scholarly journals Cross-continental experimental infections reveal distinct defence mechanisms in populations of the three-spined stickleback Gasterosteus aculeatus

2021 ◽  
Vol 288 (1959) ◽  
pp. 20211758
Author(s):  
Agnes Piecyk ◽  
Megan A. Hahn ◽  
Olivia Roth ◽  
Nolwenn M. Dheilly ◽  
David C. Heins ◽  
...  
Keyword(s):  
Gasterosteus Aculeatus ◽  
Quantitative Resistance ◽  
Parasite Burden ◽  
Interaction Effects ◽  
Host Population ◽  
Defence Mechanisms ◽  
Qualitative Resistance ◽  
Species Specific ◽  
Host Parasite ◽  
Main Effects

Epidemiological traits of host–parasite associations depend on the effects of the host, the parasite and their interaction. Parasites evolve mechanisms to infect and exploit their hosts, whereas hosts evolve mechanisms to prevent infection and limit detrimental effects. The reasons why and how these traits differ across populations still remain unclear. Using experimental cross-infection of three-spined stickleback Gasterosteus aculeatus and their species-specific cestode parasites Schistocephalus solidus from Alaskan and European populations, we disentangled host, parasite and interaction effects on epidemiological traits at different geographical scales. We hypothesized that host and parasite main effects would dominate both within and across continents, although interaction effects would show geographical variation of natural selection within and across continents. We found that mechanisms preventing infection (qualitative resistance) occurred only in a combination of hosts and parasites from different continents, while mechanisms limiting parasite burden (quantitative resistance) and reducing detrimental effects of infection (tolerance) were host-population specific. We conclude that evolution favours distinct defence mechanisms on different geographical scales and that it is important to distinguish concepts of qualitative resistance, quantitative resistance and tolerance in studies of macroparasite infections.

The regulation of host population growth by parasitic species

Parasitology ◽  
1978 ◽  
Vol 76 (2) ◽  
pp. 119-157 ◽  
Author(s):  
R. M. Anderson
Keyword(s):  
Population Growth ◽  
Reproductive Potential ◽  
Parasite Burden ◽  
Host Population ◽  
Parasitic Species ◽  
Regulatory Influence ◽  
Host Mortality ◽  
Parasite Reproduction ◽  
Over Dispersion ◽  
Host Parasite

SummaryThe nature of parasitism at the population level is defined in terms of the parasite's influence on the natural intrinsic growth rate of its host population. It is suggested that the influence on this rate is related to the average parasite burden/host and hence to the statistical distribution of parasites within the host population.Theoretical models of host–parasite associations are used to assess the regulatory influence of parasitic species on host population growth. Model predictions suggest that three specific groups of population processes are of particular importance: over-dispersion of parasite numbers/host, density dependence in parasite mortality or reproduction and parasite-induced host mortality that increases faster than linearly with the parasite burden. Other population mechanisms are shown to have a destabilizing influence, namely: parasite-induced reduction in host reproductive potential, direct parasite reproduction within the host and time delays in the development of transmission stages of the parasite.These regulatory and destabilizing processes are shown to be commonly observed features of natural host-parasite associations. It is argued that interactions in the real world are characterized by a degree of tension between these regulatory and destabilizing forces and that population rate parameter values in parasite life-cycles are very far from being a haphazard selection of all numerically possible values. It is suggested that evolutionary pressures in observed associations will tend to counteract a strong destabilizing force by an equally strong regulatory influence. Empirical evidence is shown to support this suggestion in, for example, associations between larval digeneans and molluscan hosts (parasite-induced reduction in host reproductive potential counteracted by tight density-dependent constraints on parasite population growth), and interactions between protozoan parasites and mammalian hosts (direct parasite reproduction counteracted by a well-developed immunological response by the host).The type of laboratory and field data required to improve our understanding of the dynamical properties of host–parasite population associations is discussed and it is suggested that quantitative measurement of rates of parasite-induced host mortality, degrees of over-dispersion, transmission rates and reproductive and mortality rates of both host and parasite would provide an important first step. The value of laboratory work in this area is demonstrated by reference to studies which highlight the regulatory influence of parasitic species on host population growth.

