scholarly journals Host-parasite coevolution in populations of constant and variable size

2014 ◽  
Author(s):  
Yixian Song ◽  
Chaitanya Gokhale ◽  
Andrei Papkou ◽  
Hinrich Schulenburg ◽  
Arne Traulsen
Keyword(s):  
Oscillation Frequency ◽  
Evolutionary Ecology ◽  
Analytical Investigation ◽  
Volterra Equations ◽  
Population Sizes ◽  
Cyclic Dynamics ◽  
Host Parasite ◽  
Allele Model ◽  
Single Oscillation ◽  
Gene For Gene

The matching-allele and gene-for-gene models are widely used in math- ematical approaches that study the dynamics of host-parasite interactions. Agrawal and Lively (Evolutionary Ecology Research 4:79-90, 2002) captured these two models in a single framework and numerically explored the associated time discrete dynamics of allele frequencies. Here, we present a detailed analytical investigation of this unifying framework in continuous time and provide a generalization. We extend the model to take into account changing population sizes, which result from the antagonistic nature of the interaction and follow the Lotka-Volterra equations. Under this extension, the population dynamics become most complex as the model moves away from pure matching-allele and becomes more gene-for-gene-like. While the population densities oscillate with a single oscillation frequency in the pure matching-allele model, a second oscillation frequency arises under gene-for-gene-like conditions. These observations hold for general interaction parameters and allow to infer generic patterns of the dynamics. Our results suggest that experimentally inferred dynamical patterns of host-parasite coevolution should typically be much more complex than the popular illustrations of Red Queen dynamics. A single parasite that infects more than one host can substantially alter the cyclic dynamics.

scholarly journals Computer simulation for the growing probability of additional offspring with an advantageous reversal allele in the decoupled continuous-time mutation–selection model

2016 ◽  
Vol 27 (06) ◽  
pp. 1650070
Author(s):  
Wonpyong Gill
Keyword(s):  
Computer Simulation ◽  
Continuous Time ◽  
Selective Advantage ◽  
Selection Model ◽  
Sequence Length ◽  
Theoretical Formula ◽  
Fitness Parameters ◽  
Population Sizes ◽  
Fitness Parameter ◽  
Allele Model

This study calculated the growing probability of additional offspring with the advantageous reversal allele in an asymmetric sharply-peaked landscape using the decoupled continuous-time mutation–selection model. The growing probability was calculated for various population sizes, N, sequence lengths, L, selective advantages, s, fitness parameters, k and measuring parameters, C. The saturated growing probability in the stochastic region was approximately the effective selective advantage, [Formula: see text], when [Formula: see text] and [Formula: see text]. The present study suggests that the growing probability in the stochastic region in the decoupled continuous-time mutation–selection model can be described using the theoretical formula for the growing probability in the Moran two-allele model. The selective advantage ratio, which represents the ratio of the effective selective advantage to the selective advantage, does not depend on the population size, selective advantage, measuring parameter and fitness parameter; instead the selective advantage ratio decreases with the increasing sequence length.

scholarly journals Stability of genetic polymorphism in host–parasite interactions

2006 ◽  
Vol 274 (1611) ◽  
pp. 809-817 ◽  
Author(s):  
Aurélien Tellier ◽  
James K.M Brown
Keyword(s):  
Natural Selection ◽  
Genetic Polymorphism ◽  
General Theory ◽  
Allelic Diversity ◽  
Histocompatibility Complex ◽  
Selection For ◽  
Or Gene ◽  
Almost All ◽  
Host Parasite ◽  
Gene For Gene

Allelic diversity is common at host loci involved in parasite recognition, such as the major histocompatibility complex in vertebrates or gene-for-gene relationships in plants, and in corresponding loci encoding antigenic molecules in parasites. Diverse factors have been proposed in models to account for genetic polymorphism in host–parasite recognition. Here, a simple but general theory of host–parasite coevolution is developed. Coevolution implies the existence of indirect frequency-dependent selection (FDS), because natural selection on the host depends on the frequency of a parasite gene, and vice versa . It is shown that polymorphism can be maintained in both organisms only if there is negative, direct FDS, such that the strength of natural selection for the host resistance allele, the parasite virulence allele or both declines with increasing frequency of that allele itself. This condition may be fulfilled if the parasite has more than one generation in the same host individual, a feature which is common to most diseases. It is argued that the general theory encompasses almost all factors previously proposed to account for polymorphism at corresponding host and parasite loci, including those controlling gene-for-gene interactions.

Coevolutionary interactions between host life histories and parasite life cycles

Parasitology ◽  
1998 ◽  
Vol 116 (S1) ◽  
pp. S47-S55 ◽  
Author(s):  
J. C. Koella ◽  
P. Agnew ◽  
Y. Michalakis
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Life Histories ◽  
Life History Traits ◽  
Evolutionary Ecology ◽  
Life Cycles ◽  
Microsporidian Parasite ◽  
History Of ◽  
Host Life ◽  
Host Parasite

SummarySeveral recent studies have discussed the interaction of host life-history traits and parasite life cycles. It has been observed that the life-history of a host often changes after infection by a parasite. In some cases, changes of host life-history traits reduce the costs of parasitism and can be interpreted as a form of resistance against the parasite. In other cases, changes of host life-history traits increase the parasite's transmission and can be interpreted as manipulation by the parasite. Alternatively, changes of host's life-history traits can also induce responses in the parasite's life cycle traits. After a brief review of recent studies, we treat in more detail the interaction between the microsporidian parasite Edhazardia aedis and its host, the mosquito Aedes aegypti. We consider the interactions between the host's life-history and parasite's life cycle that help shape the evolutionary ecology of their relationship. In particular, these interactions determine whether the parasite is benign and transmits vertically or is virulent and transmits horizontally.Key words: host-parasite interaction, life-history, life cycle, coevolution.

