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1
Weatherhead, Patrick J., i Gordon F. Bennett. "Ecology of Red-winged Blackbird parasitism by haematozoa". Canadian Journal of Zoology 69, nr 9 (1.09.1991): 2352–59. http://dx.doi.org/10.1139/z91-331.
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We sampled haematozoa in Red-winged Blackbirds (Agelaius phoeniceus) over three consecutive breeding seasons in eastern Ontario to identify factors that affect the reliability of quantifying parasites as this pertains to testing Hamilton and Zuk's hypothesis of sexual selection. Parasite prevalence and intensity varied seasonally, indicating that for samples to be reliable they should not be taken either early or late in the breeding season, and analysis should be limited to prevalence (presence versus absence). Among males (but not females), parasite prevalence increased with age, indicating that all individuals are not exposed to parasites early in life, and therefore tests of the "parasite" hypothesis of sexual selection are best restricted to older individuals. Resampling of known individuals within and between years showed that some individuals changed from positive to negative. Prevalence estimates also varied by year, indicating that reliable estimates of prevalence for a species, necessary for interspecific tests of the parasite hypothesis, will require extensive sampling. Overall, parasite prevalence did not vary with habitat. Parasites were detectable in only 1 of 119 nestlings sampled, indicating either lack of exposure or inadequate time for infections to reach detectable intensities. In either case, it is not possible to test the assumption that parasite resistance is heritable using blood samples from nestlings. Although males and females were parasitized by the same array of parasites, the distribution of specific parasites differed significantly (males were more heavily parasitized by leucocytozoids). If males and females generally differ in either exposure or resistance to specific parasites, the coevolutionary dynamics between host and parasite and the implications for sexual selection will require reassessment.
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GLEICHSNER, ALYSSA M., i DENNIS J. MINCHELLA. "Can host ecology and kin selection predict parasite virulence?" Parasitology 141, nr 8 (24.04.2014): 1018–30. http://dx.doi.org/10.1017/s0031182014000389.
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SUMMARYParasite virulence, or the damage a parasite does to its host, is measured in terms of both host costs (reductions in host growth, reproduction and survival) and parasite benefits (increased transmission and parasite numbers) in the literature. Much work has shown that ecological and genetic factors can be strong selective forces in virulence evolution. This review uses kin selection theory to explore how variations in host ecological parameters impact the genetic relatedness of parasite populations and thus virulence. We provide a broad overview of virulence and population genetics studies and then draw connections to existing knowledge about natural parasite populations. The impact of host movement (transporting parasites) and host resistance (filtering parasites) on the genetic structure and virulence of parasite populations is explored, and empirical studies of these factors using Plasmodium and trematode systems are proposed.
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POULIN, ROBERT, i HASEEB S. RANDHAWA. "Evolution of parasitism along convergent lines: from ecology to genomics". Parasitology 142, S1 (11.11.2013): S6—S15. http://dx.doi.org/10.1017/s0031182013001674.
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SUMMARYFrom hundreds of independent transitions from a free-living existence to a parasitic mode of life, separate parasite lineages have converged over evolutionary time to share traits and exploit their hosts in similar ways. Here, we first summarize the evidence that, at a phenotypic level, eukaryotic parasite lineages have all converged toward only six general parasitic strategies: parasitoid, parasitic castrator, directly transmitted parasite, trophically transmitted parasite, vector-transmitted parasite or micropredator. We argue that these strategies represent adaptive peaks, with the similarities among unrelated taxa within any strategy extending to all basic aspects of host exploitation and transmission among hosts and transcending phylogenetic boundaries. Then, we extend our examination of convergent patterns by looking at the evolution of parasite genomes. Despite the limited taxonomic coverage of sequenced parasite genomes currently available, we find some evidence of parallel evolution among unrelated parasite taxa with respect to genome reduction or compaction, and gene losses or gains. Matching such changes in parasite genomes with the broad phenotypic traits that define the convergence of parasites toward only six strategies of host exploitation is not possible at present. Nevertheless, as more parasite genomes become available, we may be able to detect clear trends in the evolution of parasitic genome architectures representing true convergent adaptive peaks, the genomic equivalents of the phenotypic strategies used by all parasites.
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Ezenwa, Vanessa O., Elizabeth A. Archie, Meggan E. Craft, Dana M. Hawley, Lynn B. Martin, Janice Moore i Lauren White. "Host behaviour–parasite feedback: an essential link between animal behaviour and disease ecology". Proceedings of the Royal Society B: Biological Sciences 283, nr 1828 (13.04.2016): 20153078. http://dx.doi.org/10.1098/rspb.2015.3078.
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Animal behaviour and the ecology and evolution of parasites are inextricably linked. For this reason, animal behaviourists and disease ecologists have been interested in the intersection of their respective fields for decades. Despite this interest, most research at the behaviour–disease interface focuses either on how host behaviour affects parasites or how parasites affect behaviour, with little overlap between the two. Yet, the majority of interactions between hosts and parasites are probably reciprocal, such that host behaviour feeds back on parasites and vice versa. Explicitly considering these feedbacks is essential for understanding the complex connections between animal behaviour and parasite ecology and evolution. To illustrate this point, we discuss how host behaviour–parasite feedbacks might operate and explore the consequences of feedback for studies of animal behaviour and parasites. For example, ignoring the feedback of host social structure on parasite dynamics can limit the accuracy of predictions about parasite spread. Likewise, considering feedback in studies of parasites and animal personalities may provide unique insight about the maintenance of variation in personality types. Finally, applying the feedback concept to links between host behaviour and beneficial, rather than pathogenic, microbes may shed new light on transitions between mutualism and parasitism. More generally, accounting for host behaviour–parasite feedbacks can help identify critical gaps in our understanding of how key host behaviours and parasite traits evolve and are maintained.
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Barber, Iain, i Niels J. Dingemanse. "Parasitism and the evolutionary ecology of animal personality". Philosophical Transactions of the Royal Society B: Biological Sciences 365, nr 1560 (27.12.2010): 4077–88. http://dx.doi.org/10.1098/rstb.2010.0182.
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The ecological factors responsible for the evolution of individual differences in animal personality (consistent individual differences in the same behaviour across time and contexts) are currently the subject of intense debate. A limited number of ecological factors have been investigated to date, with most attention focusing on the roles of resource competition and predation. We suggest here that parasitism may play a potentially important, but largely overlooked, role in the evolution of animal personalities. We identify two major routes by which parasites might influence the evolution of animal personality. First, because the risk of acquiring parasites can be influenced by an individual's behavioural type, local parasite regimes may impose selection on personality traits and behavioural syndromes (correlations between personality traits). Second, because parasite infections have consequences for aspects of host ‘state’, parasites might induce the evolution of individual differences in certain types of host behaviour in populations with endemic infections. Also, because infection often leads to specific changes in axes of personality, parasite infections have the potential to decouple behavioural syndromes. Host–parasite systems therefore provide researchers with valuable tools to study personality variation and behavioural syndromes from a proximate and ultimate perspective.
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Cole, David J. W. "Parasite Ecology Symposium". International Journal for Parasitology 27, nr 2 (luty 1997): 153. http://dx.doi.org/10.1016/s0020-7519(96)00141-5.
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Horn, Collin J., i Lien T. Luong. "Proximity to parasites reduces host fitness independent of infection in a Drosophila–Macrocheles system". Parasitology 145, nr 12 (13.03.2018): 1564–69. http://dx.doi.org/10.1017/s0031182018000379.
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AbstractParasites are known to have direct negative effects on host fitness; however, the indirect effects of parasitism on host fitness sans infection are less well understood. Hosts undergo behavioural and physiological changes when in proximity to parasites. Yet, there is little experimental evidence showing that these changes lead to long-term decreases in host fitness. We aimed to determine if parasite exposure affects host fitness independent of contact, because current approaches to parasite ecology may underestimate the effect of parasites on host populations. We assayed the longevity and reproductive output of Drosophila nigrospiracula exposed or not exposed to ectoparasitic Macrocheles subbadius. In order to preclude contact and infection, mites and flies were permanently separated with a mesh screen. Exposed flies had shorter lives and lower fecundity relative to unexposed flies. Recent work in parasite ecology has argued that parasite–host systems show similar processes as predator–prey systems. Our findings mirror the non-consumptive effects observed in predator–prey systems, in which prey species suffer reduced fitness even if they never come into direct contact with predators. Our results support the perspective that there are analogous effects in parasite–host systems, and suggest new directions for research in both parasite ecology and the ecology of fear.
