMR CNRS 5023), Université Claude Bernard Lyon1, Université de Lyon; Bd du 11 novembre 1918, Bât. Darwin C; 69622 Villeurbanne Cedex, France
| | - Veyrunes Frédéric
- Institut des Sciences de l'Evolution de Montpellier (UMR CNRS 5554), Université Montpellier, IRD, EPHE; 34095 Montpellier, France
| | - Renaud Sabrina
- Laboratoire de Biométrie et Biologie Evolutive (UMR CNRS 5558), Université Claude Bernard Lyon 1, Université de Lyon; 69622 Villeurbanne Cedex, France
| | - Roussel Damien
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (UMR CNRS 5023), Université Claude Bernard Lyon1, Université de Lyon; Bd du 11 novembre 1918, Bât. Darwin C; 69622 Villeurbanne Cedex, France
| | - Voituron Yann
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (UMR CNRS 5023), Université Claude Bernard Lyon1, Université de Lyon; Bd du 11 novembre 1918, Bât. Darwin C; 69622 Villeurbanne Cedex, France
| |
Collapse
|
24
|
Tyler NJC, Gregorini P, Parker KL, Hazlerigg DG. Animal responses to environmental variation: physiological mechanisms in ecological models of performance in deer (Cervidae). ANIMAL PRODUCTION SCIENCE 2020. [DOI: 10.1071/an19418] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Context
Proper assessment of the consequences of environmental variation on animals depends on our ability to predict how they will perform under different circumstances. This requires two kinds of information. We need to know which environmental factors influence animal performance and their mode of action, i.e. whether a given factor acts alone or through interaction with other factors, directly or indirectly, instantaneously or after a delay and so on. This essentially correlative process falls within the domain of ecology. We also need to know what determines the direction, amplitude and limits of animal responses to environmental variation and change. This essentially experimental process falls within the domain of physiology. Physiological mechanisms are frequently poorly integrated within the correlative framework of ecological models. This is evident where programmed responses are attributed to environmental forcing and where the effect of environmental factors is evaluated without reference to the physiological state and regulatory capacity of the animal on which they act.
Aims
Here we examine ways in which the impacts of external (environmental) stimuli and constraints on performance are moderated by the animals (deer) on which they impinge.
Key results
The analysis shows (1) how trade-offs in foraging behaviour, illustrated by the timing of activity under the threat of predation, are modulated by integration of short-term metabolic feedback and animal emotions that influence the motivation to feed, (2) how the influence of thermal and nutritional challenges on performance, illustrated by the effect of weather conditions during gestation on the body mass of reindeer (Rangifer tarandus) calves at weaning, depends on the metabolic state of the female at the time the challenge occurs and (3) how annual cycles of growth, appetite and reproduction in seasonal species of deer are governed by innate circannual timers, such that their responses to seasonal changes in food supply are anticipatory and governed by rheostatic systems that adjust homeostatic set- points, rather than being purely reactive.
Conclusions
Concepts like ‘maintenance’ and ‘energy balance’, which were originally derived from non-seasonal domestic ruminants, are unable to account for annual cycles in metabolic and nutritional status in seasonal deer. Contrasting seasonal phenotypes (fat and anoestrous in summer, lean and oestrous in winter) represent adaptive solutions to the predictable challenges presented by contrasting seasonal environments, not failure of homeostasis in one season and its success in another.
Implications
The analysis and interpretation of responses to environment in terms of interaction between the external stimuli and the internal systems that govern them offer a more comprehensive, multifaceted understanding of the influence of environmental variation on performance in deer and open lines of ecological enquiry defined by non-intuitive aspects of animal function.
Collapse
|
25
|
Urlacher SS, Snodgrass JJ, Dugas LR, Sugiyama LS, Liebert MA, Joyce CJ, Pontzer H. Constraint and trade-offs regulate energy expenditure during childhood. SCIENCE ADVANCES 2019; 5:eaax1065. [PMID: 32064311 PMCID: PMC6989306 DOI: 10.1126/sciadv.aax1065] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 11/04/2019] [Indexed: 05/12/2023]
Abstract
Children's metabolic energy expenditure is central to evolutionary and epidemiological frameworks for understanding variation in human phenotype and health. Nonetheless, the impact of a physically active lifestyle and heavy burden of infectious disease on child metabolism remains unclear. Using energetic, activity, and biomarker measures, we show that Shuar forager-horticulturalist children of Amazonian Ecuador are ~25% more physically active and, in association with immune activity, have ~20% greater resting energy expenditure than children from industrial populations. Despite these differences, Shuar children's total daily energy expenditure, measured using doubly labeled water, is indistinguishable from industrialized counterparts. Trade-offs in energy allocation between competing physiological tasks, within a constrained energy budget, appear to shape childhood phenotypic variation (e.g., patterns of growth). These trade-offs may contribute to the lifetime obesity and metabolic health disparities that emerge during rapid economic development.
