scholarly journals The role of host phenology for parasite transmission

2019 ◽  
Author(s):  
Hannelore MacDonald ◽  
Erol Akçay ◽  
Dustin Brisson
Keyword(s):  
Species Interactions ◽  
Activity Period ◽  
Parasite Transmission ◽  
Nymphal Stage ◽  
Mouse Population ◽  
Tick Activity ◽  
Contact Rates ◽  
Wide Range ◽  
Host Phenology ◽  
Host Parasite

AbstractPhenology is a fundamental determinant of species distributions, abundances, and interactions. In host-parasite interactions, host phenology can affect parasite fitness due to the temporal constraints it imposes on host contact rates. However, it remains unclear how parasite transmission is shaped by the wide range of phenological patterns observed in nature. We develop a mathematical model of the Lyme disease system to study the consequences of differential tick developmental-stage phenology for the transmission of B. burgdorferi. Incorporating seasonal tick activity can increase B. burgdorferi fitness compared to continuous tick activity but can also prevent transmission completely. B. burgdorferi fitness is greatest when the activity period of the infectious nymphal stage slightly precedes the larval activity period. Surprisingly, B. burgdorferi is eradicated if the larval activity period begins long after the end of nymphal activity due to a feedback with mouse population dynamics. These results highlight the importance of phenology, a common driver of species interactions, for the fitness of a parasite.

scholarly journals The role of host phenology for parasite transmission

2020 ◽  
Author(s):  
Hannelore MacDonald ◽  
Erol Akçay ◽  
Dustin Brisson
Keyword(s):  
Species Interactions ◽  
Activity Period ◽  
Parasite Transmission ◽  
Nymphal Stage ◽  
Mouse Population ◽  
Tick Activity ◽  
Contact Rates ◽  
Wide Range ◽  
Host Phenology ◽  
Host Parasite

Abstract Phenology is a fundamental determinant of species distributions, abundances, and interactions. In host–parasite interactions, host phenology can affect parasite fitness due to the temporal constraints it imposes on host contact rates. However, it remains unclear how parasite transmission is shaped by the wide range of phenological patterns observed in nature. We develop a mathematical model of the Lyme disease system to study the consequences of differential tick developmental-stage phenology for the transmission of B. burgdorferi. Incorporating seasonal tick activity can increase B. burgdorferi fitness compared to continuous tick activity but can also prevent transmission completely. B. burgdorferi fitness is greatest when the activity period of the infectious nymphal stage slightly precedes the larval activity period. Surprisingly, B. burgdorferi is eradicated if the larval activity period begins long after the end of nymphal activity due to a feedback with mouse population dynamics. These results highlight the importance of phenology, a common driver of species interactions, for the fitness of a parasite.

scholarly journals Host phenology can select for multiple stable parasite virulence strategies

2021 ◽  
Author(s):  
Hannelore MacDonald ◽  
Dustin Brisson
Keyword(s):  
Mathematical Model ◽  
Activity Patterns ◽  
Activity Period ◽  
Parasite Transmission ◽  
Evolutionarily Stable Strategies ◽  
Geographic Locations ◽  
Seasonal Environment ◽  
Host Phenology ◽  
Evolutionary Consequences ◽  
Evolutionarily Stable

Host phenology is an important driver of parasite transmission and evolution. In a seasonal environment, monocyclic, obligate-killer parasites evolve optimal virulence strategies such that all parasite progeny are released near the end of the host season to limit parasite progeny death in the environment. It is unclear whether host seasonality imposes different constraints on polycyclic parasites such that both polycyclic and monocyclic parasites are maintained. We develop a mathematical model of a disease system with seasonal host activity to study the evolutionary consequences of host phenology on polycyclic, obligate-killer parasite virulence strategies. Seasonal host activity patterns create both monocyclic and polycyclic parasite evolutionarily stable strategies (ESS) separated by less-fit strategies (evolutionary repellors). The ESS that evolves in each system is a function of the virulence strategy of the parasite introduced into the system. The trait value for both monocyclic and polycyclic strategies is determined by two aspects of host phenology: the duration of the host activity period and the distribution in the time at which hosts first become active within each season. Longer host activity periods and more synchronous host emergence drive both the monocyclic and polycyclic strategies towards lower virulence. The results demonstrate that host phenology can, in theory, maintain diverse parasite strategies among isolated geographic locations.