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Poulin, Robert, Boris R. Krasnov, David Mouillot i David W. Thieltges. "The comparative ecology and biogeography of parasites". Philosophical Transactions of the Royal Society B: Biological Sciences 366, nr 1576 (27.08.2011): 2379–90. http://dx.doi.org/10.1098/rstb.2011.0048.
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Comparative ecology uses interspecific relationships among traits, while accounting for the phylogenetic non-independence of species, to uncover general evolutionary processes. Applied to biogeographic questions, it can be a powerful tool to explain the spatial distribution of organisms. Here, we review how comparative methods can elucidate biogeographic patterns and processes, using analyses of distributional data on parasites (fleas and helminths) as case studies. Methods exist to detect phylogenetic signals, i.e. the degree of phylogenetic dependence of a given character, and either to control for these signals in statistical analyses of interspecific data, or to measure their contribution to variance. Parasite–host interactions present a special case, as a given trait may be a parasite trait, a host trait or a property of the coevolved association rather than of one participant only. For some analyses, it is therefore necessary to correct simultaneously for both parasite phylogeny and host phylogeny, or to evaluate which has the greatest influence on trait expression. Using comparative approaches, we show that two fundamental properties of parasites, their niche breadth, i.e. host specificity, and the nature of their life cycle, can explain interspecific and latitudinal variation in the sizes of their geographical ranges, or rates of distance decay in the similarity of parasite communities. These findings illustrate the ways in which phylogenetically based comparative methods can contribute to biogeographic research.
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Rahimian, Hassan. "Parasites of fingerling herringClupea harengusL.: ecology and fine morphology". Journal of Helminthology 81, nr 2 (czerwiec 2007): 199–217. http://dx.doi.org/10.1017/s0022149x07735381.
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AbstractThe parasite fauna of young-of-the-year herringClupea harengusL., off Gullmarsfjord and Brofjorden, west coast of Sweden, was studied between May and October for 4 years, from 1994 to 1997. Fifteen species of parasites were found: two Protozoa –Trichodina sp.andCeratomyxa auerbachi; one species of uncertain affinity –Ichthyophonus hoferi; two Monogenea –Gyrodactylus harengiandPseudanthocotyloides heterocotyle; five Digenea –Cryptocotyle linguametacercariae,Cercaria pythionikemetacercariae,Hemiurus luehei,Lecithaster confususandPseudobacciger harengulae; three Cestoda plerocercoids –Bothriocephalussp., an acrobothriid and a tetraphyllid; one Nematoda –Hysterothylacium aduncumlarva; and one Copepoda –Caligus elongatus. The number of species found in this study represents more than one-sixth of all parasites reported in herring worldwide and all parasites were acquired locally. The parasite fauna of herring from the west coast of Sweden is compared with that of herring from the Baltic Sea and other areas of the north-east Atlantic. The prevalence and intensity of parasites are presented and discussed. Morphological descriptions are based on both light and scanning electron microscopy and new features are described. Possible applications of this new information about the parasite fauna, in different areas of fisheries and fish biology studies, are discussed.
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Dunn, A. M., M. J. Hatcher, R. S. Terry i C. Tofts. "Evolutionary ecology of vertically transmitted parasites: transovarial transmission of a microsporidian sex ratio distorter in Gammarus duebeni". Parasitology 111, S1 (styczeń 1995): S91—S109. http://dx.doi.org/10.1017/s0031182000075843.
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SUMMARYVertically transmitted parasites are transmitted from generation to generation of hosts usually via the host's gametes. Owing to gamete size dimorphism, the major transmission route is transovarial and selection (on the parasite) favours strategies which increase the relative frequency of the transmitting (female) host sex. These strategies impose unusual selection pressures on the host, and coevolution between hosts and vertically transmitted parasites has been implicated in speciation, in the evolution of symbiosis, and in the evolution of novel systems of host reproduction and sex determination. We review the evolutionary implications of vertically transmitted parasites in arthropods before focusing on strategies of transmission of a parasitic sex ratio distorter in Gammarus duebeni. The efficiency of parasite transmission to new hosts is a key factor underlying the relationship between vertically transmitted parasites and their hosts. Vertically transmitted parasites must overcome 2 bottlenecks in order to ensure successful infection of future host generations: first, transmission from adult to gamete; and secondly, transmission to the germ-line of the infected host. We investigate these 2 processes with regard to transovarial transmission by a microsporidian parasite in Gammarus duebeni. Parasite transmission from adult to eggs is highly efficient, with 96% of eggs of infected mothers inheriting the infection, whereas transmission to germ-line within infected embryos is relatively inefficient (72%). We measure parasite distribution between cells of developing embryos, and use these distributions to infer possible mechanisms of parasite transmission to germ-line. Parasite distribution within the embryo is dependent on host cell lineage, and is not consistent with unbiased segregation between daughter cells. These results indicate that parasites segregate together at host cell division, and may reflect a strategy of differential segregation to the host germ-line. We consider alternative parasite strategies at the cell-level in terms of their evolutionary implications.
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MUÑOZ, G., A. S. GRUTTER i T. H. CRIBB. "Endoparasite communities of five fish species (Labridae: Cheilininae) from Lizard Island: how important is the ecology and phylogeny of the hosts?" Parasitology 132, nr 3 (7.12.2005): 363–74. http://dx.doi.org/10.1017/s0031182005009133.
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The parasite community of animals is generally influenced by host physiology, ecology, and phylogeny. Therefore, sympatric and phylogenetically related hosts with similar ecologies should have similar parasite communities. To test this hypothesis we surveyed the endoparasites of 5 closely related cheilinine fishes (Labridae) from the Great Barrier Reef. They were Cheilinus chlorourus, C. trilobatus, C. fasciatus, Epibulus insidiator and Oxycheilinus diagramma. We examined the relationship between parasitological variables (richness, abundance and diversity) and host characteristics (body weight, diet and phylogeny). The 5 fishes had 31 parasite species with 9–18 parasite species per fish species. Cestode larvae (mostly Tetraphyllidea) were the most abundant and prevalent parasites followed by nematodes and digeneans. Parasites, body size and diet of hosts differed between fish species. In general, body weight, diet and host phylogeny each explained some of the variation in richness and composition of parasites among the fishes. The 2 most closely related species, Cheilinus chlorourus and C. trilobatus, had broadly similar parasites but the other fish species differed significantly in all variables. However, there was no all-encompassing pattern. This may be because different lineages of parasites may react differently to ecological variables. We also argue that adult parasites may respond principally to host diet. In contrast, larval parasite composition may respond both to host diet and predator-prey interactions because this is the path by which many parasites complete their life-cycles. Finally, variation in parasite phylogeny and parasite life-cycles among hosts likely increase the complexity of the system making it difficult to find all-encompassing patterns between host characteristics and parasites, particularly when all the species in rich parasite communities are considered.
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Mohammed, Ryan S., Stanley D. King, Paul Bentzen, David Marcogliese, Cock van Oosterhout i Jackie Lighten. "Parasite diversity and ecology in a model species, the guppy ( Poecilia reticulata ) in Trinidad". Royal Society Open Science 7, nr 1 (styczeń 2020): 191112. http://dx.doi.org/10.1098/rsos.191112.
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The guppy ( Poecilia reticulata ) is a model species in ecology and evolution. Many studies have examined effects of predators on guppy behaviour, reproduction, survival strategies, feeding and other life-history traits, but few have studied variation in their parasite diversity. We surveyed parasites of 18 Trinidadian populations of guppy, to provide insight on the geographical mosaic of parasite variability, which may act as a source of natural selection acting on guppies. We found 21 parasite species, including five new records for Trinidad. Spatial variation in parasite diversity was significantly higher than that of piscine predators, and significant variation in parasite richness among individuals and populations was correlated with: (i) host size, (ii) snail species richness, and (iii) the distance between populations. Differences in parasite species richness are likely to play an important, yet underestimated role in the biology of this model species of vertebrate ecology and evolution.
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Auld, Stuart K. J. R., Catherine L. Searle i Meghan A. Duffy. "Parasite transmission in a natural multihost–multiparasite community". Philosophical Transactions of the Royal Society B: Biological Sciences 372, nr 1719 (13.03.2017): 20160097. http://dx.doi.org/10.1098/rstb.2016.0097.
