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Porfiri M, De Lellis P, Aung E, Meneses S, Abaid N, Waters JS, Garnier S. Reverse social contagion as a mechanism for regulating mass behaviors in highly integrated social systems. PNAS NEXUS 2024; 3:pgae246. [PMID: 38962249 PMCID: PMC11220668 DOI: 10.1093/pnasnexus/pgae246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 06/05/2024] [Indexed: 07/05/2024]
Abstract
Mass behavior is the rapid adoption of similar conduct by all group members, with potentially catastrophic outcomes such as mass panic. Yet, these negative consequences are rare in integrated social systems such as social insect colonies, thanks to mechanisms of social regulation. Here, we test the hypothesis that behavioral deactivation between active individuals is a powerful social regulator that reduces energetic spending in groups. Borrowing from scaling theories for human settlements and using behavioral data on harvester ants, we derive ties between the hypermetric scaling of the interaction network and the hypometric scaling of activity levels, both relative to the colony size. We use elements of economics theory and metabolic measurements collected with the behavioral data to link activity and metabolic scalings with group size. Our results support the idea that metabolic scaling across social systems is the product of different balances between their social regulation mechanisms.
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Affiliation(s)
- Maurizio Porfiri
- Center for Urban Science and Progress, New York University, Brooklyn, NY 11201, USA
- Department of Mechanical and Aerospace Engineering, Tandon School of Engineering, New York University, Brooklyn, NY 11201, USA
- Department of Biomedical Engineering, Tandon School of Engineering, New York University, Brooklyn, NY 11201, USA
| | - Pietro De Lellis
- Department of Electrical Engineering and Information Technology, University of Naples Federico II, Naples 80125, Italy
| | - Eighdi Aung
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA
| | - Santiago Meneses
- Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Nicole Abaid
- Department of Mathematics, Virginia Tech, Blacksburg, VA 24061, USA
| | - Jane S Waters
- Department of Biology, Providence College, Providence, RI 02918, USA
| | - Simon Garnier
- Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
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2
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Chen J, Guo X, Charbonneau D, Azizi A, Fewell J, Kang Y. Dynamics of Information Flow and Task Allocation of Social Insect Colonies: Impacts of Spatial Interactions and Task Switching. Bull Math Biol 2024; 86:50. [PMID: 38581473 DOI: 10.1007/s11538-024-01280-6] [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: 12/21/2022] [Accepted: 03/03/2024] [Indexed: 04/08/2024]
Abstract
Models of social interaction dynamics have been powerful tools for understanding the efficiency of information spread and the robustness of task allocation in social insect colonies. How workers spatially distribute within the colony, or spatial heterogeneity degree (SHD), plays a vital role in contact dynamics, influencing information spread and task allocation. We used agent-based models to explore factors affecting spatial heterogeneity and information flow, including the number of task groups, variation in spatial arrangements, and levels of task switching, to study: (1) the impact of multiple task groups on SHD, contact dynamics, and information spread, and (2) the impact of task switching on SHD and contact dynamics. Both models show a strong linear relationship between the dynamics of SHD and contact dynamics, which exists for different initial conditions. The multiple-task-group model without task switching reveals the impacts of the number and spatial arrangements of task locations on information transmission. The task-switching model allows task-switching with a probability through contact between individuals. The model indicates that the task-switching mechanism enables a dynamical state of task-related spatial fidelity at the individual level. This spatial fidelity can assist the colony in redistributing their workforce, with consequent effects on the dynamics of spatial heterogeneity degree. The spatial fidelity of a task group is the proportion of workers who perform that task and have preferential walking styles toward their task location. Our analysis shows that the task switching rate between two tasks is an exponentially decreasing function of the spatial fidelity and contact rate. Higher spatial fidelity leads to more agents aggregating to task location, reducing contact between groups, thus making task switching more difficult. Our results provide important insights into the mechanisms that generate spatial heterogeneity and deepen our understanding of how spatial heterogeneity impacts task allocation, social interaction, and information spread.
