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Suh DC, Lance SL, Park AW. Abiotic and biotic factors jointly influence the contact and environmental transmission of a generalist pathogen. Ecol Evol 2024; 14:e70167. [PMID: 39157664 PMCID: PMC11329300 DOI: 10.1002/ece3.70167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 07/26/2024] [Accepted: 07/30/2024] [Indexed: 08/20/2024] Open
Abstract
The joint influence of abiotic and biotic factors is important for understanding the transmission of generalist pathogens. Abiotic factors such as temperature can directly influence pathogen persistence in the environment and will also affect biotic factors, such as host community composition and abundance. At intermediate spatial scales, the effects of temperature, community composition, and host abundance are expected to contribute to generalist pathogen transmission. We use a simple transmission model to explain and predict how host community composition, host abundance, and environmental pathogen persistence times can independently and jointly influence transmission. Our transmission model clarifies how abiotic and biotic factors can synergistically support the transmission of a pathogen. The empirical data show that high community competence, high abundance, and low temperatures correlate with high levels of transmission of ranavirus in larval amphibian communities. Discrete wetlands inhabited by larval amphibians in the presence of ranavirus provide a compelling case study comprising distinct host communities at a spatial scale anticipated to demonstrate abiotic and biotic influence on transmission. We use these host communities to observe phenomena demonstrated in our theoretical model. These findings emphasize the importance of considering both abiotic and biotic factors, and concomitant direct and indirect mechanisms, in the study of pathogen transmission and should extend to other generalist pathogens with the capacity for environmental transmission.
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Affiliation(s)
- Daniel C. Suh
- Odum School of EcologyUniversity of GeorgiaAthensGeorgiaUSA
- Center for the Ecology of Infectious DiseasesUniversity of GeorgiaAthensGeorgiaUSA
| | - Stacey L. Lance
- Center for the Ecology of Infectious DiseasesUniversity of GeorgiaAthensGeorgiaUSA
- Savannah River Ecology LaboratoryUniversity of GeorgiaAikenSouth CarolinaUSA
| | - Andrew W. Park
- Odum School of EcologyUniversity of GeorgiaAthensGeorgiaUSA
- Center for the Ecology of Infectious DiseasesUniversity of GeorgiaAthensGeorgiaUSA
- Department of Infectious Diseases, College of Veterinary MedicineUniversity of GeorgiaAthensGeorgiaUSA
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2
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Johnson PTJ, Stewart Merrill TE, Dean AD, Fenton A. Diverging effects of host density and richness across biological scales drive diversity-disease outcomes. Nat Commun 2024; 15:1937. [PMID: 38431719 PMCID: PMC10908850 DOI: 10.1038/s41467-024-46091-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 02/14/2024] [Indexed: 03/05/2024] Open
Abstract
Understanding how biodiversity affects pathogen transmission remains an unresolved question due to the challenges in testing potential mechanisms in natural systems and how these mechanisms vary across biological scales. By quantifying transmission of an entire guild of parasites (larval trematodes) within 902 amphibian host communities, we show that the community-level drivers of infection depend critically on biological scale. At the individual host scale, increases in host richness led to fewer parasites per host for all parasite taxa, with no effect of host or predator densities. At the host community scale, however, the inhibitory effects of richness were counteracted by associated increases in total host density, leading to no overall change in parasite densities. Mechanistically, we find that while average host competence declined with increasing host richness, total community competence remained stable due to additive assembly patterns. These results help reconcile disease-diversity debates by empirically disentangling the roles of alternative ecological drivers of parasite transmission and how such effects depend on biological scale.
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Affiliation(s)
- Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA.
| | - Tara E Stewart Merrill
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
- Coastal and Marine Laboratory, Florida State University, St. Teresa, FL, USA
| | - Andrew D Dean
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Andy Fenton
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, UK
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3
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Millien V, Leo SST, Turney S, Gonzalez A. It's about time: small mammal communities and Lyme disease emergence. Sci Rep 2023; 13:14513. [PMID: 37667029 PMCID: PMC10477272 DOI: 10.1038/s41598-023-41901-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/31/2023] [Indexed: 09/06/2023] Open
Abstract
Theory predicts that biodiversity changes due to climate warming can mediate the rate of disease emergence. The mechanisms linking biodiversity-disease relationships have been described both theoretically and empirically but remain poorly understood. We investigated the relations between host diversity and abundance and Lyme disease risk in southern Quebec, a region where Lyme disease is rapidly emerging. We found that both the abundance of small mammal hosts and the relative abundance of the tick's natural host, the white-footed mouse (Peromyscus leucopus), influenced measures of disease risk in tick vectors (Borrelia burgdorferi infection abundance and prevalence in tick vectors). Our results suggest that the increase in Lyme disease risk is modulated by regional processes involving the abundance and composition of small mammal assemblages. However, the nature and strength of these relationships was dependent both on time and geographic area. The strong effect of P. leucopus abundance on disease risk we report here is of significant concern, as this competent host is predicted to increase in abundance and occurrence in the region, with the northern shift in the range of North American species under climate warming.
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Affiliation(s)
- V Millien
- Redpath Museum, McGill University, Montréal, QC, H3A 0C4, Canada.
- Department of Biology, McGill University, Montréal, QC, H3A 1B1, Canada.
| | - S S T Leo
- Redpath Museum, McGill University, Montréal, QC, H3A 0C4, Canada
- Department of Biology, McGill University, Montréal, QC, H3A 1B1, Canada
| | - S Turney
- Redpath Museum, McGill University, Montréal, QC, H3A 0C4, Canada
- Department of Biology, McGill University, Montréal, QC, H3A 1B1, Canada
| | - A Gonzalez
- Department of Biology, McGill University, Montréal, QC, H3A 1B1, Canada
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4
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Gonzalez Daza W, Muylaert RL, Sobral-Souza T, Lemes Landeiro V. Malaria Risk Drivers in the Brazilian Amazon: Land Use-Land Cover Interactions and Biological Diversity. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:6497. [PMID: 37569037 PMCID: PMC10419050 DOI: 10.3390/ijerph20156497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/06/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023]
Abstract
Malaria is a prevalent disease in several tropical and subtropical regions, including Brazil, where it remains a significant public health concern. Even though there have been substantial efforts to decrease the number of cases, the reoccurrence of epidemics in regions that have been free of cases for many years presents a significant challenge. Due to the multifaceted factors that influence the spread of malaria, influencing malaria risk factors were analyzed through regional outbreak cluster analysis and spatio-temporal models in the Brazilian Amazon, incorporating climate, land use/cover interactions, species richness, and number of endemic birds and amphibians. Results showed that high amphibian and bird richness and endemism correlated with a reduction in malaria risk. The presence of forest had a risk-increasing effect, but it depended on its juxtaposition with anthropic land uses. Biodiversity and landscape composition, rather than forest formation presence alone, modulated malaria risk in the period. Areas with low endemic species diversity and high human activity, predominantly anthropogenic landscapes, posed high malaria risk. This study underscores the importance of considering the broader ecological context in malaria control efforts.
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Affiliation(s)
- William Gonzalez Daza
- Programa do Pós-Graduação em Ecologia e Conservação da Biodiversidade, Departamento de Biociências, Av. Fernando Corrêa da Costa, 2367, Cuiabá 78060-900, MT, Brazil
| | - Renata L. Muylaert
- Molecular Epidemiology and Public Health Laboratory, School of Veterinary Science, Massey University, Palmerston North 4472, New Zealand;
| | - Thadeu Sobral-Souza
- Departamento de Botânica e Ecologia, Instituto de Biociências, Universidade Federal de Mato Grosso (UFMT), Cuiabá 78060-900, MT, Brazil; (T.S.-S.); (V.L.L.)
| | - Victor Lemes Landeiro
- Departamento de Botânica e Ecologia, Instituto de Biociências, Universidade Federal de Mato Grosso (UFMT), Cuiabá 78060-900, MT, Brazil; (T.S.-S.); (V.L.L.)
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5
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Tamayo-Quintero J, Martínez-de la Puente J, San-José M, González-Quevedo C, Rivera-Gutiérrez HF. Bird community effects on avian malaria infections. Sci Rep 2023; 13:11681. [PMID: 37468559 DOI: 10.1038/s41598-023-38660-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 07/12/2023] [Indexed: 07/21/2023] Open
Abstract
In community assembly processes, interspecific interactions play an important role in shaping community diversity, especially at the local scale. Changes in species richness or abundance can modify local infectious disease dynamics, either reducing or increasing the risk of transmission within the community. This study evaluates the effects of bird community on avian haemosporidians infections in a Neotropical region. Bird samples were collected from areas surrounding three dams, and molecular analysis were performed to identify blood-parasitic haemosporidia infecting the birds. Generalized linear models were used to analyze the relationships between the bird community and the prevalence, number of infections, and richness of avian haemosporidian lineages. Non-significant effects of bird community dominance and richness on the prevalence of avian parasites and the number of infections of Haemoproteus were found. However, there was evidence of an amplification effect. Host dominance was associated with the total number of infections, the number Plasmodium infections and the expected richness of Plasmodium lineages, while the expected richness of Haemoproteus lineages was associated with the richness of bird species. These findings highlight the role of host community dominance and richness in the dynamics of parasite infections, potentially influenced by the availability of competent hosts. This study contributes significantly to our understanding of blood parasite diversity in tropical birds within a relatively understudied region of South America.
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Affiliation(s)
- Juliana Tamayo-Quintero
- Grupo de Ecología y Evolución de Vertebrados, Instituto de Biología, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medellín, Colombia.
| | | | - Miriam San-José
- Charles Darwin Foundation, Charles Darwin Research Station, Puerto Ayora, Ecuador
| | - Catalina González-Quevedo
- Grupo de Ecología y Evolución de Vertebrados, Instituto de Biología, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medellín, Colombia
| | - Héctor F Rivera-Gutiérrez
- Grupo de Ecología y Evolución de Vertebrados, Instituto de Biología, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medellín, Colombia
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6
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Hanthanan Arachchilage K, Hussaini MY, Cogan NG, Cortez MH. Exploring how ecological and epidemiological processes shape multi-host disease dynamics using global sensitivity analysis. J Math Biol 2023; 86:83. [PMID: 37154947 DOI: 10.1007/s00285-023-01912-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 12/24/2022] [Accepted: 03/31/2023] [Indexed: 05/10/2023]
Abstract
We use global sensitivity analysis (specifically, Partial Rank Correlation Coefficients) to explore the roles of ecological and epidemiological processes in shaping the temporal dynamics of a parameterized SIR-type model of two host species and an environmentally transmitted pathogen. We compute the sensitivities of disease prevalence in each host species to model parameters. Sensitivity rankings are calculated, interpreted biologically, and contrasted for cases where the pathogen is introduced into a disease-free community and cases where a second host species is introduced into an endemic single-host community. In some cases the magnitudes and dynamics of the sensitivities can be predicted only by knowing the host species' characteristics (i.e., their competitive abilities and disease competence) whereas in other cases they can be predicted by factors independent of the species' characteristics (specifically, intraspecific versus interspecific processes or a species' roles of invader versus resident). For example, when a pathogen is initially introduced into a disease-free community, disease prevalence in both hosts is more sensitive to the burst size of the first host than the second host. In comparison, disease prevalence in each host is more sensitive to its own infection rate than the infection rate of the other host species. In total, this study illustrates that global sensitivity analysis can provide useful insight into how ecological and epidemiological processes shape disease dynamics and how those effects vary across time and system conditions. Our results show that sensitivity analysis can provide quantification and direction when exploring biological hypotheses.
