scholarly journals Annual environmental variation influences host tolerance to parasites

2019 ◽  
Vol 286 (1897) ◽  
pp. 20190049 ◽  
Author(s):  
Sabrina M. McNew ◽  
Sarah A. Knutie ◽  
Graham B. Goodman ◽  
Angela Theodosopoulos ◽  
Ashley Saulsberry ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Environmental Variation ◽  
Host Population ◽  
Variable Environment ◽  
Host Parasite Interactions ◽  
Video Observations ◽  
Single Host ◽  
Parental Provisioning ◽  
Host Tolerance ◽  
Host Parasite

When confronted with a parasite or pathogen, hosts can defend themselves by resisting or tolerating the attack. While resistance can be diminished when resources are limited, it is unclear how robust tolerance is to changes in environmental conditions. Here, we investigate the sensitivity of tolerance in a single host population living in a highly variable environment. We manipulated the abundance of an invasive parasitic fly, Philornis downsi , in nests of Galápagos mockingbirds ( Mimus parvulus ) over four field seasons and measured host fitness in response to parasitism. Mockingbird tolerance to P. downsi varied significantly among years and decreased when rainfall was limited. Video observations indicate that parental provisioning of nestlings appears key to tolerance: in drought years, mockingbirds likely do not have sufficient resources to compensate for the effects of P. downsi . These results indicate that host tolerance is a labile trait and suggest that environmental variation plays a major role in mediating the consequences of host–parasite interactions.

scholarly journals Evolution of phenotypic fluctuation under host-parasite interactions

2021 ◽  
Vol 17 (11) ◽  
pp. e1008694
Author(s):  
Naoto Nishiura ◽  
Kunihiko Kaneko
Keyword(s):  
Gene Expression ◽  
Species Interactions ◽  
Species Interaction ◽  
Phenotypic Variance ◽  
Variable Environment ◽  
Host Parasite Interactions ◽  
Variable Environments ◽  
Single Host ◽  
Sufficient Degree ◽  
Host Parasite

Robustness and plasticity are essential features that allow biological systems to cope with complex and variable environments. In a constant environment, robustness, i.e., insensitivity of phenotypes, is expected to increase, whereas plasticity, i.e., the changeability of phenotypes, tends to diminish. Under a variable environment, existence of plasticity will be relevant. The robustness and plasticity, on the other hand, are related to phenotypic variances. As phenotypic variances decrease with the increase in robustness to perturbations, they are expected to decrease through the evolution. However, in nature, phenotypic fluctuation is preserved to a certain degree. One possible cause for this is environmental variation, where one of the most important “environmental” factors will be inter-species interactions. As a first step toward investigating phenotypic fluctuation in response to an inter-species interaction, we present the study of a simple two-species system that comprises hosts and parasites. Hosts are expected to evolve to achieve a phenotype that optimizes fitness. Then, the robustness of the corresponding phenotype will be increased by reducing phenotypic fluctuations. Conversely, plasticity tends to evolve to avoid certain phenotypes that are attacked by parasites. By using a dynamic model of gene expression for the host, we investigate the evolution of the genotype-phenotype map and of phenotypic variances. If the host–parasite interaction is weak, the fittest phenotype of the host evolves to reduce phenotypic variances. In contrast, if there exists a sufficient degree of interaction, the phenotypic variances of hosts increase to escape parasite attacks. For the latter case, we found two strategies: if the noise in the stochastic gene expression is below a certain threshold, the phenotypic variance increases via genetic diversification, whereas above this threshold, it is increased mediated by noise-induced phenotypic fluctuation. We examine how the increase in the phenotypic variances caused by parasite interactions influences the growth rate of a single host, and observed a trade-off between the two. Our results help elucidate the roles played by noise and genetic mutations in the evolution of phenotypic fluctuation and robustness in response to host–parasite interactions.

scholarly journals Hidden paths to endless forms most wonderful: Parasite-blind diversification of host quality