Field Evidence of Trematode-Induced Gigantism in Hydrobia Spp. (Gastropoda: Prosobranchia)

1997 ◽  
Vol 77 (3) ◽  
pp. 785-800 ◽  
Author(s):  
A.M. Gorbushin
Keyword(s):  
Growth Rate ◽  
Growth Response ◽  
Host Population ◽  
Trematode Species ◽  
Age Group ◽  
Experimental Conditions ◽  
Field Evidence ◽  
Penis Size ◽  
Species Specific ◽  
Host Parasite

The study of growth rates in the prosobranch snails Hydrobia ulvae and H. ventrosa under field conditions showed that growth rate of snails infected by different trematode species is species-specific. Trematodes from the families Microphallidae and Heterophyidae cause gigantic growth whereas species from families Notocotylidae and Bunocotylidae have no effect on growth rate. This discrepancy is attributed to the different pathogenicity of the parasites. However, under experimental conditions with different host population densities the effect of infection by Bunocotyle progenetica effect varies from a tendency to stunt the growth (under high density) to a significant increase in growth rate (under low density). The effect of Himasthla sp. (Echinostomatidae) was shown to be population-specific. These findings agree with a previously reported hypothesis that the growth response of trematode-infected snails depends (among other things) on supplement of host-parasite system with food. Trematode infection caused parasitic castration in all studied host-parasite combinations. It is argued that the phenomenon of gigantism in infected snails is a consequence of the reduced sexual ability of the host. The correlation between snail growth rate and penis size of infected males was negative. The correlation between growth rate and penis size was not found in uninfected snails from the same age group

The effect of the acanthocephalan Pomphorhynchus laevis upon the respiration of its intermediate host, Gammarus pulex

Parasitology ◽  
1974 ◽  
Vol 68 (2) ◽  
pp. 271-284 ◽  
Author(s):  
A. E. Rumpus ◽  
C. R. Kennedy
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Host Population ◽  
Gammarus Pulex ◽  
Multiple Infections ◽  
Pomphorhynchus Laevis ◽  
Respiration Rates ◽  
Physiological Processes ◽  
Stage Of Development ◽  
Host Parasite

The respiration rates of individual Gammarus pulex infected by larval Pomphorhynchus laevis were investigated with particular reference to the stage of development of the host and parasite and to the water temperature. At 20°C the oxygen consumption of Gammarus of all sizes was reduced by an average of 19·3 % by the presence of cystacanths of the parasite, but was unaffected by the presence of acanthellae. It is considered that the small size of this larval stage, in relation to that of its host, is responsible for the failure to detect an effect. Multiple infections did not exert any greater effect upon host respiration than single cystacanths, nor did it appear that the parasite had different effects upon hosts of different sexes. At 10°C no significant differences were observed between the respiration rates of infected and uninfected gammarids. The parasite was probably still depressing the host respiration rate at this temperature, but the oxygen uptake of G. pulex is so low that the differences between infected and uninfected individuals were too small to be detected. The parasite has a direct effect upon the physiological processes of the host, but neither the mechanism of this nor the reasons for the different effects found in different host-parasite systems are yet understood. Despite the pronounced effect of P. laevis on respiration of individual hosts, its effect upon the oxygen consumption of a natural host population is small since only a small proportion of the population carries infections and water temperatures remain below 10°C for over half the year.

Population variation in the metabolic response of deer mice to infection with Capillaria hepatica (Nematoda)

2001 ◽  
Vol 79 (4) ◽  
pp. 554-561 ◽  
Author(s):  
Shawn Meagher ◽  
Timothy P O'Connor
Keyword(s):  
Cold Stress ◽  
Metabolic Response ◽  
Host Population ◽  
Population Variation ◽  
Deer Mice ◽  
Negative Consequences ◽  
Capillaria Hepatica ◽  
Generation Times ◽  
Stress Maximum ◽  
Host Parasite

The effects of parasites on their hosts can vary among host populations, but few studies have examined geographic variation in host-parasite interactions. We examined the effects of Capillaria hepatica (Nematoda) infection on deer mice (Peromyscus maniculatus gracilis) from two different populations. Specifically, we measured the basal metabolic rate (BMR), cold-stress maximum oxygen consumption (MRpeak), metabolic scope (MRpeak/BMR), and thermogenic endurance of infected and uninfected mice from one population with, and a second population without, a history with C. hepatica. Infection had no effect on BMR, but did have effects on cold-stress measures. A previous study documented a significant relationship between survival and MRpeak in wild deer mice; hence, the effects of infection on the parameters that we measured could influence fitness. Only mice that had no historical association with C. hepatica displayed negative consequences of infection, which suggests that the historical host population has evolved mechanisms to cope with infection. Models of the evolution of virulence should include evolutionary responses of both hosts and parasites, particularly when systems involve macroparasites that have long generation times.

Consistent differences in macroparasite community composition among populations of three-spined sticklebacks,Gasterosteus aculeatusL.