Collapse
Affiliation(s)
- Samuel S. Urlacher
- Department of Anthropology, Baylor University, 1214 South 4th Street, Waco, TX 76706, USA
- Department of Evolutionary Anthropology, Duke University, 130 Science Drive, Durham, NC 27708, USA
- Corresponding author. (S.S.U.); (H.P.)
| | - J. Josh Snodgrass
- Department of Anthropology, University of Oregon, 1321 Kincaid Street, Eugene, OR 97403, USA
| | - Lara R. Dugas
- Department of Preventive Medicine and Epidemiology, Loyola University Chicago, 2160 South First Avenue, Maywood, IL 60153, USA
| | - Lawrence S. Sugiyama
- Department of Anthropology, University of Oregon, 1321 Kincaid Street, Eugene, OR 97403, USA
| | - Melissa A. Liebert
- Department of Anthropology, Northern Arizona University, 5 East McConnell Drive, Flagstaff, AZ 86011, USA
| | - Cara J. Joyce
- Department of Preventive Medicine and Epidemiology, Loyola University Chicago, 2160 South First Avenue, Maywood, IL 60153, USA
| | - Herman Pontzer
- Department of Evolutionary Anthropology, Duke University, 130 Science Drive, Durham, NC 27708, USA
- Duke Global Health Institute, Duke University, 310 Trent Drive, Durham, NC 27710, USA
- Corresponding author. (S.S.U.); (H.P.)
| |
Collapse
|
26
|
Mathot KJ, Dingemanse NJ, Nakagawa S. The covariance between metabolic rate and behaviour varies across behaviours and thermal types: meta‐analytic insights. Biol Rev Camb Philos Soc 2018; 94:1056-1074. [DOI: 10.1111/brv.12491] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 11/26/2018] [Accepted: 11/30/2018] [Indexed: 12/22/2022]
Affiliation(s)
- Kimberley J. Mathot
- Canada Research Chair in Integrative Ecology, Department of Biological SciencesUniversity of Alberta CW405 Biological Sciences Building, T6G 2E9 Edmonton Alberta Canada
- NIOZ Royal Netherlands Institute for Sea ResearchDepartment of Coastal Systems and Utrecht University 1790 AB, den Burg, Texel The Netherlands
| | - Niels J. Dingemanse
- Behavioural Ecology, Department Biology IILudwig‐Maximilians University of Munich Grosshadener Strasse 2, DE‐82152, Planegg‐Martinsried, Munich Germany
| | - Shinichi Nakagawa
- Evolution and Ecology Research Centre and School of Biological, Earth and Environmental SciencesUniversity of New South Wales Sydney New South Wales 2052 Australia
- Diabetes and Metabolism Division, Garvan Institute of Medical Research 384 Victoria Street, Darlinghurst, Sydney New South Wales 2010 Australia
| |
Collapse
|
27
|
Hooten MB, Scharf HR, Morales JM. Running on empty: recharge dynamics from animal movement data. Ecol Lett 2018; 22:377-389. [PMID: 30548152 DOI: 10.1111/ele.13198] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/25/2018] [Accepted: 11/14/2018] [Indexed: 02/06/2023]
Abstract
Vital rates such as survival and recruitment have always been important in the study of population and community ecology. At the individual level, physiological processes such as energetics are critical in understanding biomechanics and movement ecology and also scale up to influence food webs and trophic cascades. Although vital rates and population-level characteristics are tied with individual-level animal movement, most statistical models for telemetry data are not equipped to provide inference about these relationships because they lack the explicit, mechanistic connection to physiological dynamics. We present a framework for modelling telemetry data that explicitly includes an aggregated physiological process associated with decision making and movement in heterogeneous environments. Our framework accommodates a wide range of movement and physiological process specifications. We illustrate a specific model formulation in continuous-time to provide direct inference about gains and losses associated with physiological processes based on movement. Our approach can also be extended to accommodate auxiliary data when available. We demonstrate our model to infer mountain lion (Puma concolor; in Colorado, USA) and African buffalo (Syncerus caffer; in Kruger National Park, South Africa) recharge dynamics.
Collapse
Affiliation(s)
- Mevin B Hooten
- U.S. Geological Survey, Colorado Cooperative Fish and Wildlife Research Unit, Department of Fish, Wildlife, and Conservation and Department of Statistics, Colorado State University, Fort Collins, CO, 80523, USA
| | - Henry R Scharf
- Department of Statistics, Colorado State University, Fort Collins, CO, 80523, USA
| | - Juan M Morales
- Grupo de Ecología Cuantitativa, INIBIOMA, Universidad Nacional del Comahue, CONICET, Bariloche S4140, Argentina
| |
Collapse
|
28
|
Czenze ZJ, Tucker JL, Clare EL, Littlefair JE, Hemprich‐Bennett D, Oliveira HFM, Brigham RM, Hickey AJR, Parsons S. Spatiotemporal and demographic variation in the diet of New Zealand lesser short-tailed bats ( Mystacina tuberculata). Ecol Evol 2018; 8:7599-7610. [PMID: 30151174 PMCID: PMC6106186 DOI: 10.1002/ece3.4268] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 04/15/2018] [Accepted: 05/08/2018] [Indexed: 11/17/2022] Open
Abstract
Variation in the diet of generalist insectivores can be affected by site-specific traits including weather, habitat, and season, as well as demographic traits such as reproductive status and age. We used molecular methods to compare diets of three distinct New Zealand populations of lesser short-tailed bats, Mystacina tuberculata. Summer diets were compared between a southern cold-temperate (Eglinton) and a northern population (Puroera). Winter diets were compared between Pureora and a subtropical offshore island population (Hauturu). This also permitted seasonal diet comparisons within the Pureora population. Lepidoptera and Diptera accounted for >80% of MOTUs identified from fecal matter at each site/season. The proportion of orders represented within prey and the Simpson diversity index, differed between sites and seasons within the Pureora population. For the Pureora population, the value of the Simpson diversity index was higher in summer than winter and was higher in Pureora compared to Eglinton. Summer Eglinton samples revealed that juvenile diets appeared to be more diverse than other demographic groups. Lactating females had the lowest dietary diversity during summer in Pureora. In Hauturu, we found a significant negative relationship between mean ambient temperature and prey richness. Our data suggest that M. tuberculata incorporate a narrower diversity of terrestrial insects than previously reported. This provides novel insights into foraging behavior and ecological interactions within different habitats. Our study is the first from the Southern Hemisphere to use molecular techniques to examine spatiotemporal variation in the diet of a generalist insectivore that inhabits a contiguous range with several habitat types and climates.
