1
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Lichtenstein JLL, Schmitz OJ. Incorporating neurological and behavioral mechanisms of sociality into predator-prey models. Front Behav Neurosci 2023; 17:1122458. [PMID: 37138660 PMCID: PMC10149790 DOI: 10.3389/fnbeh.2023.1122458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 03/30/2023] [Indexed: 05/05/2023] Open
Abstract
Consumer-resource population models drive progress in predicting and understanding predation. However, they are often built by averaging the foraging outcomes of individuals to estimate per capita functional responses (functions that describe predation rate). Reliance on per-capita functional responses rests on the assumption that that individuals forage independently without affecting each other. Undermining this assumption, extensive behavioral neuroscience research has made clear that facilitative and antagonistic interactions among conspecifics frequently alter foraging through interference competition and persistent neurophysiological changes. For example, repeated social defeats dysregulates rodent hypothalamic signaling, modulating appetite. In behavioral ecology, similar mechanisms are studied under the concept of dominance hierarchies. Neurological and behavioral changes in response to conspecifics undoubtedly play some sort of role in the foraging of populations, but modern predator-prey theory does not explicitly include them. Here we describe how some modern approaches to population modeling might account for this. Further, we propose that spatial predator-prey models can be modified to describe plastic changes in foraging behavior driven by intraspecific interaction, namely individuals switching between patches or plastic strategies to avoid competition. Extensive neurological and behavioral ecology research suggests that interactions among conspecifics help shape populations' functional responses. Modeling interdependent functional responses woven together by behavioral and neurological mechanisms may thus be indispensable in predicting the outcome of consumer-resource interactions across systems.
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Affiliation(s)
- James L. L. Lichtenstein
- Department of Biology, Kenyon College, Gambier, OH, United States
- Yale School of the Environment, Yale University, New Haven, CT, United States
- *Correspondence: James L. L. Lichtenstein,
| | - Oswald J. Schmitz
- Yale School of the Environment, Yale University, New Haven, CT, United States
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2
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Plastic energy allocation toward life-history functions in a consumer-resource interaction : Analyzing the temporal patterns of the consumer-resource dynamics. J Math Biol 2022; 85:68. [PMID: 36416949 DOI: 10.1007/s00285-022-01834-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/03/2022] [Accepted: 11/07/2022] [Indexed: 11/24/2022]
Abstract
Various environmental alterations resulting from the current global change compromise the persistence of species in their habitual environment. To cope with the obvious risk of extinction, plastic responses provide organisms with rapid acclimatization to new environments. The premise of plastic rescue has been theoretically studied from mathematical models in both deterministic and stochastic environments, focusing on analyzing the persistence and stability of the populations. Here, we evaluate this premise in the framework of a consumer-resource interaction considering the energy investment towards reproduction vs. maintenance as a plastic trait according to positive/negative variation of the available resource. A basic consumer-resource mathematical model is formulated based on the principle of biomass conversion that incorporates the energy allocation toward vital functions of the life-cycle of consumer individuals. Our mathematical approach is based on the impulsive differential equations at fixed moments considering two impulsive effects associated with the instants at which consumers obtain environmental information and when energy allocation strategy change occurs. From a preliminary analysis of the non-plastic temporal dynamics, namely when the energy allocation is constant over time and without experiencing changes concerning the variation of resources, both the persistence and stability of the consumer-resource dynamic are dependent on the energy allocation strategies belonging to a set termed stability range. We found that the plastic energy allocation can promote a stable dynamical pattern in the consumer-resource interaction depending on both the magnitude of the energy allocation change and the time lag between environmental sensibility instants and when the expression of the plastic trait occurs.
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3
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Gibert JP, Han Z, Wieczynski DJ, Votzke S, Yammine A. Feedbacks between size and density determine rapid eco‐phenotypic dynamics. Funct Ecol 2022. [DOI: 10.1111/1365-2435.14070] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Ze‐Yi Han
- Department of Biology Duke University Durham NC USA
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4
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Rocca JD, Yammine A, Simonin M, Gibert JP. Protist Predation Influences the Temperature Response of Bacterial Communities. Front Microbiol 2022; 13:847964. [PMID: 35464948 PMCID: PMC9022080 DOI: 10.3389/fmicb.2022.847964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/08/2022] [Indexed: 01/04/2023] Open
Abstract
Temperature strongly influences microbial community structure and function, in turn contributing to global carbon cycling that can fuel further warming. Recent studies suggest that biotic interactions among microbes may play an important role in determining the temperature responses of these communities. However, how predation regulates these microbiomes under future climates is still poorly understood. Here, we assess whether predation by a key global bacterial consumer—protists—influences the temperature response of the community structure and function of a freshwater microbiome. To do so, we exposed microbial communities to two cosmopolitan protist species—Tetrahymena thermophila and Colpidium sp.—at two different temperatures, in a month-long microcosm experiment. While microbial biomass and respiration increased with temperature due to community shifts, these responses changed over time and in the presence of protists. Protists influenced microbial biomass and respiration rate through direct and indirect effects on bacterial community structure, and predator presence actually reduced microbial respiration at elevated temperature. Indicator species analyses showed that these predator effects were mostly determined by phylum-specific bacterial responses to protist density and cell size. Our study supports previous findings that temperature is an important driver of microbial communities but also demonstrates that the presence of a large predator can mediate these responses to warming.