Parasitology ◽  
2012 ◽  
Vol 139 (11) ◽  
pp. 1478-1491 ◽  
Author(s):  
JOB DE ROIJ ◽  
ANDREW D. C. MacCOLL
Keyword(s):  
Spatial Variation ◽  
Community Composition ◽  
Gasterosteus Aculeatus ◽  
Parasite Community ◽  
Field Studies ◽  
Habitat Characteristics ◽  
Parasite Communities ◽  
Geographical Distances ◽  
Host Parasite ◽  
Relative Differences

SUMMARYParasite ecologists are often interested in the repeatability of patterns in parasite communities in space and/or time, because of implications for the dynamics of host-parasite interactions. Field studies usually examine temporal and spatial variation in isolation or limit themselves to a small number of host populations. Here, we studied the macroparasite communities of 12 populations of three-spined stickleback,Gasterosteus aculeatusL., on North Uist, Scotland, separated by small geographical distances, during the breeding season in 2 consecutive years (2007 and 2008) to determine: (1) the extent of spatial variation in macroparasite communities, (2) whether this variation is consistent across years, and (3) whether habitat characteristics can explain differences in macroparasite community composition among populations. We found substantial variation in parasite communities among populations. Generally, measures of parasite community composition were higher in 2008 than in 2007, but this effect of year was consistent across populations, such that the relative differences in these measures among populations changed little between years. These data suggest that there is short-term stability in the spatial variation in macroparasite communities of North Uist sticklebacks. However, none of the 5 habitat characteristics measured explained spatial variation in any measure of parasite community composition.

Exploring the Role of Interaction Effects in Visual Conjoint Analysis

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Brian Sylcott ◽  
Jeremy J. Michalek ◽  
Jonathan Cagan
Keyword(s):  
Conjoint Analysis ◽  
Consumer Preferences ◽  
Consumer Preference ◽  
Interaction Effects ◽  
Fractional Factorial ◽  
Main Effects ◽  
Full Factorial ◽  
Biased Estimates ◽  
Data Requirements

In conjoint analysis, interaction effects characterize how preference for the level of one product attribute is dependent on the level of another attribute. When interaction effects are negligible, a main effects fractional factorial experimental design can be used to reduce data requirements and survey cost. This is particularly important when the presence of many parameters or levels makes full factorial designs intractable. However, if interaction effects are relevant, main effects design can create biased estimates and lead to erroneous conclusions. This work investigates consumer preference interactions in the nontraditional context of visual choice-based conjoint analysis, where the conjoint attributes are parameters that define a product's shape. Although many conjoint studies assume interaction effects to be negligible, they may play a larger role for shape parameters. The role of interaction effects is explored in two visual conjoint case studies. The results suggest that interactions can be either negligible or dominant in visual conjoint, depending on consumer preferences. Generally, we suggest using randomized designs to avoid any bias resulting from the presence of interaction effects.

Streckziehen keramischer Grünfolien*/Stretch drawing of ceramic green tapes - Investigation of the factors influencing to the stretch drawing capacity of ceramic green tapes

2016 ◽  
Vol 106 (11-12) ◽  
pp. 847-850
Author(s):  
Q. Spiller ◽  
M. Baumeister ◽  
J. Prof. Fleischer
Keyword(s):  
Statistical Methods ◽  
Three Dimensional ◽  
Interaction Effects ◽  
Powder Technology ◽  
Factors Influencing ◽  
Statistische Methoden ◽  
Main Effects

Im Bereich der Pulvertechnologie stellt das Streckziehen keramischer Grünfolien eine wirtschaftliche Möglichkeit dar, dreidimensionale Halbzeuge herzustellen. Im Rahmen des AiF-Projekts „Inka“ werden die Einflüsse der Prozess- und Geometrieparameter auf die Streckziehfähigkeit von keramischen Grünfolien aus dem Werkstoff ZrO2 experimentell untersucht. Dabei kommen statistische Methoden zur Ermittlung der Haupt- und Wechselwirkungseffekte zum Einsatz.   In the field of powder technology stretch drawing is an economic way to produce three-dimensional semi-finished products. In the context of the AIF Project “Inka“ the influences of process and geometry parameters are experimental examined on stretch drawing capacity of ceramic green tapes of material ZrO2. Statistical methods are used to find out main effects and interaction effects.

scholarly journals Main Effects and Interaction Effects of Bank Ownership Types and Bank Core Capital Category to the Bank NPL Performance

2021 ◽  
Vol 5 (1) ◽  
pp. 39-50
Author(s):  
Fongnawati Budhijono
Keyword(s):  
Financial Services ◽  
Secondary Data ◽  
Interaction Effects ◽  
Financial Reports ◽  
Management Capability ◽  
Main Effect ◽  
Bank Ownership ◽  
Asset Quality ◽  
Main Effects ◽  
Ownership Types