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Affiliation(s)
| | - Mohammed Y Hussaini
- Department of Mathematics, Florida State University, Tallahassee, Fl, 32306, USA
| | - N G Cogan
- Department of Mathematics, Florida State University, Tallahassee, Fl, 32306, USA
| | - Michael H Cortez
- Department of Biological Science, Florida State University, Tallahassee, Fl, 32306, USA.
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7
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Halliday FW, Czyżewski S, Laine AL. Intraspecific trait variation and changing life-history strategies explain host community disease risk along a temperature gradient. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220019. [PMID: 36744568 PMCID: PMC9900715 DOI: 10.1098/rstb.2022.0019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 01/02/2023] [Indexed: 02/07/2023] Open
Abstract
Predicting how climate change will affect disease risk is complicated by the fact that changing environmental conditions can affect disease through direct and indirect effects. Species with fast-paced life-history strategies often amplify disease, and changing climate can modify life-history composition of communities thereby altering disease risk. However, individuals within a species can also respond to changing conditions with intraspecific trait variation. To test the effect of temperature, as well as inter- and intraspecifc trait variation on community disease risk, we measured foliar disease and specific leaf area (SLA; a proxy for life-history strategy) on more than 2500 host (plant) individuals in 199 communities across a 1101 m elevational gradient in southeastern Switzerland. There was no direct effect of increasing temperature on disease. Instead, increasing temperature favoured species with higher SLA, fast-paced life-history strategies. This effect was balanced by intraspecific variation in SLA: on average, host individuals expressed lower SLA with increasing temperature, and this effect was stronger among species adapted to warmer temperatures and lower latitudes. These results demonstrate how impacts of changing temperature on disease may depend on how temperature combines and interacts with host community structure while indicating that evolutionary constraints can determine how these effects are manifested under global change. This article is part of the theme issue 'Infectious disease ecology and evolution in a changing world'.
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Affiliation(s)
- Fletcher W. Halliday
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland
| | - Szymon Czyżewski
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland
| | - Anna-Liisa Laine
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland
- Research Centre for Ecological Change, Organismal & Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, PO Box 65, Helsinki FI-00014, Finland
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8
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Schenck FR, DuBois K, Kardish MR, Stachowicz JJ, Hughes AR. The effect of warming on seagrass wasting disease depends on host genotypic identity and diversity. Ecology 2023; 104:e3959. [PMID: 36530038 DOI: 10.1002/ecy.3959] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/22/2022] [Indexed: 12/23/2022]
Abstract
Temperature increases due to climate change have affected the distribution and severity of diseases in natural systems, causing outbreaks that can destroy host populations. Host identity, diversity, and the associated microbiome can affect host responses to both infection and temperature, but little is known about how they could function as important mediators of disease in altered thermal environments. We conducted an 8-week warming experiment to test the independent and interactive effects of warming, host genotypic identity, and host genotypic diversity on the prevalence and intensity of infections of seagrass (Zostera marina) by the wasting disease parasite (Labyrinthula zosterae). At elevated temperatures, we found that genotypically diverse host assemblages had reduced infection intensity, but not reduced prevalence, relative to less diverse assemblages. This dilution effect on parasite intensity was the result of both host composition effects as well as emergent properties of biodiversity. In contrast with the benefits of genotypic diversity under warming, diversity actually increased parasite intensity slightly in ambient temperatures. We found mixed support for the hypothesis that a growth-defense trade-off contributed to elevated disease intensity under warming. Changes in the abundance (but not composition) of a few taxa in the host microbiome were correlated with genotype-specific responses to wasting disease infections under warming, consistent with the emerging evidence linking changes in the host microbiome to the outcome of host-parasite interactions. This work emphasizes the context dependence of biodiversity-disease relationships and highlights the potential importance of interactions among biodiversity loss, climate change, and disease outbreaks in a key foundation species.
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Affiliation(s)
- Forest R Schenck
- Marine Science Center, Northeastern University, Nahant, Massachusetts, USA.,Massachusetts Division of Marine Fisheries, Gloucester, Massachusetts, USA
| | - Katherine DuBois
- Department of Evolution and Ecology, University of California, Davis, California, USA
| | - Melissa R Kardish
- Department of Evolution and Ecology, University of California, Davis, California, USA
| | - John J Stachowicz
- Department of Evolution and Ecology, University of California, Davis, California, USA.,Center for Population Biology, University of California, Davis, California, USA
| | - A Randall Hughes
- Marine Science Center, Northeastern University, Nahant, Massachusetts, USA
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9
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Wood CL, Vanhove MPM. Is the world wormier than it used to be? We'll never know without natural history collections. J Anim Ecol 2023; 92:250-262. [PMID: 35959636 DOI: 10.1111/1365-2656.13794] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 07/25/2022] [Indexed: 11/28/2022]
Abstract
Many disease ecologists and conservation biologists believe that the world is wormier than it used to be-that is, that parasites are increasing in abundance through time. This argument is intuitively appealing. Ecologists typically see parasitic infections, through their association with disease, as a negative endpoint, and are accustomed to attributing negative outcomes to human interference in the environment, so it slots neatly into our worldview that habitat destruction, biodiversity loss and climate change should have the collateral consequence of causing outbreaks of parasites. But surprisingly, the hypothesis that parasites are increasing in abundance through time remains entirely untested for the vast majority of wildlife parasite species. Historical data on parasites are nearly impossible to find, which leaves no baseline against which to compare contemporary parasite burdens. If we want to know whether the world is wormier than it used to be, there is only one major research avenue that will lead to an answer: parasitological examination of specimens preserved in natural history collections. Recent advances demonstrate that, for many specimen types, it is possible to extract reliable data on parasite presence and abundance. There are millions of suitable specimens that exist in collections around the world. When paired with contemporaneous environmental data, these parasitological data could even point to potential drivers of change in parasite abundance, including climate, pollution or host density change. We explain how to use preserved specimens to address pressing questions in parasite ecology, give a few key examples of how collections-based parasite ecology can resolve these questions, identify some pitfalls and workarounds, and suggest promising areas for research. Natural history specimens are 'parasite time capsules' that give ecologists the opportunity to test whether infectious disease is on the rise and to identify what forces might be driving these changes over time. This approach will facilitate major advances in a new sub-discipline: the historical ecology of parasitism.
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Affiliation(s)
- Chelsea L Wood
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA
| | - Maarten P M Vanhove
- Centre for Environmental Sciences, Research Group Zoology: Biodiversity & Toxicology, Hasselt University, Diepenbeek, Belgium
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10
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Liu X, Xiao Y, Lin Z, Wang X, Hu K, Liu M, Zhao Y, Qi Y, Zhou S. Spatial scale-dependent dilution effects of biodiversity on plant diseases in grasslands. Ecology 2023; 104:e3944. [PMID: 36477908 DOI: 10.1002/ecy.3944] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 11/03/2022] [Accepted: 11/07/2022] [Indexed: 12/12/2022]
Abstract
The rapid biodiversity losses of the Anthropocene have motivated ecologists to understand how biodiversity affects infectious diseases. Spatial scale is thought to moderate negative biodiversity-disease relationships (i.e., dilution effects) in zoonotic diseases, whereas evidence from plant communities for an effect of scale remains limited, especially at local scales where the mechanisms (e.g., encounter reduction) underlying dilution effects actually work. Here, we tested how spatial scale affects the direction and magnitude of biodiversity-disease relationships. We utilized a 10-year-old nitrogen addition experiment in a Tibetan alpine meadow, with 0, 5, 10, and 15 g/m2 nitrogen addition treatments. Within the treatment plots, we arranged a total of 216 quadrats (of either 0.125 × 0.125 m, 0.25 × 0.25 m or 0.5 × 0.5 m size) to test how the sample area affects the relationship between plant species richness and foliar fungal disease severity. We found that the dilution effects were stronger in the 0.125 × 0.125 m and 0.25 × 0.25 m quadrats, compared with 0.5 × 0.5 m quadrats. There was a significant interaction between species richness and nitrogen addition in the 0.125 × 0.125 m and 0.25 × 0.25 m quadrats, indicating that a dilution effect was more easily observed under higher levels of nitrogen addition. Based on multigroup structural equation models, we found that even accounting for the direct impact of nitrogen addition (i.e., "nitrogen-disease hypothesis"), the dilution effect still worked at the 0.125 × 0.125 m scale. Overall, these findings suggest that spatial scale directly determines the occurrence of dilution effects, and can partly explain the observed variation in biodiversity-disease relationships in grasslands. Next-generation frameworks for predicting infectious diseases under rapid biodiversity loss scenarios need to incorporate spatial information.
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Affiliation(s)
- Xiang Liu
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Yao Xiao
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Ziyuan Lin
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Xingxing Wang
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Kui Hu
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Mu Liu
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Ecology, Lanzhou University, Lanzhou, China
| | - Yimin Zhao
- Key Laboratory of Genetics and Germplasm Innovation of Tropical Special Forest Trees and Ornamental Plants, Ministry of Education, College of Forestry, Hainan University, Haikou, China
| | - Yanwen Qi
- Key Laboratory of Genetics and Germplasm Innovation of Tropical Special Forest Trees and Ornamental Plants, Ministry of Education, College of Forestry, Hainan University, Haikou, China
| | - Shurong Zhou
- Key Laboratory of Genetics and Germplasm Innovation of Tropical Special Forest Trees and Ornamental Plants, Ministry of Education, College of Forestry, Hainan University, Haikou, China
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11
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Chen S, Liu X, He Q, Zhou S. Higher-order interactions on disease transmission can reverse the dilution effect or weaken the amplification effect to unimodal pattern. Ecol Modell 2022. [DOI: 10.1016/j.ecolmodel.2022.110156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Chen L, Kong P, Hou L, Zhou Y, Zhou L. Host community composition, community assembly pattern, and disease transmission mode jointly determine the direction and strength of the diversity-disease relationship. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1032931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Rapid global biodiversity loss and increasing emerging infectious diseases underscore the significance of identifying the diversity-disease relationship. Although experimental evidence supports the existence of dilution effects in several natural ecosystems, we still know very little about the conditions under which a dilution effect will occur. Using a multi-host Susceptible-Infected-Recovered model, we found when disease transmission was density-dependent, the diversity-disease relationship could exhibit an increasing, decreasing, or non-monotonic trend, which mainly depended on the patterns of community assembly. However, the combined effects of the host competence-abundance relationship and species extinction order may reverse or weaken this trend. In contrast, when disease transmission was frequency-dependent, the diversity-disease relationship only showed a decreasing trend, the host competence-abundance relationship and species extinction order did not alter this decreasing trend, but it could reduce the detectability of the dilution effect and affect disease prevalence. Overall, a combination of disease transmission mode, community assembly pattern, and host community composition determines the direction or strength of the diversity-disease relationship. Our work helps explain why previous studies came to different conclusions about the diversity-disease relationship and provides a deeper understanding of the pathogen transmission dynamics in actual communities.