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Affiliation(s)
- Jennifer D Rocca
- Department of Biology, Duke University, Durham, NC, United States.,Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, United States
| | - Andrea Yammine
- Department of Biology, Duke University, Durham, NC, United States
| | - Marie Simonin
- Department of Biology, Duke University, Durham, NC, United States.,University of Angers, Institut Agro, Institut National de la Recherche Agronomique, L'Institut de Recherche en Horticulture et Semences, Structure Fédérative de Recherche Qualité et Santé du Végétal, Angers, France
| | - Jean P Gibert
- Department of Biology, Duke University, Durham, NC, United States
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5
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Grosklos G, Cortez MH. Evolutionary and Plastic Phenotypic Change Can Be Just as Fast as Changes in Population Densities. Am Nat 2021; 197:47-59. [PMID: 33417519 DOI: 10.1086/711928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractEvolution and plasticity can drive population-level phenotypic change (e.g., changes in the mean phenotype) on timescales comparable to changes in population densities. However, it is unclear whether phenotypic change has the potential to be just as fast as changes in densities or whether comparable rates of change occur only when densities are changing slow enough for phenotypes to keep pace. Moreover, it is unclear whether this depends on the mode of adaptation. Using scaling theory and fast-slow dynamical systems theory, we develop a method for comparing maximum rates of density and phenotypic change estimated from population-level time-series data. We apply our method to 30 published empirical studies where changes in morphological traits are caused by evolution, plasticity, or an unknown combination. For every study, the maximum rate of phenotypic change was between 0.5 and 2.5 times faster than the maximum rate of change in density. Moreover, there were no systematic differences between systems with different modes of adaptation. Our results show that plasticity and evolution can drive phenotypic change just as fast as changes in densities. We discuss the implications of our results in terms of the strengths of feedbacks between population densities and traits.
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6
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DeLong JP. Detecting the Signature of Body Mass Evolution in the Broad-Scale Architecture of Food Webs. Am Nat 2020; 196:443-453. [PMID: 32970468 DOI: 10.1086/710350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractBody mass-based links between predator and prey are fundamental to the architecture of food webs. These links determine who eats whom across trophic levels and strongly influence the population abundance, flow of energy, and stability properties of natural communities. Body mass links scale up to create predator-prey mass relationships across species, but the origin of these relationships is unclear. Here I show that predator-prey mass relationships are consistent with the idea that body mass evolves to maximize a dependable supply of resource uptake. I used a global database of ~2,100 predator-prey links and a mechanistic optimization model to correctly predict the slope of the predator-prey mass scaling relationships across species generally and for nine taxonomic subsets. The model also predicted cross-group variation in the heights of the body mass relationships, providing an integrated explanation for mass relationships and their variation across taxa. The results suggest that natural selection on body mass at the local scale is detectable in ecological organization at the macro scale.
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7
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Elsadany AA, Din Q, Salman SM. Qualitative properties and bifurcations of discrete-time Bazykin–Berezovskaya predator–prey model. INT J BIOMATH 2020. [DOI: 10.1142/s1793524520500400] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The positive connection between the total individual fitness and population density is called the demographic Allee effect. A demographic Allee effect with a critical population size or density is strong Allee effect. In this paper, discrete counterpart of Bazykin–Berezovskaya predator–prey model is introduced with strong Allee effects. The steady states of the model, the existence and local stability are examined. Moreover, proposed discrete-time Bazykin–Berezovskaya predator–prey is obtained via implementation of piecewise constant method for differential equations. This model is compared with its continuous counterpart by applying higher-order implicit Runge–Kutta method (IRK) with very small step size. The comparison yields that discrete-time model has sensitive dependence on initial conditions. By implementing center manifold theorem and bifurcation theory, we derive the conditions under which the discrete-time model exhibits flip and Niemark–Sacker bifurcations. Moreover, numerical simulations are provided to validate the theoretical results.
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Affiliation(s)
- A. A. Elsadany
- Department of Mathematics, College of Science and Humanities in Al-Kharj, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
- Department of Basic Science, Faculty of Computers and Informatics, Ismailia, Suez Canal University, Egypt
| | - Qamar Din
- Department of Mathematics, The University of Poonch Rawalakot, Rawalakot 12350, Pakistan
| | - S. M. Salman
- Department of Mathematics, Faculty of Education, Alexandria University, Alexandria, Egypt
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8
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DeLong JP, Lyon S. Temperature alters the shape of predator-prey cycles through effects on underlying mechanisms. PeerJ 2020; 8:e9377. [PMID: 32596054 PMCID: PMC7307560 DOI: 10.7717/peerj.9377] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/27/2020] [Indexed: 12/27/2022] Open
Abstract
Background Predicting the effects of climate warming on the dynamics of ecological systems requires understanding how temperature influences birth rates, death rates and the strength of species interactions. The temperature dependance of these processes—which are the underlying mechanisms of ecological dynamics—is often thought to be exponential or unimodal, generally supported by short-term experiments. However, ecological dynamics unfold over many generations. Our goal was to empirically document shifts in predator–prey cycles over the full range of temperatures that can possibly support a predator–prey system and then to uncover the effect of temperature on the underlying mechanisms driving those changes. Methods We measured the population dynamics of the Didinium-Paramecium predator–prey system across a wide range of temperatures to reveal systematic changes in the dynamics of the system. We then used ordinary differential equation fitting to estimate parameters of a model describing the dynamics, and used these estimates to assess the long-term temperature dependance of all the underlying mechanisms. Results We found that predator–prey cycles shrank in state space from colder to hotter temperatures and that both cycle period and amplitude varied with temperature. Model parameters showed mostly unimodal responses to temperature, with one parameter (predator mortality) increasing monotonically with temperature and one parameter (predator conversion efficiency) invariant with temperature. Our results indicate that temperature can have profound, systematic effects on ecological dynamics, and these can arise through diverse and simultaneous changes in multiple underlying mechanisms. Predicting the effects of temperature on ecological dynamics may require additional investigation into how the underlying drivers of population dynamics respond to temperature beyond a short-term, acute response.
