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Cox DTC, Gaston KJ. Cathemerality: a key temporal niche. Biol Rev Camb Philos Soc 2024; 99:329-347. [PMID: 37839797 DOI: 10.1111/brv.13024] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 10/01/2023] [Accepted: 10/02/2023] [Indexed: 10/17/2023]
Abstract
Given the marked variation in abiotic and biotic conditions between day and night, many species specialise their physical activity to being diurnal or nocturnal, and it was long thought that these strategies were commonly fairly fixed and invariant. The term 'cathemeral', was coined in 1987, when Tattersall noted activity in a Madagascan primate during the hours of both daylight and darkness. Initially thought to be rare, cathemerality is now known to be a quite widespread form of time partitioning amongst arthropods, fish, birds, and mammals. Herein we provide a synthesis of present understanding of cathemeral behaviour, arguing that it should routinely be included alongside diurnal and nocturnal strategies in schemes that distinguish and categorise species across taxa according to temporal niche. This synthesis is particularly timely because (i) the study of animal activity patterns is being revolutionised by new and improved technologies; (ii) it is becoming apparent that cathemerality covers a diverse range of obligate to facultative forms, each with their own common sets of functional traits, geographic ranges and evolutionary history; (iii) daytime and nighttime activity likely plays an important but currently neglected role in temporal niche partitioning and ecosystem functioning; and (iv) cathemerality may have an important role in the ability of species to adapt to human-mediated pressures.
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Affiliation(s)
- Daniel T C Cox
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
| | - Kevin J Gaston
- Environment and Sustainability Institute, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
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Fromm B, Sorger T. Rapid adaptation of cellular metabolic rate to the MicroRNA complements of mammals and its relevance to the evolution of endothermy. iScience 2024; 27:108740. [PMID: 38327773 PMCID: PMC10847693 DOI: 10.1016/j.isci.2023.108740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 09/13/2023] [Accepted: 12/12/2023] [Indexed: 02/09/2024] Open
Abstract
The metabolic efficiency of mammalian cells depends on the attenuation of intrinsic translation noise by microRNAs. We devised a metric of cellular metabolic rate (cMR), rMR/Mexp optimally fit to the number of microRNA families (mirFam), that is robust to variation in mass and sensitive to body temperature (Tb), consistent with the heat dissipation limit theory of Speakman and Król (2010). Using mirFam as predictor, an Ornstein-Uhlenbeck process of stabilizing selection, with an adaptive shift at the divergence of Boreoeutheria, accounted for 95% of the variation in cMR across mammals. Branchwise rates of evolution of cMR, mirFam and Tb concurrently increased 6- to 7-fold at the divergence of Boreoeutheria, independent of mass. Cellular MR variation across placental mammals was also predicted by the sum of model conserved microRNA-target interactions, revealing an unexpected degree of integration of the microRNA-target apparatus into the energy economy of the mammalian cell.
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Affiliation(s)
- Bastian Fromm
- The Arctic University Museum of Norway, UiT- The Arctic University of Norway, Tromsø, Norway
| | - Thomas Sorger
- Department of Biology, Roger Williams University, Bristol, RI 02809, USA
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Nowack J, Stawski C, Geiser F, Levesque DL. Rare and Opportunistic Use of Torpor in Mammals-An Echo from the Past? Integr Comp Biol 2023; 63:1049-1059. [PMID: 37328423 PMCID: PMC10714912 DOI: 10.1093/icb/icad067] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 05/25/2023] [Accepted: 05/29/2023] [Indexed: 06/18/2023] Open
Abstract
Torpor was traditionally seen as a winter survival mechanism employed by animals living in cold and highly seasonal habitats. Although we now know that torpor is also used by tropical and subtropical species, and in response to a variety of triggers, torpor is still largely viewed as a highly controlled, seasonal mechanism shown by Northern hemisphere species. To scrutinize this view, we report data from a macroanalysis in which we characterized the type and seasonality of torpor use from mammal species currently known to use torpor. Our findings suggest that predictable, seasonal torpor patterns reported for Northern temperate and polar species are highly derived forms of torpor expression, whereas the more opportunistic and variable forms of torpor that we see in tropical and subtropical species are likely closer to the patterns expressed by ancestral mammals. Our data emphasize that the torpor patterns observed in the tropics and subtropics should be considered the norm and not the exception.