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13
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Occhibove F, Kenobi K, Swain M, Risley C. An eco-epidemiological modeling approach to investigate dilution effect in two different tick-borne pathosystems. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2550. [PMID: 35092122 PMCID: PMC9286340 DOI: 10.1002/eap.2550] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 10/20/2021] [Accepted: 10/27/2021] [Indexed: 05/05/2023]
Abstract
Disease (re)emergence appears to be driven by biodiversity decline and environmental change. As a result, it is increasingly important to study host-pathogen interactions within the context of their ecology and evolution. The dilution effect is the concept that higher biodiversity decreases pathogen transmission. It has been observed especially in zoonotic vector-borne pathosystems, yet evidence against it has been found. In particular, it is still debated how the community (dis)assembly assumptions and the degree of generalism of vectors and pathogens affect the direction of the biodiversity-pathogen transmission relationship. The aim of this study was to use empirical data and mechanistic models to investigate dilution mechanisms in two rodent-tick-pathogen systems differing in their vector degree of generalism. A community was assembled to include ecological interactions that expand from purely additive to purely substitutive. Such systems are excellent candidates to analyze the link between vector ecology, community (dis)assembly dynamics, and pathogen transmission. To base our mechanistic models on empirical data, rodent live-trapping, including tick sampling, was conducted in Wales across two seasons for three consecutive years. We have developed a deterministic single-vector, multi-host compartmental model that includes ecological relationships with non-host species, uniquely integrating theoretical and observational approaches. To describe pathogen transmission across a gradient of community diversity, the model was populated with parameters describing five different scenarios differing in ecological complexity; each based around one of the pathosystems: Ixodes ricinus (generalist tick)-Borrelia burgdorferi and I. trianguliceps (small mammals specialist tick)-Babesia microti. The results suggested that community composition and interspecific dynamics affected pathogen transmission with different dilution outcomes depending on the vector degree of generalism. The model provides evidence that dilution and amplification effects are not mutually exclusive in the same community but depend on vector ecology and the epidemiological output considered (i.e., the "risk" of interest). In our scenarios, more functionally diverse communities resulted in fewer infectious rodents, supporting the dilution effect. In the pathosystem with generalist vector we identified a hump shaped relationship between diversity and infections in hosts, while for that characterized by specialist tick, this relationship was more complex and more dependent upon specific parameter values.
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Affiliation(s)
- Flavia Occhibove
- IBERS, Aberystwyth UniversityAberystwythUK
- UK Centre for Ecology & HydrologyWallingfordUK
| | - Kim Kenobi
- Department of MathematicsAberystwyth UniversityAberystwythUK
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14
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Espira LM, Brouwer AF, Han BA, Foufopoulos J, Eisenberg JNS. Dilution of Epidemic Potential of Environmentally Transmitted Infectious Diseases for Species with Partially Overlapping Habitats. Am Nat 2022; 199:E43-E56. [PMID: 35077275 PMCID: PMC9136953 DOI: 10.1086/717413] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/27/2023]
Abstract
AbstractSpecies diversity may play an important role in the modulation of pathogen transmission through the dilution effect. Infectious disease models can help elucidate mechanisms that may underlie this effect. While many modeling studies have assumed direct host-to-host transmission, many pathogens are transmitted through the environment. We present a mathematical modeling analysis exploring conditions under which we observe the dilution effect in systems with environmental transmission where host species interact through fully or partially overlapping habitats. We measure the strength of the dilution effect by the relative decrease in the basic reproduction number of two-species assemblages compared with that of a focal host species. We find that a dilution effect is most likely when the pathogen is environmentally persistent (frequency-dependent-like transmission). The magnitude of this effect is strongest when the species with the greater epidemic potential is relatively slow to pick up pathogens in the environment (density-dependent transmission) and the species with the lesser epidemic potential is efficient at picking up pathogens (frequency-dependent transmission). These findings suggest that measurable factors, including pathogen persistence and the host's relative efficiency of pathogen pickup, can guide predictions of when biodiversity might lead to a dilution effect and may thus give concrete direction to future ecological work.
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Affiliation(s)
- Leon M. Espira
- Department of Epidemiology, University of Michigan, Ann Arbor, MI 48109
| | - Andrew F. Brouwer
- Department of Epidemiology, University of Michigan, Ann Arbor, MI 48109
| | - Barbara A. Han
- Cary Institute of Ecosystem Studies, Millbrook, NY 12545
| | - Johannes Foufopoulos
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI 48109
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15
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Kocher A, Cornuault J, Gantier JC, Manzi S, Chavy A, Girod R, Dusfour I, Forget PM, Ginouves M, Prévot G, Guégan JF, Bañuls AL, de Thoisy B, Murienne J. Biodiversity and vector-borne diseases: host dilution and vector amplification occur simultaneously for Amazonian leishmaniases. Mol Ecol 2022; 32:1817-1831. [PMID: 35000240 DOI: 10.1111/mec.16341] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 12/02/2021] [Accepted: 12/23/2021] [Indexed: 11/29/2022]
Abstract
Changes in biodiversity may impact infectious disease transmission through multiple mechanisms. We explored the impact of biodiversity changes on the transmission of Amazonian leishmaniases, a group of wild zoonoses transmitted by phlebotomine sand flies (Psychodidae), which represent an important health burden in a region where biodiversity is both rich and threatened. Using molecular analyses of sand fly pools and blood-fed dipterans, we characterized the disease system in forest sites in French Guiana undergoing different levels of human-induced disturbance. We show that the prevalence of Leishmania parasites in sand flies correlates positively with the relative abundance of mammal species known as Leishmania reservoirs. In addition, Leishmania reservoirs tend to dominate in less diverse mammal communities, in accordance with the dilution effect hypothesis. This results in a negative relationship between Leishmania prevalence and mammal diversity. On the other hand, higher mammal diversity is associated with higher sand fly density, possibly because more diverse mammal communities harbor higher biomass and more abundant feeding resources for sand flies, although more research is needed to identify the factors that shape sand fly communities. As a consequence of these antagonistic effects, decreased mammal diversity comes with an increase of parasite prevalence in sand flies, but has no detectable impact on the density of infected sand flies. These results represent additional evidence that biodiversity changes may simultaneously dilute and amplify vector-borne disease transmission through different mechanisms that need to be better understood before drawing generalities on the biodiversity-disease relationship.
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Affiliation(s)
- Arthur Kocher
- Laboratoire Évolution et Diversité Biologique (UMR5174 EDB) - CNRS, IRD, Université Toulouse III Paul Sabatier - Toulouse, France.,MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France.,Institut Pasteur de la Guyane, Cayenne, France.,Transmission, Infection, Diversification & Evolution Group, Max-Planck Institute for the Science of Human History, Kahlaische Str. 10, 07745, Jena, Germany
| | - Josselin Cornuault
- Real Jardín Botánico CSIC, Plaza Murillo 2, 28014, Madrid, Spain.,ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Jean-Charles Gantier
- Laboratoire des Identifications Fongiques et Entomo-parasitologiques, Mennecy, France
| | - Sophie Manzi
- Laboratoire Évolution et Diversité Biologique (UMR5174 EDB) - CNRS, IRD, Université Toulouse III Paul Sabatier - Toulouse, France
| | - Agathe Chavy
- Institut Pasteur de la Guyane, Cayenne, France.,TBIP, Université de Guyane, 97300, Cayenne, France
| | | | | | - Pierre-Michel Forget
- Muséum National d'Histoire Naturelle, UMR-7179 MECADEV (Mécanismes Adaptatifs et Evolution), MNHN-CNRS, Brunoy, France
| | - Marine Ginouves
- TBIP, Université de Guyane, 97300, Cayenne, France.,Université de Lille, CNRS, Inserm, Institut Pasteur de Lille, U1019-UMR9017-CIIL Centre d'Infection et d'Immunité de Lille, 59000, Lille, France
| | - Ghislaine Prévot
- TBIP, Université de Guyane, 97300, Cayenne, France.,Université de Lille, CNRS, Inserm, Institut Pasteur de Lille, U1019-UMR9017-CIIL Centre d'Infection et d'Immunité de Lille, 59000, Lille, France
| | - Jean-François Guégan
- MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France.,INRAE, Cirad, Université de Montpellier, UMR ASTRE, Montpellier, France
| | | | - Benoit de Thoisy
- Institut Pasteur de la Guyane, Cayenne, France.,Association Kwata, Cayenne, French Guiana
| | - Jérôme Murienne
- Laboratoire Évolution et Diversité Biologique (UMR5174 EDB) - CNRS, IRD, Université Toulouse III Paul Sabatier - Toulouse, France
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16
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Rosenthal LM, Brooks WR, Rizzo DM. Species densities, assembly order, and competence jointly determine the diversity–disease relationship. Ecology 2021; 103:e3622. [DOI: 10.1002/ecy.3622] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/12/2021] [Accepted: 12/09/2021] [Indexed: 11/12/2022]
Affiliation(s)
- Lisa M. Rosenthal
- Department of Plant Pathology University of California Davis California USA
- Graduate Group in Ecology University of California Davis California USA
| | | | - David M. Rizzo
- Department of Plant Pathology University of California Davis California USA
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17
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Rosenthal LM, Simler-Williamson AB, Rizzo DM. Community-level prevalence of a forest pathogen, not individual-level disease risk, declines with tree diversity. Ecol Lett 2021; 24:2477-2489. [PMID: 34510681 DOI: 10.1111/ele.13871] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/18/2021] [Accepted: 08/10/2021] [Indexed: 11/27/2022]
Abstract
Understanding why diversity sometimes limits disease is essential for managing outbreaks; however, mechanisms underlying this 'dilution effect' remain poorly understood. Negative diversity-disease relationships have previously been detected in plant communities impacted by an emerging forest disease, sudden oak death. We used this focal system to empirically evaluate whether these relationships were driven by dilution mechanisms that reduce transmission risk for individuals or from the fact that disease was averaged across the host community. We integrated laboratory competence measurements with plant community and symptom data from a large forest monitoring network. Richness increased disease risk for bay laurel trees, dismissing possible dilution mechanisms. Nonetheless, richness was negatively associated with community-level disease prevalence because the disease was aggregated among hosts that vary in disease susceptibility. Aggregating observations (which is surprisingly common in other dilution effect studies) can lead to misinterpretations of dilution mechanisms and bias towards a negative diversity-disease relationship.
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Affiliation(s)
- Lisa M Rosenthal
- Graduate Group in Ecology, University of California, Davis, California, USA.,Department of Plant Pathology, University of California, Davis, California, USA
| | | | - David M Rizzo
- Department of Plant Pathology, University of California, Davis, California, USA
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18
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Keesing F, Ostfeld RS. Dilution effects in disease ecology. Ecol Lett 2021; 24:2490-2505. [PMID: 34482609 PMCID: PMC9291114 DOI: 10.1111/ele.13875] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 08/19/2021] [Indexed: 01/03/2023]
Abstract
For decades, people have reduced the transmission of pathogens by adding low‐quality hosts to managed environments like agricultural fields. More recently, there has been interest in whether similar ‘dilution effects’ occur in natural disease systems, and whether these effects are eroded as diversity declines. For some pathogens of plants, humans and other animals, the highest‐quality hosts persist when diversity is lost, so that high‐quality hosts dominate low‐diversity communities, resulting in greater pathogen transmission. Meta‐analyses reveal that these natural dilution effects are common. However, studying them remains challenging due to limitations on the ability of researchers to manipulate many disease systems experimentally, difficulties of acquiring data on host quality and confusion about what should and should not be considered a dilution effect. Because dilution effects are widely used in managed disease systems and have been documented in a variety of natural disease systems, their existence should not be considered controversial. Important questions remain about how frequently they occur and under what conditions to expect them. There is also ongoing confusion about their relationships to both pathogen spillover and general biogeographical correlations between diversity and disease, which has resulted in an inconsistent and confusing literature. Progress will require rigorous and creative research.
