1
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McCarthy JS, Brown KE, King CK, Nielsen UN, Plaisted K, Wallace SMN, Reichman SM. Population growth of two limno-terrestrial Antarctic microinvertebrates in different aqueous soil media. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:33086-33097. [PMID: 38676867 PMCID: PMC11133119 DOI: 10.1007/s11356-024-32905-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 03/10/2024] [Indexed: 04/29/2024]
Abstract
Terrestrial microinvertebrates provide important carbon and nutrient cycling roles in soil environments, particularly in Antarctica where larger macroinvertebrates are absent. The environmental preferences and ecology of rotifers and tardigrades in terrestrial environments, including in Antarctica, are not as well understood as their temperate aquatic counterparts. Developing laboratory cultures is critical to provide adequate numbers of individuals for controlled laboratory experimentation. In this study, we explore aspects of optimising laboratory culturing for two terrestrially sourced Antarctic microinvertebrates, a rotifer (Habrotrocha sp.) and a tardigrade (Acutuncus antarcticus). We tested a soil elutriate and a balanced salt solution (BSS) to determine their suitability as culturing media. Substantial population growth of rotifers and tardigrades was observed in both media, with mean rotifer population size increasing from 5 to 448 ± 95 (soil elutriate) and 274 ± 78 (BSS) individuals over 60 days and mean tardigrade population size increasing from 5 to 187 ± 65 (soil elutriate) and 138 ± 37 (BSS) over 160 days. We also tested for optimal dilution of soil elutriate in rotifer cultures, with 20-80% dilutions producing the largest population growth with the least variation in the 40% dilution after 36 days. Culturing methods developed in this study are recommended for use with Antarctica microinvertebrates and may be suitable for similar limno-terrestrial microinvertebrates from other regions.
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Affiliation(s)
- Jordan S McCarthy
- Centre for Anthropogenic Pollution Impact and Management (CAPIM), University of Melbourne, Parkville, VIC, 3010, Australia
- School of BioSciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Kathryn E Brown
- Environmental Stewardship Program, Australian Antarctic Division, 203 Channel Highway, Kingston, TAS, 7050, Australia
| | - Catherine K King
- Environmental Stewardship Program, Australian Antarctic Division, 203 Channel Highway, Kingston, TAS, 7050, Australia
| | - Uffe N Nielsen
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2750, Australia
| | - Katie Plaisted
- Centre for Anthropogenic Pollution Impact and Management (CAPIM), University of Melbourne, Parkville, VIC, 3010, Australia
- School of BioSciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Stephanie M N Wallace
- Centre for Anthropogenic Pollution Impact and Management (CAPIM), University of Melbourne, Parkville, VIC, 3010, Australia
- School of BioSciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Suzie M Reichman
- Centre for Anthropogenic Pollution Impact and Management (CAPIM), University of Melbourne, Parkville, VIC, 3010, Australia.
- School of BioSciences, University of Melbourne, Parkville, VIC, 3010, Australia.
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2
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Ehlman SM, Scherer U, Wolf M. Developmental feedbacks and the emergence of individuality. ROYAL SOCIETY OPEN SCIENCE 2022; 9:221189. [PMID: 36465682 DOI: 10.6084/m9.figshare.c.6315476] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/07/2022] [Indexed: 05/24/2023]
Abstract
Behavioural individuality is a hallmark of animal life, with major consequences for fitness, ecology, and evolution. One of the most widely invoked explanations for this variation is that feedback loops between an animal's behaviour and its state (e.g. physiology, informational state, social rank, etc.) trigger and shape the development of individuality. Despite their often-cited importance, however, little is known about the ultimate causes of such feedbacks. Expanding on a previously employed model of adaptive behavioural development under uncertainty, we find that (i) behaviour-state feedbacks emerge as a direct consequence of adaptive behavioural development in particular selective environments and (ii) that the sign of these feedbacks, and thus the consequences for the development of behavioural individuality, can be directly predicted by the shape of the fitness function, with increasing fitness benefits giving rise to positive feedbacks and trait divergence and decreasing fitness benefits leading to negative feedbacks and trait convergence. Our findings provide a testable explanatory framework for the emergence of developmental feedbacks driving individuality and suggest that such feedbacks and their associated patterns of behavioural diversity are a direct consequence of adaptive behavioural development in particular selective environments.