scholarly journals The impact of environmental change on host–parasite coevolutionary dynamics

2010 ◽  
Vol 278 (1716) ◽  
pp. 2283-2292 ◽  
Author(s):  
Rafal Mostowy ◽  
Jan Engelstädter
Keyword(s):  
Environmental Change ◽  
Environmental Changes ◽  
Selective Pressure ◽  
Time Windows ◽  
Gene Interactions ◽  
Genotype By Environment ◽  
Host Parasite ◽  
The Impact ◽  
Antagonistic Interactions ◽  
Gene For Gene

Environmental factors are known to affect the strength and the specificity of interactions between hosts and parasites. However, how this shapes patterns of coevolutionary dynamics is not clear. Here, we construct a simple mathematical model to study the effect of environmental change on host–parasite coevolutionary outcome when interactions are of the matching-alleles or the gene-for-gene type. Environmental changes may effectively alter the selective pressure and the level of specialism in the population. Our results suggest that environmental change altering the specificity of selection in antagonistic interactions can produce alternating time windows of cyclical allele-frequency dynamics and cessation thereof. This type of environmental impact can also explain the maintenance of polymorphism in gene-for-gene interactions without costs. Overall, our study points to the potential consequences of environmental variation in coevolution, and thus the importance of characterizing genotype-by-genotype-by-environment interactions in natural host–parasite systems, especially those that change the direction of selection acting between the two species.

scholarly journals Microsatellite variation in honey bee (Apis mellifera L.) populations: hierarchical genetic structure and test of the infinite allele and stepwise mutation models.

Genetics ◽  
1995 ◽  
Vol 140 (2) ◽  
pp. 679-695 ◽  
Author(s):  
A Estoup ◽  
L Garnery ◽  
M Solignac ◽  
J M Cornuet
Keyword(s):  
Apis Mellifera ◽  
Phylogenetic Trees ◽  
Microsatellite Data ◽  
Effective Population ◽  
Average Heterozygosity ◽  
Microsatellite Variation ◽  
Infinite Allele Model ◽  
Population Sizes ◽  
Stepwise Mutation ◽  
Allele Model

Abstract Samples from nine populations belonging to three African (intermissa, scutellata and capensis) and four European (mellifera, ligustica, carnica and cecropia) Apis mellifera subspecies were scored for seven microsatellite loci. A large amount of genetic variation (between seven and 30 alleles per locus) was detected. Average heterozygosity and average number of alleles were significantly higher in African than in European subspecies, in agreement with larger effective population sizes in Africa. Microsatellite analyses confirmed that A. mellifera evolved in three distinct and deeply differentiated lineages previously detected by morphological and mitochondrial DNA studies. Dendrogram analysis of workers from a given population indicated that super-sisters cluster together when using a sufficient number of microsatellite data whereas half-sisters do not. An index of classification was derived to summarize the clustering of different taxonomic levels in large phylogenetic trees based on individual genotypes. Finally, individual population x loci data were used to test the adequacy of the two alternative mutation models, the infinite allele model (IAM) and the stepwise mutation models. The better fit overall of the IAM probably results from the majority of the microsatellites used including repeats of two or three different length motifs (compound microsatellites).

scholarly journals Social hosts evade predation but have deadlier parasites

2021 ◽  
Author(s):  
Jason Walsman ◽  
Mary J. Janecka ◽  
David R. Clark ◽  
Rachael D. Kramp ◽  
Faith Rovenolt ◽  
...  
Keyword(s):  
Social Behaviour ◽  
Evolutionary Ecology ◽  
Group Living ◽  
Common Garden ◽  
Virulence Evolution ◽  
The Common ◽  
Trinidadian Guppy ◽  
Host Parasite ◽  
Predator Defence ◽  
Insight Into

AbstractParasites exploit hosts to replicate and transmit, but overexploitation kills both host and parasite1: parasite virulence evolves to balance these costs and benefits. Predators can in theory shift this balance by consuming hosts2–4. However, the non-consumptive effects of predators may be as important as their consumptive effects5. Here, we use an eco-coevolutionary model to show that predators select for host grouping, a common anti-predator, defensive social behaviour6. Host grouping simultaneously increases parasite transmission, thus within-host parasite competition, and therefore favours more exploitative, virulent, parasites7. When parametrized with data from the guppy-Gyrodactylus spp. system, including our experimentally demonstrated trade-off between virulence and transmission, our model accurately predicted the common garden-assayed virulence of 18 parasite lines collected from four Trinidadian guppy populations under different predation regimes. The quantitative match between theory and data lends credence to the model’s insight that the non-consumptive, social behaviour pathway is entirely responsible for the observed increase in virulence with predation pressure. Our results indicate that parasites play an important, underappreciated role in guppy evolutionary ecology. Moreover, group living is a common anti-predator defence6 and our general model accommodates host-parasite interactions across taxa: its insight into the interactions among predation, sociality, and virulence evolution may apply broadly. Our results additionally suggest that social distancing, by reducing host-host contact, can select for less virulent parasites and pathogens.

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