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Journal ArticleDOI

Parasitism effects on coexistence and stability within simple trophic modules.

07 Dec 2018-Journal of Theoretical Biology (Academic Press)-Vol. 458, pp 68-77
TL;DR: The consequences of parasitism on coexistence and stability within a simple trophic module: one predator consuming two prey species in competition are investigated and suggest that parasites potentially increase species coexistence.
About: This article is published in Journal of Theoretical Biology.The article was published on 2018-12-07 and is currently open access. It has received 8 citations till now. The article focuses on the topics: Paradox of enrichment & Trophic level.

Summary (2 min read)

1. Introduction

  • The authors first consider infection of the prey, then of the predator species.
  • In each case, the authors first tackle virulence effects (on reproduction or mortality rates), then interaction effects (changes in trophic interactions).
  • Such an approach is however limited, as it neglects important ecological feedbacks (e.g. parasitepredator competition when prey species are infected).
  • The authors aims are to understand how the consequences of parasitism depend on the host trophic level or on parasite effect (virulence or interaction).
  • Predicting how interaction effects alter stability is more difficult as they may modify both the energy transfer (destabilizing the system), and the distribution of interaction strengths within the module (Fig. 1c ).

2.4. Method of analysis of the different models

  • For all scenarios, the authors perform numerical analyses using Mathematica® 11.1.1 (Wolfram research).
  • First, using the structured models, the authors simulate the effect of a parasite addition in a non-infected system.
  • Such simulations illustrate how the impacts vary depending on the parasitism effect (virulence or interaction) and on the infected species (predator or prey).
  • For both the unstructured and the structured models, the authors then analyze the effects of parasitism more globally, through 2D-bifurcation diagrams (one dimension showing variations in virulence effects, the other variations in interaction effects).

3.1. Effects of parasite addition in the three-species structured models

  • Concerning stability, consistent with their predictions (Fig. 1c ), the authors observe that virulence effects do not change stability when the prey is infected (Figs 2a,b ), as such effects neither affect the efficiency of energy transfers (interaction rates), nor the distribution of trophic interaction strengths.
  • As expected, virulence effects stabilize the system when predators are infected (Figs 2d,e), as they increase predator mortality.
  • Interaction effects change stability in more complex ways.
  • On Figs 2d-e, the authors however note that stabilization by virulence effects dominates the complex consequences of interaction effects.

3.2. Effects of parasitism in the unstructured model

  • The intensity of parasitism also affects the dynamical stability of their system (presence/absence of oscillation).
  • For prey infection (Fig. 3a ), virulence effects destabilize the system (arrow 2).
  • This contradicts their prediction that stability should not be affected, as virulence effects do not modify interaction strength.
  • Interaction effects destabilize the system (arrow 3).
  • The authors note that, when increasing simultaneously the two effects, higher stability is eventually achieved.

3.3. Coexistence and stability in structured models of infection

  • Effects of parasitism on stability are more idiosyncratic.
  • For infected prey (Fig. 3b ), the area of oscillations is greatly reduced in the structured system.
  • When the parasite is maintained in the system, virulence and interaction effects seldom lead to an oscillating system (Fig. A1a-b ) or stabilize an unstable one (Fig. A1c ).
  • Such stabilizing effects may be explained by the fact that the structured model explicitly accounts for an additional negative feedback between the predator and parasite populations.
  • Interaction effects (arrow 2) first destabilize the system, in coherence with their predictions (Fig. 1c ).

4. Discussion

  • While the authors mostly focus here on the effects of parasitism on the ecological dynamics of the community, they propose that parasitism may affect the evolution of predator foraging activities.
  • According to the theories of optimal and adaptive foraging, selection favors predators foraging on the energetically most profitable prey (Charnov, 1976a (Charnov, , 1976b;; Emlen, 1966; MacArthur & Pianka, 1966) .
  • Parasites altering the vulnerability of host species reduce either the search time or the handling time.
  • The authors therefore expect that the adaptation of predator foraging in response to parasitism may lead to vast changes in the relative intensity of trophic interactions, thereby altering coexistence conditions (direct modifications of apparent competition, Holt [1977] ) or system stability (by altering the distribution of interaction strengths, McCann et al. [1998] ).