Infection by a vertically-transmitted microsporidian parasite is associated with a female-biased sex ratio and survival advantage in the amphipod Gammarus roeseli

Parasitology ◽  
2007 ◽  
Vol 134 (10) ◽  
pp. 1363-1367 ◽  
Author(s):  
E. R. HAINE ◽  
S. MOTREUIL ◽  
T. RIGAUD
Keyword(s):  
Sex Ratio ◽  
Species Interactions ◽  
Negative Effects ◽  
Microsporidian Parasite ◽  
Host Fitness ◽  
Gammarus Roeseli ◽  
Ratio Distortion ◽  
Biased Sex Ratio ◽  
Host Parasite ◽  
Specific Virulence

SUMMARYVertically transmitted parasites may have positive, neutral or negative effects on host fitness, and are also predicted to exhibit sex-specific virulence to increase the proportion or fitness of the transmitting sex. We investigated these predictions in a study on the survival and sex ratio of offspring of the amphipod Gammarus roeseli from females infected by the vertically transmitted microsporidia Nosema granulosis. We found, to our knowledge, the first evidence for a positive relationship between N. granulosis infection and host survival. Infection was associated with sex ratio distortion, not by male-killing, but probably by parasite-induced feminization of putative G. roeseli males. This microsporidia also feminizes another amphipod host, Gammarus duebeni, which is phylogenetically and biogeographically distant from G. roeseli. Our study suggests that the reproductive system of gammarids is easily exploited by these vertically-transmitted parasites, although the effects of infections on host fitness may depend on specific host-parasite species interactions.

scholarly journals Temperature-dependent changes to host-parasite interactions alter the thermal performance of a bacterial host

2019 ◽  
Author(s):  
Daniel Padfield ◽  
Meaghan Castledine ◽  
Angus Buckling
Keyword(s):  
Thermal Performance ◽  
Species Interactions ◽  
High Growth ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Temperature Dependent ◽  
Evolutionary Mechanisms ◽  
Data Accessibility ◽  
Cost Of Resistance ◽  
Host Parasite

AbstractThermal performance curves (TPCs) are used to predict changes in species interactions, and hence range shifts, disease dynamics and community composition, under forecasted climate change. Species interactions might in turn affect TPCs. Here, we investigate whether temperature-dependent changes in a microbial host-parasite interaction (the bacterium Pseudomonas fluorescens, and its bacteriophage, SBWФ2) changes the host TPC. The bacteriophage had a narrower infectivity range, with their critical thermal maximum ∼6°C lower than those at which the bacteria still had high growth. Consequently, in the presence of phage, the host TPC had a higher optimum temperature and a lower maximum growth rate. These changes were driven by a temperature-dependent evolution, and cost, of resistance; the largest cost of resistance occurring where bacteria grew best in the absence of phage. Our work highlights how ecological and evolutionary mechanisms can alter the effect of a parasite on host thermal performance, even over very short timescales.Data accessibility statementAll data and R code used in the analysis will be made available on GitHub and archived on Zenodo.

scholarly journals How host phenology impacts multi-season epidemic cycles

2021 ◽  
Author(s):  
Hannelore MacDonald ◽  
Dustin Brisson
Keyword(s):  
Mathematical Model ◽  
Population Dynamics ◽  
Population Cycles ◽  
Seasonal Activity ◽  
Host Interactions ◽  
Host Phenology ◽  
Demographic Impact ◽  
Host Parasite ◽  
Parasite Populations ◽  
Parasite Dynamics

Parasite-host interactions can result in periodic population dynamics when parasites over-exploit host populations. The timing of host seasonal activity, or host phenology, determines the frequency and demographic impact of parasite-host interactions which may govern if the parasite can sufficiently over-exploit their hosts to drive population cycles. We describe a mathematical model of a monocyclic, obligate-killer parasite system with seasonal host activity to investigate the consequences of host phenology on host-parasite dynamics. The results suggest that parasites can reach the densities necessary to destabilize host dynamics and drive cycling in only some phenological scenarios, such as environments with short seasons and synchronous host emergence. Further, only parasite lineages that are sufficiently adapted to phenological scenarios with short seasons and synchronous host emergence can achieve the densities necessary to over-exploit hosts and produce population cycles. Host-parasite cycles can also generate an eco-evolutionary feedback that slows parasite adaptation to the phenological environment as rare advantageous phenotypes are driven to extinction when introduced in phases of the cycle where host populations are small and parasite populations are large. The results demonstrate that seasonal environments can drive population cycling in a restricted set of phenological patterns and provides further evidence that the rate of adaptive evolution depends on underlying ecological dynamics.