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Affiliation(s)
- John P DeLong
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Shelby Lyon
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
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9
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DeLong JP, Belmaker J. Ecological pleiotropy and indirect effects alter the potential for evolutionary rescue. Evol Appl 2019; 12:636-654. [PMID: 30828379 PMCID: PMC6383740 DOI: 10.1111/eva.12745] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 11/25/2018] [Indexed: 11/29/2022] Open
Abstract
Invading predators can negatively affect naïve prey populations due to a lack of evolved defenses. Many species therefore may be at risk of extinction due to overexploitation by exotic predators. Yet the strong selective effect of predation might drive evolution of imperiled prey toward more resistant forms, potentially allowing the prey to persist. We evaluated the potential for evolutionary rescue in an imperiled prey using Gillespie eco-evolutionary models (GEMs). We focused on a system parameterized for protists where changes in prey body size may influence intrinsic rate of population growth, space clearance rate (initial slope of the functional response), and the energetic benefit to predators. Our results show that the likelihood of rescue depends on (a) whether multiple parameters connected to the same evolving trait (i.e., ecological pleiotropy) combine to magnify selection, (b) whether the evolving trait causes negative indirect effects on the predator population by altering the energy gain per prey, (c) whether heritable trait variation is sufficient to foster rapid evolution, and (d) whether prey abundances are stable enough to avoid very rapid extinction. We also show that when evolution fosters rescue by increasing the prey equilibrium abundance, invasive predator populations also can be rescued, potentially leading to additional negative effects on other species. Thus, ecological pleiotropy, indirect effects, and system dynamics may be important factors influencing the potential for evolutionary rescue for both imperiled prey and invading predators. These results suggest that bolstering trait variation may be key to fostering evolutionary rescue, but also that the myriad direct and indirect effects of trait change could either make rescue outcomes unpredictable or, if they occur, cause rescue to have side effects such as bolstering the populations of invasive species.
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Affiliation(s)
| | - Jonathan Belmaker
- School of Zoology, George S. Wise Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
- The Steinhardt Museum of Natural HistoryTel Aviv UniversityTel AvivIsrael
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10
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Gibert JP, Yeakel JD. Eco-Evolutionary Origins of Diverse Abundance, Biomass, and Trophic Structures in Food Webs. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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11
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Rosenbaum B, Raatz M, Weithoff G, Fussmann GF, Gaedke U. Estimating Parameters From Multiple Time Series of Population Dynamics Using Bayesian Inference. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2018.00234] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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12
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Theodosiou L, Hiltunen T, Becks L. The role of stressors in altering eco‐evolutionary dynamics. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13263] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Loukas Theodosiou
- Community Dynamics GroupMax Planck Institute for Evolutionary Biology Plön Germany
- Department of Microbial Population BiologyMax Planck Institute for Evolutionary Biology Plön Germany
| | - Teppo Hiltunen
- Department of MicrobiologyUniversity of Helsinki Helsinki Finland
- Department of BiologyUniversity of Turku Turku Finland
| | - Lutz Becks
- Community Dynamics GroupMax Planck Institute for Evolutionary Biology Plön Germany
- Limnology ‐ Aquatic Ecology and Evolution, Limnological InstituteUniversity of Konstanz Konstanz Germany
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13
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Affiliation(s)
- Pierre Quévreux
- Sorbonne Universités, Sorbonne Paris Cité, Paris Diderot Univ Paris 07, CNRS, INRA, IRD, UPEC, Inst. d'Écologie et des Sciences de l'Environnement - Paris, iEES-Paris, 4 place Jussieu; FR-75252 Paris France
| | - Ulrich Brose
- EcoNetLab, German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Leipzig Germany
- Inst. of Biodiversity, Friedrich Schiller Univ. Jena; Jena Germany
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14
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Malerba ME, Palacios MM, Marshall DJ. Do larger individuals cope with resource fluctuations better? An artificial selection approach. Proc Biol Sci 2018; 285:rspb.2018.1347. [PMID: 30068687 DOI: 10.1098/rspb.2018.1347] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 07/11/2018] [Indexed: 11/12/2022] Open
Abstract
Size determines the rate at which organisms acquire and use resources but it is unclear what size should be favoured under unpredictable resource regimes. Some theories claim smaller organisms can grow faster following a resource pulse, whereas others argue larger species can accumulate more resources and maintain growth for longer periods between resource pulses. Testing these theories has relied on interspecific comparisons, which tend to confound body size with other life-history traits. As a more direct approach, we used 280 generations of artificial selection to evolve a 10-fold difference in mean body size between small- and large-selected phytoplankton lineages of Dunaliella tertiolecta, while controlling for biotic and abiotic variables. We then quantified how body size affected the ability of this species to grow at nutrient-replete conditions and following periods of nitrogen or phosphorous deprivation. Overall, smaller cells showed slower growth, lower storage capacity and poorer recovery from phosphorous depletion, as predicted by the 'fasting endurance hypothesis'. However, recovery from nitrogen limitation was independent of size-a finding unanticipated by current theories. Phytoplankton species are responsible for much of the global carbon fixation and projected trends of cell size decline could reduce primary productivity by lowering the ability of a cell to store resources.
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Affiliation(s)
- Martino E Malerba
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia .,School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
| | - Maria M Palacios
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia.,School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
| | - Dustin J Marshall
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia.,School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
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15
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Rosenbaum B, Rall BC. Fitting functional responses: Direct parameter estimation by simulating differential equations. Methods Ecol Evol 2018. [DOI: 10.1111/2041-210x.13039] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Benjamin Rosenbaum
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐Leipzig Leipzig Germany
- Institute of BiodiversityFriedrich Schiller University Jena Jena Germany
| | - Björn C. Rall
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐Leipzig Leipzig Germany
- Institute of BiodiversityFriedrich Schiller University Jena Jena Germany
- Department of Aquatic EcologyNetherlands Institute of Ecology (NIOO‐KNAW) Wageningen The Netherlands
- Department of Terrestrial EcologyNetherlands Institute of Ecology (NIOO‐KNAW) Wageningen The Netherlands
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16
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DeLong JP, Al-Ameeli Z, Lyon S, Van Etten JL, Dunigan DD. Size-dependent Catalysis of Chlorovirus Population Growth by A Messy Feeding Predator. MICROBIAL ECOLOGY 2018; 75:847-853. [PMID: 29119315 DOI: 10.1007/s00248-017-1106-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
Many chloroviruses replicate in endosymbiotic zoochlorellae that are protected from infection by their symbiotic host. To reach the high virus concentrations that often occur in natural systems, a mechanism is needed to release zoochlorellae from their hosts. We demonstrate that the ciliate predator Didinium nasutum foraging on zoochlorellae-bearing Paramecium bursaria can release live zoochlorellae from the ruptured prey cell that can then be infected by chloroviruses. The catalysis process is very effective, yielding roughly 95% of the theoretical infectious virus yield as determined by sonication of P. bursaria. Chlorovirus activation is more effective with smaller Didinia, as larger Didinia typically consume entire P. bursaria cells without rupturing them, precluding the release of zoochlorellae. We also show that the timing of Chlorovirus growth is tightly linked to the predator-prey cycle between Didinium and Paramecium, with the most rapid increase in chloroviruses temporally linked to the peak foraging rate of Didinium, supporting the idea that predator-prey cycles can drive cycles of Chlorovirus abundance.