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Citations
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01 Jan 1993

217 citations

Journal ArticleDOI
TL;DR: This paper contributes to recent efforts to unite predator-prey and parasite-host theory under a general consumer-resource framework and considers the relative importance of each parasite-induced indirect interaction type and demonstrates their population-, community-, and ecosystem-level consequences.

32 citations

Journal ArticleDOI
TL;DR: The effect of contamination may be fundamental to understanding disease progression in community ecology because it is shown that extremely deficient or toxic copper may have a destabilizing effect on the underlying host-resource dynamics.

7 citations

Posted ContentDOI
18 Apr 2020-bioRxiv
TL;DR: It is shown that the virulence effect leads to specialisation on the non-infected prey while the interaction effect, by increasing prey profitability, favors specialisationOn the infected prey, and that interaction effects systematically lead to a high niche overlap, ultimately resulting in the loss of the parasite.
Abstract: As acknowledged by Optimal Foraging theories, predator diets depend on prey profitability. Parasites, ubiquitous in food webs, are known to affect simultaneously host vulnerability to predation and host energy contents, thereby affecting profitabilities. In this work, we study the eco-evolutionary consequences of prey infection on predator diet. We also analyze the consequences for coexistence between prey, predators and parasites. We model a trophic module with one predator and two prey species, one of these prey being infected by a parasite, and distinguish between two effects of infection: a decrease in host fecundity (virulence effect) and an increase in vulnerability to predation (interaction effect). Predator foraging may evolve toward specialist or generalist strategies, the latter being less efficient on a given resource. We show that the virulence effect leads to specialisation on the non-infected prey while the interaction effect, by increasing prey profitability, favors specialisation on the infected prey. Combining the two effects at intermediate intensities promotes either generalist predators or the diversification of foraging strategies (coexistence of specialists), depending of trade-off shape. We then investigate how the evolution of predator diet affects the niche overlap between predator and parasite. We show that interaction effects systematically lead to a high niche overlap, ultimately resulting in the loss of the parasite. Virulence effects conversely favor coexistence by allowing a separation of the predator and parasite niches.

4 citations


Cites background or methods from "Parasitism effects on coexistence a..."

  • ...…on coexistence While we know that parasitism may directly constrain coexistence of prey by changing the relative weight of direct and apparent competition (Prosnier et al. 2018), here we highlight that evolutionary dynamics in response to parasitism may favor coexistence in trophic modules....

    [...]

  • ...The ecological model was previously analyzed by Prosnier et al. (2018)....

    [...]

  • ...Used values are those proposed in Prosnier et al. (2018) and based on Hutson and Vickers (1983)....

    [...]

  • ...5b,c, see also Prosnier et al. 2018)....

    [...]

  • ...The consequences of parasitism on food webs regarding trophic cascades (Buck and Ripple 2017) or in terms of stabilisation (Hilker and Schmitz 2008; Prosnier et al. 2018) or destabilisation (Hudson et al. 1998; Prosnier et al. 2018) are most often investigated through the lens of ecology....

    [...]