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Affiliation(s)
- Sean M Ehlman
- SCIoI Excellence Cluster, Berlin, Germany
- Humboldt University, Berlin, Germany
- IGB - Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Ulrike Scherer
- SCIoI Excellence Cluster, Berlin, Germany
- Humboldt University, Berlin, Germany
- IGB - Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Max Wolf
- SCIoI Excellence Cluster, Berlin, Germany
- IGB - Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
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3
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Ehlman SM, Scherer U, Wolf M. Developmental feedbacks and the emergence of individuality. ROYAL SOCIETY OPEN SCIENCE 2022; 9:221189. [PMID: 36465682 PMCID: PMC9709565 DOI: 10.1098/rsos.221189] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/07/2022] [Indexed: 05/08/2023]
Abstract
Behavioural individuality is a hallmark of animal life, with major consequences for fitness, ecology, and evolution. One of the most widely invoked explanations for this variation is that feedback loops between an animal's behaviour and its state (e.g. physiology, informational state, social rank, etc.) trigger and shape the development of individuality. Despite their often-cited importance, however, little is known about the ultimate causes of such feedbacks. Expanding on a previously employed model of adaptive behavioural development under uncertainty, we find that (i) behaviour-state feedbacks emerge as a direct consequence of adaptive behavioural development in particular selective environments and (ii) that the sign of these feedbacks, and thus the consequences for the development of behavioural individuality, can be directly predicted by the shape of the fitness function, with increasing fitness benefits giving rise to positive feedbacks and trait divergence and decreasing fitness benefits leading to negative feedbacks and trait convergence. Our findings provide a testable explanatory framework for the emergence of developmental feedbacks driving individuality and suggest that such feedbacks and their associated patterns of behavioural diversity are a direct consequence of adaptive behavioural development in particular selective environments.
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Affiliation(s)
- Sean M. Ehlman
- SCIoI Excellence Cluster, Berlin, Germany
- Humboldt University, Berlin, Germany
- IGB – Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Ulrike Scherer
- SCIoI Excellence Cluster, Berlin, Germany
- Humboldt University, Berlin, Germany
- IGB – Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Max Wolf
- SCIoI Excellence Cluster, Berlin, Germany
- IGB – Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
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4
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Ehlman SM, Scherer U, Wolf M. Developmental feedbacks and the emergence of individuality. ROYAL SOCIETY OPEN SCIENCE 2022; 9:221189. [PMID: 36465682 DOI: 10.5281/zenodo.7299681] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/07/2022] [Indexed: 05/24/2023]
Abstract
Behavioural individuality is a hallmark of animal life, with major consequences for fitness, ecology, and evolution. One of the most widely invoked explanations for this variation is that feedback loops between an animal's behaviour and its state (e.g. physiology, informational state, social rank, etc.) trigger and shape the development of individuality. Despite their often-cited importance, however, little is known about the ultimate causes of such feedbacks. Expanding on a previously employed model of adaptive behavioural development under uncertainty, we find that (i) behaviour-state feedbacks emerge as a direct consequence of adaptive behavioural development in particular selective environments and (ii) that the sign of these feedbacks, and thus the consequences for the development of behavioural individuality, can be directly predicted by the shape of the fitness function, with increasing fitness benefits giving rise to positive feedbacks and trait divergence and decreasing fitness benefits leading to negative feedbacks and trait convergence. Our findings provide a testable explanatory framework for the emergence of developmental feedbacks driving individuality and suggest that such feedbacks and their associated patterns of behavioural diversity are a direct consequence of adaptive behavioural development in particular selective environments.