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19
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Alternative transmission pathways for guinea worm in dogs: implications for outbreak risk and control. Int J Parasitol 2021; 51:1027-1034. [PMID: 34246634 DOI: 10.1016/j.ijpara.2021.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/10/2021] [Accepted: 05/13/2021] [Indexed: 11/24/2022]
Abstract
Guinea worm (Dracunculus medinensis) has exerted a high human health burden in parts of Africa. Complete eradication of Guinea worm disease (dracunculiasis) may be delayed by the circulation of the parasite in domestic dogs. As with humans, dogs acquire the parasite by directly ingesting infected copepods, and recent evidence suggests that consuming frogs that ingested infected copepods as tadpoles may be a viable transmission route (paratenic route). To understand the relative contributions of direct and paratenic transmission routes, we developed a mathematical model that describes transmission of Guinea worm between dogs, copepods and frogs. We explored how the parasite basic reproductive number (R0) depends on parameters amenable to actionable interventions under three scenarios: frogs/tadpoles do not consume copepods; tadpoles consume copepods but frogs do not contribute to transmission; and frogs are paratenic hosts. We found a non-monotonic relationship between the number of dogs and R0. Generally, frogs can contribute to disease control by removing infected copepods from the waterbody even when paratenic transmission can occur. However, paratenic transmission could play an important role in maintaining the parasite when direct transmission is reduced by interventions focused on reducing copepod ingestion by dogs. Together, these suggest that the most effective intervention strategies may be those which focus on the reduction of copepods, as this reduces outbreak potential irrespective of the importance of the paratenic route.
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20
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Cortez MH, Duffy MA. The Context-Dependent Effects of Host Competence, Competition, and Pathogen Transmission Mode on Disease Prevalence. Am Nat 2021; 198:179-194. [PMID: 34260871 DOI: 10.1086/715110] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractBiodiversity in communities is changing globally, including the gain and loss of host species in host-pathogen communities. Increased host diversity can cause infection prevalence in a focal host to increase (amplification) or decrease (dilution). However, it is unclear what general rules govern the context-dependent effects, in part because theories for pathogens with different transmission modes have developed largely independently. Using a two-host model, we explore how the pathogen transmission mode and characteristics of a second host (disease competence and competitive ability) influence disease prevalence in a focal host. Our work shows how the theories for pathogens with environmental transmission, density-dependent direct transmission, and frequency-dependent direct transmission can be unified. Our work also identifies general rules about how host and pathogen characteristics affect amplification/dilution. For example, higher-competence hosts promote amplification, unless they are strong interspecific competitors; strong interspecific competitors promote dilution, unless they are large sources of new infections; and dilution occurs under frequency-dependent direct transmission more than density-dependent direct transmission, unless interspecific host competition is sufficiently strong. Our work helps explain how the characteristics of the pathogen and a second host affect disease prevalence in a focal host.
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21
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Cortez MH. Using sensitivity analysis to identify factors promoting higher versus lower infection prevalence in multi-host communities. J Theor Biol 2021; 526:110766. [PMID: 34019849 DOI: 10.1016/j.jtbi.2021.110766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 05/04/2021] [Accepted: 05/12/2021] [Indexed: 10/21/2022]
Abstract
Relationships between host species richness and levels of disease in a focal host are likely to be context-dependent, depending on the characteristics of which particular host species are present in a community. I use a multi-host epidemiological model with environmental transmission to explore how the characteristics of the host species (e.g., competence and competitive ability), host density, and the pathogen transmission mechanism affect the proportion of infected individuals (i.e., infection prevalence) in a focal host. My sensitivity-based approach identifies the indirect pathways through which specific ecological and epidemiological processes affect focal host infection prevalence. This in turn yields predictions about the context-dependent rules governing whether increased host species richness increases (amplifies) or decreases (dilutes) infection prevalence in a focal host. For example, in many cases, amplification and dilution are predicted to occur when added host species are sources or sinks of infectious propagules, respectively. However, if the added host species have strong and asymmetric competitive effects on resident host species, then amplification and dilution are predicted to occur when the added host species have stronger competitive effects on resident host species that are sources or sinks of infectious propagules, respectively. My results also predict that greater dilution and less amplification is more likely to occur under frequency-dependent direct transmission than density-dependent direct transmission when (i) the added hosts have lower competence than resident host species and (ii) interspecific competition between the added host species and resident host species is lower; the opposite conditions promote greater amplification and less dilution under frequency-dependent direct transmission. This work helps identify and explain the mechanisms shaping the context-dependent relationships between host species richness and disease in multi-host communities.
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Affiliation(s)
- Michael H Cortez
- Depart of Biological Science, Florida State University, Tallahassee, FL 32306, United States.
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22
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Halliday FW, Jalo M, Laine AL. The effect of host community functional traits on plant disease risk varies along an elevational gradient. eLife 2021; 10:67340. [PMID: 33983120 PMCID: PMC8208817 DOI: 10.7554/elife.67340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 05/10/2021] [Indexed: 01/17/2023] Open
Abstract
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 toward more fast-paced life-history strategies are predicted to increase disease, yet their independent and interactive effects on disease in natural communities remain unknown. Here, we address this challenge by surveying foliar disease symptoms in 220, 0.5 m-diameter herbaceous plant communities along a 1100-m 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. Climate change is causing shifts in the ecology and biodiversity of different world regions at unprecedented rates. Global warming is also linked with changes in the risk for certain infectious diseases in humans, but also in animals and plants. There are several possible mechanisms for this. For one thing, changing weather patterns may affect how pathogens grow and reproduce. For another, the distribution ranges of animal and plant hosts of certain disease-causing pathogens are changing because of global warming. This means that the distributions of pathogens are also changing, and so is the severity of the diseases that they cause. Increasing temperatures may also influence the physiological traits that make host species suitable for pathogens. This is because the traits that allow species to survive or adapt to changes in their environment may also make them better at hosting and transmitting the pathogens that cause disease. For example, in plant communities, rising temperatures could favor species with faster growth rates, quicker reproduction and high dispersal, and these traits are often associated with more efficient spread of disease. Despite a lot of research into the effects of climate, it remains unclear how temperature, pathogen growth and reproduction, and host species’ traits and distributions combine and interact to alter infectious disease risk, especially in wild plant communities. To investigate this, Halliday, Jalo and Laine studied an area in southeast Switzerland where natural temperature and biodiversity change gradually through the region. The aim was to explore how relationships between plant biodiversity, pathogens and disease risk change with temperature, and to understand whether environmental or biological factors influence infectious disease risk more. Halliday, Jalo and Laine measured the levels of fungal diseases found in the leaves of plant communities spanning 1,100 meters of elevation, showing that higher temperatures increase disease risk both directly and indirectly. Directly, higher temperatures increased pathogen growth and reproduction, and indirectly, they influenced which plants were present and therefore able to act as disease hosts. The results also indicated that temperature can affect how the traits of plants drive the transmission rates of fungal pathogens. Important predictors of disease risk were traits relating to the growth rate of host plants, which tended to increase in areas with low elevation where the surface of the soil was warm. This study represents the first analysis, in wild plants, of how changing temperatures, the traits of shifting host species, and resident parasite populations interact to impact infectious disease risk. The insights Halliday, Jalo and Laine provided could aid in predicting how global climate change will influence infectious disease risk.
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Affiliation(s)
- Fletcher W Halliday
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zurich, Switzerland
| | - Mikko Jalo
- Faculty of Biological and Environmental sciences, University of Helsinki, Helsinki, Finland
| | - Anna-Liisa Laine
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zurich, Switzerland.,Faculty of Biological and Environmental sciences, University of Helsinki, Helsinki, Finland
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23
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Schatz AM, Park AW. Host and parasite traits predict cross-species parasite acquisition by introduced mammals. Proc Biol Sci 2021; 288:20210341. [PMID: 33947240 PMCID: PMC8097221 DOI: 10.1098/rspb.2021.0341] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/01/2021] [Indexed: 01/02/2023] Open
Abstract
Species invasions and range shifts can lead to novel host-parasite communities, but we lack general rules on which new associations are likely to form. While many studies examine parasite sharing among host species, the directionality of transmission is typically overlooked, impeding our ability to derive principles of parasite acquisition. Consequently, we analysed parasite records from the non-native ranges of 11 carnivore and ungulate species. Using boosted regression trees, we modelled parasite acquisition within each zoogeographic realm of a focal host's non-native range, using a suite of predictors characterizing the parasites themselves and the host community in which they live. We found that higher parasite prevalence among established hosts increases the likelihood of acquisition, particularly for generalist parasites. Non-native host species are also more likely to acquire parasites from established host species to which they are closely related; however, the acquisition of several parasite groups is biased to phylogenetically specialist parasites, indicating potential costs of parasite generalism. Statistical models incorporating these features provide an accurate prediction of parasite acquisition, indicating that measurable host and parasite traits can be used to estimate the likelihood of new host-parasite associations forming. This work provides general rules to help anticipate novel host-parasite associations created by climate change and other anthropogenic influences.
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Affiliation(s)
- Annakate M. Schatz
- Odum School of Ecology, University of Georgia, Athens, GA, USA
- Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA
| | - Andrew W. Park
- Odum School of Ecology, University of Georgia, Athens, GA, USA
- Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
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24
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Fearon ML, Tibbetts EA. Pollinator community species richness dilutes prevalence of multiple viruses within multiple host species. Ecology 2021; 102:e03305. [PMID: 33571384 DOI: 10.1002/ecy.3305] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 11/24/2020] [Indexed: 01/01/2023]
Abstract
Most pathogens are embedded in complex communities composed of multiple interacting hosts, but we are still learning how community-level factors, such as host diversity, abundance, and composition, contribute to pathogen spread for many host-pathogen systems. Evaluating relationships among multiple pathogens and hosts may clarify whether particular host or pathogen traits consistently drive links between community factors and pathogen prevalence. Pollinators are a good system to test how community composition influences pathogen spread because pollinator communities are extremely variable and contain several multi-host pathogens transmitted on shared floral resources. We conducted a field survey of four pollinator species to test the prevalence of three RNA viruses (deformed wing virus, black queen cell virus, and sacbrood virus) among pollinator communities with variable species richness, abundance, and composition. All three viruses showed a similar pattern of prevalence among hosts. Apis mellifera and Bombus impatiens had significantly higher viral prevalence than Lasioglossum spp. and Eucera pruinosa. In each species, lower virus prevalence was most strongly linked with greater pollinator community species richness. In contrast, pollinator abundance, species-specific pollinator abundance, and community composition were not associated with virus prevalence. Our results support a consistent dilution effect for multiple viruses and host species. Pollinators in species-rich communities had lower viral prevalence than pollinators from species-poor communities, when accounting for differences in pollinator abundance. Species-rich communities likely had lower viral prevalence because species-rich communities contained more native bee species likely to be poor viral hosts than species-poor communities, and all communities contained the highly competent hosts A. mellifera and B. impatiens. Interestingly, the strength of the dilution effect was not consistent among hosts. Instead, host species with low viral prevalence exhibited weaker dilution effects compared to hosts with high viral prevalence. Therefore, host species susceptibility and competence for each virus may contribute to variation in the strength of dilution effects. This study expands biodiversity-disease studies to the pollinator-virus system, finding consistent evidence of the dilution effect among multiple similar pathogens that infect "replicate" host communities.