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Affiliation(s)
- Jun Chen
- Simon A. Levin Mathematical and Computational Modeling Sciences Center, Arizona State University, 1031 Palm Walk, Tempe, AZ, 85281, USA
| | - Xiaohui Guo
- School of Life Sciences, Arizona State University, Tempe, AZ, 85281, USA
| | | | - Asma Azizi
- Department of Mathematics, Kennesaw State University, Marrieta, GA, 30060, USA
| | - Jennifer Fewell
- School of Life Sciences, Arizona State University, Tempe, AZ, 85281, USA
| | - Yun Kang
- Sciences and Mathematics Faculty, College of Integrative Sciences and Arts, Arizona State University, Mesa, AZ, 85212, USA.
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3
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Naug D. Metabolic scaling as an emergent outcome of variation in metabolic rate. Philos Trans R Soc Lond B Biol Sci 2024; 379:20220495. [PMID: 38186273 PMCID: PMC10772609 DOI: 10.1098/rstb.2022.0495] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 11/06/2023] [Indexed: 01/09/2024] Open
Abstract
The allometric scaling of metabolic rate and what drives it are major questions in biology with a long history. Since the metabolic rate at any level of biological organization is an emergent property of its lower-level constituents, it is an outcome of the intrinsic heterogeneity among these units and the interactions among them. However, the influence of lower-level heterogeneity on system-level metabolic rate is difficult to investigate, given the tightly integrated body plan of unitary organisms. In this context, social insects such as honeybees can serve as important model systems because unlike unitary organisms, these superorganisms can be taken apart and reassembled in different configurations to study metabolic rate and its various drivers at different levels of organization. This commentary discusses the background of such an approach and how combining it with artificial selection to generate heterogeneity in metabolic rate with an analytical framework to parse out the different mechanisms that contribute to the effects of heterogeneity can contribute to the various models of metabolic scaling. Finally, the absence of the typical allometric scaling relationship among different species of honeybees is discussed as an important prospect for deciphering the role of top-down ecological factors on metabolic scaling. This article is part of the theme issue 'The evolutionary significance of variation in metabolic rates'.
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Affiliation(s)
- Dhruba Naug
- Department of Biology, Colorado State University, 1878 Campus Delivery, Fort Collins, CO 80523, USA
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4
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Metcalfe NB, Bellman J, Bize P, Blier PU, Crespel A, Dawson NJ, Dunn RE, Halsey LG, Hood WR, Hopkins M, Killen SS, McLennan D, Nadler LE, Nati JJH, Noakes MJ, Norin T, Ozanne SE, Peaker M, Pettersen AK, Przybylska-Piech A, Rathery A, Récapet C, Rodríguez E, Salin K, Stier A, Thoral E, Westerterp KR, Westerterp-Plantenga MS, Wojciechowski MS, Monaghan P. Solving the conundrum of intra-specific variation in metabolic rate: A multidisciplinary conceptual and methodological toolkit: New technical developments are opening the door to an understanding of why metabolic rate varies among individual animals of a species: New technical developments are opening the door to an understanding of why metabolic rate varies among individual animals of a species. Bioessays 2023; 45:e2300026. [PMID: 37042115 DOI: 10.1002/bies.202300026] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 04/13/2023]
Abstract
Researchers from diverse disciplines, including organismal and cellular physiology, sports science, human nutrition, evolution and ecology, have sought to understand the causes and consequences of the surprising variation in metabolic rate found among and within individual animals of the same species. Research in this area has been hampered by differences in approach, terminology and methodology, and the context in which measurements are made. Recent advances provide important opportunities to identify and address the key questions in the field. By bringing together researchers from different areas of biology and biomedicine, we describe and evaluate these developments and the insights they could yield, highlighting the need for more standardisation across disciplines. We conclude with a list of important questions that can now be addressed by developing a common conceptual and methodological toolkit for studies on metabolic variation in animals.