2020 ◽  
Author(s):  
Lisa Freund ◽  
Marie Vasse ◽  
Gregory J. Velicer
Keyword(s):  
Growth Suppression ◽  
Host Population ◽  
Host Quality ◽  
Evolution Theory ◽  
Evolutionary Diversification ◽  
Adaptive Landscapes ◽  
Host Parasite Interactions ◽  
Parasite Evolution ◽  
Host Parasite ◽  
Selective Environment

Evolutionary diversification can occur in allopatry or sympatry, can be unselected or driven by selection, and can be phenotypically manifested immediately or remain phenotypically latent until later manifestation in a newly encountered environment. Diversification of host-parasite interactions is frequently studied in the context of intrinsically selective coevolution, but the potential for host-parasite interaction phenotypes to diversify latently during parasite-blind evolution is rarely considered. Here we use a social bacterium experimentally adapted to several environments in the absence of phage to analyse allopatric diversification of latent host quality - the degree to which a host population supports a viral epidemic. Phage-blind evolution reduced host quality overall, with some bacteria becoming completely resistant to growth suppression by phage. Selective-environment differences generated only mild divergence in host-quality. However, selective environments nonetheless played a major role in shaping evolution by determining the degree of stochastic diversification among replicate populations within treatments. Ancestral motility genotype was also found to strongly shape patterns of latent hostquality evolution and diversification. These outcomes show that adaptive landscapes can differ in how they constrain stochastic diversification of a latent phenotype and that major effects of selection on biological diversification can be missed by focusing on trait means. Collectively, our findings suggest that latent-phenotype evolution (LPE) should inform host-parasite evolution theory and that diversification should be conceived broadly to include latent phenotypes.

Population interactions between a parasitic castrator, Probopyrus pandalicola (Isopoda: Bopyridae), and one of its freshwater shrimp hosts, Palaemonetes paludosus (Decapoda: Caridea)

Parasitology ◽  
1979 ◽  
Vol 79 (3) ◽  
pp. 431-449 ◽  
Author(s):  
J. T. Beck
Keyword(s):  
Host Population ◽  
Acartia Tonsa ◽  
Parasite Control ◽  
Freshwater Shrimp ◽  
Free Swimming ◽  
Host Parasite Interactions ◽  
Population Interactions ◽  
Parasitic Castrator ◽  
Host Parasite ◽  
And Control

SUMMARYFreshwater shrimp, Palaemonetes paludosus, infected by the bopyrid isopod, Probopyrus pandalicola, occurred as far as 33 km upstream in many coastal rivers and canals throughout Florida. Free-swimming isopod larvae and the intermediate copepod host, Acartia tonsa, were collected in the plankton of the Wakulla River, and it appeared that cryptoniscus larvae swam at least as far as 13 km upstream to infect the definitive shrimp host after leaving the copepod in brackish water. In the Wakulla River infection levels ranged from 87·5 to 100%. In contrast, at McBride's Slough infection levels fluctuated from 0·9 to 93·2%. In the St Marks River the frequency of infected shrimp gradually increased from 0% upstream to 96%, 6 km further downstream. A significantly greater percentage of female than male hosts were infected, but only females of size classes less than 31 mm long had a greater frequency of infection. Female P. pandalicola were greatly under-dispersed (coefficient of dispersion (s2/x¯) less than 1) throughout the host population; 99·6% of the infected hosts carried only 1 female parasite. Control of P. pandalicola at the infrapopulation level is probably accomplished by some mode of intraspecific competition, and control at the suprapopulation level occurs through an upstream limitation of the transmission range of the cryptoniscus larval stage. Host–parasite interactions appear to be unstable.

scholarly journals To delay once or twice: the effect of hypobiosis and free-living stages on the stability of host–parasite interactions