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Understanding the transmission and dynamics of infectious diseases in natural communities requires understanding the extent to which the ecology, evolution and epidemiology of those diseases are shaped by alternative hosts. We performed laboratory experiments to test how parasite spillover affected traits associated with transmission in two co-occurring parasites: the bacterium Pasteuria ramosa and the fungus Metschnikowia bicuspidata . Both parasites were capable of transmission from the reservoir host ( Daphnia dentifera ) to the spillover host ( Ceriodaphnia dubia ), but this occurred at a much higher rate for the fungus than the bacterium. We quantified transmission potential by combining information on parasite transmission and growth rate, and used this to compare parasite fitness in the two host species. For both parasites, transmission potential was lower in the spillover host. For the bacterium, virulence was higher in the spillover host. Transmission back to the original host was high for both parasites, with spillover influencing transmission rate of the fungus but not the bacterium. Thus, while inferior, the spillover host is not a dead-end for either parasite. Overall, our results demonstrate that the presence of multiple hosts in a community can have important consequences for disease transmission, and host and parasite fitness. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
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DALLAS, TAD, ANDREW W. PARK i JOHN M. DRAKE. "Predictability of helminth parasite host range using information on geography, host traits and parasite community structure". Parasitology 144, nr 2 (20.10.2016): 200–205. http://dx.doi.org/10.1017/s0031182016001608.
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SUMMARYHost–parasite associations are complex interactions dependent on aspects of hosts (e.g. traits, phylogeny or coevolutionary history), parasites (e.g. traits and parasite interactions) and geography (e.g. latitude). Predicting the permissive host set or the subset of the host community that a parasite can infect is a central goal of parasite ecology. Here we develop models that accurately predict the permissive host set of 562 helminth parasites in five different parasite taxonomic groups. We developed predictive models using host traits, host taxonomy, geographic covariates, and parasite community composition, finding that models trained on parasite community variables were more accurate than any other covariate group, even though parasite community covariates only captured a quarter of the variance in parasite community composition. This suggests that it is possible to predict the permissive host set for a given parasite, and that parasite community structure is an important predictor, potentially because parasite communities are interacting non-random assemblages.
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Sarabian, Cecile, Val Curtis i Rachel McMullan. "Evolution of pathogen and parasite avoidance behaviours". Philosophical Transactions of the Royal Society B: Biological Sciences 373, nr 1751 (4.06.2018): 20170256. http://dx.doi.org/10.1098/rstb.2017.0256.
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All free-living animals are subject to intense selection pressure from parasites and pathogens resulting in behavioural adaptations that can help potential hosts to avoid falling prey to parasites. This special issue on the evolution of parasite avoidance behaviour was compiled following a Royal Society meeting in 2017. Here we have assembled contributions from a wide range of disciplines including genetics, ecology, parasitology, behavioural science, ecology, psychology and epidemiology on the disease avoidance behaviour of a wide range of species. Taking an interdisciplinary and cross-species perspective allows us to sketch out the strategies, mechanisms and consequences of parasite avoidance and to identify gaps and further questions. Parasite avoidance strategies must include avoiding parasites themselves and cues to their presence in conspecifics, heterospecifics, foods and habitat. Further, parasite avoidance behaviour can be directed at constructing parasite-retardant niches. Mechanisms of parasite avoidance behaviour are generally less well characterized, though nematodes, rodents and human studies are beginning to elucidate the genetic, hormonal and neural architecture that allows animals to recognize and respond to cues of parasite threat. While the consequences of infection are well characterized in humans, we still have much to learn about the epidemiology of parasites of other species, as well as the trade-offs that hosts make in parasite defence versus other beneficial investments like mating and foraging. Finally, in this overview we conclude that it is legitimate to use the word ‘ disgust' to describe parasite avoidance systems, in the same way that ‘fear' is used to describe animal predator avoidance systems. Understanding disgust across species offers an excellent system for investigating the strategies, mechanisms and consequences of behaviour and could be a vital contribution towards the understanding and conservation of our planet's ecosystems. This article is part of the Theo Murphy meeting issue ‘Evolution of pathogen and parasite avoidance behaviours'.
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KENNEDY, C. R. "The ecology of parasites of freshwater fishes: the search for patterns". Parasitology 136, nr 12 (14.04.2009): 1653–62. http://dx.doi.org/10.1017/s0031182009005794.
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SUMMARYDevelopments in the study of the ecology of helminth parasites of freshwater fishes over the last half century are reviewed. Most research has of necessity been field based and has involved the search for patterns in population and community dynamics that are repeatable in space and time. Mathematical models predict that under certain conditions host and parasite populations can attain equilibrial levels through operation of regulatory factors. Such factors have been identified in several host-parasite systems and some parasite populations have been shown to persist over long time-periods. However, there is no convincing evidence that fish parasite populations are stable and regulated since in all cases alternative explanations are equally acceptable and it appears that they are non-equilibrial systems. It has proved particularly difficult to detect replicable patterns in parasite communities. Inter-specific competition, evidenced by functional and numerical responses, has been detected in several communities but its occurrence is erratic and its significance unclear. Some studies have failed to find any nested patterns in parasite community structure and richness, whereas others have identified such patterns although they are seldom constant over space and time. Departures from randomness appear to be the exception and then only temporary. It appears that parasite communities are non-equilibrial, stochastic assemblages rather than structured and organized.
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Hechinger, Ryan F., Kate L. Sheehan i Andrew V. Turner. "Metabolic theory of ecology successfully predicts distinct scaling of ectoparasite load on hosts". Proceedings of the Royal Society B: Biological Sciences 286, nr 1917 (18.12.2019): 20191777. http://dx.doi.org/10.1098/rspb.2019.1777.
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The impacts of parasites on hosts and the role that parasites play in ecosystems must be underlain by the load of parasites in individual hosts. To help explain and predict parasite load across a broad range of species, quantitative theory has been developed based on fundamental relationships between organism size, temperature and metabolic rate. Here, we elaborate on an aspect of that ‘scaling theory for parasitism’, and test a previously unexplored prediction, using new data for total ectoparasite load from 263 wild birds of 42 species. We reveal that, despite the expected substantial variation in parasite load among individual hosts, (i) the theory successfully predicts the distinct increase of ectoparasite load with host body size, indicating the importance of geometric scaling constraints on access to host resources, (ii) ectoparasite load appears ultimately limited by access—not to host space—but to host energy, and (iii) there is a currency-dependent shift in taxonomic dominance of parasite load on larger birds. Hence, these results reveal a seemingly new macroecological pattern, underscore the utility of energy flux as a currency for parasitism and highlight the promise of using scaling theory to provide baseline expectations for parasite load for a diversity of host species.
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Rea, J. G., i S. W. B. Irwin. "The ecology of host-finding behaviour and parasite transmission: past and future perspectives". Parasitology 109, S1 (1994): S31—S39. http://dx.doi.org/10.1017/s0031182000085061.
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SUMMARYHost location by parasites can be achieved by either active or passive mechanisms. In spite of their significance, the efficacy of these methods has been little researched. High fecundity in parasites is discussed in terms of the role it plays in dispersal and transmission. Some concepts developed by mainstream behavioural ecologists are outlined and their relevance to parasitology is indicated. ‘Reproductive value’ is recommended as an appropriate measure of the costs and benefits of behavioural acts. Although costs of reproduction have been rarely studied in parasites, they are likely to occur in cosexual insects, nematodes and crustaceans. Experiments using captive hosts and/orin vitrocultivation could help in the construction of realistic optimality models. We suggest that r- and K-selection theory could assist in the study of the evolution of parasite behaviour. We discuss how parasite populations are dispersed and controlled and consider the implications of overdispersion. WTe outline three sources of signals to which parasites may respond and suggest that understanding evolutionary mechanisms and community organisation of parasites and hosts requires evaluation of fundamental behavioural responses to environmental signals. The study of closely related groups of parasites and their hosts may advance our knowledge of the evolution of parasite life cycles and the evolutionary costs and benefits of behavioural acts.
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Walker, Josephine G., Michaela Plein, Eric R. Morgan i Peter A. Vesk. "Uncertain links in host–parasite networks: lessons for parasite transmission in a multi-host system". Philosophical Transactions of the Royal Society B: Biological Sciences 372, nr 1719 (13.03.2017): 20160095. http://dx.doi.org/10.1098/rstb.2016.0095.