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Affiliation(s)
- John P DeLong
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68588-0118, USA.
| | - Zeina Al-Ameeli
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, 68583-0961, USA
| | - Shelby Lyon
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68588-0118, USA
| | - James L Van Etten
- Department of Plant Pathology/Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0900, USA
| | - David D Dunigan
- Department of Plant Pathology/Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, 68583-0900, USA.
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17
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Clements CF, Ozgul A. Indicators of transitions in biological systems. Ecol Lett 2018; 21:905-919. [PMID: 29601665 DOI: 10.1111/ele.12948] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 11/22/2017] [Accepted: 02/22/2018] [Indexed: 12/13/2022]
Abstract
In the face of global biodiversity declines, predicting the fate of biological systems is a key goal in ecology. One popular approach is the search for early warning signals (EWSs) based on alternative stable states theory. In this review, we cover the theory behind nonlinearity in dynamic systems and techniques to detect the loss of resilience that can indicate state transitions. We describe the research done on generic abundance-based signals of instability that are derived from the phenomenon of critical slowing down, which represent the genesis of EWSs research. We highlight some of the issues facing the detection of such signals in biological systems - which are inherently complex and show low signal-to-noise ratios. We then document research on alternative signals of instability, including measuring shifts in spatial autocorrelation and trait dynamics, and discuss potential future directions for EWSs research based on detailed demographic and phenotypic data. We set EWSs research in the greater field of predictive ecology and weigh up the costs and benefits of simplicity vs. complexity in predictive models, and how the available data should steer the development of future methods. Finally, we identify some key unanswered questions that, if solved, could improve the applicability of these methods.
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Affiliation(s)
- Christopher F Clements
- School of Biosciences, The University of Melbourne, Parkville, Vic., 3010, Australia.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, 8057, Switzerland
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, 8057, Switzerland
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18
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Li Y, Rall BC, Kalinkat G. Experimental duration and predator satiation levels systematically affect functional response parameters. OIKOS 2018. [DOI: 10.1111/oik.04479] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yuanheng Li
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Leipzig Germany
- J. F. Blumenbach Inst. of Zoology and Anthropology, Georg August Univ.; Göttingen Germany
| | - Björn C. Rall
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; Leipzig Germany
- Inst. of Ecology, Friedrich Schiller Univ. Jena; Jena Germany
| | - Gregor Kalinkat
- Dept of Biology and Ecology of Fishes; Leibniz-Inst. of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310; DE-12587 Berlin Germany
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19
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DeLong JP, Hanley TC, Gibert JP, Puth LM, Post DM. Life history traits and functional processes generate multiple pathways to ecological stability. Ecology 2017; 99:5-12. [DOI: 10.1002/ecy.2070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 09/07/2017] [Accepted: 10/17/2017] [Indexed: 11/08/2022]
Affiliation(s)
- John P. DeLong
- School of Biological Sciences; University of Nebraska-Lincoln; Lincoln Nebraska 68588 USA
| | - Torrance C. Hanley
- Marine Science Center; Northeastern University; Nahant Massachusetts 01908 USA
| | - Jean P. Gibert
- School of Biological Sciences; University of Nebraska-Lincoln; Lincoln Nebraska 68588 USA
| | - Linda M. Puth
- Department of Ecology and Evolutionary Biology; Yale University; New Haven Connecticut 06520 USA
| | - David M. Post
- Department of Ecology and Evolutionary Biology; Yale University; New Haven Connecticut 06520 USA
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20
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Gibert JP, Allen RL, Hruska RJ, DeLong JP. The ecological consequences of environmentally induced phenotypic changes. Ecol Lett 2017; 20:997-1003. [DOI: 10.1111/ele.12797] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 03/30/2017] [Accepted: 05/15/2017] [Indexed: 11/26/2022]
Affiliation(s)
- Jean P. Gibert
- School of Biological Sciences University of Nebraska–Lincoln Lincoln Nebraska68588 USA
| | - Rachel L. Allen
- School of Biological Sciences University of Nebraska–Lincoln Lincoln Nebraska68588 USA
| | - Ron J. Hruska
- School of Biological Sciences University of Nebraska–Lincoln Lincoln Nebraska68588 USA
| | - John P. DeLong
- School of Biological Sciences University of Nebraska–Lincoln Lincoln Nebraska68588 USA
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21
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DeLong JP. Ecological Pleiotropy Suppresses the Dynamic Feedback Generated by a Rapidly Changing Trait. Am Nat 2017; 189:592-597. [PMID: 28410029 DOI: 10.1086/691100] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Population dynamics may carry a signature of an ecology-evolution-ecology feedback, known as eco-evolutionary dynamics, when functionally important traits change. Given current theory, the absence of a feedback from a trait with strong links to species interactions should not occur. In a previous study with the Didinium-Paramecium predator-prey system, however, rapid and large-magnitude changes in predator cell volume occurred without any noticeable effect on the population dynamics. Here I resolve this theory-data conflict by showing that ecological pleiotropy-when a trait has more than one functional effect on an ecological process-suppresses shifts in dynamics that would arise, given the links between cell volume and the species interaction. Whether eco-evolutionary dynamics arise, therefore, depends not just on the ecology-evolution feedback but on the net effect that a trait has on different parts of the underlying interaction.