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Affiliation(s)
- Neil B Metcalfe
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Jakob Bellman
- Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Pierre Bize
- Swiss Ornithological Institute, Sempach, Switzerland
| | - Pierre U Blier
- Département de Biologie, Université de Québec à Rimouski, Rimouski, Canada
| | - Amélie Crespel
- Department of Biology, University of Turku, Turku, Finland
| | - Neal J Dawson
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Ruth E Dunn
- Lancaster Environment Centre, University of Lancaster, Lancaster, UK
| | - Lewis G Halsey
- School of Life and Health Sciences, University of Roehampton, London, UK
| | - Wendy R Hood
- Department of Biological Sciences, Auburn University, Auburn, USA
| | - Mark Hopkins
- School of Food Science and Nutrition, Leeds University, Leeds, UK
| | - Shaun S Killen
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Darryl McLennan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Lauren E Nadler
- Ocean and Earth Science, NOC, University of Southampton, Southampton, UK
| | - Julie J H Nati
- Ocean Sciences Center, Memorial University of Newfoundland, St John's, Canada
| | - Matthew J Noakes
- School of Animal, Plant, and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Tommy Norin
- DTU Aqua: National Institute of Aquatic Resources, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Susan E Ozanne
- Wellcome-MRC Institute of Metabolic Science, University of Cambridge, Cambridge, UK
| | | | - Amanda K Pettersen
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
- School of Life & Environmental Sciences, The University of Sydney, Sydney, Australia
| | - Anna Przybylska-Piech
- Department of Vertebrate Zoology & Ecology, Nicolaus Copernicus University, Toruń, Poland
| | - Alann Rathery
- School of Life and Health Sciences, University of Roehampton, London, UK
| | - Charlotte Récapet
- Universite de Pau et des Pays de l'Adour, E2S UPPA, INRAE, ECOBIOP, Saint-Pée-sur-, Nivelle, France
| | - Enrique Rodríguez
- Department of Genetics, Evolution & Environment, University College London, London, UK
| | - Karine Salin
- IFREMER, Univ Brest, CNRS, IRD, Laboratory of Environmental Marine Sciences, Plouzané, France
| | - Antoine Stier
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR 5023 LEHNA, Villeurbanne, France
| | - Elisa Thoral
- Department of Biology, Lund University, Lund, Sweden
| | - Klaas R Westerterp
- Department of Nutrition & Movement Sciences, Maastricht University, Maastricht, The Netherlands
| | | | - Michał S Wojciechowski
- Department of Vertebrate Zoology & Ecology, Nicolaus Copernicus University, Toruń, Poland
| | - Pat Monaghan
- School of Biodiversity, One Health & Veterinary Medicine, University of Glasgow, Glasgow, UK
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5
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Toth JM, Fewell JH, Waters JS. Scaling of ant colony interaction networks. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2022.993627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In social insect colonies, individuals are physically independent but functionally integrated by interaction networks which provide a foundation for communication and drive the emergence of collective behaviors, including nest architecture, division of labor, and potentially also the social regulation of metabolic rates. To investigate the relationship between interactions, metabolism, and colony size, we varied group size for harvester ant colonies (Pogonomyrmex californicus) and assessed their communication networks based on direct antennal contacts and compared these results with proximity networks and a random movement simulation. We found support for the hypothesis of social regulation; individuals did not interact with each other randomly but exhibited restraint. Connectivity scaled hypometrically with colony size, per-capita interaction rate was scale-invariant, and smaller colonies exhibited higher measures of closeness centrality and edge density, correlating with higher per-capita metabolic rates. Although the immediate energetic cost for two ants to interact is insignificant, the downstream effects of receiving and integrating social information can have metabolic consequences. Our results indicate that individuals in larger colonies are relatively more insulated from each other, a factor that may reduce or filter noisy stimuli and contribute to the hypometric scaling of their metabolic rates, and perhaps more generally, the evolution of larger colony sizes.