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Affiliation(s)
- Michelle L Fearon
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | - Elizabeth A Tibbetts
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, 48109, USA
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25
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Saadani M, Hönig L, Bien S, Koehler M, Rutten G, Wubet T, Braun U, Bruelheide H. Local Tree Diversity Suppresses Foliar Fungal Infestation and Decreases Morphological But Not Molecular Richness in a Young Subtropical Forest. J Fungi (Basel) 2021; 7:173. [PMID: 33673628 PMCID: PMC7997179 DOI: 10.3390/jof7030173] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/19/2021] [Accepted: 02/23/2021] [Indexed: 12/25/2022] Open
Abstract
Leaf fungal pathogens alter their host species' performance and, thus, changes in fungal species composition can translate into effects at the tree community scale. Conversely, the functional diversity of tree species in a host tree's local neighbourhood can affect the host's foliar fungal infestation. Therefore, understanding the factors that affect fungal infestations is important to advance our understanding of biodiversity-ecosystem functioning (BEF) relationships. Here we make use of the largest BEF tree experiment worldwide, the BEF-China experiment, where we selected tree host species with different neighbour species. Identifying fungal taxa by microscopy and by high-throughput DNA sequencing techniques based on the internal transcribed spacer (ITS) rDNA region, we analysed the fungal richness and infestation rates of our target trees as a function of local species richness. Based on the visual microscopic assessment, we found that a higher tree diversity reduced fungal richness and host-specific fungal infestation in the host's local neighbourhood, while molecular fungal richness was unaffected. This diversity effect was mainly explained by the decrease in host proportion. Thus, the dilution of host species in the local neighbourhood was the primary mechanism in reducing the fungal disease severity. Overall, our study suggests that diverse forests will suffer less from foliar fungal diseases compared to those with lower diversity.
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Affiliation(s)
- Mariem Saadani
- Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108 Halle, Germany; (L.H.); (S.B.); (M.K.); (G.R.); (U.B.); (H.B.)
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstr. 4, 04103 Leipzig, Germany;
| | - Lydia Hönig
- Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108 Halle, Germany; (L.H.); (S.B.); (M.K.); (G.R.); (U.B.); (H.B.)
| | - Steffen Bien
- Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108 Halle, Germany; (L.H.); (S.B.); (M.K.); (G.R.); (U.B.); (H.B.)
- Senckenberg Museum of Natural History Görlitz, PF 300 154, 02806 Görlitz, Germany
| | - Michael Koehler
- Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108 Halle, Germany; (L.H.); (S.B.); (M.K.); (G.R.); (U.B.); (H.B.)
| | - Gemma Rutten
- Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108 Halle, Germany; (L.H.); (S.B.); (M.K.); (G.R.); (U.B.); (H.B.)
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstr. 4, 04103 Leipzig, Germany;
| | - Tesfaye Wubet
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstr. 4, 04103 Leipzig, Germany;
- Department of Community Ecology, UFZ-Helmholtz Centre for Environmental Research, Theodor-Lieser-Str. 4, D-06120 Halle, Germany
| | - Uwe Braun
- Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108 Halle, Germany; (L.H.); (S.B.); (M.K.); (G.R.); (U.B.); (H.B.)
| | - Helge Bruelheide
- Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108 Halle, Germany; (L.H.); (S.B.); (M.K.); (G.R.); (U.B.); (H.B.)
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Puschstr. 4, 04103 Leipzig, Germany;
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26
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Peterson AC, Ghersi BM, Riegel C, Wunder EA, Childs JE, Blum MJ. Amplification of pathogenic Leptospira infection with greater abundance and co-occurrence of rodent hosts across a counter-urbanizing landscape. Mol Ecol 2020; 30:2145-2161. [PMID: 33107122 DOI: 10.1111/mec.15710] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 10/12/2020] [Accepted: 10/15/2020] [Indexed: 01/20/2023]
Abstract
Land use change can elevate disease risk by creating conditions beneficial to species that carry zoonotic pathogens. Observations of concordant global trends in increased pathogen prevalence or disease incidence and landscape change have generated concerns that urbanization could increase transmission risk of some pathogens. Yet host-pathogen relationships underlying transmission risk have not been well characterized within cities, even where contact between humans and species capable of transmitting pathogens of concern occurs. We addressed this deficit by testing the hypothesis that areas in cities experiencing greater population loss and infrastructure decline (i.e., counter-urbanization) can support a greater diversity of host species and a larger and more diverse pool of pathogens. We did so by characterizing pathogenic Leptospira infection relative to rodent host richness and abundance across a mosaic of abandonment in post-Katrina New Orleans (Louisiana, USA). We found that Leptospira infection loads were highest in areas that harboured increased rodent species richness (which ranged from one to four rodent species detected). Areas with greater host co-occurrence also harboured a greater abundance of hosts, including the host species most likely to carry high infection loads, indicating that Leptospira infection can be amplified by increases in overall and relative host abundance. Evidence of shared infection among rodent host species indicates that cross-species transmission of Leptospira probably increases infection at sites with greater host richness. Additionally, evidence that rodent co-occurrence and abundance and Leptospira infection load parallel abandonment suggests that counter-urbanization can elevate zoonotic disease risk within cities, particularly in underserved communities that are burdened with disproportionate concentrations of derelict properties.
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Affiliation(s)
- Anna C Peterson
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA
| | - Bruno M Ghersi
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA
| | - Claudia Riegel
- City of New Orleans Mosquito, Termite, Rodent Control Board, New Orleans, LA, USA
| | - Elsio A Wunder
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA.,Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil
| | - James E Childs
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Michael J Blum
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA
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Chen L, Liu X, Peng Z, Zhou S. Species distribution patterns and the scale of host interactions quantitatively but not qualitatively affect the diversity–disease relationship. Ecol Modell 2020. [DOI: 10.1016/j.ecolmodel.2020.109268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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28
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Halliday FW, Rohr JR, Laine A. Biodiversity loss underlies the dilution effect of biodiversity. Ecol Lett 2020; 23:1611-1622. [PMID: 32808427 PMCID: PMC7693066 DOI: 10.1111/ele.13590] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/14/2020] [Accepted: 07/16/2020] [Indexed: 01/16/2023]
Abstract
The dilution effect predicts increasing biodiversity to reduce the risk of infection, but the generality of this effect remains unresolved. Because biodiversity loss generates predictable changes in host community competence, we hypothesised that biodiversity loss might drive the dilution effect. We tested this hypothesis by reanalysing four previously published meta-analyses that came to contradictory conclusions regarding generality of the dilution effect. In the context of biodiversity loss, our analyses revealed a unifying pattern: dilution effects were inconsistently observed for natural biodiversity gradients, but were commonly observed for biodiversity gradients generated by disturbances causing losses of biodiversity. Incorporating biodiversity loss into tests of generality of the dilution effect further indicated that scale-dependency may strengthen the dilution effect only when biodiversity gradients are driven by biodiversity loss. Together, these results help to resolve one of the most contentious issues in disease ecology: the generality of the dilution effect.
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Affiliation(s)
- Fletcher W. Halliday
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurich8057Switzerland
| | - Jason R. Rohr
- Department of Biological SciencesEck Institute of Global HealthEnvironmental Change InitiativeUniversity of Notre DameNotre DameINUSA
| | - Anna‐Liisa Laine
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurich8057Switzerland
- Organismal & Evolutionary Biology Research ProgramUniversity of HelsinkiPO Box 65HelsinkiFI‐00014Finland
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29
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Hoi AG, Gilbert B, Mideo N. Deconstructing the Impact of Malaria Vector Diversity on Disease Risk. Am Nat 2020; 196:E61-E70. [PMID: 32813999 DOI: 10.1086/710005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractRecent years have seen significant progress in understanding the impact of host community assemblage on disease risk, yet diversity in disease vectors has rarely been investigated. Using published malaria and mosquito surveys from Kenya, we analyzed the relationship between malaria prevalence and multiple axes of mosquito diversity: abundance, species richness, and composition. We found a net amplification of malaria prevalence by vector species richness, a result of a strong direct positive association between richness and prevalence alongside a weak indirect negative association between the two, mediated through mosquito community composition. One plausible explanation of these patterns is species niche complementarity, whereby less competent vector species contribute to disease transmission by filling spatial or temporal gaps in transmission left by dominant vectors. A greater understanding of vector community assemblage and function, as well as any interactions between host and vector biodiversity, could offer insights to both fundamental and applied ecology.
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30
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Towards a mechanistic understanding of competence: a missing link in diversity-disease research. Parasitology 2020; 147:1159-1170. [PMID: 32517830 DOI: 10.1017/s0031182020000943] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Biodiversity loss may increase the risk of infectious disease in a phenomenon known as the dilution effect. Circumstances that increase the likelihood of disease dilution are: (i) when hosts vary in their competence, and (ii) when communities disassemble predictably, such that the least competent hosts are the most likely to go extinct. Despite the central role of competence in diversity-disease theory, we lack a clear understanding of the factors underlying competence, as well as the drivers and extent of its variation. Our perspective piece encourages a mechanistic understanding of competence and a deeper consideration of its role in diversity-disease relationships. We outline current evidence, emerging questions and future directions regarding the basis of competence, its definition and measurement, the roots of its variation and its role in the community ecology of infectious disease.
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31
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Claar DC, Wood CL. Pulse Heat Stress and Parasitism in a Warming World. Trends Ecol Evol 2020; 35:704-715. [PMID: 32439076 DOI: 10.1016/j.tree.2020.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 04/03/2020] [Accepted: 04/06/2020] [Indexed: 01/15/2023]
Abstract
Infectious disease outbreaks emerged across the globe during the recent 2015-2016 El Niño event, re-igniting research interest in how climate events influence disease dynamics. While the relationship between long-term warming and the transmission of disease-causing parasites has received substantial attention, we do not yet know how pulse heat events - common phenomena in a warming world - will alter parasite transmission. The effects of pulse warming on ecological and evolutionary processes are complex and context dependent, motivating research to understand how climate oscillations drive host health and disease. Here, we develop a framework for evaluating and predicting the effects of pulse warming on parasitic infection. Specifically, we synthesize how pulse heat stress affects hosts, parasites, and the ecological interactions between them.