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Affiliation(s)
- Julia Nowack
- School of Biological and Environmental Sciences, Liverpool John Moores University, L3 3AF Liverpool, UK
| | - Clare Stawski
- School of Science, Technology and Engineering, University of the Sunshine Coast (USC), Maroochydore DC, QLD 4558, Australia
| | - Fritz Geiser
- Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW 2351, Australia
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Nowack J, Mzilikazi N, Dausmann KH. Saving energy via short and shallow torpor bouts. J Therm Biol 2023; 114:103572. [PMID: 37344030 DOI: 10.1016/j.jtherbio.2023.103572] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/04/2023] [Accepted: 04/05/2023] [Indexed: 06/23/2023]
Abstract
Maintaining a high and stable body temperature as observed in most endothermic mammals and birds is energetically costly and many heterothermic species reduce their metabolic demands during energetic bottlenecks through the use of torpor. With the increasing number of heterotherms revealed in a diversity of habitats, it becomes apparent that triggers and patterns of torpor use are more variable than previously thought. Here, we report the previously overlooked use of, shallow rest-time torpor (body temperature >30 °C) in African lesser bushbabies, Galago moholi. Body core temperature of three adult male bushbabies recorded over five months showed a clear bimodal distribution with an average active modal temperature of 39.2 °C and a resting modal body temperature of 36.7 °C. Shallow torpor was observed in two out of three males (n = 29 torpor bouts) between June and August (austral winter), with body temperatures dropping to an overall minimum of 30.7 °C and calculated energy savings of up to 10%. We suggest that shallow torpor may be an ecologically important, yet mostly overlooked energy-saving strategy employed by heterothermic mammals. Our data emphasise that torpor threshold temperatures need to be used with care if we aim to fully understand the level of physiological plasticity displayed by heterothermic species.
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Affiliation(s)
- Julia Nowack
- School of Biological and Environmental Sciences, Liverpool John Moores University, Byrom Street, Liverpool, United Kingdom; Department of Biology, Institute of Cell and Systems Biology of Animals, Functional Ecology, University Hamburg, Hamburg, Germany.
| | - Nomakwezi Mzilikazi
- Department of Zoology, Nelson Mandela University, Port Elizabeth, South Africa
| | - Kathrin H Dausmann
- Department of Biology, Institute of Cell and Systems Biology of Animals, Functional Ecology, University Hamburg, Hamburg, Germany
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Flexible energy-saving strategies in female temperate-zone bats. J Comp Physiol B 2022; 192:805-814. [PMID: 35939092 PMCID: PMC9550788 DOI: 10.1007/s00360-022-01452-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 07/06/2022] [Accepted: 07/19/2022] [Indexed: 12/02/2022]
Abstract
Torpor is characterized by an extreme reduction in metabolism and a common energy-saving strategy of heterothermic animals. Torpor is often associated with cold temperatures, but in the last decades, more diverse and flexible forms of torpor have been described. For example, tropical bat species maintain a low metabolism and heart rate at high ambient and body temperatures. We investigated whether bats (Nyctalus noctula) from the cooler temperate European regions also show this form of torpor with metabolic inhibition at high body temperatures, and whether this would be as pronounced in reproductive as in non-reproductive bats. We simultaneously measured metabolic rate, heart rate, and skin temperature in non-reproductive and pregnant females at a range of ambient temperatures. We found that they can decouple metabolic rate and heart rate from body temperature: they maintained an extremely low metabolism and heart rate when exposed to ambient temperatures changing from 0 to 32.5 °C, irrespective of reproductive status. When we simulated natural temperature conditions, all non-reproductive bats used torpor throughout the experiment. Pregnant bats used variable strategies from torpor, to maintaining normothermy, or a combination of both. Even a short torpor bout during the day saved up to 33% of the bats' total energy expenditure. Especially at higher temperatures, heart rate was a much better predictor of metabolic rate than skin temperature. We suggest that the capability to flexibly save energy across a range of ambient temperatures within and between reproductive states may be an important ability of these bats and possibly other temperate-zone heterotherms.
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Bastos B, Pradhan N, Tarroso P, Brito JC, Boratyński Z. Environmental determinants of minimum body temperature in mammals. JOURNAL OF VERTEBRATE BIOLOGY 2021. [DOI: 10.25225/jvb.21004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Bárbara Bastos
- CIBIO/InBIO, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal; e-mail: , , , ,
| | - Nelish Pradhan
- CIBIO/InBIO, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal; e-mail: , , , ,
| | - Pedro Tarroso
- CIBIO/InBIO, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal; e-mail: , , , ,
| | - José C. Brito
- CIBIO/InBIO, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal; e-mail: , , , ,
| | - Zbyszek Boratyński
- CIBIO/InBIO, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal; e-mail: , , , ,
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