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Affiliation(s)
- Sean M Ehlman
- SCIoI Excellence Cluster, Berlin, Germany
- Humboldt University, Berlin, Germany
- IGB - Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Ulrike Scherer
- SCIoI Excellence Cluster, Berlin, Germany
- Humboldt University, Berlin, Germany
- IGB - Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Max Wolf
- SCIoI Excellence Cluster, Berlin, Germany
- IGB - Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
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5
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Tate AT, Van Cleve J. Bet-hedging in innate and adaptive immune systems. Evol Med Public Health 2022; 10:256-265. [PMID: 35712085 PMCID: PMC9195227 DOI: 10.1093/emph/eoac021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 05/18/2022] [Indexed: 11/13/2022] Open
Abstract
Immune system evolution is shaped by the fitness costs and trade-offs associated with mounting an immune response. Costs that arise mainly as a function of the magnitude of investment, including energetic and immunopathological costs, are well-represented in studies of immune system evolution. Less well considered, however, are the costs of immune cell plasticity and specialization. Hosts in nature encounter a large diversity of microbes and parasites that require different and sometimes conflicting immune mechanisms for defense, but it takes precious time to recognize and correctly integrate signals for an effective polarized response. In this perspective, we propose that bet-hedging can be a viable alternative to plasticity in immune cell effector function, discuss conditions under which bet-hedging is likely to be an advantageous strategy for different arms of the immune system, and present cases from both innate and adaptive immune systems that suggest bet-hedging at play.
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Affiliation(s)
- Ann T Tate
- Department of Biological Sciences, Vanderbilt University , 465 21st Ave S. , Nashville, TN 37232, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation , Nashville, TN, USA
- Evolutionary Studies Institute, Vanderbilt University , Nashville, TN, USA
| | - Jeremy Van Cleve
- Department of Biology, University of Kentucky , 101 T.H. Morgan Building , Lexington, KY 40506, USA
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6
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Haaland TR, Wright J, Ratikainen II. Individual reversible plasticity as a genotype-level bet-hedging strategy. J Evol Biol 2021; 34:1022-1033. [PMID: 33844340 DOI: 10.1111/jeb.13788] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/24/2021] [Accepted: 04/05/2021] [Indexed: 10/21/2022]
Abstract
Reversible plasticity in phenotypic traits allows organisms to cope with environmental variation within lifetimes, but costs of plasticity may limit just how well the phenotype matches the environmental optimum. An additional adaptive advantage of plasticity might be to reduce fitness variance, in other words: bet-hedging to maximize geometric (rather than simply arithmetic) mean fitness. Here, we model the evolution of plasticity in the form of reaction norm slopes, with increasing costs as the slope or degree of plasticity increases. We find that greater investment in plasticity (i.e. a steeper reaction norm slope) is favoured in scenarios promoting bet-hedging as a response to multiplicative fitness accumulation (i.e. coarser environmental grains and fewer time steps prior to reproduction), because plasticity lowers fitness variance across environmental conditions. In contrast, in scenarios with finer environmental grain and many time steps prior to reproduction, bet-hedging plays less of a role and individual-level optimization favours evolution of shallower reaction norm slopes. However, the opposite pattern holds if plasticity costs themselves result in increased fitness variation, as might be the case for production costs of plasticity that depend on how much change is made to the phenotype each time step. We discuss these contrasting predictions from this partitioning of adaptive plasticity into short-term individual benefits versus long-term genotypic (bet-hedging) benefits, and how this approach enhances our understanding of the evolution of optimum levels of plasticity in examples from thermal physiology to advances in avian lay dates.
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Affiliation(s)
- Thomas R Haaland
- Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jonathan Wright
- Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Trondheim, Norway
| | - Irja I Ratikainen
- Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Trondheim, Norway
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7
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Cohort splitting from plastic bet-hedging: insights from empirical and theoretical investigations in a wolf spider. THEOR ECOL-NETH 2020. [DOI: 10.1007/s12080-020-00475-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AbstractBet-hedging strategies help organisms to decrease variance in their fitness in unpredictably changing environments, by which way lineage fitness can be maximized in the given environment. As one strategy, diversified bet-hedging helps to achieve that by increasing phenotypic variation in fitness-related traits. For example, in diversified tracking, parents may divide the developmental phenotypes of their offspring within broods, leading to cohort splitting among the progeny. Such diversification, though, should be probabilistic and sensitive to no external stimuli. However, it was recently highlighted that plasticity in response to environmental stimuli may be part of a more dynamic case of bet-hedging. Current understanding and empirical observations of such a plastic bet-hedging remain limited. Here I use a theoretical investigation relying on empirical grounds in a specific case of cohort splitting in the wolf spider Pardosa agrestis (Westring 1861). I investigated whether cohort splitting might be a bet-hedging strategy in females of P. agrestis, and whether it would be expected to be static or plastic bet-hedging. Results show that cohort splitting is likely a bet-hedging strategy in this species, by which females maximize their lineage fitness. Also, cohort splitting appears to arise from plastic bet-hedging, as in simulated populations where both static and plastic bet-hedging females occur, the latter have considerably higher geometric mean fitness. I discuss theoretical and empirical observations in light of the current theory, and draw predictions on specific aspects of this case of plastic bet-hedging.