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For many parasites, the full set of hosts that are susceptible to infection is not known, and this could lead to a bias in estimates of transmission. We used counts of individual adult parasites from historical parasitology studies in southern Africa to map a bipartite network of the nematode parasites of herbivore hosts that occur in Botswana. Bipartite networks are used in community ecology to represent interactions across trophic levels. We used a Bayesian hierarchical model to predict the full set of host–parasite interactions from existing data on parasitic gastrointestinal nematodes of wild and domestic ungulates given assumptions about the distribution of parasite counts within hosts, while accounting for the relative uncertainty of less sampled species. We used network metrics to assess the difference between the observed and predicted networks, and to explore the connections between hosts via their shared parasites using a host–host unipartite network projected from the bipartite network. The model predicts a large number of missing links and identifies red hartebeest, giraffe and steenbok as the hosts that have the most uncertainty in parasite diversity. Further, the unipartite network reveals clusters of herbivores that have a high degree of parasite sharing, and these clusters correspond closely with phylogenetic distance rather than with the wild/domestic boundary. These results provide a basis for predicting the risk of cross-species transmission of nematode parasites in areas where livestock and wildlife share grazing land. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
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Pedersen, Amy B., i Andy Fenton. "Emphasizing the ecology in parasite community ecology". Trends in Ecology & Evolution 22, nr 3 (marzec 2007): 133–39. http://dx.doi.org/10.1016/j.tree.2006.11.005.
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Mierzejewski, Monika K., Collin J. Horn i Lien T. Luong. "Ecology of fear: environment-dependent parasite avoidance among ovipositing Drosophila". Parasitology 146, nr 12 (15.07.2019): 1564–70. http://dx.doi.org/10.1017/s0031182019000854.
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AbstractHabitat avoidance is an anti-parasite behaviour exhibited by at-risk hosts that can minimize exposure to parasites. Because environments are often heterogeneous, host decision-making with regards to habitat use may be affected by the presence of parasites and habitat quality simultaneously. In this study we examine how the ovipositing behaviour of a cactiphilic fruit fly, Drosophila nigrospiracula, is affected by the presence of an ectoparasitic mite, Macrocheles subbadius, in conjunction with other environmental factors – specifically the presence or absence of conspecific eggs and host plant tissue. We hypothesized that the trade-off between site quality and parasite avoidance should favour ovipositing at mite-free sites even if it is of inferior quality. We found that although flies avoided mites in homogeneous environments (86% of eggs at mite-free sites), site quality overwhelmed mite avoidance. Both conspecific eggs (65% of eggs at infested sites with other Drosophila eggs) and host plant tissue (78% of eggs at infested sites with cactus) overpowered mite avoidance. Our results elucidate the context-dependent decision-making of hosts in response to the presence of parasites in variable environments, and suggest how the ecology of fear and associated trade-offs may influence the relative investment in anti-parasite behaviour in susceptible hosts.
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Cizauskas, Carrie A., Colin J. Carlson, Kevin R. Burgio, Chris F. Clements, Eric R. Dougherty, Nyeema C. Harris i Anna J. Phillips. "Parasite vulnerability to climate change: an evidence-based functional trait approach". Royal Society Open Science 4, nr 1 (styczeń 2017): 160535. http://dx.doi.org/10.1098/rsos.160535.
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Despite the number of virulent pathogens that are projected to benefit from global change and to spread in the next century, we suggest that a combination of coextinction risk and climate sensitivity could make parasites at least as extinction prone as any other trophic group. However, the existing interdisciplinary toolbox for identifying species threatened by climate change is inadequate or inappropriate when considering parasites as conservation targets. A functional trait approach can be used to connect parasites' ecological role to their risk of disappearance, but this is complicated by the taxonomic and functional diversity of many parasite clades. Here, we propose biological traits that may render parasite species particularly vulnerable to extinction (including high host specificity, complex life cycles and narrow climatic tolerance), and identify critical gaps in our knowledge of parasite biology and ecology. By doing so, we provide criteria to identify vulnerable parasite species and triage parasite conservation efforts.
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Mahony, Kate E., Sharon A. Lynch, Xavier de Montaudouin i Sarah C. Culloty. "Extrinsic and intrinsic drivers of parasite prevalence and parasite species richness in a marine bivalve". PLOS ONE 17, nr 9 (26.09.2022): e0274474. http://dx.doi.org/10.1371/journal.pone.0274474.
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Parasite species richness is influenced by a range of drivers including host related factors (e.g. host size) and environmental factors (e.g. seawater temperature). However, identification of modulators of parasite species richness remains one of the great unanswered questions in ecology. The common cockle Cerastoderma edule is renowned for its diversity and abundance of parasites, yet drivers of parasite species richness in cockles have not been examined to investigate the association of both macro and microparasite communities. Using cockles as a model species, some of the key drivers of parasite prevalence and parasite species richness were investigated. Objectives of this 19-month survey were to determine the influence of the environment, host-parasite dynamics and parasite associations on parasite species richness and prevalence at two different geographic latitudes, chosen based on environmental differences. The highest parasite species richness was recorded in the northern sites, and this was potentially influenced by a range of interactions between the host, the pathogens and the environment. Parasite prevalence increased with host size and age, and parasite species richness increased with reduced salinity. A number of interactions between parasites, and between parasites and pathologies may be influencing parasite infection dynamics. New and concerning information is also presented regarding interactions between parasites and their environment. A number of parasites and potential pathogens (bacteria, Trichodina ciliates, metacercariae, trematode sporocysts) may be advantaged under climate change conditions (warming seas, increased precipitation), increasing disease incidence, which may prove detrimental not just for cockles, but for other bivalve species in the future.
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Herrera, James, i Charles L. Nunn. "Behavioural ecology and infectious disease: implications for conservation of biodiversity". Philosophical Transactions of the Royal Society B: Biological Sciences 374, nr 1781 (29.07.2019): 20180054. http://dx.doi.org/10.1098/rstb.2018.0054.
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Behaviour underpins interactions among conspecifics and between species, with consequences for the transmission of disease-causing parasites. Because many parasites lead to declines in population size and increased risk of extinction for threatened species, understanding the link between host behaviour and disease transmission is particularly important for conservation management. Here, we consider the intersection of behaviour, ecology and parasite transmission, broadly encompassing micro- and macroparasites. We focus on behaviours that have direct impacts on transmission, as well as the behaviours that result from infection. Given the important role of parasites in host survival and reproduction, the effects of behaviour on parasitism can scale up to population-level processes, thus affecting species conservation. Understanding how conservation and infectious disease control strategies actually affect transmission potential can therefore often only be understood through a behavioural lens. We highlight how behavioural perspectives of disease ecology apply to conservation by reviewing the different ways that behavioural ecology influences parasite transmission and conservation goals. This article is part of the theme issue ‘Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation’.
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Grenfell, B. T., i F. M. D. Gulland. "Introduction: Ecological impact of parasitism on wildlife host populations". Parasitology 111, S1 (styczeń 1995): S3—S14. http://dx.doi.org/10.1017/s0031182000075788.
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The study of parasite population dynamics has been one of the major developments in ecology over the last 15 years (Kennedy, 1975). The seminal articles of Crofton (1971) and Anderson & May (1978, 1979; May & Anderson, 1978, 1979) began this process by illustrating the potential role of parasites in regulating or destabilizing the dynamics of wildlife host populations. Since then, a variety of empirical and theoretical studies (reviewed by Grenfell & Dobson, 1995) have explored the role of parasites in natural populations. In parallel with these population dynamical developments, a growing interest in the evolutionary ecology of parasites has also led to a large literature, examining the evolutionary impact of parasites and the importance of host-parasite coevolution (Hamilton, 1982; May & Anderson, 1990; Lively & Apanius, 1995; Read et al. 1995; Herre, this volume).
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Beer, A., T. Ingram i H. S. Randhawa. "Role of ecology and phylogeny in determining tapeworm assemblages in skates (Rajiformes)". Journal of Helminthology 93, nr 6 (12.09.2018): 738–51. http://dx.doi.org/10.1017/s0022149x18000809.
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AbstractAn understanding of the mechanisms that determine host and parasite relationships is a central aim in parasitology. Association of a parasite species with a host species may be influenced primarily by phylogenetic constraints that cause parasite species to co-speciate with their host species, or predominantly by ecological parameters that influence all other co-evolutionary scenarios. This study aimed to investigate the role of co-speciation as well as other co-evolutionary scenarios in influencing the assemblages of tapeworm parasites (marine cestodes) in skate hosts (Rajiformes) using a modification of the PACo (Procrustean Approach to Cophylogeny) method. The study found that phylogeny and host ecology are both significant predictors of skate–tapeworm relationships, implying that co-speciation as well as other co-evolutionary scenarios are shaping these associations. The study also investigated the key ecological parameters influencing host-switching and found that host diet, distribution depth, average body size and geographical location have a combined effect. Given the importance of parasites in ensuring healthy and stable marine ecosystems, the findings of this study have implications for conservation management worldwide.