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Affiliation(s)
- Danielle C Claar
- University of Washington School of Aquatic and Fishery Sciences, Seattle, WA 98105, USA; NOAA Climate and Global Change Postdoctoral Scholar, Boulder, CO 80301, USA.
| | - Chelsea L Wood
- University of Washington School of Aquatic and Fishery Sciences, Seattle, WA 98105, USA
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32
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Wilber MQ, Johnson PTJ, Briggs CJ. Disease hotspots or hot species? Infection dynamics in multi-host metacommunities controlled by species identity, not source location. Ecol Lett 2020; 23:1201-1211. [PMID: 32357383 DOI: 10.1111/ele.13518] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/29/2020] [Accepted: 03/25/2020] [Indexed: 01/12/2023]
Abstract
Pathogen persistence in host communities is influenced by processes operating at the individual host to landscape-level scale, but isolating the relative contributions of these processes is challenging. We developed theory to partition the influence of host species, habitat patches and landscape connectivity on pathogen persistence within metacommunities of hosts and pathogens. We used this framework to quantify the contributions of host species composition and habitat patch identity on the persistence of an amphibian pathogen across the landscape. By sampling over 11 000 hosts of six amphibian species, we found that a single host species could maintain the pathogen in 91% of observed metacommunities. Moreover, this dominant maintenance species contributed, on average, twice as much to landscape-level pathogen persistence compared to the most influential source patch in a metacommunity. Our analysis demonstrates substantial inequality in how species and patches contribute to pathogen persistence, with important implications for targeted disease management.
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Affiliation(s)
- Mark Q Wilber
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA, 93106, USA
| | - Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309, USA
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA, 93106, USA
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33
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A note on species richness and the variance of epidemic severity. J Math Biol 2020; 80:2055-2074. [PMID: 32314014 DOI: 10.1007/s00285-020-01489-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 03/13/2020] [Indexed: 10/24/2022]
Abstract
The commonly observed negative correlation between the number of species in an ecological community and disease risk, typically referred to as "the dilution effect", has received a substantial amount of attention over the past decade. Attempts to test this relationship experimentally have revealed that, in addition to the mean disease risk decreasing with species number, so too does the variance of disease risk. This is referred to as the "variance reduction effect", and has received relatively little attention in the disease-diversity literature. Here, we set out to clarify and quantify some of these relationships in an idealized model of a randomly assembled multi-species community undergoing an epidemic. We specifically investigate the variance of the community disease reproductive ratio, a multi-species extension of the basic reproductive ratio [Formula: see text], for a family of random-parameter community SIR models, and show how the variance of community [Formula: see text] varies depending on whether transmission is density or frequency-dependent. We finally outline areas of further research on how changes in variance affect transmission dynamics in other systems.
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34
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Abstract
While many viruses of wild mammals are capable of infecting humans, our understanding of zoonotic potential is incomplete. Viruses vary in their degree of generalism, characterized by the phylogenetic relationships of their hosts. Among the dimensions of this phylogenetic landscape, phylogenetic aggregation, which is largely overlooked in studies of parasite host range, emerges in this study as a key predictor of zoonotic status of viruses. Plausibly, viruses that exhibit aggregation, typified by discrete clusters of related host species, may (i) have been able to close the phylogenetic distance to humans, (ii) have subsequently acquired an epidemiologically relevant host and (iii) exhibit relatively high fitness in realized host communities, which are frequently phylogenetically aggregated. These mechanisms associated with phylogenetic aggregation may help explain why correlated fundamental traits, such as the ability of viruses to replicate in the cytoplasm, are associated with zoonoses.
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Affiliation(s)
- Andrew W Park
- Odum School of Ecology, Center for the Ecology of Infectious Diseases and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
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35
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Rohr JR, Civitello DJ, Halliday FW, Hudson PJ, Lafferty KD, Wood CL, Mordecai EA. Towards common ground in the biodiversity-disease debate. Nat Ecol Evol 2019; 4:24-33. [PMID: 31819238 PMCID: PMC7224049 DOI: 10.1038/s41559-019-1060-6] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 11/13/2019] [Indexed: 01/16/2023]
Abstract
The disease ecology community has struggled to come to consensus on whether biodiversity reduces or increases infectious disease risk, a question that directly affects policy decisions for biodiversity conservation and public health. Here, we summarize the primary points of contention regarding biodiversity–disease relationships and suggest that vector-borne, generalist wildlife and zoonotic pathogens are the types of parasites most likely to be affected by changes to biodiversity. One synthesis on this topic revealed a positive correlation between biodiversity and human disease burden across countries, but as biodiversity changed over time within these countries, this correlation became weaker and more variable. Another synthesis—a meta-analysis of generally smaller-scale experimental and field studies—revealed a negative correlation between biodiversity and infectious diseases (a dilution effect) in various host taxa. These results raise the question of whether biodiversity–disease relationships are more negative at smaller spatial scales. If so, biodiversity conservation at the appropriate scales might prevent wildlife and zoonotic diseases from increasing in prevalence or becoming problematic (general proactive approaches). Further, protecting natural areas from human incursion should reduce zoonotic disease spillover. By contrast, for some infectious diseases, managing particular species or habitats and targeted biomedical approaches (targeted reactive approaches) might outperform biodiversity conservation as a tool for disease control. Importantly, biodiversity conservation and management need to be considered alongside other disease management options. These suggested guiding principles should provide common ground that can enhance scientific and policy clarity for those interested in simultaneously improving wildlife and human health. There has been intense debate as to whether biodiversity increases or reduces the risk of infectious disease. This Review is the result of researchers from both sides of the debate attempting to reach a consensus.
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Affiliation(s)
- Jason R Rohr
- Department of Biological Sciences, Eck Institute of Global Health, Environmental Change Initiative, University of Notre Dame, Notre Dame, IN, USA.
| | | | - Fletcher W Halliday
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Peter J Hudson
- Center for Infectious Disease Dynamics, Biology Department, The Pennsylvania State University, University Park, PA, USA
| | - Kevin D Lafferty
- Western Ecological Research Center, US Geological Survey, c/o Marine Science Institute, University of California, Santa Barbara, CA, USA
| | - Chelsea L Wood
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA
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36
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Halliday FW, Rohr JR. Measuring the shape of the biodiversity-disease relationship across systems reveals new findings and key gaps. Nat Commun 2019; 10:5032. [PMID: 31695043 PMCID: PMC6834853 DOI: 10.1038/s41467-019-13049-w] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 10/17/2019] [Indexed: 11/24/2022] Open
Abstract
Diverse host communities commonly inhibit the spread of parasites at small scales. However, the generality of this effect remains controversial. Here, we present the analysis of 205 biodiversity-disease relationships on 67 parasite species to test whether biodiversity-disease relationships are generally nonlinear, moderated by spatial scale, and sensitive to underrepresentation in the literature. Our analysis of the published literature reveals that biodiversity-disease relationships are generally hump-shaped (i.e., nonlinear) and biodiversity generally inhibits disease at local scales, but this effect weakens as spatial scale increases. Spatial scale is, however, related to study design and parasite type, highlighting the need for additional multiscale research. Few studies are unrepresentative of communities at low diversity, but missing data at low diversity from field studies could result in underreporting of amplification effects. Experiments appear to underrepresent high-diversity communities, which could result in underreporting of dilution effects. Despite context dependence, biodiversity loss at local scales appears to increase disease, suggesting that at local scales, biodiversity loss could negatively impact human and wildlife populations.
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Affiliation(s)
- Fletcher W Halliday
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Jason R Rohr
- Department of Biological Sciences, Eck Institute of Global Health, Environmental Change Initiative, 180 Galvin Life Science Center, University of Notre Dame, 46556, Notre Dame, IN, USA
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37
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Kirk D, Shea D, Start D. Host traits and competitive ability jointly structure disease dynamics and community assembly. J Anim Ecol 2019; 88:1379-1391. [PMID: 31120552 DOI: 10.1111/1365-2656.13028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 04/03/2019] [Indexed: 01/13/2023]
Abstract
Parasitism and competition are both ubiquitous interactions in ecological communities. The ability of host species to interact directly via competition and indirectly through shared parasites suggests that host traits related to competition and parasitism are likely important in structuring communities and disease dynamics. Specifically, those host traits affecting competition and those mediating parasitism are often correlated either because of trade-offs (in resource acquisition or resource allocation) or condition dependence, yet the consequences of these trait relationships for community and epidemiological dynamics are poorly understood. We conducted a literature review of parasite-related host traits-competitive ability relationships. We found that transmission-competitive ability relationships were most often reported, and that superior competitors exhibited elevated transmission relative to their less-competitive counterparts in nearly 80% of the cases. We also found a significant number of virulence-competitive ability and parasite shedding-competitive ability relationships. We investigated these links by altering the relationship between host competitive ability and three parasite-related traits (transmission, virulence and parasite shedding rates) in a simple model, incorporating competitive asymmetries in a multi-host community. We show that these relationships can lead to a range of different communities. For example, depending on the strength and direction of these distinct trait relationships, we observed communities with anywhere from high parasite prevalence to complete parasite extinction, and either one, two or the maximum of three host species coexisting. Our results suggest that parasite-competitive ability relationships may be common in nature, that further integration of these relationships can produce novel and unexpected community and disease dynamics, and that generalizations may allow for the prediction of how parasitism and competition jointly structure disease and diversity in natural communities.
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Affiliation(s)
- Devin Kirk
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Dylan Shea
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Denon Start
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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38
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Tornabene BJ, Blaustein AR, Briggs CJ, Calhoun DM, Johnson PTJ, McDevitt-Galles T, Rohr JR, Hoverman JT. The influence of landscape and environmental factors on ranavirus epidemiology in a California amphibian assemblage. FRESHWATER BIOLOGY 2018; 63:639-651. [PMID: 30127540 PMCID: PMC6097636 DOI: 10.1111/fwb.13100] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/16/2018] [Indexed: 06/08/2023]
Abstract
A fundamental goal of disease ecology is to determine the landscape and environmental processes that drive disease dynamics at different biological levels to guide management and conservation. Although ranaviruses (family Iridoviridae) are emerging amphibian pathogens, few studies have conducted comprehensive field surveys to assess potential drivers of ranavirus disease dynamics.We examined the factors underlying patterns in site-level ranavirus presence and individual-level ranavirus infection in 76 ponds and 1,088 individuals representing 5 amphibian species within the East Bay region of California.Based on a competing-model approach followed by variance partitioning, landscape and biotic variables explained the most variation in site-level presence. However, biotic and individual-level variables explained the most variation in individual-level infection.Distance to nearest ranavirus-infected pond (the landscape factor) was more important than biotic factors at the site-level; however, biotic factors were most influential at the individual-level. At the site level, the probability of ranavirus presence correlated negatively with distance to nearest ranavirus-positive pond, suggesting that the movement of water or mobile taxa (e.g., adult amphibians, birds, reptiles) may facilitate the movement of ranavirus between ponds and across the landscape.Taxonomic richness associated positively with ranavirus presence at the site-level, but vertebrate richness associated negatively with infection prevalence in the host population. This might reflect the contrasting influences of diversity on pathogen colonization versus transmission among hosts.Amphibian host species differed in their likelihood of ranavirus infection: American bullfrogs (Rana catesbeiana) had the weakest association with infection while rough-skinned newts (Taricha granulosa) had the strongest. After accounting for host species effects, hosts with greater snout-vent length had a lower probability of infection.Our study demonstrates the array of landscape, environmental, and individual-level factors associated with ranavirus epidemiology. Moreover, our study helps illustrate that the importance of these factors varies with biological level.