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8
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Haaland TR, Wright J, Ratikainen II. Generalists versus specialists in fluctuating environments: a bet‐hedging perspective. OIKOS 2020. [DOI: 10.1111/oik.07109] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Thomas Ray Haaland
- Centre for Biodiversity Dynamics, Dept of Biology, Norwegian Univ. of Science and Technology Høgskoleringen 5 NO‐7044 Trondheim Norway
- Dept of Evolutionary Biology and Environmental Studies, Univ. of Zürich Winterthurerstrasse 190 CH‐8057 Zürich Switzerland
| | - Jonathan Wright
- Centre for Biodiversity Dynamics, Dept of Biology, Norwegian Univ. of Science and Technology Høgskoleringen 5 NO‐7044 Trondheim Norway
| | - Irja Ida Ratikainen
- Centre for Biodiversity Dynamics, Dept of Biology, Norwegian Univ. of Science and Technology Høgskoleringen 5 NO‐7044 Trondheim Norway
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9
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Bruijning M, Metcalf CJE, Jongejans E, Ayroles JF. The Evolution of Variance Control. Trends Ecol Evol 2020; 35:22-33. [PMID: 31519463 PMCID: PMC7482585 DOI: 10.1016/j.tree.2019.08.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 08/08/2019] [Accepted: 08/12/2019] [Indexed: 12/12/2022]
Abstract
Genetically identical individuals can be phenotypically variable, even in constant environmental conditions. The ubiquity of this phenomenon, known as 'intra-genotypic variability', is increasingly evident and the relevant mechanistic underpinnings are beginning to be understood. In parallel, theory has delineated a number of formal expectations for contexts in which such a feature would be adaptive. Here, we review empirical evidence across biological systems and theoretical expectations, including nonlinear averaging and bet hedging. We synthesize existing results to illustrate the dependence of selection outcomes both on trait characteristics, features of environmental variability, and species' demographic context. We conclude by discussing ways to bridge the gap between empirical evidence of intra-genotypic variability, studies demonstrating its genetic component, and evidence that it is adaptive.
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Affiliation(s)
- Marjolein Bruijning
- Department of Animal Ecology and Physiology, Radboud University, 6500, GL, Nijmegen, The Netherlands; Department of Ecology and Evolutionary Biology, Princeton University, 08540 Princeton, NJ, USA
| | - C Jessica E Metcalf
- Department of Ecology and Evolutionary Biology, Princeton University, 08540 Princeton, NJ, USA
| | - Eelke Jongejans
- Department of Animal Ecology and Physiology, Radboud University, 6500, GL, Nijmegen, The Netherlands
| | - Julien F Ayroles
- Department of Ecology and Evolutionary Biology, Princeton University, 08540 Princeton, NJ, USA.