Collapse
Affiliation(s)
- Zenon J. Czenze
- School of Biological SciencesUniversity of AucklandAucklandNew Zealand
| | - J. Leon Tucker
- School of Biological and Chemical SciencesQueen Mary University of LondonLondonUK
| | - Elizabeth L. Clare
- School of Biological and Chemical SciencesQueen Mary University of LondonLondonUK
| | - Joanne E. Littlefair
- School of Biological and Chemical SciencesQueen Mary University of LondonLondonUK
| | | | | | | | | | - Stuart Parsons
- School of Biological SciencesUniversity of AucklandAucklandNew Zealand
- Present address:
School of Earth, Environmental and Biological SciencesQueensland University of TechnologyBrisbaneQLDAustralia
| |
Collapse
|
29
|
Levesque DL, Tuen AA, Lovegrove BG. Staying hot to fight the heat-high body temperatures accompany a diurnal endothermic lifestyle in the tropics. J Comp Physiol B 2018; 188:707-716. [PMID: 29623412 DOI: 10.1007/s00360-018-1160-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 03/20/2018] [Accepted: 04/01/2018] [Indexed: 11/25/2022]
Affiliation(s)
- Danielle L Levesque
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia.
- School of Biology and Ecology, University of Maine, Orono, ME, 04469, USA.
| | - Andrew Alek Tuen
- School of Biology and Ecology, University of Maine, Orono, ME, 04469, USA
| | - Barry G Lovegrove
- School of Life Sciences, University of KwaZulu-Natal, P/Bag X01, Scottsville, 3209, South Africa
| |
Collapse
|
30
|
Milling CR, Rachlow JL, Chappell MA, Camp MJ, Johnson TR, Shipley LA, Paul DR, Forbey JS. Seasonal temperature acclimatization in a semi-fossorial mammal and the role of burrows as thermal refuges. PeerJ 2018; 6:e4511. [PMID: 29576977 PMCID: PMC5858582 DOI: 10.7717/peerj.4511] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 02/26/2018] [Indexed: 01/08/2023] Open
Abstract
Small mammals in habitats with strong seasonal variation in the thermal environment often exhibit physiological and behavioral adaptations for coping with thermal extremes and reducing thermoregulatory costs. Burrows are especially important for providing thermal refuge when above-ground temperatures require high regulatory costs (e.g., water or energy) or exceed the physiological tolerances of an organism. Our objective was to explore the role of burrows as thermal refuges for a small endotherm, the pygmy rabbit (Brachylagus idahoensis), during the summer and winter by quantifying energetic costs associated with resting above and below ground. We used indirect calorimetry to determine the relationship between energy expenditure and ambient temperature over a range of temperatures that pygmy rabbits experience in their natural habitat. We also measured the temperature of above- and below-ground rest sites used by pygmy rabbits in eastern Idaho, USA, during summer and winter and estimated the seasonal thermoregulatory costs of resting in the two microsites. Although pygmy rabbits demonstrated seasonal physiological acclimatization, the burrow was an important thermal refuge, especially in winter. Thermoregulatory costs were lower inside the burrow than in above-ground rest sites for more than 50% of the winter season. In contrast, thermal heterogeneity provided by above-ground rest sites during summer reduced the role of burrows as a thermal refuge during all but the hottest periods of the afternoon. Our findings contribute to an understanding of the ecology of small mammals in seasonal environments and demonstrate the importance of burrows as thermal refuge for pygmy rabbits.
Collapse
Affiliation(s)
- Charlotte R Milling
- Department of Fish and Wildlife Sciences, University of Idaho, Moscow, ID, USA.,School of Environment and Natural Resources, Ohio State University, Columbus, OH, USA
| | - Janet L Rachlow
- Department of Fish and Wildlife Sciences, University of Idaho, Moscow, ID, USA
| | - Mark A Chappell
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, Riverside, CA, USA
| | - Meghan J Camp
- School of the Environment, Washington State University, Pullman, WA, USA
| | - Timothy R Johnson
- Department of Statistical Science, University of Idaho, Moscow, ID, USA
| | - Lisa A Shipley
- School of the Environment, Washington State University, Pullman, WA, USA
| | - David R Paul
- Department of Movement Sciences, University of Idaho, Moscow, ID, USA
| | | |
Collapse
|
31
|
Czenze ZJ, Jonasson KA, Willis CKR. Thrifty Females, Frisky Males: Winter Energetics of Hibernating Bats from a Cold Climate. Physiol Biochem Zool 2017. [DOI: 10.1086/692623] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
32
|
Bieber C, Cornils JS, Hoelzl F, Giroud S, Ruf T. The costs of locomotor activity? Maximum body temperatures and the use of torpor during the active season in edible dormice. J Comp Physiol B 2017; 187:803-814. [PMID: 28321493 PMCID: PMC5486539 DOI: 10.1007/s00360-017-1080-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 12/14/2016] [Accepted: 02/26/2017] [Indexed: 12/11/2022]
Abstract
Measuring T b during the active season can provide information about the timing of reproduction and the use of short bouts of torpor and may be used as a proxy for the locomotor activity of animals (i.e., maximum T b). This kind of information is especially important to understand life-history strategies and energetic costs and demands in hibernating mammals. We investigated T b throughout the active season in edible dormice (Glis glis), since they (i) have an expensive arboreal life-style, (ii) are known to show short bouts of torpor, and (iii) are adapted to pulsed resources (mast of beech trees). We show here for the first time that maximum T b's in free-living active dormice (during the night) increase regularly and for up to 8 h above 40 °C, which corresponds to slight hyperthermia, probably due to locomotor activity. The highest weekly mean maximum T b was recorded 1 week prior to hibernation (40.45 ± 0.07 °C). At the beginning of the active season and immediately prior to hibernation, the mean maximum T b's were lower. The time dormice spent at T b above 40 °C varied between sexes, depending on mast conditions. The date of parturition could be determined by a sudden increase in mean T b (plus 0.49 ± 0.04 °C). The occurrence of short torpor bouts (<24 h) was strongly affected by the mast situation with much higher torpor frequencies in mast-failure years. Our data suggest that locomotor activity is strongly affected by environmental conditions, and that sexes respond differently to these changes.