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22
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Predators catalyze an increase in chloroviruses by foraging on the symbiotic hosts of zoochlorellae. Proc Natl Acad Sci U S A 2016; 113:13780-13784. [PMID: 27821770 DOI: 10.1073/pnas.1613843113] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Virus population growth depends on contacts between viruses and their hosts. It is often unclear how sufficient contacts are made between viruses and their specific hosts to generate spikes in viral abundance. Here, we show that copepods, acting as predators, can bring aquatic viruses and their algal hosts into contact. Specifically, predation of the protist Paramecium bursaria by copepods resulted in a >100-fold increase in the number of chloroviruses in 1 d. Copepod predation can be seen as an ecological "catalyst" by increasing contacts between chloroviruses and their hosts, zoochlorellae (endosymbiotic algae that live within paramecia), thereby facilitating viral population growth. When feeding, copepods passed P. bursaria through their digestive tract only partially digested, releasing endosymbiotic algae that still supported viral reproduction and resulting in a virus population spike. A simple predator-prey model parameterized for copepods consuming protists generates cycle periods for viruses consistent with those observed in natural ponds. Food webs are replete with similar symbiotic organisms, and we suspect the predator catalyst mechanism is capable of generating blooms for other endosymbiont-targeting viruses.
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23
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Schneider FD, Brose U, Rall BC, Guill C. Animal diversity and ecosystem functioning in dynamic food webs. Nat Commun 2016; 7:12718. [PMID: 27703157 PMCID: PMC5059466 DOI: 10.1038/ncomms12718] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 07/27/2016] [Indexed: 11/22/2022] Open
Abstract
Species diversity is changing globally and locally, but the complexity of ecological communities hampers a general understanding of the consequences of animal species loss on ecosystem functioning. High animal diversity increases complementarity of herbivores but also increases feeding rates within the consumer guild. Depending on the balance of these counteracting mechanisms, species-rich animal communities may put plants under top-down control or may release them from grazing pressure. Using a dynamic food-web model with body-mass constraints, we simulate ecosystem functions of 20,000 communities of varying animal diversity. We show that diverse animal communities accumulate more biomass and are more exploitative on plants, despite their higher rates of intra-guild predation. However, they do not reduce plant biomass because the communities are composed of larger, and thus energetically more efficient, plant and animal species. This plasticity of community body-size structure reconciles the debate on the consequences of animal species loss for primary productivity.
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Affiliation(s)
- Florian D Schneider
- Institut des Sciences de l'Evolution (ISEM), Université Montpellier, CNRS, IRD, UMR 5554, C.C.065, 34095 Montpellier Cedex 05, France
- Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, 60325 Frankfurt am Main, Germany
| | - Ulrich Brose
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher, Platz 5e, 04103 Leipzig, Germany
- Institute of Ecology, Friedrich Schiller Universtiy Jena, Dornburger-Strasse 159, 07743 Jena, Germany
| | - Björn C Rall
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher, Platz 5e, 04103 Leipzig, Germany
- Institute of Ecology, Friedrich Schiller Universtiy Jena, Dornburger-Strasse 159, 07743 Jena, Germany
| | - Christian Guill
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box, 94248, 1090 GE Amsterdam, The Netherlands
- Institute of Biochemistry and Biology, University of Potsdam, Maulbeerallee 2, 14469 Potsdam, Germany
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24
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Functional ecology of aquatic phagotrophic protists – Concepts, limitations, and perspectives. Eur J Protistol 2016; 55:50-74. [DOI: 10.1016/j.ejop.2016.03.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 03/15/2016] [Accepted: 03/23/2016] [Indexed: 01/02/2023]
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25
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Gibert JP, Chelini MC, Rosenthal MF, DeLong JP. Crossing regimes of temperature dependence in animal movement. GLOBAL CHANGE BIOLOGY 2016; 22:1722-36. [PMID: 26854767 DOI: 10.1111/gcb.13245] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 01/21/2016] [Accepted: 01/29/2016] [Indexed: 05/16/2023]
Abstract
A pressing challenge in ecology is to understand the effects of changing global temperatures on food web structure and dynamics. The stability of these complex ecological networks largely depends on how predator-prey interactions may respond to temperature changes. Because predators and prey rely on their velocities to catch food or avoid being eaten, understanding how temperatures may affect animal movement is central to this quest. Despite our efforts, we still lack a mechanistic understanding of how the effect of temperature on metabolic processes scales up to animal movement and beyond. Here, we merge a biomechanical approach, the Metabolic Theory of Ecology and empirical data to show that animal movement displays multiple regimes of temperature dependence. We also show that crossing these regimes has important consequences for population dynamics and stability, which depend on the parameters controlling predator-prey interactions. We argue that this dependence upon interaction parameters may help explain why experimental work on the temperature dependence of interaction strengths has so far yielded conflicting results. More importantly, these changes in the temperature dependence of animal movement can have consequences that go well beyond ecological interactions and affect, for example, animal communication, mating, sensory detection, and any behavioral modality dependent on the movement of limbs. Finally, by not taking into account the changes in temperature dependence reported here we might not be able to properly forecast the impact of global warming on ecological processes and propose appropriate mitigation action when needed.
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Affiliation(s)
- Jean P Gibert
- School of Biological Sciences, University of Nebraska - Lincoln, Lincoln, NE, 68588, USA
| | - Marie-Claire Chelini
- School of Biological Sciences, University of Nebraska - Lincoln, Lincoln, NE, 68588, USA
| | - Malcolm F Rosenthal
- School of Biological Sciences, University of Nebraska - Lincoln, Lincoln, NE, 68588, USA
| | - John P DeLong
- School of Biological Sciences, University of Nebraska - Lincoln, Lincoln, NE, 68588, USA
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26
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Clements CF, Ozgul A. Including trait-based early warning signals helps predict population collapse. Nat Commun 2016; 7:10984. [PMID: 27009968 PMCID: PMC4820807 DOI: 10.1038/ncomms10984] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 02/05/2016] [Indexed: 11/11/2022] Open
Abstract
Foreseeing population collapse is an on-going target in ecology, and this has led to the development of early warning signals based on expected changes in leading indicators before a bifurcation. Such signals have been sought for in abundance time-series data on a population of interest, with varying degrees of success. Here we move beyond these established methods by including parallel time-series data of abundance and fitness-related trait dynamics. Using data from a microcosm experiment, we show that including information on the dynamics of phenotypic traits such as body size into composite early warning indices can produce more accurate inferences of whether a population is approaching a critical transition than using abundance time-series alone. By including fitness-related trait information alongside traditional abundance-based early warning signals in a single metric of risk, our generalizable approach provides a powerful new way to assess what populations may be on the verge of collapse. Predicting population collapse by monitoring key early warning signals in time-series data may highlight when interventions are needed. Here, the authors show that including information on phenotypic traits like body size can more accurately predict critical transitions than abundance data alone.