2008 ◽  
Vol 5 (25) ◽  
pp. 919-928 ◽  
Author(s):  
Sabrina Gaba ◽  
Sébastien Gourbière
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Time Delay ◽  
Host Population ◽  
Previous Attempt ◽  
Maximal Effect ◽  
Parasite Life Cycle ◽  
Free Living ◽  
Host Parasite Interactions ◽  
Host Parasite

The life cycle of many endoparasites can be delayed by free-living infective stages and a developmental arrestment in the host referred to as hypobiosis. We investigated the effects of hypobiosis and its interaction with delay in the free-living stages on host–parasite population dynamics by expanding a previous attempt by Dobson & Hudson. When the parasite life cycle does not include free-living stages, hypobiosis destabilizes the host–parasite interactions, irrespective of the assumptions about the regulation of the host population dynamics. Interestingly, the destabilizing effect varies in a nonlinear way with the duration of hypobiosis, the maximal effect being expected for three to five months delay. When the parasite life cycle involves free-living stages, hypobiosis of short or intermediate duration increases the destabilizing effect of the first time delay. However, hypobiosis of a duration of five months or more can stabilize interactions, irrespective of the regulation of the host population dynamics. Overall, we confirmed that hypobiosis is an unusual time delay as it can stabilize a two-way interaction. Contrary to the previous conclusions, such an atypical effect does not require self-regulation of the host population, but instead depends on the existence of free-living stages.

Global stability and Hopf bifurcation of a host–parasite system

2017 ◽  
Vol 10 (04) ◽  
pp. 1750047
Author(s):  
Xuerui Wei ◽  
Zhipeng Qiu
Keyword(s):  
Hopf Bifurcation ◽  
Time Scale ◽  
Sufficient Conditions ◽  
Host Population ◽  
Complete Analysis ◽  
Logistic Growth ◽  
Free Living ◽  
Dynamical Mechanism ◽  
Host Parasite Interactions ◽  
Host Parasite

Understanding the dynamical mechanism of the host–parasite interactions is one of important issues on host–parasite association. In this paper, we formulate a three-dimensional host–macroparasite system to describe the host–parasite interactions, which includes the logistic growth rate of host population, the important free-living stage and the host fecundity reduction due to parasite infection. The purpose of the paper is to investigate the asymptotical behavior of the system. By using the properties of the solution to non-autonomous linear system, the basic production number [Formula: see text] is proved to be a threshold which determines the outcome of the parasites. If [Formula: see text], the parasite will eventually die out, and if [Formula: see text] the parasite will be uniformly persistent. Hopf bifurcation of the system is further studied, and sufficient conditions for the Hopf bifurcation are obtained. By using the singular perturbation techniques, the system is separated into two time scales with a faster time scale for the free-living infective particles and a slower time scale for the population dynamics of host and parasite, and then a complete analysis of the dynamics on the slow manifold is conducted. The theoretical results show that the level of aggregation of parasites within host may influence the persistence and stability of the system.

The distribution of echinostome parasites in ponds and implications for larval anuran survival

Parasitology ◽  
2017 ◽  
Vol 144 (6) ◽  
pp. 801-811 ◽  
Author(s):  
JOHN A. MARINO ◽  
MANJA P. HOLLAND ◽  
EARL E. WERNER
Keyword(s):  
Community Dynamics ◽  
Field Survey ◽  
Host Population ◽  
Intermediate Hosts ◽  
Enclosure Experiment ◽  
Host Parasite Interactions ◽  
Fitness Consequences ◽  
Prevalence Proportion ◽  
Population And Community Dynamics ◽  
Host Parasite