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Harrison JF, Biewener A, Bernhardt JR, Burger JR, Brown JH, Coto ZN, Duell ME, Lynch M, Moffett ER, Norin T, Pettersen AK, Smith FA, Somjee U, Traniello JFA, Williams TM. White Paper: An Integrated Perspective on the Causes of Hypometric Metabolic Scaling in Animals. Integr Comp Biol 2022; 62:icac136. [PMID: 35933126 PMCID: PMC9724154 DOI: 10.1093/icb/icac136] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 04/16/2022] [Accepted: 05/19/2022] [Indexed: 11/15/2022] Open
Abstract
Larger animals studied during ontogeny, across populations, or across species, usually have lower mass-specific metabolic rates than smaller animals (hypometric scaling). This pattern is usually observed regardless of physiological state (e.g. basal, resting, field, maximally-active). The scaling of metabolism is usually highly correlated with the scaling of many life history traits, behaviors, physiological variables, and cellular/molecular properties, making determination of the causation of this pattern challenging. For across-species comparisons of resting and locomoting animals (but less so for across populations or during ontogeny), the mechanisms at the physiological and cellular level are becoming clear. Lower mass-specific metabolic rates of larger species at rest are due to a) lower contents of expensive tissues (brains, liver, kidneys), and b) slower ion leak across membranes at least partially due to membrane composition, with lower ion pump ATPase activities. Lower mass-specific costs of larger species during locomotion are due to lower costs for lower-frequency muscle activity, with slower myosin and Ca++ ATPase activities, and likely more elastic energy storage. The evolutionary explanation(s) for hypometric scaling remain(s) highly controversial. One subset of evolutionary hypotheses relies on constraints on larger animals due to changes in geometry with size; for example, lower surface-to-volume ratios of exchange surfaces may constrain nutrient or heat exchange, or lower cross-sectional areas of muscles and tendons relative to body mass ratios would make larger animals more fragile without compensation. Another subset of hypotheses suggests that hypometric scaling arises from biotic interactions and correlated selection, with larger animals experiencing less selection for mass-specific growth or neurolocomotor performance. A additional third type of explanation comes from population genetics. Larger animals with their lower effective population sizes and subsequent less effective selection relative to drift may have more deleterious mutations, reducing maximal performance and metabolic rates. Resolving the evolutionary explanation for the hypometric scaling of metabolism and associated variables is a major challenge for organismal and evolutionary biology. To aid progress, we identify some variation in terminology use that has impeded cross-field conversations on scaling. We also suggest that promising directions for the field to move forward include: 1) studies examining the linkages between ontogenetic, population-level, and cross-species allometries, 2) studies linking scaling to ecological or phylogenetic context, 3) studies that consider multiple, possibly interacting hypotheses, and 4) obtaining better field data for metabolic rates and the life history correlates of metabolic rate such as lifespan, growth rate and reproduction.
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Affiliation(s)
- Jon F Harrison
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Andrew Biewener
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Joanna R Bernhardt
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Yale Institute for Biospheric Studies, New Haven, CT 06520, USA
| | - Joseph R Burger
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA
| | - James H Brown
- Center for Evolutionary and Theoretical Immunology, The University of New Mexico, Albuquerque, NM 87131, USA
| | - Zach N Coto
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Meghan E Duell
- Department of Biology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85281, USA
| | - Emma R Moffett
- Department of Ecology and Evolution, University of California, Irvine, CA 92697, USA
| | - Tommy Norin
- DTU Aqua | National Institute of Aquatic Resources, Technical University of Denmark, Anker Engelunds Vej 1 Bygning 101A, 2800 Kgs. Lyngby, Denmark
| | - Amanda K Pettersen
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
| | - Felisa A Smith
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Ummat Somjee
- Smithsonian Tropical Research Institute, Panama City, Panama
| | | | - Terrie M Williams
- Division of Physical and Biological Sciences, University of California, Santa Cruz, CA 95064, USA
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7
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Coto ZN, Traniello JFA. Social Brain Energetics: Ergonomic Efficiency, Neurometabolic Scaling, and Metabolic Polyphenism in Ants. Integr Comp Biol 2022; 62:icac048. [PMID: 35617153 PMCID: PMC9825342 DOI: 10.1093/icb/icac048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/04/2022] [Accepted: 05/11/2022] [Indexed: 01/12/2023] Open
Abstract
Metabolism, a metric of the energy cost of behavior, plays a significant role in social evolution. Body size and metabolic scaling are coupled, and a socioecological pattern of increased body size is associated with dietary change and the formation of larger and more complex groups. These consequences of the adaptive radiation of animal societies beg questions concerning energy expenses, a substantial portion of which may involve the metabolic rates of brains that process social information. Brain size scales with body size, but little is understood about brain metabolic scaling. Social insects such as ants show wide variation in worker body size and morphology that correlates with brain size, structure, and worker task performance, which is dependent on sensory inputs and information-processing ability to generate behavior. Elevated production and maintenance costs in workers may impose energetic constraints on body size and brain size that are reflected in patterns of metabolic scaling. Models of brain evolution do not clearly predict patterns of brain metabolic scaling, nor do they specify its relationship to task performance and worker ergonomic efficiency, two key elements of social evolution in ants. Brain metabolic rate is rarely recorded and therefore the conditions under which brain metabolism influences the evolution of brain size are unclear. We propose that studies of morphological evolution, colony social organization, and worker ergonomic efficiency should be integrated with analyses of species-specific patterns of brain metabolic scaling to advance our understanding of brain evolution in ants.