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Affiliation(s)
- Christopher F Clements
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich CH-8057, Switzerland
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich CH-8057, Switzerland
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27
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DeLong JP, Gibert JP. Gillespie eco-evolutionary models (GEMs) reveal the role of heritable trait variation in eco-evolutionary dynamics. Ecol Evol 2016; 6:935-45. [PMID: 26941937 PMCID: PMC4761774 DOI: 10.1002/ece3.1959] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 12/07/2015] [Accepted: 12/09/2015] [Indexed: 11/27/2022] Open
Abstract
Heritable trait variation is a central and necessary ingredient of evolution. Trait variation also directly affects ecological processes, generating a clear link between evolutionary and ecological dynamics. Despite the changes in variation that occur through selection, drift, mutation, and recombination, current eco-evolutionary models usually fail to track how variation changes through time. Moreover, eco-evolutionary models assume fitness functions for each trait and each ecological context, which often do not have empirical validation. We introduce a new type of model, Gillespie eco-evolutionary models (GEMs), that resolves these concerns by tracking distributions of traits through time as eco-evolutionary dynamics progress. This is done by allowing change to be driven by the direct fitness consequences of model parameters within the context of the underlying ecological model, without having to assume a particular fitness function. GEMs work by adding a trait distribution component to the standard Gillespie algorithm - an approach that models stochastic systems in nature that are typically approximated through ordinary differential equations. We illustrate GEMs with the Rosenzweig-MacArthur consumer-resource model. We show not only how heritable trait variation fuels trait evolution and influences eco-evolutionary dynamics, but also how the erosion of variation through time may hinder eco-evolutionary dynamics in the long run. GEMs can be developed for any parameter in any ordinary differential equation model and, furthermore, can enable modeling of multiple interacting traits at the same time. We expect GEMs will open the door to a new direction in eco-evolutionary and evolutionary modeling by removing long-standing modeling barriers, simplifying the link between traits, fitness, and dynamics, and expanding eco-evolutionary treatment of a greater diversity of ecological interactions. These factors make GEMs much more than a modeling advance, but an important conceptual advance that bridges ecology and evolution through the central concept of heritable trait variation.
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Affiliation(s)
- John P. DeLong
- School of Biological SciencesUniversity of Nebraska – LincolnLincolnNebraska68588
| | - Jean P. Gibert
- School of Biological SciencesUniversity of Nebraska – LincolnLincolnNebraska68588
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28
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DeLong JP, Forbes VE, Galic N, Gibert JP, Laport RG, Phillips JS, Vavra JM. How fast is fast? Eco-evolutionary dynamics and rates of change in populations and phenotypes. Ecol Evol 2016; 6:573-81. [PMID: 26843940 PMCID: PMC4729258 DOI: 10.1002/ece3.1899] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 11/23/2015] [Accepted: 11/24/2015] [Indexed: 11/14/2022] Open
Abstract
It is increasingly recognized that evolution may occur in ecological time. It is not clear, however, how fast evolution – or phenotypic change more generally – may be in comparison with the associated ecology, or whether systems with fast ecological dynamics generally have relatively fast rates of phenotypic change. We developed a new dataset on standardized rates of change in population size and phenotypic traits for a wide range of species and taxonomic groups. We show that rates of change in phenotypes are generally no more than 2/3, and on average about 1/4, the concurrent rates of change in population size. There was no relationship between rates of population change and rates of phenotypic change across systems. We also found that the variance of both phenotypic and ecological rates increased with the mean across studies following a power law with an exponent of two, while temporal variation in phenotypic rates was lower than in ecological rates. Our results are consistent with the view that ecology and evolution may occur at similar time scales, but clarify that only rarely do populations change as fast in traits as they do in abundance.
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Affiliation(s)
- John P DeLong
- School of Biological Sciences University of Nebraska - Lincoln Lincoln Nebraska 68588
| | - Valery E Forbes
- School of Biological Sciences University of Nebraska - Lincoln Lincoln Nebraska 68588
| | - Nika Galic
- School of Biological Sciences University of Nebraska - Lincoln Lincoln Nebraska 68588
| | - Jean P Gibert
- School of Biological Sciences University of Nebraska - Lincoln Lincoln Nebraska 68588
| | - Robert G Laport
- School of Biological Sciences University of Nebraska - Lincoln Lincoln Nebraska 68588
| | - Joseph S Phillips
- School of Biological Sciences University of Nebraska - Lincoln Lincoln Nebraska 68588
| | - Janna M Vavra
- School of Biological Sciences University of Nebraska - Lincoln Lincoln Nebraska 68588
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29
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Brooks ME, Mugabo M, Rodgers GM, Benton TG, Ozgul A. How well can body size represent effects of the environment on demographic rates? Disentangling correlated explanatory variables. J Anim Ecol 2015; 85:318-28. [PMID: 26620593 DOI: 10.1111/1365-2656.12465] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 10/20/2015] [Indexed: 11/28/2022]
Abstract
Demographic rates are shaped by the interaction of past and current environments that individuals in a population experience. Past environments shape individual states via selection and plasticity, and fitness-related traits (e.g. individual size) are commonly used in demographic analyses to represent the effect of past environments on demographic rates. We quantified how well the size of individuals captures the effects of a population's past and current environments on demographic rates in a well-studied experimental system of soil mites. We decomposed these interrelated sources of variation with a novel method of multiple regression that is useful for understanding nonlinear relationships between responses and multicollinear explanatory variables. We graphically present the results using area-proportional Venn diagrams. Our novel method was developed by combining existing methods and expanding upon them. We showed that the strength of size as a proxy for the past environment varied widely among vital rates. For instance, in this organism with an income breeding life history, the environment had more effect on reproduction than individual size, but with substantial overlap indicating that size encompassed some of the effects of the past environment on fecundity. This demonstrates that the strength of size as a proxy for the past environment can vary widely among life-history processes within a species, and this variation should be taken into consideration in trait-based demographic or individual-based approaches that focus on phenotypic traits as state variables. Furthermore, the strength of a proxy will depend on what state variable(s) and what demographic rate is being examined; that is, different measures of body size (e.g. length, volume, mass, fat stores) will be better or worse proxies for various life-history processes.