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Affiliation(s)
- Brian J Tornabene
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907-2061
| | - Andrew R Blaustein
- Integrative Biology, 3029 Cordley Hall, Oregon State University, Corvallis, OR 97331-2914
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9610
| | - Dana M Calhoun
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO 80309-0334
| | - Pieter T J Johnson
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO 80309-0334
| | - Travis McDevitt-Galles
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO 80309-0334
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620
| | - Jason T Hoverman
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907-2061
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39
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Halliday FW, Heckman RW, Wilfahrt PA, Mitchell CE. A multivariate test of disease risk reveals conditions leading to disease amplification. Proc Biol Sci 2018; 284:rspb.2017.1340. [PMID: 29046374 DOI: 10.1098/rspb.2017.1340] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 09/14/2017] [Indexed: 02/06/2023] Open
Abstract
Theory predicts that increasing biodiversity will dilute the risk of infectious diseases under certain conditions and will amplify disease risk under others. Yet, few empirical studies demonstrate amplification. This contrast may occur because few studies have considered the multivariate nature of disease risk, which includes richness and abundance of parasites with different transmission modes. By combining a multivariate statistical model developed for biodiversity-ecosystem-multifunctionality with an extensive field manipulation of host (plant) richness, composition and resource supply to hosts, we reveal that (i) host richness alone could not explain most changes in disease risk, and (ii) shifting host composition allowed disease amplification, depending on parasite transmission mode. Specifically, as predicted from theory, the effect of host diversity on parasite abundance differed for microbes (more density-dependent transmission) and insects (more frequency-dependent transmission). Host diversity did not influence microbial parasite abundance, but nearly doubled insect parasite abundance, and this amplification effect was attributable to variation in host composition. Parasite richness was reduced by resource addition, but only in species-rich host communities. Overall, this study demonstrates that multiple drivers, related to both host community and parasite characteristics, can influence disease risk. Furthermore, it provides a framework for evaluating multivariate disease risk in other systems.
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Affiliation(s)
- Fletcher W Halliday
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert W Heckman
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Peter A Wilfahrt
- Curriculum for the Environment and Ecology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Charles E Mitchell
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA.,Curriculum for the Environment and Ecology, University of North Carolina, Chapel Hill, NC 27599, USA
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40
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Faust CL, Dobson AP, Gottdenker N, Bloomfield LSP, McCallum HI, Gillespie TR, Diuk-Wasser M, Plowright RK. Null expectations for disease dynamics in shrinking habitat: dilution or amplification? Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0173. [PMID: 28438921 DOI: 10.1098/rstb.2016.0173] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2016] [Indexed: 11/12/2022] Open
Abstract
As biodiversity declines with anthropogenic land-use change, it is increasingly important to understand how changing biodiversity affects infectious disease risk. The dilution effect hypothesis, which points to decreases in biodiversity as critical to an increase in infection risk, has received considerable attention due to the allure of a win-win scenario for conservation and human well-being. Yet some empirical data suggest that the dilution effect is not a generalizable phenomenon. We explore the response of pathogen transmission dynamics to changes in biodiversity that are driven by habitat loss using an allometrically scaled multi-host model. With this model, we show that declining habitat, and thus declining biodiversity, can lead to either increasing or decreasing infectious-disease risk, measured as endemic prevalence. Whether larger habitats, and thus greater biodiversity, lead to a decrease (dilution effect) or increase (amplification effect) in infection prevalence depends upon the pathogen transmission mode and how host competence scales with body size. Dilution effects were detected for most frequency-transmitted pathogens and amplification effects were detected for density-dependent pathogens. Amplification effects were also observed over a particular range of habitat loss in frequency-dependent pathogens when we assumed that host competence was greatest in large-bodied species. By contrast, only amplification effects were observed for density-dependent pathogens; host competency only affected the magnitude of the effect. These models can be used to guide future empirical studies of biodiversity-disease relationships across gradients of habitat loss. The type of transmission, the relationship between host competence and community assembly, the identity of hosts contributing to transmission, and how transmission scales with area are essential factors to consider when elucidating the mechanisms driving disease risk in shrinking habitat.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.
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Affiliation(s)
- Christina L Faust
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA .,Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Andrew P Dobson
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - Nicole Gottdenker
- Department of Veterinary Pathology, University of Georgia, Athens, GA 30602, USA
| | - Laura S P Bloomfield
- Emmett Interdisciplinary Program in Environment and Resources, Stanford University, Stanford, CA 94305, USA
| | - Hamish I McCallum
- Environmental Futures Research Institute and Griffith School of Environment, Griffith University, Brisbane, Queensland 4222, Australia
| | - Thomas R Gillespie
- Department of Environmental Sciences, Rollins School of Public Health; Program In Population, Biology, Ecology and Evolution; Emory University, Atlanta, GA 30322, USA.,Department of Environmental Health, Rollins School of Public Health; Program In Population, Biology, Ecology and Evolution; Emory University, Atlanta, GA 30322, USA
| | - Maria Diuk-Wasser
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY 10027, USA
| | - Raina K Plowright
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
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41
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Maslov S, Sneppen K. Severe population collapses and species extinctions in multihost epidemic dynamics. Phys Rev E 2017; 96:022412. [PMID: 28950542 DOI: 10.1103/physreve.96.022412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Indexed: 01/21/2023]
Abstract
Most infectious diseases, including more than half of known human pathogens, are not restricted to just one host, yet much of the mathematical modeling of infections has been limited to a single species. We investigate consequences of a single epidemic propagating in multiple species and compare and contrast it with the endemic steady state of the disease. We use the two-species susceptible-infected-recovered model to calculate the severity of postepidemic collapses in populations of two-host species as a function of their initial population sizes, the times individuals remain infectious, and the matrix of infection rates. We derive the criteria for a very large, extinction-level, population collapse in one or both of the species. The main conclusion of our study is that a single epidemic could drive a species with high mortality rate to local or even global extinction provided that it is coinfected with an abundant species. Such collapse-driven extinctions depend on factors different than those in the endemic steady state of the disease.
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Affiliation(s)
- Sergei Maslov
- Department of Bioengineering and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Kim Sneppen
- Center for Models of Life, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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Al-Shorbaji F, Roche B, Britton R, Andreou D, Gozlan R. Influence of predation on community resilience to disease. J Anim Ecol 2017; 86:1147-1158. [PMID: 28758196 DOI: 10.1111/1365-2656.12722] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 06/01/2017] [Indexed: 02/05/2023]
Abstract
Outbreaks of generalist pathogens are influenced by host community structure, including population density and species diversity. Within host communities predation can influence pathogen transmission rates, prevalence and impacts. However, the influence of predation on community resilience to outbreaks of generalist pathogens is not fully understood. The role of predation on host community resilience to disease was assessed using an epidemiological multi-host susceptible-exposed-infectious-recovered model. Sphaerothecum destruens, an emerging fungal-like generalist pathogen, was used as a model pathogen. Six cyprinid and salmonid fishes, including an asymptomatic carrier, were selected as model hosts that are known to be impacted by S. destruens, and they were used within a model host community. Pathogen release into the host community was via introduction of the asymptomatic carrier. Mortality from infection, pathogen incubation rate, and host recovery rate were set to a range of evidence-based values in each species and were varied in secondary consumers to predict top-down effects of infection on the resilience of a host community. Predation pressure within the fish community was varied to test its effects on infection prevalence and host survival in the community. Model predictions suggested that predation of the asymptomatic hosts by fishes in the host community was insufficient to eliminate S. destruens. Sphaerothecum destruens persisted in the community due to its rapid transmission from the asymptomatic host to susceptible host fishes. Following transmission, pathogen prevalence in the community was driven by transmission within and between susceptible host fishes, indicating low host community resilience. However, introducing low densities of a highly specific piscivorous fish into the community to pre-date asymptomatic hosts could limit pathogen prevalence in the host community, thus increasing resilience. The model predictions indicate that whilst resilience to this generalist pathogen in the host community was low, this could be increased using management interventions. The results suggest that this model has high utility for predicting community resilience to disease and thus can be applied to other generalist parasites to determine risks of disease emergence.
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Affiliation(s)
- Farah Al-Shorbaji
- Bournemouth University, Faculty of Science and Technology, Dorset, UK
| | - Benjamin Roche
- Unit for Mathematical and Computer Modelling of Complex Systems, Institute of Research for Development, Montpellier, France.,Institut de Recherche pour le Développement UMR MIVEGEC IRD-CNRS-Université de Montpellier, Centre IRD de Montpellier, Montpellier, France
| | - Robert Britton
- Bournemouth University, Faculty of Science and Technology, Dorset, UK
| | - Demetra Andreou
- Bournemouth University, Faculty of Science and Technology, Dorset, UK
| | - Rodolphe Gozlan
- Institut de Recherche pour le Développement UMR MIVEGEC IRD-CNRS-Université de Montpellier, Centre IRD de Montpellier, Montpellier, France.,Institut de Recherche pour le Développement UMR BOREA IRD-MNHN-Université Pierre et Marie Curie, Muséum National d'Histoire Naturelle, Paris Cedex 5, France
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43
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Searle CL, Cortez MH, Hunsberger KK, Grippi DC, Oleksy IA, Shaw CL, de la Serna SB, Lash CL, Dhir KL, Duffy MA. Population Density, Not Host Competence, Drives Patterns of Disease in an Invaded Community. Am Nat 2016; 188:554-566. [PMID: 27788345 DOI: 10.1086/688402] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Generalist parasites can strongly influence interactions between native and invasive species. Host competence can be used to predict how an invasive species will affect community disease dynamics; the addition of a highly competent, invasive host is predicted to increase disease. However, densities of invasive and native species can also influence the impacts of invasive species on community disease dynamics. We examined whether information on host competence alone could be used to accurately predict the effects of an invasive host on disease in native hosts. We first characterized the relative competence of an invasive species and a native host species to a native parasite. Next, we manipulated species composition in mesocosms and found that host competence results did not accurately predict community dynamics. While the invasive host was more competent than the native, the presence of the native (lower competence) host increased disease in the invasive (higher competence) host. To identify potential mechanisms driving these patterns, we analyzed a two-host, one-parasite model parameterized for our system. Our results demonstrate that patterns of disease were primarily driven by relative population densities, mediated by asymmetry in intra- and interspecific competition. Thus, information on host competence alone may not accurately predict how an invasive species will influence disease in native species.
