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.

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.

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.

Estimating effective population size for a cestode parasite infecting three-spined sticklebacks

Parasitology ◽  
2019 ◽  
Vol 146 (07) ◽  
pp. 883-896
Author(s):  
Hannah M. Strobel ◽  
Sara J. Hays ◽  
Kristine N. Moody ◽  
Michael J. Blum ◽  
David C. Heins
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Gasterosteus Aculeatus ◽  
Microsatellite Data ◽  
Effective Population ◽  
Cestode Parasite ◽  
Schistocephalus Solidus ◽  
Host Parasite Interactions ◽  
Parasite Evolution ◽  
Host Parasite

AbstractRemarkably few attempts have been made to estimate contemporary effective population size (Ne) for parasitic species, despite the valuable perspectives it can offer on the tempo and pace of parasite evolution as well as coevolutionary dynamics of host–parasite interactions. In this study, we utilized multi-locus microsatellite data to derive single-sample and temporal estimates of contemporaryNefor a cestode parasite (Schistocephalus solidus) as well as three-spined stickleback hosts (Gasterosteus aculeatus) in lakes across Alaska. Consistent with prior studies, both approaches recovered small and highly variable estimates of parasite and hostNe. We also found that estimates of hostNeand parasiteNewere sensitive to assumptions about population genetic structure and connectivity. And, while prior work on the stickleback–cestode system indicates that physiographic factors external to stickleback hosts largely govern genetic variation inS. solidus, our findings indicate that stickleback host attributes and factors internal to the host – namely body length, genetic diversity and infection – shape contemporaryNeof cestode parasites.

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.

scholarly journals The implications of immunopathology for parasite evolution

2012 ◽  
Vol 279 (1741) ◽  
pp. 3234-3240 ◽  
Author(s):  
Alex Best ◽  
Gráinne Long ◽  
Andy White ◽  
Mike Boots
Keyword(s):  
Immune Response ◽  
Disease Severity ◽  
Host Immune Response ◽  
Disease Symptoms ◽  
Direct Damage ◽  
Host Parasite Interactions ◽  
Parasite Evolution ◽  
Selection For ◽  
Host Parasite ◽  
Individual Disease

By definition, parasites harm their hosts, but in many infections much of the pathology is driven by the host immune response rather than through direct damage inflicted by parasites. While these immunopathological effects are often well studied and understood mechanistically in individual disease interactions, there remains relatively little understanding of their broader impact on the evolution of parasites and their hosts. Here, we theoretically investigate the implications of immunopathology, broadly defined as additional mortality associated with the host's immune response, on parasite evolution. In particular, we examine how immunopathology acting on different epidemiological traits (namely transmission, virulence and recovery) affects the evolution of disease severity. When immunopathology is costly to parasites, such that it reduces their fitness, for example by decreasing transmission, there is always selection for increased disease severity. However, we highlight a number of host–parasite interactions where the parasite may benefit from immunopathology, and highlight scenarios that may lead to the evolution of slower growing parasites and potentially reduced disease severity. Importantly, we find that conclusions on disease severity are highly dependent on how severity is measured. Finally, we discuss the effect of treatments used to combat disease symptoms caused by immunopathology.

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 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 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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