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Affiliation(s)
- Zach N Coto
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - James F A Traniello
- Department of Biology, Boston University, Boston, MA 02215, USA
- Graduate Program in Neuroscience, Boston University, Boston, MA 02215, USA
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8
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Hierarchy Establishment from Nonlinear Social Interactions and Metabolic Costs: An Application to Harpegnathos saltator. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12094239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Social hierarchies are ubiquitous in social groups such as human societies and social insect colonies; however, the factors that maintain these hierarchies are less clear. Motivated by the shared reproductive hierarchy of the ant species Harpegnathos saltator, we have developed simple compartmental nonlinear differential equations to explore how key life-history and metabolic rate parameters may impact and determine its colony size and the length of its shared hierarchy. Our modeling approach incorporates nonlinear social interactions and metabolic theory. The results from the proposed model, which were linked with limited data, show that: (1) the proportion of reproductive individuals decreases over colony growth; (2) an increase in mortality rates can diminish colony size but may also increase the proportion of reproductive individuals; and (3) the metabolic rates have a major impact in the colony size and structure of a shared hierarchy.
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9
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Ko H, Komilian K, Waters JS, Hu DL. Metabolic scaling of fire ants (Solenopsis invicta) engaged in collective behaviors. Biol Open 2022; 11:274512. [PMID: 35217864 PMCID: PMC8905630 DOI: 10.1242/bio.059076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 01/12/2022] [Indexed: 01/19/2023] Open
Abstract
During flash floods, fire ants (Solenopsis invicta Buren) link their bodies together to build rafts to stay afloat, and towers to anchor onto floating vegetation. Can such challenging conditions facilitate synchronization and coordination, resulting in energy savings per capita? To understand how stress affects metabolic rate, we used constant-volume respirometry to measure the metabolism of fire ant workers. Group metabolic rates were measured in a series of conditions: at normal state, at three elevated temperatures, during rafting, and during tower-building. We hypothesized that the metabolic rate of ants at various temperatures would scale isometrically (proportionally with the group mass). Indeed, we found metabolic rates scaled isometrically under all temperature conditions, giving evidence that groups of ants differ from entire colonies, which scale allometrically. We then hypothesized that the metabolism of ants engaged in rafting and tower-building would scale allometrically. We found partial evidence for this hypothesis: ants rafting for short times had allometric metabolic rates, but this effect vanished after 30 min. Rafting for long times and tower-building both scaled isometrically. Tower-building consumed the same energy per capita as ants in their normal state. Rafting ants consumed almost 43% more energy than ants in their normal state, with smaller rafts consuming more energy per capita. Together, our results suggest that stressful conditions requiring coordination can influence metabolic demand. This article has an associated First Person interview with the first author of the paper. Summary: We measured the metabolism of fire ant rafts engaged in collective behaviors such as tower and raft building. We found that except for rafting at early stages, the metabolism scales isometrically with group size, indicating no group benefit in metabolism.