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Affiliation(s)
- Mollie E Brooks
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Marianne Mugabo
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Gwendolen M Rodgers
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Timothy G Benton
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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30
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Van Allen BG, Rudolf VHW. Habitat-mediated carry-over effects lead to context-dependent outcomes of species interactions. J Anim Ecol 2015; 84:1646-56. [PMID: 26060938 DOI: 10.1111/1365-2656.12408] [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: 12/16/2014] [Accepted: 05/30/2015] [Indexed: 11/28/2022]
Abstract
When individuals disperse, their performance in newly colonized habitats can be influenced by the conditions they experienced in the past, leading to environmental carry-over effects. While carry-over effects are ubiquitous in animal and plant systems, their impact on species interactions and coexistence are largely ignored in traditional coexistence theory. Here we used a combination of modelling and experiments with two competing species to examine when and how such environmental carry-over effects influence community dynamics and competitive exclusions. We found that variation in the natal habitat quality of colonizing individuals created carry-over effects which altered competitive coefficients, fecundity and mortality rates, and extinction probabilities of both species. As a consequence, the dynamics of competitive exclusion within and across habitat types was contingent on the natal habitat of colonizing individuals, indicating that spatial carry-over effects can fundamentally alter the dynamics and outcome of interspecific competition. Interestingly, carry-over effects persistently influenced dynamics in systems with interspecific competition for the entire duration of the experiment while carry-over effects were transient and only influenced initial dynamics in single-species populations. Thus carry-over effects can be enhanced by species interactions, suggesting that their long-term effects may often not be accurately predicted by single-species studies. Given that carry-over effects are ubiquitous in heterogeneous landscapes, our results provide a novel mechanism that could help explain variation in the structure of natural communities.
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Affiliation(s)
- Benjamin G Van Allen
- Department of Ecology and Evolutionary Biology, Rice University, MS-170, Houston, TX, 77005, USA
| | - Volker H W Rudolf
- Department of Ecology and Evolutionary Biology, Rice University, MS-170, Houston, TX, 77005, USA
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31
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O'Gorman EJ. Integrating comparative functional response experiments into global change research. J Anim Ecol 2015; 83:525-7. [PMID: 26051857 DOI: 10.1111/1365-2656.12216] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 02/12/2014] [Indexed: 11/28/2022]
Abstract
There is a growing appreciation for the importance of non-consumptive effects in predator-prey interaction research, which can often outweigh the importance of direct feeding. Barrios-O'Neill et al. (2014) report a novel method to characterize such effects by comparing the functional response of native and introduced intermediate consumers in the presence and absence of a higher predator. The invader exhibited stronger direct feeding and was also more resistant to intimidation by the higher predator. This experimental framework may be incorporated into mainstream global change research, for example, to quantify the importance of non-consumptive effects for the success or failure of biological invasions.
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Affiliation(s)
- Eoin J O'Gorman
- Silwood Park Campus, Imperial College London, Buckhurst Road, Ascot, Berkshire, SL5 7PY, UK
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32
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Li J, Montagnes DJS. Restructuring fundamental predator-prey models by recognising prey-dependent conversion efficiency and mortality rates. Protist 2015; 166:211-23. [PMID: 25819465 DOI: 10.1016/j.protis.2015.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 02/17/2015] [Accepted: 02/18/2015] [Indexed: 01/13/2023]
Abstract
Incorporating protozoa into population models (from simple predator-prey explorations to complex food web simulations) is of conceptual, ecological, and economic importance. From theoretical and empirical perspectives, we expose unappreciated complexity in the traditional predator-prey model structure and provide a parsimonious solution, especially for protistologists. We focus on how prey abundance alters two key components of models: predator conversion efficiency (e, the proportion of prey converted to predator, before mortality loss) and predator mortality (δ, the portion of the population lost though death). Using a well-established model system (Paramecium and Didinium), we collect data to parameterize a range of existing and novel population models that differ in the functional forms of e and δ. We then compare model simulations to an empirically obtained time-series of predator-prey population dynamics. The analysis indicates that prey-dependent e and δ should be considered when structuring population models and that both prey and predator biomass also vary with prey abundance. Both of these impact the ability of the model to predict population dynamics and, therefore, should be included in theoretical model evaluations and assessment of ecosystem dynamics associated with biomass flux.
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Affiliation(s)
- Jiqiu Li
- Laboratory of Protozoology, KLB07006, College of Life Science, South China Normal University, Guangzhou 510631, China
| | - David J S Montagnes
- Institute of Integrative Biology, BioSciences Building, University of Liverpool, Liverpool, UK L6 97ZB.
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33
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DeLong JP, Gilbert B, Shurin JB, Savage VM, Barton BT, Clements CF, Dell AI, Greig HS, Harley CDG, Kratina P, McCann KS, Tunney TD, Vasseur DA, O'Connor MI. The body size dependence of trophic cascades. Am Nat 2015; 185:354-66. [PMID: 25674690 DOI: 10.1086/679735] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Trophic cascades are indirect positive effects of predators on resources via control of intermediate consumers. Larger-bodied predators appear to induce stronger trophic cascades (a greater rebound of resource density toward carrying capacity), but how this happens is unknown because we lack a clear depiction of how the strength of trophic cascades is determined. Using consumer resource models, we first show that the strength of a trophic cascade has an upper limit set by the interaction strength between the basal trophic group and its consumer and that this limit is approached as the interaction strength between the consumer and its predator increases. We then express the strength of a trophic cascade explicitly in terms of predator body size and use two independent parameter sets to calculate how the strength of a trophic cascade depends on predator size. Both parameter sets predict a positive effect of predator size on the strength of a trophic cascade, driven mostly by the body size dependence of the interaction strength between the first two trophic levels. Our results support previous empirical findings and suggest that the loss of larger predators will have greater consequences on trophic control and biomass structure in food webs than the loss of smaller predators.