Credit management capability is seen as a crucial aspect for banks sustainability. The variable that is directly related to bank credit risk is a non-performing loan (NPL) which is commonly used to assess the asset quality of a bank. The purpose of this research is to analyze main effects and interaction effects of  bank ownership types and bank core capital category (BUKU) to the bank NPL performance. The study was conducted using secondary data obtained from bank quarterly reports from the Financial Services Authority (OJK) through the website ojk.go.id, bank financial reports, and infobank magazine. Bank’s performance in the classification of bank ownership types and bank core capital category were evaluated with respect to bank’s  NPL which in this case is used as  indicator of the bank’s performance. Tests were performed using TWO WAY ANOVA and  Post Hoc Test. The findings of this study found that the main effect type of bank ownership had a significant effect on the performance of NPL management, the main effect of banks’ BUKU had no significant effect on the performance of NPL management and the interaction effect of bank type and banks’ BUKU had a significant effect on the performance of NPL management.  

scholarly journals Zooming into Real-Life Extraversion – How Personality and Situation Shape Sociability in Social Interactions

2016 ◽  
Author(s):  
Simon Mats Breil ◽  
Katharina Geukes ◽  
Robert Edmund Wilson ◽  
Steffen Nestler ◽  
Simine Vazire ◽  
...  
Keyword(s):  
Social Interactions ◽  
Specific Interaction ◽  
Real Life ◽  
Interaction Effects ◽  
Complex Interplay ◽  
Sampling Studies ◽  
Social Perspectives ◽  
Context Shape ◽  
Event Based ◽  
Main Effects

Here, we provide you with supplemental material (additional tables, data, R-Codes) and a Preprint to the manuscript "Zooming into Real-Life Extraversion - How Personality and Context Shape Sociability in Social Interactions" by Breil et al. (under review). Abstract:What predicts sociable behavior? While main effects of personality and situation characteristics on sociability are well established, the determinants of sociable behavior within real-life social interactions are understudied. Moreover, although such effects are often hypothesized, there is to date little evidence of person-situation interaction effects. Finally, previous research focused on self-reported behavior ratings, and less is known on the partner’s social perspective, i.e. how partners perceive and influence an actor’s behavior. In the current research we investigated predictors of sociable behavior in real-life social interactions across social perspectives, including person and situation main effects as well as person-situation interaction effects. In two experience-sampling studies (Study 1: N = 394, US, time-based; Study 2: N = 124, Germany, event-based), we assessed personality traits with self- and informant reports, self-reported sociable behavior during real-life social interaction, and corresponding information on the situation (dimensional ratings of situation characteristics and categorical situation classifications). In Study 2, we additionally assessed interaction partner-reported behavior. Multilevel analyses provided consistent evidence for main effects of personality and situation features, and for person-situation interaction effects. First, extraverts acted more sociable in general. Second, individuals behaved more sociable in hedonic/positive/low-duty situations (vs. eudaimonic/negative/high-duty situations). Third, the latter was particularly true for extraverts. Further specific interaction effects were found for the other social perspectives. These results are discussed regarding the complex interplay of persons and situations in shaping human behavior.

scholarly journals Zooming into Real-Life Extraversion – how Personality and Situation Shape Sociability in Social Interactions

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Simon M. Breil ◽  
Katharina Geukes ◽  
Robert E. Wilson ◽  
Steffen Nestler ◽  
Simine Vazire ◽  
...  
Keyword(s):  
Social Interactions ◽  
Specific Interaction ◽  
Real Life ◽  
Interaction Effects ◽  
Behavioral Models ◽  
Social Perspective ◽  
Sampling Studies ◽  
Social Perspectives ◽  
Event Based ◽  
Main Effects

What predicts sociable behavior? While main effects of personality and situation characteristics on sociability are well established, there is little evidence for the existence of person-situation interaction effects within real-life social interactions. Moreover, previous research has focused on self-reported behavior ratings, and less is known about the partner’s social perspective, i.e. how partners perceive and influence an actor’s behavior. In the current research, we investigated predictors of sociable behavior in real-life social interactions across social perspectives, including person and situation main effects as well as person-situation interaction effects. In two experience-sampling studies (Study 1: N = 394, US, time-based; Study 2: N = 124, Germany, event-based), we assessed personality traits with self- and informant-reports, self-reported sociable behavior during real-life social interactions, and corresponding information on the situation (categorical situation classifications and dimensional ratings of situation characteristics). In Study 2, we additionally assessed interaction partner-reported actor behavior. Multilevel analyses provided evidence for main effects of personality and situation features, as well as small but consistent evidence for person-situation interaction effects. First, extraverts acted more sociable in general. Second, individuals behaved more sociable in low-effort/positive/low-duty situations (vs. high-effort/negative/high-duty situations). Third, the latter was particularly true for extraverts. Further specific interaction effects were found for the partner’s social perspective. These results are discussed regarding their accordance with different behavioral models (e.g., Trait Activation Theory) and their transferability to other behavioral domains.

Sign in / Sign up

Export Citation Format

Share Document