Collapse
Affiliation(s)
- Claudia Bieber
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine Vienna, Savoyenstraße 1, 1160, Vienna, Austria.
| | - Jessica S Cornils
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine Vienna, Savoyenstraße 1, 1160, Vienna, Austria
| | - Franz Hoelzl
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine Vienna, Savoyenstraße 1, 1160, Vienna, Austria
| | - Sylvain Giroud
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine Vienna, Savoyenstraße 1, 1160, Vienna, Austria
| | - Thomas Ruf
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine Vienna, Savoyenstraße 1, 1160, Vienna, Austria
| |
Collapse
|
33
|
Body temperature responses to handling stress in wintering Black-capped Chickadees (Poecile atricapillus L.). Physiol Behav 2017; 179:49-54. [PMID: 28528893 DOI: 10.1016/j.physbeh.2017.05.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 05/17/2017] [Accepted: 05/17/2017] [Indexed: 11/20/2022]
Abstract
Body temperature variation in response to acute stress is typically characterized by peripheral vasoconstriction and a concomitant increase in core body temperature (stress-induced hyperthermia). It is poorly understood how this response differs between species and within individuals of the same species, and how it is affected by the environment. We therefore investigated stress-induced body temperature changes in a non-model species, the Black-capped Chickadee, in two environmental conditions: outdoors in low ambient temperature (mean: -6.6°C), and indoors, in milder ambient temperature close to thermoneutrality (mean: 18.7°C). Our results show that the change in body temperature in response to the same handling stressor differs in these conditions. In cold environments, we noted a significant decrease in core body temperature (-2.9°C), whereas the response in mild indoor conditions was weak and non-significant (-0.6°C). Heat loss in outdoor birds was exacerbated when birds were handled for longer time. This may highlight the role of behavioral thermoregulation and heat substitution from activity to body temperature maintenance in harsh condition. Importantly, our work also indicates that changes in the physical properties of the bird during handling (conductive cooling from cold hands, decreased insulation from compression of plumage and prevention of ptiloerection) may have large consequences for thermoregulation. This might explain why females, the smaller sex, lost more heat than males in the experiment. Because physiological and physical changes during handling may carry over to affect predation risk and maintenance of energy balance during short winter days, we advice caution when designing experimental protocols entailing prolonged handling of small birds in cold conditions.
Collapse
|
34
|
Swanson DL, McKechnie AE, Vézina F. How low can you go? An adaptive energetic framework for interpreting basal metabolic rate variation in endotherms. J Comp Physiol B 2017; 187:1039-1056. [PMID: 28401293 DOI: 10.1007/s00360-017-1096-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 03/13/2017] [Accepted: 04/06/2017] [Indexed: 11/24/2022]
Abstract
Adaptive explanations for both high and low body mass-independent basal metabolic rate (BMR) in endotherms are pervasive in evolutionary physiology, but arguments implying a direct adaptive benefit of high BMR are troublesome from an energetic standpoint. Here, we argue that conclusions about the adaptive benefit of BMR need to be interpreted, first and foremost, in terms of energetics, with particular attention to physiological traits on which natural selection is directly acting. We further argue from an energetic perspective that selection should always act to reduce BMR (i.e., maintenance costs) to the lowest level possible under prevailing environmental or ecological demands, so that high BMR per se is not directly adaptive. We emphasize the argument that high BMR arises as a correlated response to direct selection on other physiological traits associated with high ecological or environmental costs, such as daily energy expenditure (DEE) or capacities for activity or thermogenesis. High BMR thus represents elevated maintenance costs required to support energetically demanding lifestyles, including living in harsh environments. BMR is generally low under conditions of relaxed selection on energy demands for high metabolic capacities (e.g., thermoregulation, activity) or conditions promoting energy conservation. Under these conditions, we argue that selection can act directly to reduce BMR. We contend that, as a general rule, BMR should always be as low as environmental or ecological conditions permit, allowing energy to be allocated for other functions. Studies addressing relative reaction norms and response times to fluctuating environmental or ecological demands for BMR, DEE, and metabolic capacities and the fitness consequences of variation in BMR and other metabolic traits are needed to better delineate organismal metabolic responses to environmental or ecological selective forces.
