Host community structure and infestation by ixodid ticks: repeatability, dilution effect and ecological specialization

SUMMARYLyme disease is caused by bacteria of theBorrelia burgdorferigenospecies complex and transmitted by Ixodid ticks. In North America only one pathogenic genospecies occurs, in Europe there are several. According to the dilution effect hypothesis (DEH), formulated in North America, nymphal infection prevalence (NIP) decreases with increasing host diversity since host species differ in transmission potential. We analysedBorreliainfection in nymphs from 94 forest stands in Belgium, which are part of a diversification gradient with a supposedly related increasing host diversity: from pine stands without to oak stands with a shrub layer. We expected changing tree species and forest structure to increase host diversity and decrease NIP. In contrast with the DEH, NIP did not differ between different forest types. Genospecies diversity however, and presumably also host diversity, was higher in oak than in pine stands. Infected nymphs tended to harbourBorrelia afzeliiinfection more often in pine stands whileBorrelia gariniiandBorrelia burgdorferiss. infection appeared to be more prevalent in oak stands. This has important health consequences, since the latter two cause more severe disease manifestations. We show that the DEH must be nuanced for Europe and should consider the response of multiple pathogenic genospecies.

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Deforestation, host community structure, and amphibian disease risk

Basic and Applied Ecology ◽

10.1016/j.baae.2015.08.004 ◽

2016 ◽

Vol 17 (1) ◽

pp. 72-80 ◽

Cited By ~ 14

Author(s):

C. Guilherme Becker ◽

David Rodriguez ◽

Ana V. Longo ◽

L. Felipe Toledo ◽

Carolina Lambertini ◽

...

Keyword(s):

Community Structure ◽

Disease Risk ◽

Host Community ◽

Amphibian Disease

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Community diversity reduces Schistosoma mansoni transmission, host pathology and human infection risk

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2008.1718 ◽

2009 ◽

Vol 276 (1662) ◽

pp. 1657-1663 ◽

Cited By ~ 57

Author(s):

Pieter T.J Johnson ◽

Peder J Lund ◽

Richard B Hartson ◽

Timothy P Yoshino

Keyword(s):

Community Structure ◽

Schistosoma Mansoni ◽

Host Density ◽

Biodiversity Loss ◽

Infection Risk ◽

Human Infection ◽

Host Community ◽

Community Diversity ◽

Complex Life Cycle ◽

Intermediate Hosts

Global biodiversity loss and disease emergence are two of the most challenging issues confronting science and society. Recently, observed linkages between species-loss and vector-borne infections suggest that biodiversity may help reduce pathogenic infections in humans and wildlife, but the mechanisms underlying this relationship and its applicability to a broader range of pathogens have remained speculative. Here, we experimentally evaluated the effects of host community structure on transmission of the human pathogen, Schistosoma mansoni , which alternates between snail intermediate hosts and vertebrate definitive hosts. By manipulating parasite exposure and community diversity, we show that heterospecific communities cause a 25–50 per cent reduction in infection among snail hosts ( Biomphalaria glabrata ). Infected snails raised alongside non-host snails ( Lymnaea or Helisoma sp.) also produced 60–80 per cent fewer cercariae, suggesting that diverse communities could reduce human infection risk. Because focal host density was held constant during experiments, decreases in transmission resulted entirely from diversity-mediated pathways. Finally, the decrease in infection in mixed-species communities led to an increase in reproductive output by hosts, representing a novel example of parasite-mediated facilitation. Our results underscore the significance of community structure on transmission of complex life-cycle pathogens, and we emphasize enhanced integration between ecological and parasitological research on the diversity–disease relationship.

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Host community structure and the maintenance of pathogen diversity

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2007.0415 ◽

2007 ◽

Vol 274 (1619) ◽

pp. 1715-1721 ◽

Cited By ~ 19

Author(s):

Caroline Buckee ◽

Leon Danon ◽

Sunetra Gupta

Keyword(s):

Community Structure ◽

Spatial Differentiation ◽

Host Community ◽

Contact Network ◽

Strong Mixing ◽

Metapopulation Model ◽

Pathogen Population ◽

Antigenic Diversity ◽

Pathogen Diversity ◽

Pathogen Populations

Community structure has been widely identified as a feature of many real-world networks. It has been shown that the antigenic diversity of a pathogen population can be significantly affected by the contact network of its hosts; however, the effects of community structure have not yet been explored. Here, we examine the congruence between patterns of antigenic diversity in pathogen populations in neighbouring communities, using both a deterministic metapopulation model and individual-based formulations. We show that the spatial differentiation of the pathogen population can only be maintained at levels of coupling far lower than that necessary for the host populations to remain distinct. Therefore, identifiable community structure in host networks may not reflect differentiation of the processes occurring upon them and, conversely, a lack of genetic differentiation between pathogens from different host communities may not reflect strong mixing between them.