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Tavares, L. E. R., J. L. Luque i A. J. A. Bicudo. "Community ecology of metazoan parasites of the anchovy Anchoa tricolor (Osteichthyes: Engraulidae) from the coastal zone of the State of Rio de Janeiro, Brazil". Brazilian Journal of Biology 65, nr 3 (sierpień 2005): 533–40. http://dx.doi.org/10.1590/s1519-69842005000300019.
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Between October 2001 and March 2002, 103 specimens of A. tricolor from Angra dos Reis (23°01'S, 44°19'W), in the coastal zone of the State of Rio de Janeiro, Brazil, were analyzed in order to study their metazoan parasite infracommunities. Ten species of metazoan parasites were collected: 4 digeneans, 1 cestode, 1 acantocephalan, 2 nematodes, 1 copepod, and 1 hirudinean; 77.7% of the fishes were parasitized by one or more metazoan, with a mean of 3.5 ± 6.2 parasite/fish. Digenean was the most dominant with 4 species that accounted for 53.2% of the total parasites collected; Ergasilus sp. was the most abundant species. Abundance and prevalence of Parahemiurus merus (Linton, 1910) were positively correlated with the total length of host. Relationships between total body length of fish and both total parasite abundance and mean parasite species richness were observed. Mean parasite diversity of species was correlated to host's total length, with significant differences found between male and female fishes. Two pairs of larval species showed significant positive association and covariation. The metazoan parasite infracommunities of A. tricolor presented dominance of larval endoparasites; correlation of parasite abundance, diversity, and species richness with host total length; and low number of parasite interspecific relationships. The parasite community of A. tricolor showed some similarities with the parasite community of another South American Atlantic engraulid.
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Farrell, Maxwell J., Andrew W. Park, Clayton E. Cressler, Tad Dallas, Shan Huang, Nicole Mideo, Ignacio Morales-Castilla, T. Jonathan Davies i Patrick Stephens. "The ghost of hosts past: impacts of host extinction on parasite specificity". Philosophical Transactions of the Royal Society B: Biological Sciences 376, nr 1837 (20.09.2021): 20200351. http://dx.doi.org/10.1098/rstb.2020.0351.
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A growing body of research is focused on the extinction of parasite species in response to host endangerment and declines. Beyond the loss of parasite species richness, host extinction can impact apparent parasite host specificity, as measured by host richness or the phylogenetic distances among hosts. Such impacts on the distribution of parasites across the host phylogeny can have knock-on effects that may reshape the adaptation of both hosts and parasites, ultimately shifting the evolutionary landscape underlying the potential for emergence and the evolution of virulence across hosts. Here, we examine how the reshaping of host phylogenies through extinction may impact the host specificity of parasites, and offer examples from historical extinctions, present-day endangerment, and future projections of biodiversity loss. We suggest that an improved understanding of the impact of host extinction on contemporary host–parasite interactions may shed light on core aspects of disease ecology, including comparative studies of host specificity, virulence evolution in multi-host parasite systems, and future trajectories for host and parasite biodiversity. This article is part of the theme issue ‘Infectious disease macroecology: parasite diversity and dynamics across the globe’.
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Moreira, J., F. Paschoal, AD Cezar i JL Luque. "Community ecology of the metazoan parasites of Brazilian sardinella, Sardinella brasiliensis (Steindachner, 1879) (Actinopterygii: Clupeidae) from the coastal zone of the State of Rio de Janeiro, Brazil". Brazilian Journal of Biology 75, nr 3 (25.08.2015): 736–41. http://dx.doi.org/10.1590/1519-6984.00114.
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AbstractBetween March 2010 and August 2011 were necropsied 100 specimens of Sardinella brasiliensis (Steindachner, 1879), from the coast of the State of Rio de Janeiro, Brazil (22°51’S, 43°56’W), to study their community of metazoan parasites. All specimens of S. brasiliensis were parasitized by at least one species of metazoan parasite, with mean of 68.7 ± 71.2 parasites/fish. Eleven species were collected: 3 digeneans, 1 monogenean, 2 cestodes, 3 nematodes and 2 copepods. The digenean Myosaccium ecaude Montgomery was the most abundant, prevalent, and dominant species, representing 72.7% of metazoan parasites collected, showing positive correlation between host’s total length and parasite abundance. Total parasite abundance was positively correlated with host’s total length. Three pairs of adult endoparasites showed significant positive association and covariation. The parasite community of S. brasiliensis showed dominance by digeneans. Sardinella brasiliensis represents new host record for most found parasite species.
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Thompson, R. C. A., i A. J. Lymbery. "Genetic variability in parasites and host—parasite interactions". Parasitology 112, S1 (marzec 1996): S7—S22. http://dx.doi.org/10.1017/s0031182000076629.
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SUMMARYWe have examined genetic variability in parasites in the context of ecological interactions with the host. Recent research onEchinococcus, GiardiaandCryptosporidiumhas been used to illustrate: (i) the problems that parasite variability and species recognition pose for understanding the complex and often controversial relationship between parasite and host occurrence; (ii) the need for accurate parasite characterization and the application of appropriate molecular techniques to studies on parasite transmission if fundamental questions about zoonotic relationships and risk factors are to be answered; (iii) our lack of understanding about within-host interactions between genetically heterogeneous parasites at the inter-and intraspecific levels, and the significance of such interactions with respect to evolutionary considerations and the clinical outcome of parasite infections. If advances in molecular biology and mathematical ecology are to be realized, we need to give serious consideration to the development of appropriate species concepts and in vivo systems for testing the predictions and assumptions of theoretical models.
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Araujo, Adauto, Karl Reinhard, Luiz Fernando Ferreira, Elisa Pucu i Pedro Paulo Chieffi. "Paleoparasitology: the origin of human parasites". Arquivos de Neuro-Psiquiatria 71, nr 9B (wrzesień 2013): 722–26. http://dx.doi.org/10.1590/0004-282x20130159.
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Parasitism is composed by three subsystems: the parasite, the host, and the environment. There are no organisms that cannot be parasitized. The relationship between a parasite and its host species most of the time do not result in damage or disease to the host. However, in a parasitic disease the presence of a given parasite is always necessary, at least in a given moment of the infection. Some parasite species that infect humans were inherited from pre-hominids, and were shared with other phylogenetically close host species, but other parasite species were acquired from the environment as humans evolved. Human migration spread inherited parasites throughout the globe. To recover and trace the origin and evolution of infectious diseases, paleoparasitology was created. Paleoparasitology is the study of parasites in ancient material, which provided new information on the evolution, paleoepidemiology, ecology and phylogenetics of infectious diseases.
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Holand, H., H. Jensen, T. Kvalnes, J. Tufto, H. Pärn, B.-E. Sæther i T. H. Ringsby. "Parasite prevalence increases with temperature in an avian metapopulation in northern Norway". Parasitology 146, nr 8 (12.04.2019): 1030–35. http://dx.doi.org/10.1017/s0031182019000337.
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AbstractClimate and weather conditions may have substantial effects on the ecology of both parasites and hosts in natural populations. The strength and shape of the effects of weather on parasites and hosts are likely to change as global warming affects local climate. These changes may in turn alter fundamental elements of parasite–host dynamics. We explored the influence of temperature and precipitation on parasite prevalence in a metapopulation of avian hosts in northern Norway. We also investigated if annual change in parasite prevalence was related to winter climate, as described by the North Atlantic Oscillation (NAO). We found that parasite prevalence increased with temperature within-years and decreased slightly with increasing precipitation. We also found that a mild winter (positive winter NAO index) was associated with higher mean parasite prevalence the following year. Our results indicate that both local and large scale weather conditions may affect the proportion of hosts that become infected by parasites in natural populations. Understanding the effect of climate and weather on parasite–host relationships in natural populations is vital in order to predict the full consequence of global warming.
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GORTON, MARY J., EMILY L. KASL, JILLIAN T. DETWILER i CHARLES D. CRISCIONE. "Testing local-scale panmixia provides insights into the cryptic ecology, evolution, and epidemiology of metazoan animal parasites". Parasitology 139, nr 8 (4.04.2012): 981–97. http://dx.doi.org/10.1017/s0031182012000455.