Collapse
Affiliation(s)
- David L Swanson
- Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD, 57069, USA.
| | - Andrew E McKechnie
- Department of Zoology and Entomology, DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - François Vézina
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, QC, Canada.,Groupe de recherche sur les environnements nordiques BORÉAS, Centre d'Études Nordiques, Centre de la Science de la Biodiversité du Québec, Rimouski, QC, Canada
| |
Collapse
|
35
|
Careau V. Energy Intake, Basal Metabolic Rate, and Within-Individual Trade-Offs in Men and Women Training for a Half Marathon: A Reanalysis. Physiol Biochem Zool 2017; 90:392-398. [PMID: 28384424 DOI: 10.1086/691338] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Understanding the mechanisms governing energy budgets during periods of high energy expenditure is important from both an evolutionary physiology and behavioral ecology perspective. In particular, we still know too little about the linkages between key components such as daily energy expenditure (DEE), daily energy intake (DEI), and basal metabolic rate (BMR). Westerterp et al. repeatedly measured DEI (self-reported), BMR (respirometry), and body composition (fat mass) in 23 adult subjects as they transitioned from an inactive lifestyle and trained during 44 wk in preparation of running a half marathon. Here, I reanalyzed this data set using bivariate mixed models to partition the phenotypic correlation between DEI and BMR at the among- and within-individual levels. Reported DEI and BMR were positively correlated at the among-individual level (i.e., individuals with high average reported DEI also have a high average BMR). However, reported DEI and BMR were not correlated within individuals. There was a negative within-individual relationship between BMR and surplus energy (i.e., the energy intake above BMR = DEI - BMR), suggesting the presence of compensation mechanisms between BMR and other energy-demanding activities occurring within individuals. Thus, the principles governing energy budget were different at the among- and within-individual levels. To the extent that this situation is applicable to wild animals experiencing different levels of DEE throughout their annual cycle, the results presented here could explain why the relationships between BMR and other components of the energy budget (e.g., activity, growth, reproduction) are often context dependent.
Collapse
|
36
|
Affiliation(s)
- Yaroslav I Molkov
- Department of Mathematics and Statistics, Georgia State University , GA, USA
| | - Dmitry V Zaretsky
- Department of Emergency Medicine, Department of Pharmacology and Toxicology, Indiana University School of Medicine , Indianapolis, IN, USA
| |
Collapse
|
37
|
Kearney MR, Porter WP, Murphy SA. An estimate of the water budget for the endangered night parrot of Australia under recent and future climates. ACTA ACUST UNITED AC 2016. [DOI: 10.1186/s40665-016-0027-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
38
|
Klüg-Baerwald B, Gower L, Lausen C, Brigham R. Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada. CAN J ZOOL 2016. [DOI: 10.1139/cjz-2016-0055] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Winter activity of bats is common, yet poorly understood. Other studies suggest a relationship between winter activity and ambient temperature, particularly temperature at sunset. We recorded echolocation calls to determine correlates of hourly bat activity in Dinosaur Provincial Park, Alberta, Canada. We documented bat activity in temperatures as low as −10.4 °C. We observed big brown bats (Eptesicus fuscus (Palisot de Beauvois, 1796)) flying at colder temperatures than species of Myotis bats (genus Myotis Kaup, 1829). We show that temperature and wind are important predictors of winter activity by E. fuscus and Myotis, and that Myotis may also use changes in barometric pressure to cue activity. In the absence of foraging opportunity, we suggest these environmental factors relate to heat loss and thus the energetic cost of flight. To understand the energetic consequences of bat flight in cold temperatures, we estimated energy expenditure during winter flights of E. fuscus and little brown myotis (Myotis lucifugus (Le Conte, 1831)) using species-specific parameters. We estimated that winter flight uses considerable fat stores and that flight thermogenesis could mitigate energetic costs by 20% or more. We also show that temperature-dependent interspecific differences in winter activity likely stem from differences between species in heat loss and potential for activity–thermoregulatory heat substitution.
Collapse
Affiliation(s)
- B.J. Klüg-Baerwald
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
| | - L.E. Gower
- School of Biosciences, Sir Martin Evans Building, Cardiff University, Museum Avenue, Cardiff CF10 3AX, United Kingdom
| | - C.L. Lausen
- Wildlife Conservation Society Canada, P.O. Box 606, Kaslo, BC V0G 1M0, Canada
| | - R.M. Brigham
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada
| |
Collapse
|
39
|
Levesque DL, Nowack J, Stawski C. Modelling mammalian energetics: the heterothermy problem. ACTA ACUST UNITED AC 2016. [DOI: 10.1186/s40665-016-0022-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
|
40
|
van der Vinne V, Gorter JA, Riede SJ, Hut RA. Diurnality as an energy-saving strategy: energetic consequences of temporal niche switching in small mammals. ACTA ACUST UNITED AC 2016; 218:2585-93. [PMID: 26290592 DOI: 10.1242/jeb.119354] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Endogenous daily (circadian) rhythms allow organisms to anticipate daily changes in the environment. Most mammals are specialized to be active during the night (nocturnal) or day (diurnal). However, typically nocturnal mammals become diurnal when energetically challenged by cold or hunger. The circadian thermo-energetics (CTE) hypothesis predicts that diurnal activity patterns reduce daily energy expenditure (DEE) compared with nocturnal activity patterns. Here, we tested the CTE hypothesis by quantifying the energetic consequences of relevant environmental factors in mice. Under natural conditions, diurnality reduces DEE by 6-10% in energetically challenged mice. Combined with night-time torpor, as observed in mice under prolonged food scarcity, DEE can be reduced by ∼20%. The dominant factor determining the energetic benefit of diurnality is thermal buffering provided by a sheltered resting location. Compared with nocturnal animals, diurnal animals encounter higher ambient temperatures during both day and night, leading to reduced thermogenesis costs in temperate climates. Analysis of weather station data shows that diurnality is energetically beneficial on almost all days of the year in a temperate climate region. Furthermore, diurnality provides energetic benefits at all investigated geographical locations on European longitudinal and latitudinal transects. The reduction of DEE by diurnality provides an ultimate explanation for temporal niche switching observed in typically nocturnal small mammals under energetically challenging conditions. Diurnality allows mammals to compensate for reductions in food availability and temperature as it reduces energetic needs. The optimal circadian organization of an animal ultimately depends on the balance between energetic consequences and other fitness consequences of the selected temporal niche.