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The effect of host community functional traits on plant disease risk varies along an elevational gradient

eLife ◽

10.7554/elife.67340 ◽

2021 ◽

Vol 10 ◽

Author(s):

Fletcher W Halliday ◽

Mikko Jalo ◽

Anna-Liisa Laine

Keyword(s):

Community Structure ◽

Disease Risk ◽

Environmental Gradients ◽

Elevational Gradient ◽

Host Community ◽

Interactive Effects ◽

Life History Strategies ◽

Herbaceous Plant ◽

Field Evidence ◽

Increasing Temperature

Quantifying the relative impact of environmental conditions and host community structure on disease is one of the greatest challenges of the 21st century, as both climate and biodiversity are changing at unprecedented rates. Both increasing temperature and shifting host communities towards more fast-paced life-history strategies are predicted to increase disease, yet their independent and interactive effects on disease in natural communities remains unknown. Here, we address this challenge by surveying foliar disease symptoms in 220, 0.5 meter-diameter herbaceous plant communities along a 1100-meter elevational gradient. We find that increasing temperature associated with lower elevation can increase disease by (1) relaxing constraints on parasite growth and reproduction, (2) determining which host species are present in a given location, and (3) strengthening the positive effect of host community pace-of-life on disease. These results provide the first field evidence, under natural conditions, that environmental gradients can alter how host community structure affects disease.

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Avian host community structure and prevalence of West Nile virus in Chicago, Illinois

Oecologia ◽

10.1007/s00442-008-1224-6 ◽

2008 ◽

Vol 159 (2) ◽

pp. 415-424 ◽

Cited By ~ 61

Author(s):

Scott R. Loss ◽

Gabriel L. Hamer ◽

Edward D. Walker ◽

Marilyn O. Ruiz ◽

Tony L. Goldberg ◽

...

Keyword(s):

Community Structure ◽

West Nile Virus ◽

Host Community ◽

Avian Host ◽

West Nile

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Predictors of parasite and pathogen infections in urban rodents of central Argentina

Journal of Helminthology ◽

10.1017/s0022149x21000523 ◽

2021 ◽

Vol 95 ◽

Author(s):

B. Fitte ◽

R. Cavia ◽

M. del Rosario Robles ◽

A. Dellarupe ◽

J.M. Unzaga ◽

...

Keyword(s):

Latin America ◽

Community Structure ◽

Rattus Rattus ◽

Zoonotic Diseases ◽

Host Community ◽

Hymenolepis Diminuta ◽

Sedimentation Technique ◽

Infection Source ◽

Leptospira Borgpetersenii ◽

Polymerase Chain

Abstract Urban rodents are associated with parasites and pathogens, which present health risks for humans, but information on factors related to parasite and pathogen infection in rodents in cities of Latin America is scarce. This study analyzes the hosts, host community structure and environmental characteristics of parasite and pathogen fauna present in the three species of urban rodents in an urban area of South America. Rodents were captured seasonally in seven different neighborhoods. Digestive tracts were dissected under stereoscopic microscopy and feces were processed using a sedimentation technique. Protozoa and bacteria were detected through polymerase chain reaction and indirect immunofluorescence techniques. In Rattus norvegicus, Rattus rattus and Mus musculus, ten helminths, three protozoa and two bacteria were found. Six were zoonotic: Toxoplasma gondii; Hymenolepis diminuta; Rodentolepis nana; Strobilocercus fasciolaris; Leptospira borgpetersenii; and Leptospira interrogans. The parasite and pathogen infections were influenced by the host species, the host community structure, the season, and the presence of streams in the neighborhood. Urban rodents may be the infection source of many zoonotic diseases and it is important to generate public policies for this problem. This study is one example of the situation of many cities of Latin America, where peripheral neighborhoods are growing dramatically.