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SUMMARYWhen every individual has an equal chance of mating with other individuals, the population is classified as panmictic. Amongst metazoan parasites of animals, local-scale panmixia can be disrupted due to not only non-random mating, but also non-random transmission among individual hosts of a single host population or non-random transmission among sympatric host species. Population genetics theory and analyses can be used to test the null hypothesis of panmixia and thus, allow one to draw inferences about parasite population dynamics that are difficult to observe directly. We provide an outline that addresses 3 tiered questions when testing parasite panmixia on local scales: is there greater than 1 parasite population/species, is there genetic subdivision amongst infrapopulations within a host population, and is there asexual reproduction or a non-random mating system? In this review, we highlight the evolutionary significance of non-panmixia on local scales and the genetic patterns that have been used to identify the different factors that may cause or explain deviations from panmixia on a local scale. We also discuss how tests of local-scale panmixia can provide a means to infer parasite population dynamics and epidemiology of medically relevant parasites.
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Springer, Andrea, i Peter M. Kappeler. "Intestinal parasite communities of six sympatric lemur species at Kirindy Forest, Madagascar". Primate Biology 3, nr 2 (7.09.2016): 51–63. http://dx.doi.org/10.5194/pb-3-51-2016.
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Abstract. Intestinal parasites impact host health, survival and reproductive success and therefore exert selective pressures on hosts' ecology and behavior. Thus, characterizing and comparing the parasitic fauna of different wildlife hosts sharing the same habitat can provide insights into the mechanisms underlying variation in parasitism, as well as the role of parasites as possible conservation threats. Several host traits have been proposed to generate differences in parasite diversity among different host species, including phylogeny, host body mass, host longevity, diet, and differences in ranging and social behavior. Here, we provide an overview of intestinal helminths and protozoa detected by fecal microscopy in six sympatric lemur species in Kirindy Forest, western Madagascar. The described patterns indicate that host phylogeny and diet may play an important role in shaping intestinal parasite assemblages in this system, as the closely related, omnivorous cheirogaleids showed the strongest overlap in parasite communities. No indication was found for an effect of body mass or longevity on parasite species richness. Regarding the effect of sociality, the two group-living lemur species, Propithecus verreauxi and Eulemur rufifrons, harbored directly transmitted parasites at higher prevalence than solitary foragers, but not at higher diversity. Effects of season and sex on parasite prevalence confirm the results of previous studies, with higher prevalence in the energetically demanding dry season and a male bias in parasitism. We highlight the opportunities of exploring the parasitic fauna of wildlife from a community ecology and evolutionary perspective, and identify prospects for future research on lemur parasitism.
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Sobecka, Ewa, Ewa Łuczak, Beata Więcaszek i Artur Antoszek. "Parasite community structure of cod from Bear Island (Barents Sea) and Pomeranian Bay (Baltic Sea)". Polish Polar Research 32, nr 3 (1.01.2011): 253–62. http://dx.doi.org/10.2478/v10183-011-0016-6.
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Parasite community structure of cod from Bear Island (Barents Sea) and Pomeranian Bay (Baltic Sea) A total of 142 cods: 60 from the South-East Ground of Bear Island and 82 from the Pomeranian Bay (Baltic Sea) were examined for their ecto- and endoparasites. Twenty different parasite species, comprising one Myxosporea, three Cestoda, four Digenea, seven Nematoda, three Acanthocephala and two Crustacea were found. The parasite component communities comprised 1446 individuals (17 species, six higher taxa) from the Bear Island and 6588 individuals (nine species, three higher taxa) from Pomeranian Bay. The observed parasite host specificity was low, and the intensity in a single fish ranged from one to 279 specimens. The eudominant parasite species were Echinorhynchus gadi, Hemiurus levinseni and Contracaecum osculatum. The dominant parasite communities from the Bear Island were nematodes, but acanthocephalans dominated in cod from the Baltic Sea. It appears that one group of parasites, better adapted for the specific conditions of the macrohabitat, has replaced another. The most prevalent parasites were E. gadi, Anisakis simplex, C. osculatum and Hysterothylacium aduncum, and the mean values of crowding were the highest for E. gadi and Pomphorhynchus laevis. The nematode Camallanus lacustris was noted in this host species for the first time. Only six species of parasites were common to cod from both fishing grounds.
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Legas, Mohammed Seid. "THE ECOLOGICAL HOSTS SHIFT OF PARASITES AND THE OUTBREAK OF EMERGING INFECTIOUS DISEASES: A REVIEW". International Journal of Research -GRANTHAALAYAH 5, nr 8 (31.08.2017): 104–8. http://dx.doi.org/10.29121/granthaalayah.v5.i8.2017.2189.
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Parasites are organisms which metabolically depend upon their hosts. To understand the ecological host shift of a parasite, it is important to look the host-parasite associations with respect to ecological change and factors that generate, maintain, and constrain the associations with implications for a wide range of ecological issues, including the dynamics of emerging infectious diseases. Although, the ecological significance of parasites is almost overlooked for several years by ecologists, considerable efforts are being made to understand their functional importance in ecosystems. Parasites play vital role in the trophic cascades of the food web. Environmental change caused by anthropogenic activities result host shift of specialist parasites and this shift of specialized parasites can rapidly to new hosts via ecological fitting play an important role in the ecology and evolution of host-parasite associations. This condition is the primary cause for the Emerging Infectious Diseases when parasite species begin infecting and causing disease in host species with which they have no previous history of association. Therefore, understanding the host parasites interaction and distribution of known and potential pathogens is a vital precondition for optimizing their positive, while minimizing their negative effects on conservation, restoration and sustained development programs.
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Weatherhead, Patrick J., i Gordon F. Bennett. "Ecology of parasitism of Brown-headed Cowbirds by haematozoa". Canadian Journal of Zoology 70, nr 1 (1.01.1992): 1–7. http://dx.doi.org/10.1139/z92-001.
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We quantified haematozoa infections in 964 Brown-headed Cowbirds (Molothrus ater) sampled over three summers in eastern Ontario. Our objective was to use the cowbird–haematozoa system to assess practical and theoretical aspects of testing Hamilton and Zuk's parasite hypothesis of sexual selection. We found that most individuals resampled within and between years were consistently scored as parasitized or unparasitized, although some individuals changed status, including going from parasitized to unparasitized. Many hatching-year birds were parasitized, which suggests substantial early exposure to parasites. Significant variation within and between years in general parasite prevalence, specific parasite prevalence, and intensity of infections indicated that population estimates of parasitism would be highly dependent on when birds were sampled and on the age and sex composition of the sample. Analysis of body condition and within-season recapture patterns indicated that parasitism did not have a negative effect on the health of cowbirds. Parasitized birds were also recaptured at the same rate as unparasitized birds between years, indicating that there were no viability effects due to parasitism. Our results suggest a number of pitfalls, some of which are potentially critical, to using haematozoa infections in passerines to test the Hamilton and Zuk hypothesis.
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Hofmeester, Tim R., Esther J. Bügel, Bob Hendrikx, Miriam Maas, Frits F. J. Franssen, Hein Sprong i Kevin D. Matson. "Parasite Load and Site-Specific Parasite Pressure as Determinants of Immune Indices in Two Sympatric Rodent Species". Animals 9, nr 12 (22.11.2019): 1015. http://dx.doi.org/10.3390/ani9121015.
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Wildlife is exposed to parasites from the environment. This parasite pressure, which differs among areas, likely shapes the immunological strategies of animals. Individuals differ in the number of parasites they encounter and host, and this parasite load also influences the immune system. The relative impact of parasite pressure vs. parasite load on different host species, particularly those implicated as important reservoirs of zoonotic pathogens, is poorly understood. We captured bank voles (Myodes glareolus) and wood mice (Apodemus sylvaticus) at four sites in the Netherlands. We sampled sub-adult males to quantify their immune function, infestation load for ecto- and gastrointestinal parasites, and infection status for vector-borne microparasites. We then used regression trees to test if variation in immune indices could be explained by among-site differences (parasite pressure), among-individual differences in infestation intensity and infection status (parasite load), or other intrinsic factors. Regression trees revealed splits among sites for haptoglobin, hemagglutination, and body-mass corrected spleen size. We also found splits based on infection/infestation for haptoglobin, hemolysis, and neutrophil to lymphocyte ratio. Furthermore, we found a split between species for hemolysis and splits based on body mass for haptoglobin, hemagglutination, hematocrit, and body-mass corrected spleen size. Our results suggest that both parasite pressure and parasite load influence the immune system of wild rodents. Additional studies linking disease ecology and ecological immunology are needed to understand better the complexities of host–parasite interactions and how these interactions shape zoonotic disease risk.