Collapse
Affiliation(s)
- Vincent van der Vinne
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen 9747 AG, The Netherlands
| | - Jenke A Gorter
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen 9747 AG, The Netherlands
| | - Sjaak J Riede
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen 9747 AG, The Netherlands
| | - Roelof A Hut
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen 9747 AG, The Netherlands
| |
Collapse
|
41
|
Stothart MR, Elliott KH, Wood T, Hatch SA, Speakman JR. Counting calories in cormorants: dynamic body acceleration predicts daily energy expenditure measured in pelagic cormorants. ACTA ACUST UNITED AC 2016; 219:2192-200. [PMID: 27207639 DOI: 10.1242/jeb.130526] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 05/11/2016] [Indexed: 11/20/2022]
Abstract
The integral of the dynamic component of acceleration over time has been proposed as a measure of energy expenditure in wild animals. We tested that idea by attaching accelerometers to the tails of free-ranging pelagic cormorants (Phalacrocorax pelagicus) and simultaneously estimating energy expenditure using doubly labelled water. Two different formulations of dynamic body acceleration, [vectorial and overall DBA (VeDBA and ODBA)], correlated with mass-specific energy expenditure (both R(2)=0.91). VeDBA models combining and separately parameterizing flying, diving, activity on land and surface swimming were consistently considered more parsimonious than time budget models and showed less variability in model fit. Additionally, we observed evidence for the presence of hypometabolic processes (i.e. reduced heart rate and body temperature; shunting of blood away from non-essential organs) that suppressed metabolism in cormorants while diving, which was the most metabolically important activity. We concluded that a combination of VeDBA and physiological processes accurately measured energy expenditure for cormorants.
Collapse
Affiliation(s)
- Mason R Stothart
- Department of Integrative Biology, University of Guelph, Guelph, Canada N1G 2K8
| | - Kyle H Elliott
- Department of Natural Resource Sciences, McGill University, St. Anne de Bellevue, Quebec, Canada H9X 3V9
| | - Thomas Wood
- Department of Biology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
| | - Scott A Hatch
- Institute for Seabird Research and Conservation, Anchorage, AK 99516-9951, USA
| | - John R Speakman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland AB24 2TZ, UK State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China
| |
Collapse
|
42
|
Halsey LG. Terrestrial movement energetics: current knowledge and its application to the optimising animal. J Exp Biol 2016; 219:1424-31. [DOI: 10.1242/jeb.133256] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 03/14/2016] [Indexed: 01/25/2023]
Abstract
ABSTRACT
The energetic cost of locomotion can be a substantial proportion of an animal's daily energy budget and thus key to its ecology. Studies on myriad species have added to our knowledge about the general cost of animal movement, including the effects of variations in the environment such as terrain angle. However, further such studies might provide diminishing returns on the development of a deeper understanding of how animals trade-off the cost of movement with other energy costs, and other ecological currencies such as time. Here, I propose the ‘individual energy landscape’ as an approach to conceptualising the choices facing the optimising animal. In this Commentary, first I outline previous broad findings about animal walking and running locomotion, focusing in particular on the use of net cost of transport as a metric of comparison between species, and then considering the effects of environmental perturbations and other extrinsic factors on movement costs. I then introduce and explore the idea that these factors combine with the behaviour of the animal in seeking short-term optimality to create that animal's individual energy landscape – the result of the geographical landscape and environmental factors combined with the animal's selected trade-offs. Considering an animal's locomotion energy expenditure within this context enables hard-won empirical data on transport costs to be applied to questions about how an animal can and does move through its environment to maximise its fitness, and the relative importance, or otherwise, of locomotion energy economy.
Collapse
Affiliation(s)
- Lewis G. Halsey
- Department of Life Sciences, University of Roehampton, Holybourne Avenue, London SW15 4JD, UK
| |
Collapse
|
43
|
Klinger DH, Dale JJ, Gleiss AC, Brandt T, Estess EE, Gardner L, Machado B, Norton A, Rodriguez L, Stiltner J, Farwell C, Block BA. The effect of temperature on postprandial metabolism of yellowfin tuna (Thunnus albacares). Comp Biochem Physiol A Mol Integr Physiol 2016; 195:32-8. [DOI: 10.1016/j.cbpa.2016.01.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 01/05/2016] [Accepted: 01/07/2016] [Indexed: 11/16/2022]
|
44
|
Portugal SJ, Green JA, Halsey LG, Arnold W, Careau V, Dann P, Frappell PB, Grémillet D, Handrich Y, Martin GR, Ruf T, Guillemette MM, Butler PJ. Associations between Resting, Activity, and Daily Metabolic Rate in Free-Living Endotherms: No Universal Rule in Birds and Mammals. Physiol Biochem Zool 2016; 89:251-61. [PMID: 27153134 DOI: 10.1086/686322] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Energy management models provide theories and predictions for how animals manage their energy budgets within their energetic constraints, in terms of their resting metabolic rate (RMR) and daily energy expenditure (DEE). Thus, uncovering what associations exist between DEE and RMR is key to testing these models. Accordingly, there is considerable interest in the relationship between DEE and RMR at both inter- and intraspecific levels. Interpretation of the evidence for particular energy management models is enhanced by also considering the energy spent specifically on costly activities (activity energy expenditure [AEE] = DEE - RMR). However, to date there have been few intraspecific studies investigating such patterns. Our aim was to determine whether there is a generality of intraspecific relationships among RMR, DEE, and AEE using long-term data sets for bird and mammal species. For mammals, we use minimum heart rate (fH), mean fH, and activity fH as qualitative proxies for RMR, DEE, and AEE, respectively. For the birds, we take advantage of calibration equations to convert fH into rate of oxygen consumption in order to provide quantitative proxies for RMR, DEE, and AEE. For all 11 species, the DEE proxy was significantly positively correlated with the RMR proxy. There was also evidence of a significant positive correlation between AEE and RMR in all four mammal species but only in some of the bird species. Our results indicate there is no universal rule for birds and mammals governing the relationships among RMR, AEE, and DEE. Furthermore, they suggest that birds tend to have a different strategy for managing their energy budgets from those of mammals and that there are also differences in strategy between bird species. Future work in laboratory settings or highly controlled field settings can tease out the environmental and physiological processes contributing to variation in energy management strategies exhibited by different species.