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10
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Jerney J, Ahonen SA, Hakanen P, Suikkanen S, Kremp A. Generalist Life Cycle Aids Persistence of Alexandrium ostenfeldii (Dinophyceae) in Seasonal Coastal Habitats of the Baltic Sea. JOURNAL OF PHYCOLOGY 2019; 55:1226-1238. [PMID: 31520419 PMCID: PMC6916352 DOI: 10.1111/jpy.12919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 08/29/2019] [Indexed: 05/07/2023]
Abstract
In seasonal environments, strong gradients of environmental parameters can shape life cycles of phytoplankton. Depending on the rate of environmental fluctuation, specialist or generalist strategies may be favored, potentially affecting life cycle transitions. The present study examined life cycle transitions of the toxin producing Baltic dinoflagellate Alexandrium ostenfeldii and their regulation by environmental factors (temperature and nutrients). This investigation aimed to determine whether genetic recombination of different strains is required for resting cyst formation and whether newly formed cysts are dormant. Field data (temperature and salinity) and sediment surface samples were collected from a site with recurrent blooms and germination and encystment experiments were conducted under controlled laboratory conditions. Results indicate a lack of seasonal germination pattern, set by an endogenous rhythm, as commonly found with other dinoflagellates from the Baltic Sea. Germination of quiescent cysts was triggered by temperatures exceeding 10°C and combined nutrient limitation of nitrogen and phosphorus or a drop in temperature from 16 to 10°C triggered encystment most efficiently. Genetic recombination was not mandatory for the formation of resting cysts, but supported higher numbers of resistant cysts and enhanced germination capacity after a resting period. Findings from this study confirm that A. ostenfeldii follows a generalist germination and cyst formation strategy, driven by strong seasonality, which may support its persistence and possibly expansion in marginal environments in the future, if higher temperatures facilitate a longer growth season.
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Affiliation(s)
- Jacqueline Jerney
- Marine Research CenterFinnish Environment InstituteHelsinki00790Finland
- Tvärminne Zoological StationUniversity of HelsinkiHanko10900Finland
| | | | - Päivi Hakanen
- Marine Research CenterFinnish Environment InstituteHelsinki00790Finland
| | - Sanna Suikkanen
- Marine Research CenterFinnish Environment InstituteHelsinki00790Finland
| | - Anke Kremp
- Marine Research CenterFinnish Environment InstituteHelsinki00790Finland
- Leibniz‐Institut für Ostseeforschung WarnemündeRostock18119Germany
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11
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Haaland TR, Wright J, Ratikainen II. Bet-hedging across generations can affect the evolution of variance-sensitive strategies within generations. Proc Biol Sci 2019; 286:20192070. [PMID: 31771482 PMCID: PMC6939271 DOI: 10.1098/rspb.2019.2070] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
In order to understand how organisms cope with ongoing changes in environmental variability, it is necessary to consider multiple adaptations to environmental uncertainty on different time scales. Conservative bet-hedging (CBH) represents a long-term genotype-level strategy maximizing lineage geometric mean fitness in stochastic environments by decreasing individual fitness variance, despite also lowering arithmetic mean fitness. Meanwhile, variance-prone (aka risk-prone) strategies produce greater variance in short-term payoffs, because this increases expected arithmetic mean fitness if the relationship between payoffs and fitness is accelerating. Using evolutionary simulation models, we investigate whether selection for such variance-prone strategies is counteracted by selection for bet-hedging that works to adaptively reduce fitness variance. In our model, variance proneness evolves in fine-grained environments (lower correlations among individuals in energetic state and/or payoffs), and with larger numbers of independent decision events over which resources accumulate prior to selection. Conversely, multiplicative fitness accumulation, caused by coarser environmental grain and fewer decision events selection, favours CBH via greater variance aversion. We discuss examples of variance-sensitive strategies in optimal foraging, migration, life histories and cooperative breeding using this bet-hedging perspective. By linking disparate fields of research studying adaptations to variable environments, we should be better able to understand effects of human-induced rapid environmental change.