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IMPACTS OF PHYLOGENETIC DILUTION AND CONCENTRATION EFFECTS ON SPECIES DIVERSITY AND DISTRIBUTION PATTERNS

Journal of Biological System ◽

10.1142/s0218339017500048 ◽

2017 ◽

Vol 25 (01) ◽

pp. 71-81

Author(s):

YOUHUA CHEN

Keyword(s):

Community Structure ◽

Species Diversity ◽

Relative Abundance ◽

Related Species ◽

Dilution Effect ◽

Distribution Patterns ◽

Distinct Species ◽

Closely Related Species ◽

Phylogenetic Relatedness ◽

Phylogenetic Community Structure

In theoretical ecology and community ecology, it is still unclear how phylogenetic community structure and species distributions are linked together. In this paper, a neutral model for evaluating phylogenetic constraints on species diversity and distribution patterns is developed to address these issues. To accomplish this, temporal species distribution and diversity patterns are evaluated and simulated by considering the impact of phylogenetic relatedness of species in a lattice landscape with square grids. A continuous patch for the resultant distributional range map of a species is defined as a group of grids in which the interior grids are adjacent to each other while the edge grids of the patch are isolated from other remaining grids in the range map. The adjacency or isolation of a grid with respect to another grid follows the von Neumann neighborhood criterion. The hypothesis tested is: phylogenetically closely related species tend to avoid each other (phylogenetic dilution), which produces a phylogenetic overdispersion pattern. In this case, all species have similar species abundances and distribution-patch size patterns. In contrast, if closely related species tend to associate together (phylogenetic concentration), a phylogenetic clustering pattern emerges: phylogenetically distinct species tend to have higher abundances and more large distribution patches. Using simulations, this paper presents results which demonstrate the reverse phenomenon: if it is assumed that phylogenetic relatedness of species is modeled as a dilution effect, the resultant distributional maps for evolutionarily distinct species present significantly increased numbers of continuous large patches. An evolutionarily distinct clade tends to have significantly higher relative abundance than other clades in all simulations. It was also found that if phylogenetic relatedness of species is modeled as a concentration effect, the simulated distributional map of each species would present a similar percentage of large patches for both evolutionarily unique and common clades for many cases when the community size is large enough. However, being similar to dilution effect, the resultant species relative abundance for evolutionarily unique clade is significantly higher than that for evolutionarily common clade. In conclusion, evolutionary distinct species will have more chances to survive with high populations and less fragmented distributional range in environments where the phylogenetic dilution effect is functioning. It is hoped that these results contributed to clarifying the complex associations generated by phylogenetic community structure in future ecological and evolutionary studies.

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Parasites shape community structure and dynamics in freshwater crustaceans

Parasitology ◽

10.1017/s0031182019001483 ◽

2019 ◽

Vol 147 (2) ◽

pp. 182-193

Author(s):

Olwyn C. Friesen ◽

Sarah Goellner ◽

Robert Poulin ◽

Clément Lagrue

Keyword(s):

Community Structure ◽

Host Species ◽

Host Community ◽

Crustacean Species ◽

Freshwater Crustacean ◽

Set Up ◽

High Parasite ◽

Parasite Exposure ◽

Paracalliope Fluviatilis

AbstractParasites directly and indirectly influence the important interactions among hosts such as competition and predation through modifications of behaviour, reproduction and survival. Such impacts can affect local biodiversity, relative abundance of host species and structuring of communities and ecosystems. Despite having a firm theoretical basis for the potential effects of parasites on ecosystems, there is a scarcity of experimental data to validate these hypotheses, making our inferences about this topic more circumstantial. To quantitatively test parasites' role in structuring host communities, we set up a controlled, multigenerational mesocosm experiment involving four sympatric freshwater crustacean species that share up to four parasite species. Mesocosms were assigned to either of two different treatments, low or high parasite exposure. We found that the trematode Maritrema poulini differentially influenced the population dynamics of these hosts. For example, survival and recruitment of the amphipod Paracalliope fluviatilis were dramatically reduced compared to other host species, suggesting that parasites may affect their long-term persistence in the community. Relative abundances of crustacean species were influenced by parasites, demonstrating their role in host community structure. As parasites are ubiquitous across all communities and ecosystems, we suggest that the asymmetrical effects we observed are likely widespread structuring forces.

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