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Affiliation(s)
- John P DeLong
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588
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34
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Kiełbasa A, Walczyńska A, Fiałkowska E, Pajdak-Stós A, Kozłowski J. Seasonal changes in the body size of two rotifer species living in activated sludge follow the Temperature-Size Rule. Ecol Evol 2014; 4:4678-89. [PMID: 25558362 PMCID: PMC4278820 DOI: 10.1002/ece3.1292] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 09/11/2014] [Accepted: 09/22/2014] [Indexed: 11/11/2022] Open
Abstract
Temperature-Size Rule (TSR) is a phenotypic body size response of ectotherms to changing temperature. It is known from the laboratory studies, but seasonal patterns in the field were not studied so far. We examined the body size changes in time of rotifers inhabiting activated sludge. We hypothesize that temperature is the most influencing parameter in sludge environment, leading sludge rotifers to seasonally change their body size according to TSR, and that oxygen content also induces the size response. The presence of TSR in Lecane inermis rotifer was tested in a laboratory study with two temperature and two food-type treatments. The effect of interaction between temperature and food was significant; L. inermis followed TSR in one food type only. The seasonal variability in the body sizes of the rotifers L. inermis and Cephalodella gracilis was estimated by monthly sampling and analyzed by multiple regression, in relation to the sludge parameters selected as the most influential by multivariate analysis, and predicted to alter rotifer body size (temperature and oxygen). L. inermis varied significantly in size throughout the year, and this variability is explained by temperature as predicted by the TSR, but not by oxygen availability. C. gracilis also varied in size, though this variability was explained by both temperature and oxygen. We suggest that sludge age acts as a mortality factor in activated sludge. It may have a seasonal effect on the body size of L. inermis and modify a possible effect of oxygen. Activated sludge habitat is driven by both biological processes and human regulation, yet its resident organisms follow general evolutionary rule as they do in other biological systems. The interspecific response patterns differ, revealing the importance of taking species-specific properties into account. Our findings are applicable to sludge properties enhancement through optimizing the conditions for its biological component.
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Affiliation(s)
- Anna Kiełbasa
- Institute of Environmental Sciences, Jagiellonian University Gronostajowa 7, 30-387, Krakow, Poland
| | - Aleksandra Walczyńska
- Institute of Environmental Sciences, Jagiellonian University Gronostajowa 7, 30-387, Krakow, Poland
| | - Edyta Fiałkowska
- Institute of Environmental Sciences, Jagiellonian University Gronostajowa 7, 30-387, Krakow, Poland
| | - Agnieszka Pajdak-Stós
- Institute of Environmental Sciences, Jagiellonian University Gronostajowa 7, 30-387, Krakow, Poland
| | - Jan Kozłowski
- Institute of Environmental Sciences, Jagiellonian University Gronostajowa 7, 30-387, Krakow, Poland
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35
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DeLong JP. The body-size dependence of mutual interference. Biol Lett 2014; 10:20140261. [PMID: 24919702 PMCID: PMC4090548 DOI: 10.1098/rsbl.2014.0261] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 05/23/2014] [Indexed: 11/12/2022] Open
Abstract
The parameters that drive population dynamics typically show a relationship with body size. By contrast, there is no theoretical or empirical support for a body-size dependence of mutual interference, which links foraging rates to consumer density. Here, I develop a model to predict that interference may be positively or negatively related to body size depending on how resource body size scales with consumer body size. Over a wide range of body sizes, however, the model predicts that interference will be body-size independent. This prediction was supported by a new dataset on interference and consumer body size. The stabilizing effect of intermediate interference therefore appears to be roughly constant across size, while the effect of body size on population dynamics is mediated through other parameters.
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Affiliation(s)
- John P DeLong
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
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36
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DeLong JP, Hanley TC. The rate-size trade-off structures intraspecific variation in Daphnia ambigua life history parameters. PLoS One 2013; 8:e81024. [PMID: 24312518 PMCID: PMC3849075 DOI: 10.1371/journal.pone.0081024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 10/15/2013] [Indexed: 11/23/2022] Open
Abstract
The identification of trade-offs is necessary for understanding the evolution and maintenance of diversity. Here we employ the supply-demand (SD) body size optimization model to predict a trade-off between asymptotic body size and growth rate. We use the SD model to quantitatively predict the slope of the relationship between asymptotic body size and growth rate under high and low food regimes and then test the predictions against observations for Daphnia ambigua. Close quantitative agreement between observed and predicted slopes at both food levels lends support to the model and confirms that a ‘rate-size’ trade-off structures life history variation in this population. In contrast to classic life history expectations, growth and reproduction were positively correlated after controlling for the rate-size trade-off. We included 12 Daphnia clones in our study, but clone identity explained only some of the variation in life history traits. We also tested the hypothesis that growth rate would be positively related to intergenic spacer length (i.e. the growth rate hypothesis) across clones, but we found that clones with intermediate intergenic spacer lengths had larger asymptotic sizes and slower growth rates. Our results strongly support a resource-based optimization of body size following the SD model. Furthermore, because some resource allocation decisions necessarily precede others, understanding interdependent life history traits may require a more nested approach.
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Affiliation(s)
- John P. DeLong
- Yale University, Department of Ecology and Evolutionary Biology, New Haven, Connecticut, United States of America
- * E-mail:
| | - Torrance C. Hanley
- Yale University, Department of Ecology and Evolutionary Biology, New Haven, Connecticut, United States of America
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