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Schall, J. J. "Virulence of lizard malaria: the evolutionary ecology of an ancient parasite—host association". Parasitology 100, S1 (czerwiec 1990): S35—S52. http://dx.doi.org/10.1017/s0031182000073005.
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SummaryThe negative consequences of parasitic infection (virulence) were examined for two lizard malaria parasite—host associa tions: Plasmodium agamae and P. giganteum, parasites of the rainbow lizard, Agama agania, in Sierra Leone, West Africa; and P. mexicanum in the western fence lizard, Sceloporus occidentalis, in northern California. These malaria species vary greatly in their reproductive characteristics: P. agamae produces only 8 merozoites per schizont, P. giganteum yields over 100, and P. mexicanum an intermediate number. All three parasites appear to have had an ancient association with their host. In fence lizards, infection with malaria is associated with increased numbers of immature erythrocytes, decreased haemoglobin levels, decreased maximal oxygen consumption, and decreased running stamina. Not affected were numbers of erythrocytes, resting metabolic rate, and sprint running speed which is supported by anaerobic means in lizards. Infected male fence lizards had smaller testes, stored less fat in preparation for winter dormancy, were more often socially submissive and, unexpectedly, were more extravagantly coloured on the ventral surface (a sexually dimorphic trait) than non-infected males. Females also stored less fat and produced smaller clutches of eggs, a directly observed reduction in fitness. Infected fence lizards do not develop behavioural fevers. P. mexicanum appears to have broad thermal buffering abilities and thermal tolerance; the parasite's population growth was unaffected by experimental alterations in the lizard's body temperature. The data are less complete for A. agama, but infected lizards suffered similar haematological and physiological effects. Infected animals may be socially submissive because they appear to gather less insect prey, possibly a result of being forced into inferior territories. Infection does not reduce clutch size in rainbow lizards, but may lengthen the time between clutches. These results are compared with predictions emerging from several models of the evolution of parasite virulence. The lack of behavioural fevers in fence lizards may represent a physiological constraint by the lizards in evolving a thermal tolerance large enough to allow elimination of the parasite via fever. Such constraints may be important in determining the outcome of parasite—host coevolution. Some theory predicts low virulence in old parasite—host systems and higher virulence in parasites with greater reproductive output. However, in conflict with this argument, all three malarial species exhibited similar high costs to their hosts.
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Fong, Caitlin R., Armand M. Kuris i Ryan F. Hechinger. "Parasite and host biomass and reproductive output in barnacle populations in the rocky intertidal zone". Parasitology 146, nr 3 (10.10.2018): 407–12. http://dx.doi.org/10.1017/s0031182018001634.
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AbstractThe rocky intertidal zone has a long history of ecological study with barnacles frequently serving as a model system to explore foundational theories. Parasites are often ignored in community ecology studies, and this particularly holds for true for the rocky intertidal zone. We explore the role of the isopod parasite, Hemioniscus balani, on its host, the acorn barnacle, Chthamalus fissus. We use the currencies of biomass and reproduction measured at the individual level, then applied to the population level, to evaluate the importance of this parasite to barnacle populations. We found H. balani can comprise substantial biomass in ‘apparent’ barnacle populations, sometimes even equaling barnacle biomass. Additionally, parasite reproduction sometimes matched barnacle reproduction. Thus, parasites divert substantial energy flow from the barnacle population and to near-shore communities in the form of parasite larvae. Parasites appeared to decrease barnacle reproduction per area. Potentially, this parasite may control barnacle populations, depending on the extent to which heavily infected barnacle populations contribute to barnacle populations at larger scales. These findings regarding the importance of a particular parasite for host population dynamics in this well studied ecosystem call for the integration of disease dynamics into community ecological studies of the rocky intertidal zone.
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Quigley, Benjamin J. Z., Sam P. Brown, Helen C. Leggett, Pauline D. Scanlan i Angus Buckling. "Within-host interference competition can prevent invasion of rare parasites". Parasitology 145, nr 6 (15.05.2017): 770–74. http://dx.doi.org/10.1017/s003118201700052x.
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AbstractCompetition between parasite species or genotypes can play an important role in the establishment of parasites in new host populations. Here, we investigate a mechanism by which a rare parasite is unable to establish itself in a host population if a common resident parasite is already present (a ‘priority effect’). We develop a simple epidemiological model and show that a rare parasite genotype is unable to invade if coinfecting parasite genotypes inhibit each other's transmission more than expected from simple resource partitioning. This is because a rare parasite is more likely to be in multiply-infected hosts than the common genotype, and hence more likely to pay the cost of reduced transmission. Experiments competing interfering clones of bacteriophage infecting a bacterium support the model prediction that the clones are unable to invade each other from rare. We briefly discuss the implications of these results for host-parasite ecology and (co)evolution.
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Walker, Josephine G., Amy Hurford, Jo Cable, Amy R. Ellison, Stephen J. Price i Clayton E. Cressler. "Host allometry influences the evolution of parasite host-generalism: theory and meta-analysis". Philosophical Transactions of the Royal Society B: Biological Sciences 372, nr 1719 (13.03.2017): 20160089. http://dx.doi.org/10.1098/rstb.2016.0089.
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Parasites vary widely in the diversity of hosts they infect: some parasite species are specialists—infecting just a single host species, while others are generalists, capable of infecting many. Understanding the factors that drive parasite host-generalism is of basic biological interest, but also directly relevant to predicting disease emergence in new host species, identifying parasites that are likely to have unidentified additional hosts, and assessing transmission risk. Here, we use mathematical models to investigate how variation in host body size and environmental temperature affect the evolution of parasite host-generalism. We predict that parasites are more likely to evolve a generalist strategy when hosts are large-bodied, when variation in host body size is large, and in cooler environments. We then explore these predictions using a newly updated database of over 20 000 fish–macroparasite associations. Within the database we see some evidence supporting these predictions, but also highlight mismatches between theory and data. By combining these two approaches, we establish a theoretical basis for interpreting empirical data on parasites' host specificity and identify key areas for future work that will help untangle the drivers of parasite host-generalism. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
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Stampe, Karina, Ole Næsbye Larsen i Stephanie S. Godfrey. "Ecto- and endoparasites of the King's skink (Egernia kingii) on Penguin Island". Parasitology 147, nr 10 (19.05.2020): 1094–99. http://dx.doi.org/10.1017/s0031182020000839.
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AbstractWildlife species are often host to a diversity of parasites, but our knowledge of their diversity and ecology is extremely limited, especially for reptiles. Little is known about the host-parasite ecology of the Australian lizard, the King's skink (Egernia kingii). In spring of 2015, we carried out a field-based study of a population of King's skinks on Penguin Island (Western Australia). We documented five species of parasites, including two ectoparasitic mites (an undescribed laelapid mite and Mesolaelaps australiensis), an undescribed coccidia species, and two nematode species (Pharyngodon tiliquae and Capillaria sp.). The laelapid mite was the most abundant parasite, infesting 46.9% of the 113 captured lizards. This mite species increased in prevalence and abundance over the course of the study. Infection patterns of both mites varied with lizard life-stage; sub-adults were more commonly infested with laelapid mites than adults or juveniles, and sub-adults and adults were infested by more laelapid mites than juveniles. By contrast, adults had a higher prevalence of M. australiensis than juveniles or sub-adults. Among the gastrointestinal parasites, P. tiliquae was relatively common among the sampled lizards (35.3%). These results give new important information about reptiles as parasite hosts and what factors influence infection patterns.
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CURTIS, L. A. "Ecology of larval trematodes in three marine gastropods". Parasitology 124, nr 7 (24.09.2002): 43–56. http://dx.doi.org/10.1017/s0031182002001452.
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To comprehend natural host–parasite systems, ecological knowledge of both hosts and parasites is critical. Here I present a view of marine systems based on the snail Ilyanassa obsoleta and its trematodes. This system is reviewed and two others, those of the snails Cerithidea californica and Littorina littorea, are then summarized and compared. Trematodes can profoundly affect the physiology, behaviour and spatial distribution of hosts. Studying these systems is challenging because trematodes are often embedded in host populations in unappreciated ways. Trematode prevalence is variable, but can be high in populations of all three hosts. Conditions under which single- and multiple-species infections can accumulate are considered. Adaptive relations between species are likely the most important and potentials for adaptation of parasites to hosts, hosts to parasites, and parasites to other parasites are also considered. Even if colonization rate is low, a snail population can develop high trematode prevalence, if infections persist long and the host is long-lived and abundant. Trematodes must be adapted to use their snail hosts. However, both I. obsoleta and L. littorea possess highly dispersed planktonic larvae and trematode prevalence is variable among snail populations. Host adaptation to specific infections, or even to trematodes in general, is unlikely because routine exposure to trematodes is improbable. Crawl-away juveniles of C. californica make adaptation to trematodes in that system a possibility. Trematode species in all three systems are not likely adapted to each other. Multiple-species infections are rare and definitive hosts scatter parasite eggs among snail populations with variable prevalences. Routine co-occurrence of trematodes in snails is thus unlikely. Adaptations of these larval trematodes to inhabit the snail host must, then, be the basis for what happens when they do co-occur.