Collapse
|
45
|
Lipid-induced thermogenesis is up-regulated by the first cold-water immersions in juvenile penguins. J Comp Physiol B 2016; 186:639-50. [PMID: 26924130 DOI: 10.1007/s00360-016-0975-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/01/2016] [Accepted: 02/16/2016] [Indexed: 10/22/2022]
Abstract
The passage from shore to marine life is a critical step in the development of juvenile penguins and is characterized by a fuel selection towards lipid oxidation concomitant to an enhancement of lipid-induced thermogenesis. However, mechanisms of such thermogenic improvement at fledging remain undefined. We used two different groups of pre-fledging king penguins (Aptenodytes patagonicus) to investigate the specific contribution of cold exposure during water immersion to lipid metabolism. Terrestrial penguins that had never been immersed in cold water were compared with experimentally cold-water immersed juveniles. Experimentally immersed penguins underwent ten successive immersions at approximately 9-10 °C for 5 h over 3 weeks. We evaluated adaptive thermogenesis by measuring body temperature, metabolic rate and shivering activity in fully immersed penguins exposed to water temperatures ranging from 12 to 29 °C. Both never-immersed and experimentally immersed penguins were able to maintain their homeothermy in cold water, exhibiting similar thermogenic activity. In vivo, perfusion of lipid emulsion at thermoneutrality induced a twofold larger calorigenic response in experimentally immersed than in never-immersed birds. In vitro, the respiratory rates and the oxidative phosphorylation efficiency of isolated muscle mitochondria were not improved with cold-water immersions. The present study shows that acclimation to cold water only partially reproduced the fuel selection towards lipid oxidation that characterizes penguin acclimatization to marine life.
Collapse
|
46
|
Yoo Y, LaPradd M, Kline H, Zaretskaia MV, Behrouzvaziri A, Rusyniak DE, Molkov YI, Zaretsky DV. Exercise activates compensatory thermoregulatory reaction in rats: a modeling study. J Appl Physiol (1985) 2015; 119:1400-10. [PMID: 26472864 DOI: 10.1152/japplphysiol.00392.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 10/13/2015] [Indexed: 11/22/2022] Open
Abstract
The importance of exercise is increasingly emphasized for maintaining health. However, exercise itself can pose threats to health such as the development of exertional heat shock in warm environments. Therefore, it is important to understand how the thermoregulation system adjusts during exercise and how alterations of this can contribute to heat stroke. To explore this we measured the core body temperature of rats (Tc) running for 15 min on a treadmill at various speeds in two ambient temperatures (Ta = 25°C and 32°C). We assimilated the experimental data into a mathematical model that describes temperature changes in two compartments of the body, representing the muscles and the core. In our model the core body generates heat to maintain normal body temperature, and dissipates it into the environment. The muscles produce additional heat during exercise. According to the estimation of model parameters, at Ta = 25°C, the heat generation in the core was progressively reduced with the increase of the treadmill speed to compensate for a progressive increase in heat production by the muscles. This compensation was ineffective at Ta = 32°C, which resulted in an increased rate of heat accumulation with increasing speed, as opposed to the Ta = 25°C case. Interestingly, placing an animal on a treadmill increased heat production in the muscles even when the treadmill speed was zero. Quantitatively, this "ready-to-run" phenomenon accounted for over half of the heat generation in the muscles observed at maximal treadmill speed. We speculate that this anticipatory response utilizes stress-related circuitry.
Collapse
Affiliation(s)
- Yeonjoo Yoo
- Department of Mathematical Sciences, Indiana University-Purdue University Indianapolis, Indiana
| | - Michelle LaPradd
- Department of Mathematical Sciences, Indiana University-Purdue University Indianapolis, Indiana
| | | | - Maria V Zaretskaia
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | | | - Daniel E Rusyniak
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Yaroslav I Molkov
- Department of Mathematical Sciences, Indiana University-Purdue University Indianapolis, Indiana
| | - Dmitry V Zaretsky
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| |
Collapse
|
47
|
Meyer CW, Reitmeir P, Tschöp MH. Exploration of Energy Metabolism in the Mouse Using Indirect Calorimetry: Measurement of Daily Energy Expenditure (DEE) and Basal Metabolic Rate (BMR). ACTA ACUST UNITED AC 2015; 5:205-222. [PMID: 26331756 DOI: 10.1002/9780470942390.mo140216] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Current comprehensive mouse metabolic phenotyping involves studying energy balance in cohorts of mice via indirect calorimetry, which determines heat release from changes in respiratory air composition. Here, we describe the measurement of daily energy expenditure (DEE) and basal metabolic rate (BMR) in mice. These well-defined metabolic descriptors serve as meaningful first-line read-outs for metabolic phenotyping and should be reported when exploring energy expenditure in mice. For further guidance, the issue of appropriate sample sizes and the frequency of sampling of metabolic measurements is also discussed.