scholarly journals Diverse tumour susceptibility in Collaborative Cross mice: identification of a new mouse model for human gastric tumourigenesis

Gut ◽  
2019 ◽  
Vol 68 (11) ◽  
pp. 1942-1952 ◽  
Author(s):  
Pin Wang ◽  
Yunshan Wang ◽  
Sasha A Langley ◽  
Yan-Xia Zhou ◽  
Kuang-Yu Jen ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Mouse Model ◽  
Rna Sequencing ◽  
Genetic Association ◽  
Association Analysis ◽  
Collaborative Cross ◽  
Sequencing Analysis ◽  
Genetic Association Analysis ◽  
Mouse Population ◽  
Wide Range

ObjectiveThe Collaborative Cross (CC) is a mouse population model with diverse and reproducible genetic backgrounds used to identify novel disease models and genes that contribute to human disease. Since spontaneous tumour susceptibility in CC mice remains unexplored, we assessed tumour incidence and spectrum.DesignWe monitored 293 mice from 18 CC strains for tumour development. Genetic association analysis and RNA sequencing were used to identify susceptibility loci and candidate genes. We analysed genomes of patients with gastric cancer to evaluate the relevance of genes identified in the CC mouse model and measured the expression levels of ISG15 by immunohistochemical staining using a gastric adenocarcinoma tissue microarray. Association of gene expression with overall survival (OS) was assessed by Kaplan-Meier analysis.ResultsCC mice displayed a wide range in the incidence and types of spontaneous tumours. More than 40% of CC036 mice developed gastric tumours within 1 year. Genetic association analysis identified Nfκb1 as a candidate susceptibility gene, while RNA sequencing analysis of non-tumour gastric tissues from CC036 mice showed significantly higher expression of inflammatory response genes. In human gastric cancers, the majority of human orthologues of the 166 mouse genes were preferentially altered by amplification or deletion and were significantly associated with OS. Higher expression of the CC036 inflammatory response gene signature is associated with poor OS. Finally, ISG15 protein is elevated in gastric adenocarcinomas and correlated with shortened patient OS.ConclusionsCC strains exhibit tremendous variation in tumour susceptibility, and we present CC036 as a spontaneous laboratory mouse model for studying human gastric tumourigenesis.

scholarly journals Yersinia pestis--etiologic agent of plague.

1997 ◽  
Vol 10 (1) ◽  
pp. 35-66 ◽  
Author(s):  
R D Perry ◽  
J D Fetherston
Keyword(s):  
Yersinia Pestis ◽  
Etiologic Agent ◽  
Clinical Aspects ◽  
Virulence Determinants ◽  
Health Issues ◽  
Regulatory Systems ◽  
Wide Range ◽  
Parasite Relationship ◽  
Obligate Pathogen ◽  
Host Parasite

Plague is a widespread zoonotic disease that is caused by Yersinia pestis and has had devastating effects on the human population throughout history. Disappearance of the disease is unlikely due to the wide range of mammalian hosts and their attendant fleas. The flea/rodent life cycle of Y. pestis, a gram-negative obligate pathogen, exposes it to very different environmental conditions and has resulted in some novel traits facilitating transmission and infection. Studies characterizing virulence determinants of Y. pestis have identified novel mechanisms for overcoming host defenses. Regulatory systems controlling the expression of some of these virulence factors have proven quite complex. These areas of research have provide new insights into the host-parasite relationship. This review will update our present understanding of the history, etiology, epidemiology, clinical aspects, and public health issues of plague.

scholarly journals Phenological synchrony shapes pathology in host–parasite systems

2020 ◽  
Vol 287 (1919) ◽  
pp. 20192597
Author(s):  
Travis McDevitt-Galles ◽  
Wynne E. Moss ◽  
Dana M. Calhoun ◽  
Pieter T. J. Johnson
Keyword(s):  
San Francisco ◽  
Species Interactions ◽  
Time Windows ◽  
Critical Time ◽  
Parasite Load ◽  
High Elevation ◽  
Infection Prevalence ◽  
Bay Area ◽  
Phenological Synchrony ◽  
Host Parasite