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Affiliation(s)
- Thomas R Haaland
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, 7491 Trondheim, Norway
| | - Jonathan Wright
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, 7491 Trondheim, Norway
| | - Irja I Ratikainen
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, 7491 Trondheim, Norway
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12
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Haaland TR, Botero CA. Alternative responses to rare selection events are differentially vulnerable to changes in the frequency, scope, and intensity of environmental extremes. Ecol Evol 2019; 9:11752-11761. [PMID: 31695885 PMCID: PMC6822052 DOI: 10.1002/ece3.5675] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 08/30/2019] [Accepted: 09/02/2019] [Indexed: 01/18/2023] Open
Abstract
Extreme weather events are becoming more frequent, severe, and/or widespread as a consequence of anthropogenic climate change. While the economic and ecological implications of these changes have received considerable attention, the role of evolutionary processes in determining organismal responses to these critical challenges is currently unknown. Here we develop a novel theoretical framework that explores how alternative pathways for adaptation to rare selection events can influence population-level vulnerabilities to future changes in the frequency, scope, and intensity of environmental extremes. We begin by showing that different life histories and trait expression profiles can shift the balance between additive and multiplicative properties of fitness accumulation, favoring different evolutionary responses to identical environmental phenomena. We then demonstrate that these different adaptive outcomes lead to predictable differences in population-level vulnerabilities to rapid increases in the frequency, intensity, or scope of extreme weather events. Specifically, we show that when the primary mode of fitness accumulation is additive, evolution favors ignoring environmental extremes and lineages become highly vulnerable to extinction if the frequency or scope of extreme weather events suddenly increases. Conversely, when fitness accumulates primarily multiplicatively, evolution favors bet-hedging phenotypes that cope well with historical extremes and are instead vulnerable to sudden increases in extreme event intensity. Our findings address a critical gap in our understanding of the potential consequences of rare selection events and provide a relatively simple rubric for assessing the vulnerabilities of any population of interest to changes in a wide variety of extreme environmental phenomena.
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Affiliation(s)
- Thomas R. Haaland
- Department of BiologyCentre for Biodiversity DynamicsNorwegian University of Science and TechnologyTrondheimNorway
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZürichZürichSwitzerland
| | - Carlos A. Botero
- Department of BiologyWashington University in Saint LouisSt. LouisMOUSA
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13
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Haaland TR, Wright J, Tufto J, Ratikainen II. Short-term insurance versus long-term bet-hedging strategies as adaptations to variable environments. Evolution 2018; 73:145-157. [PMID: 30549260 PMCID: PMC6590291 DOI: 10.1111/evo.13659] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 11/19/2018] [Indexed: 01/17/2023]
Abstract
Understanding how organisms adapt to environmental variation is a key challenge of biology. Central to this are bet‐hedging strategies that maximize geometric mean fitness across generations, either by being conservative or diversifying phenotypes. Theoretical models have identified environmental variation across generations with multiplicative fitness effects as driving the evolution of bet‐hedging. However, behavioral ecology has revealed adaptive responses to additive fitness effects of environmental variation within lifetimes, either through insurance or risk‐sensitive strategies. Here, we explore whether the effects of adaptive insurance interact with the evolution of bet‐hedging by varying the position and skew of both arithmetic and geometric mean fitness functions. We find that insurance causes the optimal phenotype to shift from the peak to down the less steeply decreasing side of the fitness function, and that conservative bet‐hedging produces an additional shift on top of this, which decreases as adaptive phenotypic variation from diversifying bet‐hedging increases. When diversifying bet‐hedging is not an option, environmental canalization to reduce phenotypic variation is almost always favored, except where the tails of the fitness function are steeply convex and produce a novel risk‐sensitive increase in phenotypic variance akin to diversifying bet‐hedging. Importantly, using skewed fitness functions, we provide the first model that explicitly addresses how conservative and diversifying bet‐hedging strategies might coexist.
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Affiliation(s)
- Thomas Ray Haaland
- Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jonathan Wright
- Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jarle Tufto
- Department of Mathematical Sciences, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Trondheim, Norway
| | - Irja Ida Ratikainen
- Department of Biology, Centre for Biodiversity Dynamics, Norwegian University of Science and Technology, Trondheim, Norway
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14
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Forsman A. On the role of sex differences for evolution in heterogeneous and changing fitness landscapes: insights from pygmy grasshoppers. Philos Trans R Soc Lond B Biol Sci 2018; 373:20170429. [PMID: 30150227 PMCID: PMC6125723 DOI: 10.1098/rstb.2017.0429] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2018] [Indexed: 12/16/2022] Open
Abstract
Much research has been devoted to study evolution of local adaptations by natural selection, and to explore the roles of neutral processes and developmental plasticity for patterns of diversity among individuals, populations and species. Some aspects, such as evolution of adaptive variation in phenotypic traits in stable environments, and the role of plasticity in predictable changing environments, are well understood. Other aspects, such as the role of sex differences for evolution in spatially heterogeneous and temporally changing environments and dynamic fitness landscapes, remain elusive. An increased understanding of evolution requires that sex differences in development, physiology, morphology, life-history and behaviours are more broadly considered. Studies of selection should take into consideration that the relationships linking phenotypes to fitness may vary not only according to environmental conditions but also differ between males and females. Such opposing selection, sex-by-environment interaction effects of selection and sex-specific developmental plasticity can have consequences for population differentiation, local adaptations and for the dynamics of polymorphisms. Integrating sex differences in analytical frameworks and population comparisons can therefore illuminate neglected evolutionary drivers and reconcile unexpected patterns. Here, I illustrate these issues using empirical examples from over 20 years of research on colour polymorphic Tetrix subulata and Tetrix undulata pygmy grasshoppers, and summarize findings from observational field studies, manipulation experiments, common garden breeding experiments and population genetics studies.This article is part of the theme issue 'Linking local adaptation with the evolution of sex differences'.