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YOUNG, REBECCA E., i ANDREW D. C. MACCOLL. "Spatial and temporal variation in macroparasite communities of three-spined stickleback". Parasitology 144, nr 4 (20.10.2016): 436–49. http://dx.doi.org/10.1017/s0031182016001815.
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SummaryPatterns in parasite community structure are often observed in natural systems and an important question in parasite ecology is whether such patterns are repeatable across time and space. Field studies commonly look at spatial or temporal repeatability of patterns, but they are rarely investigated in conjunction. We use a large dataset on the macroparasites of the three-spined stickleback,Gasterosteus aculeatusL., collected from 14 locations on North Uist, Scotland over an 8-year period to investigate: (1) repeatability of patterns in parasite communities among populations and whether variation is consistent across years, (2) whether variation between years can be explained by climatic variation and progression of the season and (3) whether variation in habitat characteristics explain population differences. Differences in relative abundance and prevalence across populations were observed in a number of parasites investigated indicating a lack of consistency across years in numerous parasite community measures; however, differences between populations in the prevalence and abundance of some parasites were consistent throughout the study. Average temperature did not affect parasite community, and progression of the season was only significant for two of 13 community measures. Two of the six habitat characteristics investigated (pH and calcium concentration) significantly affected parasite presence.
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Shapiro, Lillian L. M., Courtney C. Murdock, Gregory R. Jacobs, Rachel J. Thomas i Matthew B. Thomas. "Larval food quantity affects the capacity of adult mosquitoes to transmit human malaria". Proceedings of the Royal Society B: Biological Sciences 283, nr 1834 (13.07.2016): 20160298. http://dx.doi.org/10.1098/rspb.2016.0298.
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Adult traits of holometabolous insects are shaped by conditions experienced during larval development, which might impact interactions between adult insect hosts and parasites. However, the ecology of larval insects that vector disease remains poorly understood. Here, we used Anopheles stephensi mosquitoes and the human malaria parasite Plasmodium falciparum, to investigate whether larval conditions affect the capacity of adult mosquitoes to transmit malaria. We reared larvae in two groups; one group received a standard laboratory rearing diet, whereas the other received a reduced diet. Emerging adult females were then provided an infectious blood meal. We assessed mosquito longevity, parasite development rate and prevalence of infectious mosquitoes over time. Reduced larval food led to increased adult mortality and caused a delay in parasite development and a slowing in the rate at which parasites invaded the mosquito salivary glands, extending the time it took for mosquitoes to become infectious. Together, these effects increased transmission potential of mosquitoes in the high food regime by 260–330%. Such effects have not, to our knowledge, been shown previously for human malaria and highlight the importance of improving knowledge of larval ecology to better understand vector-borne disease transmission dynamics.
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Malishev, Matthew, i David J. Civitello. "Linking Bioenergetics and Parasite Transmission Models Suggests Mismatch Between Snail Host Density and Production of Human Schistosomes". Integrative and Comparative Biology 59, nr 5 (23.05.2019): 1243–52. http://dx.doi.org/10.1093/icb/icz058.
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Abstract The consequences of parasite infection for individual hosts depend on key features of host–parasite ecology underpinning parasite growth and immune defense, such as age, sex, resource supply, and environmental stressors. Scaling these features and their underlying mechanisms from the individual host is challenging but necessary, as they shape parasite transmission at the population level. Translating individual-level mechanisms across scales could inherently improve the way we think about feedbacks among parasitism, the mechanisms driving transmission, and the consequences of human impact and disease control efforts. Here, we use individual-based models (IBMs) based on general metabolic theory, Dynamic Energy Budget (DEB) theory, to scale explicit life-history features of individual hosts, such as growth, reproduction, parasite production, and death, to parasite transmission at the population level over a range of resource supplies focusing on the major human parasite, Schistosoma mansoni, and its intermediate host snail, Biomphalaria glabrata. At the individual level, infected hosts produce fewer parasites at lower resources as competition increases. At the population level, our DEB–IBM predicts brief, but intense parasite peaks early during the host growth season when resources are abundant and infected hosts are few. The timing of these peaks challenges the status quo that high densities of infected hosts produce the highest parasite densities. As expected, high resource supply boosts parasite output, but parasite output also peaks at modest to high host background mortality rates, which parallels overcompensation in stage-structured models. Our combined results reveal the crucial role of individual-level physiology in identifying how environmental conditions, time of the year, and key feedbacks within host–parasite ecology interact to define periods of elevated risk. The testable forecasts from this physiologically-explicit epidemiological model can inform disease management to reduce human risk of schistosome infection.
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Monis, Paul T., Ross H. Andrews i Christopher P. Saint. "Molecular biology techniques in parasite ecology". International Journal for Parasitology 32, nr 5 (maj 2002): 551–62. http://dx.doi.org/10.1016/s0020-7519(01)00352-6.
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Werner, Courtney S., i Charles L. Nunn. "Effect of urban habitat use on parasitism in mammals: a meta-analysis". Proceedings of the Royal Society B: Biological Sciences 287, nr 1927 (13.05.2020): 20200397. http://dx.doi.org/10.1098/rspb.2020.0397.
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Rates of urbanization are increasing globally, with consequences for the dynamics of parasites and their wildlife hosts. A small subset of mammal species have the dietary and behavioural flexibility to survive in urban settings. The changes that characterize urban ecology—including landscape transformation, modified diets and shifts in community composition—can either increase or decrease susceptibility and exposure to parasites. We used a meta-analytic approach to systematically assess differences in endoparasitism between mammals in urban and non-urban habitats. Parasite prevalence estimates in matched urban and non-urban mammal populations from 33 species were compiled from 46 published studies, and an overall effect of urban habitation on parasitism was derived after controlling for study and parasite genus. Parasite life cycle type and host order were investigated as moderators of the effect sizes. We found that parasites with complex life cycles were less prevalent in urban carnivore and primate populations than in non-urban populations. However, we found no difference in urban and non-urban prevalence for parasites in rodent and marsupial hosts, or differences in prevalence for parasites with simple life cycles in any host taxa. Our findings therefore suggest the disruption of some parasite transmission cycles in the urban ecological community.
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Tavares, L. E. R., i J. L. Luque. "Community ecology of the metazoan parasites of white sea catfish, Netuma barba (Osteichthyes: Ariidae), from the coastal zone of the state of Rio de Janeiro, Brazil". Brazilian Journal of Biology 64, nr 1 (luty 2004): 169–76. http://dx.doi.org/10.1590/s1519-69842004000100019.
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Between March 2000 and April 2001, 63 specimens of N. barba from Angra dos Reis, coastal zone of the State of Rio de Janeiro (23°0'S, 44°19'W), Brazil, were necropsied to study their infracommunities of metazoan parasites. Fifteen species of metazoan parasites were collected: 2 digeneans, 1 monogenean, 2 cestodes, 1 acantocephalan, 2 nematodes, 6 copepods, and 1 hirudinean. Ninety-six percent of the catfishes were parasitized by at least one metazoan parasite species. A total of 646 individual parasites was collected, with mean of 10.3 ± 16.6 parasites/fish. The copepods were 37.5% of the total parasite specimens collected. Lepeophtheirus monacanthus was the most dominant species and the only species with abundance positively correlated with the host total length. Host sex did not influence parasite prevalence or mean abundance of any species. The mean diversity in the infracommunities of N. barba was H = 0.130 ± 0.115 with no correlation with host's total length and without differences in relation to sex of the host. One pair of endoparasites (Dinosoma clupeola and Pseudoacanthostomum floridensis) showed positive association and covariation between their abundances and prevalences. The parasite community of N. barba from Rio de Janeiro can be defined as a complex of species with low prevalence and abundance and with scarcity of interspecific associations. However, because of both the presence of assemblages of sympatric ariid species as well as the spawning behavior characteristic of these fishes, additional comparative studies of the parasite component communities of ariids are necessaries to elucidate this pattern.