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Affiliation(s)
- Hungtang Ko
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 30332 Atlanta, GA, USA
| | - Keyana Komilian
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, 30332 Atlanta, GA, USA
| | - James S Waters
- Department of Biology, Providence College, 02918 Providence, Rhode Island, USA
| | - David L Hu
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 30332 Atlanta, GA, USA.,School of Biological Sciences, Georgia Institute of Technology, 30332 Atlanta, GA, USA
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10
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Szejner-Sigal A, Williams CM. Aggregations reduce winter metabolic rates in the diapausing ladybeetle Hippodamia convergens. JOURNAL OF INSECT PHYSIOLOGY 2022; 137:104357. [PMID: 35026302 DOI: 10.1016/j.jinsphys.2022.104357] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Revised: 12/27/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
Energy conservation is linked to survival and fitness of overwintering ectotherms, and is particularly critical in winter. Although many insects overwinter individually, some form aggregations with conspecifics. Aggregations cause metabolic suppression in some insects, but the effect of aggregations on metabolic rates and energy use in overwintering aggregations remains underexplored. The convergent ladybeetle (Hippodamia convergens) overwinters in massive aggregations, making it an ideal system for testing the effect of aggregation size on metabolic rates in overwintering insects. We measured metabolic rates of beetle aggregations of 1, 10, 25, and 50 individuals using stop-flow respirometry across two ecologically relevant temperatures, and measured locomotor activity as one possible driver of group effects on metabolic rate. Metabolic rates per beetle decreased with increasing aggregation size at both temperatures, but was more pronounced at low temperatures. Metabolic rates scaled hypometrically with mass, with deeper response at cool temperatures. Activity decreased with aggregation size, but only at low temperatures. These results suggest that individuals within aggregations enter a deeper metabolically inactive state that single individual beetles cannot achieve, which is partly but not completely explained by a reduction in locomotor activity. This group strategy for energy conservation may provide an additional selective advantage for the evolution of large overwintering aggregations.
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Affiliation(s)
- Andre Szejner-Sigal
- Department of Integrative Biology, University of California, Berkeley, CA, USA.
| | - Caroline M Williams
- Department of Integrative Biology, University of California, Berkeley, CA, USA
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11
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Straus S, González AL, Matthews P, Avilés L. Economies of scale shape energetics of solitary and group-living spiders and their webs. J Anim Ecol 2021; 91:255-265. [PMID: 34758114 DOI: 10.1111/1365-2656.13628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 10/22/2021] [Indexed: 11/28/2022]
Abstract
Metabolic scaling, whereby larger individuals use less energy per unit mass than smaller ones, may apply to the combined metabolic rate of group-living organisms as group size increases. Spiders that form groups in high disturbance environments can serve to test the hypothesis that economies of scale benefit social groups. Using solitary and group-living spiders, we tested the hypothesis that spiders exhibit negative allometry between body or colony mass and the standing mass of their webs and whether, and how, such a relationship may contribute to group-living benefits in a cooperative spider. Given the diverse architecture of spider webs-orb, tangle and sheet-and-tangle, and associated differences in silk content, we first assessed how standing web mass scales with spider mass as a function of web architecture and whether investment in silk differs among web types. As group-living spiders are predominantly found in clades that build the presumably costlier sheet-and-tangle webs, we then asked whether cost-sharing through cooperative web maintenance contributes to a positive energy budget in a social species. We found that larger spiders had a relatively smaller investment in silk per unit mass than smaller ones, but more complex sheet-and-tangle webs contained orders of magnitude more silk than simpler orb or tangle ones. In the group-living species, standing web mass per unit spider mass continued to decline as colony size increased with a similar slope as for unitary spiders. When web maintenance activities were considered, colonies also experienced reduced mass-specific energy expenditure with increasing colony size. Activity savings contributed to a net positive energy balance for medium and large colonies after inputs from the cooperative capture of large prey were accounted for. Economies of scale have been previously demonstrated in animal societies characterized by reproductive and worker castes, but not in relatively egalitarian societies as those of social spiders. Our findings illustrate the universality of scaling laws and how economies of scale may transcend hunting strategies and levels of organization.