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Al-Shorbaji F, Roche B, Gozlan R, Britton R, Andreou D. The consequences of reservoir host eradication on disease epidemiology in animal communities. Emerg Microbes Infect 2016; 5:e46. [PMID: 27165562 PMCID: PMC4893545 DOI: 10.1038/emi.2016.46] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 01/19/2016] [Accepted: 01/25/2016] [Indexed: 11/09/2022]
Abstract
Non-native species have often been linked with introduction of novel pathogens that spill over into native communities, and the amplification of the prevalence of native parasites. In the case of introduced generalist pathogens, their disease epidemiology in the extant communities remains poorly understood. Here, Sphaerothecum destruens, a generalist fungal-like fish pathogen with bi-modal transmission (direct and environmental) was used to characterise the biological drivers responsible for disease emergence in temperate fish communities. A range of biotic factors relating to both the pathogen and the surrounding host communities were used in a novel susceptible-exposed-infectious-recovered (SEIR) model to test how these factors affected disease epidemiology. These included: (i) pathogen prevalence in an introduced reservoir host (Pseudorasbora parva); (ii) the impact of reservoir host eradication and its timing and (iii) the density of potential hosts in surrounding communities and their connectedness. These were modelled across 23 combinations and indicated that the spill-over of pathogen propagules via environmental transmission resulted in rapid establishment in adjacent fish communities (<1 year). Although disease dynamics were initially driven by environmental transmission in these communities, once sufficient numbers of native hosts were infected, the disease dynamics were driven by intra-species transmission. Subsequent eradication of the introduced host, irrespective of its timing (after one, two or three years), had limited impact on the long-term disease dynamics among local fish communities. These outputs reinforced the importance of rapid detection and eradication of non-native species, in particular when such species are identified as healthy reservoirs of a generalist pathogen.
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Affiliation(s)
- Farah Al-Shorbaji
- Faculty of Science and Technology, Bournemouth University, Fern Barrow, Talbot Campus, Poole, Dorset, BH12 5BB, UK
| | - Benjamin Roche
- Unit for Mathematical and Computer Modelling of Complex Systems, Institute of Research for Development, 34394 Montpellier, France
- Pierre and Marie Curie University, 75005 Paris, France
| | - Rodolphe Gozlan
- Pierre and Marie Curie University, 75005 Paris, France
- Biology of Aquatic Organisms and Ecosystems Research Unit, Institute of Research for Development, 34394 Montpellier, France
- National Museum of Natural History, 75231 Paris, France
| | - Robert Britton
- Faculty of Science and Technology, Bournemouth University, Fern Barrow, Talbot Campus, Poole, Dorset, BH12 5BB, UK
| | - Demetra Andreou
- Faculty of Science and Technology, Bournemouth University, Fern Barrow, Talbot Campus, Poole, Dorset, BH12 5BB, UK
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45
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Abstract
The dilution effect, that high host species diversity can reduce disease risk, has attracted much attention in the context of global biodiversity decline and increasing disease emergence. Recent studies have criticized the generality of the dilution effect and argued that it only occurs under certain circumstances. Nevertheless, evidence for the existence of a dilution effect was reported in about 80% of the studies that addressed the diversity-disease relationship, and a recent meta-analysis found that the dilution effect is widespread. We here review supporting and critical studies, point out the causes underlying the current disputes. The dilution is expected to be strong when the competent host species tend to remain when species diversity declines, characterized as a negative relationship between species' reservoir competence and local extinction risk. We here conclude that most studies support a negative competence-extinction relationship. We then synthesize the current knowledge on how the diversity-disease relationship can be modified by particular species in community, by the scales of analyses, and by the disease risk measures. We also highlight the complex role of habitat fragmentation in the diversity-disease relationship from epidemiological, evolutionary and ecological perspectives, and construct a synthetic framework integrating these three perspectives. We suggest that future studies should test the diversity-disease relationship across different scales and consider the multiple effects of landscape fragmentation.
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García-Peña GE, Garchitorena A, Carolan K, Canard E, Prieur-Richard AH, Suzán G, Mills JN, Roche B, Guégan JF. Niche-based host extinction increases prevalence of an environmentally acquired pathogen. OIKOS 2016. [DOI: 10.1111/oik.02700] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Gabriel E. García-Peña
- UMR MIVEGEC, Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, UMR 5290 CNRS-IRD-Université de Montpellier, Centre de Recherche IRD; 911 Avenue Agropolis, BP 64501 FR-34394 Montpellier Cedex 5 France
- Centre de Synthèse et d'Analyse sur la Biodiversité -CESAB. Bâtiment Henri Poincaré, Domaine du Petit Arbois; FR-13857 Aix-en-Provence Cedex 3 France
| | - Andrés Garchitorena
- UMR MIVEGEC, Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, UMR 5290 CNRS-IRD-Université de Montpellier, Centre de Recherche IRD; 911 Avenue Agropolis, BP 64501 FR-34394 Montpellier Cedex 5 France
- Ecole des Hautes Etudes en Santé Publique; Rennes France
| | - Kevin Carolan
- UMR MIVEGEC, Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, UMR 5290 CNRS-IRD-Université de Montpellier, Centre de Recherche IRD; 911 Avenue Agropolis, BP 64501 FR-34394 Montpellier Cedex 5 France
- UMR Territoires, Environnement, Télédétection et Information Spatiale (TETIS) CIRAD; FR-34093 Montpellier France
| | - Elsa Canard
- UMR MIVEGEC, Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, UMR 5290 CNRS-IRD-Université de Montpellier, Centre de Recherche IRD; 911 Avenue Agropolis, BP 64501 FR-34394 Montpellier Cedex 5 France
| | | | - Gerardo Suzán
- Depto de Etología, Fauna Silvestre y Animales de Laboratorio, Facultad de Medicina Veterinaria Zootecnia; Univ. Nacional Autónoma de México, Ciudad Universitaria; México D.F. C.P. 04510 México
| | - James N. Mills
- Population Biology, Ecology and Evolution Program, Emory University; Atlanta GA USA
| | | | - Jean-François Guégan
- UMR MIVEGEC, Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, UMR 5290 CNRS-IRD-Université de Montpellier, Centre de Recherche IRD; 911 Avenue Agropolis, BP 64501 FR-34394 Montpellier Cedex 5 France
- Ecole des Hautes Etudes en Santé Publique; Rennes France
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Chen L, Zhou S. A Combination of Species Evenness and Functional Diversity Is the Best Predictor of Disease Risk in Multihost Communities. Am Nat 2015; 186:755-65. [PMID: 26655982 DOI: 10.1086/683774] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Although accumulated evidence has shown that biodiversity can play an important role in disease transmission and prevalence, it remains unclear how different measures of diversity based on taxonomy or function perform in predicting disease risk. In this article, we assess the relative ability of species richness, Shannon's evenness index, single functional traits, and several functional diversity metrics and their interactions to predict disease risk in both nonequilibrium and equilibrium communities simulated by a multihost epidemiological model. On the basis of generalized linear models and Akaike's information criterion, we found that Shannon's evenness index outperforms species richness as a single variable in explaining variation in disease risk, while the best combination consists of Shannon's evenness index and functional diversity. This study is, to our knowledge, the first to demonstrate the important role played by species evenness and functional diversity in accounting for variation in disease risk in multihost communities.
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Affiliation(s)
- Lifan Chen
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, 2005 Songhu Road, Shanghai 200438, People's Republic of China
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48
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Johnson PTJ, Ostfeld RS, Keesing F. Frontiers in research on biodiversity and disease. Ecol Lett 2015; 18:1119-33. [PMID: 26261049 PMCID: PMC4860816 DOI: 10.1111/ele.12479] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/09/2015] [Accepted: 06/23/2015] [Indexed: 12/17/2022]
Abstract
Global losses of biodiversity have galvanised efforts to understand how changes to communities affect ecological processes, including transmission of infectious pathogens. Here, we review recent research on diversity-disease relationships and identify future priorities. Growing evidence from experimental, observational and modelling studies indicates that biodiversity changes alter infection for a range of pathogens and through diverse mechanisms. Drawing upon lessons from the community ecology of free-living organisms, we illustrate how recent advances from biodiversity research generally can provide necessary theoretical foundations, inform experimental designs, and guide future research at the interface between infectious disease risk and changing ecological communities. Dilution effects are expected when ecological communities are nested and interactions between the pathogen and the most competent host group(s) persist or increase as biodiversity declines. To move beyond polarising debates about the generality of diversity effects and develop a predictive framework, we emphasise the need to identify how the effects of diversity vary with temporal and spatial scale, to explore how realistic patterns of community assembly affect transmission, and to use experimental studies to consider mechanisms beyond simple changes in host richness, including shifts in trophic structure, functional diversity and symbiont composition.
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Affiliation(s)
- Pieter T. J. Johnson
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA
| | | | - Felicia Keesing
- Biology Program, Bard College, Annandale-on-Hudson, NY 12504, USA
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49
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O'Regan SM, Vinson JE, Park AW. Interspecific Contact and Competition May Affect the Strength and Direction of Disease-Diversity Relationships for Directly Transmitted Microparasites. Am Nat 2015; 186:480-94. [PMID: 26655572 DOI: 10.1086/682721] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The frequency of opportunities for transmission is key to the severity of directly transmitted disease outbreaks in multihost communities. Transmission opportunities for generalist microparasites often arise from competitive and trophic interactions. Additionally, contact heterogeneities within and between species either hinder or promote transmission. General theory incorporating competition and contact heterogeneities for disease-diversity relationships is underdeveloped. Here, we present a formal framework to explore disease-diversity relationships for directly transmitted parasites that infect multiple host species, including influenza viruses, rabies virus, distemper viruses, and hantaviruses. We explicitly include host regulation via intra- and interspecific competition, where the latter can be dependent on or independent of interspecific contact rates (covering resource utilization overlap, habitat selection preferences, and temporal niche partitioning). We examine how these factors interact with frequency- and density-dependent transmission along with traits of the hosts in the assemblage, culminating in the derivation of a relationship describing the propensity for parasite fitness to decrease in species assemblages relative to that in single-host species. This relationship reveals that increases in biodiversity do not necessarily suppress frequency-dependent parasite transmission and that regulation of hosts via interspecific competition does not always lead to a reduction in parasite fitness. Our approach explicitly shows that species identity and ecological interactions between hosts together determine microparasite transmission outcomes in multispecies communities.
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Affiliation(s)
- Suzanne M O'Regan
- Odum School of Ecology, University of Georgia, Athens, Georgia 30602
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50
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Strauss AT, Civitello DJ, Cáceres CE, Hall SR. Success, failure and ambiguity of the dilution effect among competitors. Ecol Lett 2015; 18:916-26. [PMID: 26119173 DOI: 10.1111/ele.12468] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 02/24/2015] [Accepted: 05/28/2015] [Indexed: 11/29/2022]
Abstract
It remains challenging to predict variation in the magnitude of disease outbreaks. The dilution effect seeks to explain this variation by linking multiple host species to disease transmission. It predicts that disease risk increases for a focal host when host species diversity declines. However, when an increase in species diversity does not reduce disease, we are often unable to diagnose why. Here, we increase mechanistic and predictive clarity of the dilution effect with a general trait-based model of disease transmission in multi-host communities. Then, we parameterise and empirically test our model with a multi-generational case study of planktonic disease. The model-experiment combination shows that hosts that vary in competitive ability (R*) and potential to spread disease (R0 ) can produce three qualitatively disparate outcomes of dilution on disease: the dilution effect can succeed, fail, or be ambiguous/irrelevant.
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Affiliation(s)
| | - David J Civitello
- Department of Integrative Biology, University of South Florida, Tampa, FL, 33620, USA
| | - Carla E Cáceres
- School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Spencer R Hall
- Department of Biology, Indiana University, Bloomington, IN, 47401, USA
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