SUMMARYParasites can influence host population dynamics, community composition and evolution. Prediction of these effects, however, requires an understanding of the influence of ecological context on parasite distributions and the consequences of infection for host fitness. We address these issues with an amphibian – trematode (Digenea: Echinostomatidae) host–parasite system. We initially performed a field survey of trematode infection in first (snail) and second (larval green frog, Rana clamitans) intermediate hosts over 5 years across a landscape of 23 ponds in southeastern Michigan. We then combined this study with a tadpole enclosure experiment in eight ponds. We found echinostomes in all ponds during the survey, although infection levels in both snails and amphibians differed across ponds and years. Echinostome prevalence (proportion of hosts infected) in snails also changed seasonally depending on host species, and abundance (parasites per host) in tadpoles depended on host size and prevalence in snails. The enclosure experiment demonstrated that infection varied at sites within ponds, and tadpole survival was lower in enclosures with higher echinostome abundance. The observed effects enhance our ability to predict when and where host–parasite interactions will occur and the potential fitness consequences of infection, with implications for population and community dynamics, evolution and conservation.

scholarly journals Bayesian inference of ancestral host-parasite interactions under a phylogenetic model of host repertoire evolution

2019 ◽  
Author(s):  
Mariana P Braga ◽  
Michael Landis ◽  
Sören Nylin ◽  
Niklas Janz ◽  
Fredrik Ronquist
Keyword(s):  
Null Model ◽  
Butterfly Species ◽  
Host Parasite Interactions ◽  
Single Host ◽  
Long Time ◽  
History Of ◽  
Phylogenetic Model ◽  
Host Parasite ◽  
Gains And Losses ◽  
Coevolutionary History

AbstractIntimate ecological interactions, such as those between parasites and their hosts, may persist over long time spans, coupling the evolutionary histories of the lineages involved. Most methods that reconstruct the coevolutionary history of such associations make the simplifying assumption that parasites have a single host. Many methods also focus on congruence between host and parasite phylogenies, using cospeciation as the null model. However, there is an increasing body of evidence suggesting that the host ranges of parasites are more complex: that host ranges often include more than one host and evolve via gains and losses of hosts rather than through cospeciation alone. Here, we develop a Bayesian approach for inferring coevolutionary history based on a model accommodating these complexities. Specifically, a parasite is assumed to have a host repertoire, which includes both potential hosts and one or more actual hosts. Over time, potential hosts can be added or lost, and potential hosts can develop into actual hosts or vice versa. Thus, host colonization is modeled as a two-step process, which may potentially be influenced by host relatedness or host traits. We first explore the statistical behavior of our model by simulating evolution of host-parasite interactions under a range of parameters. We then use our approach, implemented in the program RevBayes, to infer the coevolutionary history between 34 Nymphalini butterfly species and 25 angiosperm families.

scholarly journals Evolution of Resistance in Potamopyrgus antipodarum

2015 ◽  
Vol 1 (1) ◽  
pp. 35
Author(s):  
Peyton J. Joachim
Keyword(s):  
Freshwater Snail ◽  
Potamopyrgus Antipodarum ◽  
Host Population ◽  
Snail Host ◽  
Parasite Development ◽  
Strong Selection ◽  
Single Host ◽  
Evolution Of Resistance ◽  
Host Parasite ◽  
Parasite Populations

Host-parasite interactions are believed to exert strong selection in natural communities. Most notably, parasites should select for increased resistance in hosts, while hosts should select for increased infectivity in parasites (Koskella & Lively, 2007; Koskella, Vergara, & Lively, 2011; Lohse, Guiterrez, & Kaltz, 2006). Under this coevolutionary process, can host populations evolve resistance to their rapidly evolving parasite populations? This experiment was designed to determine if hosts rapidly adapt to resist parasites that are themselves under selection to infect their hosts. The New Zealand freshwater snail, Potamopyrgus antipodarum, is naturally infected by the trematode Microphallus. Microphallus is a castrating parasite and is thus likely to impose strong selection on its snail host (Hechinger, 2012). Snails and parasites were collected from a natural lake in summer 2013. These hosts constitute the parental generation of the experiment: they were either exposed to parasite eggs (Exposed) or not exposed (Control). Parental snails matured and reproduced over the course of a year. Their offspring were then exposed to parasites collected from the same lake in summer 2014. These parasites would have had one to a few additional generations of evolution relative to 2013 parasites. After parasite development (~3 months), the offspring were dissected to determine infection status and thereby their resistance to infection. The offspring of Control parents had a significantly higher mean infection rate (35%: less resistant) than the offspring of Exposed parents (30%: more resistant). This result indicates that increased resistance to parasitism evolved in a single host generation. Our finding provides evidence that a host population can rapidly evolve resistance to a parasite population that is itself rapidly co-evolving to infect its host. We predict that the evolution of host resistance would be far greater after multiple generations of parasite selection, and this could be the subject of future study. 