Collapse
Affiliation(s)
- Carola W Meyer
- Institute for Diabetes and Obesity, Helmholtz-Zentrum München GmbH, Neuherberg, Germany
| | - Peter Reitmeir
- Institute for Health Economics and Health Care Management, Helmholtz-Zentrum München GmbH, Neuherberg, Germany
| | - Matthias H Tschöp
- Institute for Diabetes and Obesity, Helmholtz-Zentrum München GmbH, Neuherberg, Germany.,Division of Metabolic Diseases, Department of Medicine, Technische Universität München, Munich, Germany
| |
Collapse
|
48
|
Rezende EL, Bacigalupe LD. Thermoregulation in endotherms: physiological principles and ecological consequences. J Comp Physiol B 2015; 185:709-27. [PMID: 26025431 DOI: 10.1007/s00360-015-0909-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 04/18/2015] [Accepted: 04/27/2015] [Indexed: 01/01/2023]
Abstract
In a seminal study published nearly 70 years ago, Scholander et al. (Biol Bull 99:259-271, 1950) employed Newton's law of cooling to describe how metabolic rates (MR) in birds and mammals vary predictably with ambient temperature (T a). Here, we explore the theoretical consequences of Newton's law of cooling and show that a thermoregulatory polygon provides an intuitively simple and yet useful description of thermoregulatory responses in endothermic organisms. This polygon encapsulates the region in which heat production and dissipation are in equilibrium and, therefore, the range of conditions in which thermoregulation is possible. Whereas the typical U-shaped curve describes the relationship between T a and MR at rest, thermoregulatory polygons expand this framework to incorporate the impact of activity, other behaviors and environmental conditions on thermoregulation and energy balance. We discuss how this framework can be employed to study the limits to effective thermoregulation and their ecological repercussions, allometric effects and residual variation in MR and thermal insulation, and how thermoregulatory requirements might constrain locomotor or reproductive performance (as proposed, for instance, by the heat dissipation limit theory). In many systems the limited empirical knowledge on how organismal traits may respond to environmental changes prevents physiological ecology from becoming a fully developed predictive science. In endotherms, however, we contend that the lack of theoretical developments that translate current physiological understanding into formal mechanistic models remains the main impediment to study the ecological and evolutionary repercussions of thermoregulation. In spite of the inherent limitations of Newton's law of cooling as an oversimplified description of the mechanics of heat transfer, we argue that understanding how systems that obey this approximation work can be enlightening on conceptual grounds and relevant as an analytical and predictive tool to study ecological phenomena. As such, the proposed approach may constitute a powerful tool to study the impact of thermoregulatory constraints on variables related to fitness, such as survival and reproductive output, and help elucidating how species will be affected by ongoing climate change.
Collapse
Affiliation(s)
- Enrico L Rezende
- Department of Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, UK.
| | - Leonardo D Bacigalupe
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile.
| |
Collapse
|
49
|
Seasonal metabolic variation over two years in an Afrotropical passerine bird. J Therm Biol 2015; 52:58-66. [PMID: 26267499 DOI: 10.1016/j.jtherbio.2015.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 05/14/2015] [Accepted: 05/14/2015] [Indexed: 11/21/2022]
Abstract
Seasonal trends in metabolic parameters are well established in avian populations from highly seasonal environments, however, seasonal trends in metabolism of birds from lower latitudes (and of Afrotropical birds in particular) are not well understood. We investigated seasonal trends in metabolism for a small (10-12g) Afrotropical bird, the Cape White-eye (Zosterops virens), using flow-through respirometry in two summers and two winters. There was no seasonal difference in body mass between consecutive seasons. The lower critical limit of thermoneutrality was lower in winter (23°C) than in summer (28°C), as expected for a small Afrotropical bird. In the first year of the study, mean whole animal basal metabolic rate (BMR) of Cape White-eyes was significantly lower in winter than in summer, while in the second year of the study this trend was reversed, and in the middle two seasons there was no significant difference in BMR. Differences in mean temperature and mean rainfall between seasons could not account for the seasonal trends in BMR. We conclude that seasonal trends in avian BMR may vary between years, within a population.
Collapse
|
50
|
White CR, Kearney MR. Metabolic scaling in animals: methods, empirical results, and theoretical explanations. Compr Physiol 2014; 4:231-56. [PMID: 24692144 DOI: 10.1002/cphy.c110049] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Life on earth spans a size range of around 21 orders of magnitude across species and can span a range of more than 6 orders of magnitude within species of animal. The effect of size on physiology is, therefore, enormous and is typically expressed by how physiological phenomena scale with mass(b). When b ≠ 1 a trait does not vary in direct proportion to mass and is said to scale allometrically. The study of allometric scaling goes back to at least the time of Galileo Galilei, and published scaling relationships are now available for hundreds of traits. Here, the methods of scaling analysis are reviewed, using examples for a range of traits with an emphasis on those related to metabolism in animals. Where necessary, new relationships have been generated from published data using modern phylogenetically informed techniques. During recent decades one of the most controversial scaling relationships has been that between metabolic rate and body mass and a number of explanations have been proposed for the scaling of this trait. Examples of these mechanistic explanations for metabolic scaling are reviewed, and suggestions made for comparing between them. Finally, the conceptual links between metabolic scaling and ecological patterns are examined, emphasizing the distinction between (1) the hypothesis that size- and temperature-dependent variation among species and individuals in metabolic rate influences ecological processes at levels of organization from individuals to the biosphere and (2) mechanistic explanations for metabolic rate that may explain the size- and temperature-dependence of this trait.
Collapse
Affiliation(s)
- Craig R White
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland, Australia
| | | |
Collapse
|