A key challenge surrounding ongoing climate shifts is to identify how they alter species interactions, including those between hosts and parasites. Because transmission often occurs during critical time windows, shifts in the phenology of either taxa can alter the likelihood of interaction or the resulting pathology. We quantified how phenological synchrony between vulnerable stages of an amphibian host ( Pseudacris regilla ) and infection by a pathogenic trematode ( Ribeiroia ondatrae ) determined infection prevalence, parasite load and host pathology. By tracking hosts and parasite infection throughout development between low- and high-elevation regions (San Francisco Bay Area and the Southern Cascades (Mt Lassen)), we found that when phenological synchrony was high (Bay Area), each established parasite incurred a 33% higher probability of causing severe limb malformations relative to areas with less synchrony (Mt Lassen). As a result, hosts in the Bay Area had up to a 50% higher risk of pathology even while controlling for the mean infection load. Our results indicate that host–parasite interactions and the resulting pathology were the joint product of infection load and phenological synchrony, highlighting the sensitivity of disease outcomes to forecasted shifts in climate.

The risk of use small matrices to measure specialization in host–parasite interaction networks: a comment to Rivera-García et al. (2016)

Parasitology ◽  
2017 ◽  
Vol 144 (8) ◽  
pp. 1102-1106 ◽  
Author(s):  
PEDRO LUNA ◽  
ERICK J. CORRO ◽  
DIANA A. AHUATZIN-FLORES ◽  
REUBER L. ANTONIAZZI ◽  
NATHALIA BARROZO ◽  
...  
Keyword(s):  
Species Richness ◽  
Species Interactions ◽  
Simulated Data ◽  
Interaction Networks ◽  
Host Parasite Interactions ◽  
The Matrix ◽  
Bat Fly ◽  
Host Parasite

SUMMARYIn the last years, there were a growing number of studies using the metric H2′ to calculate complementary specialization in host–parasite interaction networks. However, only a few studies have explored the sensitivity of H2′ to network dimensions (i.e. species richness and number of interactions), which consequently could generate studies that are not comparable among them or lead to biased conclusions. In this study, we used the recent published study conducted by Rivera-García et al. in 2016 involving host–bat fly networks as an example to call attention to the risk of using H2′ to calculate specialization for small matrices. After conducting analyses based on both empirical and simulated data, we show that H2′ values are strongly affected by randomly allocation of species interactions to another cell in the matrix for small networks and that therefore the results and conclusions presented in Rivera-García et al. in 2016 are only an artefact of the dataset used. Therefore, we fully recommended taking into account the careful use of small networks to measuring specialization in host–parasite interactions.

Accuracy analysis of global ionospheric maps in relation to their temporal resolution and solar activity level.

2020 ◽  
Author(s):  
Beata Milanowska ◽  
Paweł Wielgosz ◽  
Anna Krypiak-Gregorczyk ◽  
Wojciech Jarmołowski
Keyword(s):  
Solar Activity ◽  
Temporal Resolution ◽  
Geomagnetic Storms ◽  
Activity Level ◽  
Activity Period ◽  
Accuracy Evaluation ◽  
Accuracy Analysis ◽  
International Gnss Service ◽  
Wide Range ◽  
Global Ionospheric Maps

<p>Since 1998 Ionosphere Associate Analysis Centers (IAAC) of the International GNSS Service (IGS) routinely provide global ionosphere maps (GIMs). They are used for a wide range of geophysical applications, including supporting precise positioning and improving space weather analysis. These GIMs are generated by different analysis centers with the use of different modelling techniques. Therefore they have different accuracy levels, which has already been evaluated in several studies. Until 2014 all GIMs were provided with 2-hour temporal resolution, and since 2015 some of the IAACs have started to provide their products with higher resolutions, up to 30 - 60 minutes. Since GIMs have different temporal resolutions, we investigated whether map interval affected their accuracies.</p><p>In this study we carried out IAAC GIM accuracy analysis for years 2014 and 2018, corresponding to high and low solar activity periods, respectively. Since in 2014 IAAC GIMs had 2-hour resolution, we also evaluated UQRG maps supplied with 15-minute interval. For low solar activity period (2018) we evaluated 4 models: CASG, CODG, EMRG and  UQRG. In addition, we studied ionosphere map performance during two selected geomagnetic storms: on 19 February 2014 and 17 March 2015. Our accuracy evaluation was based on GIM-TEC comparisons to differential STEC derived from GNSS data and VTEC derived from altimetry measurements.</p><p>The results show that temporal interval has no significant impact on the overall, annual map RMS during both high and low solar activity periods. However, during geomagnetic storms, when reducing map interval, the map accuracy improves by almost 25%.</p>

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