scholarly journals Hidden paths to endless forms most wonderful: parasite-blind diversification of host quality

2021 ◽  
Vol 288 (1949) ◽  
Author(s):  
Lisa Freund ◽  
Marie Vasse ◽  
Gregory J. Velicer
Keyword(s):  
Host Population ◽  
Host Quality ◽  
Evolution Theory ◽  
Evolutionary Diversification ◽  
Adaptive Landscapes ◽  
Host Parasite Interactions ◽  
Parasite Evolution ◽  
Host Evolution ◽  
Host Parasite ◽  
Selective Environment

Evolutionary diversification can occur in allopatry or sympatry, can be driven by selection or unselected, and can be phenotypically manifested immediately or remain latent until manifested in a newly encountered environment. Diversification of host–parasite interactions is frequently studied in the context of intrinsically selective coevolution, but the potential for host–parasite interaction phenotypes to diversify latently during parasite-blind host evolution is rarely considered. Here, we use a social bacterium experimentally adapted to several environments in the absence of phage to analyse allopatric diversification of host quality—the degree to which a host population supports a viral epidemic. Phage-blind evolution reduced host quality overall, with some bacteria becoming completely resistant to growth suppression by phage. Selective-environment differences generated only mild divergence in host quality. However, selective environments nonetheless played a major role in shaping evolution by determining the degree of stochastic diversification among replicate populations within treatments. Ancestral motility genotype was also found to strongly shape patterns of latent host-quality evolution and diversification. These outcomes show that (i) adaptive landscapes can differ in how they constrain stochastic diversification of a latent phenotype and (ii) major effects of selection on biological diversification can be missed by focusing on trait means. Collectively, our findings suggest that latent-phenotype evolution should inform host–parasite evolution theory and that diversification should be conceived broadly to include latent phenotypes.

scholarly journals Alternating lysis and lysogeny is a winning strategy in bacteriophages due to Parrondo’s Paradox

2021 ◽  
Author(s):  
Kang Hao Cheong ◽  
Tao Wen ◽  
Sean Benler ◽  
Eugene V. Koonin
Keyword(s):  
Game Theory ◽  
Population Density ◽  
Winning Strategy ◽  
Host Population ◽  
Host Cells ◽  
Dynamic Evolution ◽  
Reproduction Rate ◽  
Host Parasite Interactions ◽  
Parrondo’S Paradox ◽  
Host Parasite

AbstractTemperate bacteriophages lyse or lysogenize the host cells depending on various parameters of infection, a key one being the host population density. However, the effect of different propensities of phages for lysis and lysogeny on phage fitness is an open problem. We explore a nonlinear dynamic evolution model of competition between two phages, one of which is disadvantaged in both the lytic and lysogenic phases. We show that the disadvantaged phage can win the competition by alternating between the lytic and lysogenic phases, each of which individually is a “loser”. This counter-intuitive result recapitulates Parrondo’s paradox in game theory, whereby individually losing strategies can combine to produce a winning outcome. The results suggest that evolution of phages optimizes the ratio between the lysis and lysogeny propensities rather than the phage reproduction rate in any individual phase. These findings are expected to broadly apply to the evolution of host-parasite interactions.

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