DOI
10 Feb 2022-bioRxiv
TL;DR: In this paper , the authors investigate the consequences of infection by the iridovirus Daphnia iridescent virus 1 (DIV-1) on the reproductive success, mortality, appearance, mobility, and biochemical composition of water fleas (Daphnia magna), a widespread freshwater crustacean.
Abstract: Parasites are omnipresent, and their eco-evolutionary significance has aroused much interest from scientists. Parasites may affect their hosts in many ways with changes in density, appearance, behaviour and energy content, likely to modify their value to predators (profitability) within the optimal foraging framework. Consequently, parasites could impact predators’ diet and the trophic links through food webs. Here, we investigate the consequences of the infection by the iridovirus Daphnia iridescent virus 1 (DIV-1) on the reproductive success, mortality, appearance, mobility, and biochemical composition of water fleas (Daphnia magna), a widespread freshwater crustacean. We do predation tests and compare search time, handling time and feeding preference between infected and uninfected Daphnia when preyed upon by Notonecta sp., a common aquatic insect. Our findings show that infection does not change fecundity but reduces lifespan and thereby constrains fitness. Infected Daphnia show reduced mobility and increased color reflectance in the UV and visible domains, which potentially affects their appearance and thus vulnerability to predators. Infection increases body size and the amount of proteins but does not affect carbohydrate and lipid contents. Although infected Daphnia are longer to handle, they are preferred over uninfected individuals by aquatic insects. Taken together, our findings show that DIV-1 infection could make Daphnia more profitable to predators (24% energy increase), a positive effect that should be balanced with a lower availability due to the higher mortality of infected specimens. We also highlight that exposure to infection in asymptomatic individuals leads to ecological characteristics that differ from both healthy and symptomatic infected individuals.

3 citations

References
More filters
Journal ArticleDOI
TL;DR: In this article, the authors considered the problem of finding a causal factor which appears to be adequate to account for the magnitude of the frequent epidemics of disease which visit almost every population.
Abstract: (1) One of the most striking features in the study of epidemics is the difficulty of finding a causal factor which appears to be adequate to account for the magnitude of the frequent epidemics of disease which visit almost every population. It was with a view to obtaining more insight regarding the effects of the various factors which govern the spread of contagious epidemics that the present investigation was undertaken. Reference may here be made to the work of Ross and Hudson (1915-17) in which the same problem is attacked. The problem is here carried to a further stage, and it is considered from a point of view which is in one sense more general. The problem may be summarised as follows: One (or more) infected person is introduced into a community of individuals, more or less susceptible to the disease in question. The disease spreads from the affected to the unaffected by contact infection. Each infected person runs through the course of his sickness, and finally is removed from the number of those who are sick, by recovery or by death. The chances of recovery or death vary from day to day during the course of his illness. The chances that the affected may convey infection to the unaffected are likewise dependent upon the stage of the sickness. As the epidemic spreads, the number of unaffected members of the community becomes reduced. Since the course of an epidemic is short compared with the life of an individual, the population may be considered as remaining constant, except in as far as it is modified by deaths due to the epidemic disease itself. In the course of time the epidemic may come to an end. One of the most important probems in epidemiology is to ascertain whether this termination occurs only when no susceptible individuals are left, or whether the interplay of the various factors of infectivity, recovery and mortality, may result in termination, whilst many susceptible individuals are still present in the unaffected population. It is difficult to treat this problem in its most general aspect. In the present communication discussion will be limited to the case in which all members of the community are initially equally susceptible to the disease, and it will be further assumed that complete immunity is conferred by a single infection.

8,238 citations

01 Jan 1927
TL;DR: The present communication discussion will be limited to the case in which all members of the community are initially equally susceptible to the disease, and it will be further assumed that complete immunity is conferred by a single infection.
Abstract: (1) One of the most striking features in the study of epidemics is the difficulty of finding a causal factor which appears to be adequate to account for the magnitude of the frequent epidemics of disease which visit almost every population. It was with a view to obtaining more insight regarding the effects of the various factors which govern the spread of contagious epidemics that the present investigation was undertaken. Reference may here be made to the work of Ross and Hudson (1915-17) in which the same problem is attacked. The problem is here carried to a further stage, and it is considered from a point of view which is in one sense more general. The problem may be summarised as follows: One (or more) infected person is introduced into a community of individuals, more or less susceptible to the disease in question. The disease spreads from the affected to the unaffected by contact infection. Each infected person runs through the course of his sickness, and finally is removed from the number of those who are sick, by recovery or by death. The chances of recovery or death vary from day to day during the course of his illness. The chances that the affected may convey infection to the unaffected are likewise dependent upon the stage of the sickness. As the epidemic spreads, the number of unaffected members of the community becomes reduced. Since the course of an epidemic is short compared with the life of an individual, the population may be considered as remaining constant, except in as far as it is modified by deaths due to the epidemic disease itself. In the course of time the epidemic may come to an end. One of the most important probems in epidemiology is to ascertain whether this termination occurs only when no susceptible individuals are left, or whether the interplay of the various factors of infectivity, recovery and mortality, may result in termination, whilst many susceptible individuals are still present in the unaffected population. It is difficult to treat this problem in its most general aspect. In the present communication discussion will be limited to the case in which all members of the community are initially equally susceptible to the disease, and it will be further assumed that complete immunity is conferred by a single infection.