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Affiliation(s)
- Samantha Straus
- Department of Zoology & Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Angélica L González
- Biology Department & Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA
| | - Philip Matthews
- Department of Zoology & Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
| | - Leticia Avilés
- Department of Zoology & Biodiversity Research Centre, University of British Columbia, Vancouver, BC, Canada
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12
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Coto ZN, Traniello JFA. Brain Size, Metabolism, and Social Evolution. Front Physiol 2021; 12:612865. [PMID: 33708134 PMCID: PMC7940180 DOI: 10.3389/fphys.2021.612865] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/01/2021] [Indexed: 12/24/2022] Open
Affiliation(s)
- Zach N Coto
- Department of Biology, Boston University, Boston, MA, United States
| | - James F A Traniello
- Department of Biology, Boston University, Boston, MA, United States.,Graduate Program in Neuroscience, Boston University, Boston, MA, United States
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13
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Chick LD, Waters JS, Diamond SE. Pedal to the metal: Cities power evolutionary divergence by accelerating metabolic rate and locomotor performance. Evol Appl 2021; 14:36-52. [PMID: 33519955 PMCID: PMC7819567 DOI: 10.1111/eva.13083] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 07/23/2020] [Accepted: 07/27/2020] [Indexed: 12/27/2022] Open
Abstract
Metabolic rates of ectotherms are expected to increase with global trends of climatic warming. But the potential for rapid, compensatory evolution of lower metabolic rate in response to rising temperatures is only starting to be explored. Here, we explored rapid evolution of metabolic rate and locomotor performance in acorn-dwelling ants (Temnothorax curvispinosus) in response to urban heat island effects. We reared ant colonies within a laboratory common garden (25°C) to generate a laboratory-born cohort of workers and tested their acute plastic responses to temperature. Contrary to expectations, urban ants exhibited a higher metabolic rate compared with rural ants when tested at 25°C, suggesting a potentially maladaptive evolutionary response to urbanization. Urban and rural ants had similar metabolic rates when tested at 38°C, as a consequence of a diminished plastic response of the urban ants. Locomotor performance also evolved such that the running speed of urban ants was faster than rural ants under warmer test temperatures (32°C and 42°C) but slower under a cooler test temperature (22°C). The resulting specialist-generalist trade-off and higher thermal optimum for locomotor performance might compensate for evolved increases in metabolic rate by allowing workers to more quickly scout and retrieve resources.
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Affiliation(s)
- Lacy D. Chick
- Department of BiologyCase Western Reserve UniversityClevelandOHUSA
- Hawken SchoolGates MillsOHUSA
| | | | - Sarah E. Diamond
- Department of BiologyCase Western Reserve UniversityClevelandOHUSA
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14
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Rediscovering and Reviving Old Observations and Explanations of Metabolic Scaling in Living Systems. SYSTEMS 2018. [DOI: 10.3390/systems6010004] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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15
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Harrison JF. Do Performance-Safety Tradeoffs Cause Hypometric Metabolic Scaling in Animals? Trends Ecol Evol 2017; 32:653-664. [PMID: 28760361 DOI: 10.1016/j.tree.2017.05.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 05/25/2017] [Accepted: 05/30/2017] [Indexed: 10/19/2022]
Abstract
Hypometric scaling of aerobic metabolism in animals has been widely attributed to constraints on oxygen (O2) supply in larger animals, but recent findings demonstrate that O2 supply balances with need regardless of size. Larger animals also do not exhibit evidence of compensation for O2 supply limitation. Because declining metabolic rates (MRs) are tightly linked to fitness, this provides significant evidence against the hypothesis that constraints on supply drive hypometric scaling. As an alternative, ATP demand might decline in larger animals because of performance-safety tradeoffs. Larger animals, which typically reproduce later, exhibit risk-reducing strategies that lower MR. Conversely, smaller animals are more strongly selected for growth and costly neurolocomotory performance, elevating metabolism.
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Affiliation(s)
- Jon F Harrison
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
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