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Affiliation(s)
- Anders Forsman
- Ecology and Evolution in Microbial Model Systems, EEMiS, Department of Biology and Environmental Science, Linnaeus University, 391 82 Kalmar, Sweden
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15
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Variation in salinity tolerance between and within anadromous subpopulations of pike (Esox 1ucius). Sci Rep 2018; 8:22. [PMID: 29311634 PMCID: PMC5758576 DOI: 10.1038/s41598-017-18413-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 12/11/2017] [Indexed: 12/19/2022] Open
Abstract
Environmental heterogeneity is a key determinant of genetic and phenotypic diversity. Stable and homogenous environments tends to result in evolution of specialism and local adaptations, while temporally unpredictable environments may maintain a diversity of specialists, promote generalist strategies, or favour diversified bet hedging strategies. We compared salinity tolerance between two anadromous subpopulations of pike (Esox Lucius) that utilize freshwater spawning sites with different salinity regimes. Eggs from each population were artificially fertilized and incubated in a salinity gradient (0, 3, 5, 7, and 9 psu) using a split-brood design. Effects on embryonic development, hatching success, survival of larvae, and fry body length were compared between populations and families. The population naturally spawning in the stable freshwater habitat showed signs of specialization for freshwater spawning. The population exposed to fluctuating selective pressure in a spawning area with occasional brackish water intrusions tolerated higher salinities and displayed considerable variation in reaction norms. Genetic differences and plasticity of salinity tolerance may enable populations to cope with changes in salinity regimes associated with future climate change. That geographically adjacent subpopulations can constitute separate units with different genetic characteristics must be considered in management and conservation efforts to avoid potentially negative effects of genetic admixture on population fitness and persistence.
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Tarazona E, García-Roger EM, Carmona MJ. Experimental evolution of bet hedging in rotifer diapause traits as a response to environmental unpredictability. OIKOS 2017. [DOI: 10.1111/oik.04186] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Eva Tarazona
- Inst. Cavanilles de Biodiversitat i Biologia Evolutiva, Univ. de València; A.O. 22085, ES-46071 Valencia Spain
| | - Eduardo M. García-Roger
- Inst. Cavanilles de Biodiversitat i Biologia Evolutiva, Univ. de València; A.O. 22085, ES-46071 Valencia Spain
| | - María José Carmona
- Inst. Cavanilles de Biodiversitat i Biologia Evolutiva, Univ. de València; A.O. 22085, ES-46071 Valencia Spain
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Polačik M, Smith C, Reichard M. Maternal source of variability in the embryo development of an annual killifish. J Evol Biol 2017; 30:738-749. [DOI: 10.1111/jeb.13038] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/22/2016] [Accepted: 12/26/2016] [Indexed: 01/24/2023]
Affiliation(s)
- M. Polačik
- Institute of Vertebrate Biology; Czech Academy of Sciences; Brno Czech Republic
| | - C. Smith
- Institute of Vertebrate Biology; Czech Academy of Sciences; Brno Czech Republic
- School of Biology; University of St Andrews; St Andrews United Kingdom
- Bell-Pettigrew Museum of Natural History; University of St Andrews; St Andrews United Kingdom
| | - M. Reichard
- Institute of Vertebrate Biology; Czech Academy of Sciences; Brno Czech Republic
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