7,769 citations

Book
01 Jan 1934
TL;DR: For three-quarters of a century past more has been written about natural selection and the struggle for existence that underlies the selective process, than perhaps about any other single idea in the whole realm of Biology as discussed by the authors.
Abstract: For three-quarters of a century past more has been written about natural selection and the struggle for existence that underlies the selective process, than perhaps about any other single idea in the whole realm of Biology. We have seen natural selection laid on its Sterbebett, and subsequently revived again in the most recent times to a remarkable degree of vigor. There can be no doubt that the old idea has great survival value.

2,641 citations

Journal ArticleDOI
TL;DR: In order to study the consequences of predator-mediated apparent competition in isolation from other complicating factors, a model community is analyzed in which there is no direct interspecific competition among the prey.

2,265 citations


"Parasitism effects on coexistence a..." refers background in this paper

  • ...…parasitism (virulence vs interaction effects), on the species that is infected (predator or prey), but that they can be understood to some extent based on classical ecological theories based on apparent competition (Holt, 1977) and interaction strength (McCann et al., 1998; Rip and McCann, 2011)....

    [...]

  • ...The inclusion of a predator in a competitive system would affect coexistence through apparent competition (Holt, 1977)....

    [...]

Journal ArticleDOI
29 Jan 1971-Science
TL;DR: Man must be very careful in attempting to enrich an ecosystem in order to increase its food yield, because there is a real chance that such activity may result in decimation of the food species that are wanted in greater abundance.
Abstract: Six reasonable models of trophic exploitation in a two-species ecosystem whose exploiters compete only by depleting each other's resource supply are presented. In each case, increasing the supply of limiting nutrients or energy tends to destroy the steady state. Thus man must be very careful in attempting to enrich an ecosystem in order to increase its food yield. There is a real chance that such activity may result in decimation of the food species that are wanted in greater abundance.

1,767 citations


"Parasitism effects on coexistence a..." refers background in this paper

  • ...We systematically assessed two basic hypotheses: that heterogeneity in interaction strengths increases stability (McCann et al., 1998) and that stability depends on relative energy fluxes (ratio between attack rates and predator mortality rates [Rip and McCann, 2011; Rosenzweig, 1971])....

    [...]

  • ...Considering the paradox of enrichment, a classical result in ecological theory is that stability decreases when larger energy flows (predation rate) occur for a given predator loss rate (predator mortality rate) (Rosenzweig, 1971; Rip and McCann, 2011)....

    [...]

  • ...While parasitism can affect stability positively or negatively depending on the scenario, the ratio between energy fluxes and predator mortality rates largely explain the effects of predator infection on system stability, as proposed in previous works (Rosenzweig, 1971; Rip and McCann, 2011)....

    [...]

Frequently Asked Questions (1)
Q1. What are the contributions mentioned in the paper "Parasitism effects on coexistence and stability within simple trophic modules" ?

In this paper, the authors present the work of the Equipe Neuro-Ethologie Sensorielle, ENES/Neuro-PSI, CNRS UMR 9197, Université de Lyon/Saint-Etienne, 23 rue Michelon, 42023 Saint-Ebien Cedex 10 2, France.