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Duarte ME, Lewandowski M, de Mendonça RS, Simoni S, Navia D. Genetic analysis of the tomato russet mite provides evidence of oligophagy and a widespread pestiferous haplotype. EXPERIMENTAL & APPLIED ACAROLOGY 2023; 89:171-199. [PMID: 36795266 DOI: 10.1007/s10493-023-00777-4] [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: 11/04/2022] [Accepted: 01/24/2023] [Indexed: 06/18/2023]
Abstract
Worldwide, the tomato russet mite (TRM), Aculops lycopersici (Eriophyidae), is a key pest on cultivated tomato in addition to infesting other cultivated and wild Solanaceae; however, basic information on TRM supporting effective control strategies is still lacking, mainly regarding its taxonomic status and genetic diversity and structure. As A. lycopersici is reported on different species and genera of host plants, populations associated with different host plants may constitute specialized cryptic species, as shown for other eriophyids previously considered generalists. The main aims of this study were to (i) confirm the TRM taxonomic unity of populations from different host plants and localities as well as the species' oligophagy, and (ii) to advance the understanding of TRM host relationship and invasion history. For this purpose, we evaluated the genetic variability and structure of populations from different host plants along crucial areas of occurrence, including the area of potential origin, based on DNA sequences of mitochondrial (cytochrome c oxidase subunit I) and nuclear (internal transcribed spacer, D2 28S) genomic regions. Specimens from South America (Brazil) and Europe (France, Italy, Poland, The Netherlands) were collected from tomato and other solanaceous species from the genera Solanum and Physalis. Final TRM datasets were composed of 101, 82 and 50 sequences from the COI (672 bp), ITS (553 bp) and D2 (605 bp) regions, respectively. Distributions and frequencies of haplotypes (COI) and genotypes (D2 and ITS1) were inferred; pairwise genetic distance comparisons, and phylogenetic analysis were performed, including Bayesian Inference (BI) combined analysis. Our results showed that genetic divergences for mitochondrial and nuclear genomic regions from TRM associated with different host plants were lower than those observed in other eriophyid taxa, confirming conspecificity of TRM populations and oligophagy of this eriophyid mite. Four haplotypes (cH) were identified from the COI sequences with cH1 being the most frequent, representing 90% of all sequences occurring in all host plants studied (Brazil, France, The Netherlands); the other haplotypes were present exclusively in Brazilian populations. Six variants (I) were identified from the ITS sequences: I-1 was the most frequent (76.5% of all sequences), spread in all countries and associated with all host plants, except S. nigrum. Just one D2 sequence variant was found in all studied countries. The genetic homogeneity among populations highlights the occurrence of a highly invasive and oligophagous haplotype. These results failed to corroborate the hypothesis that differential symptomatology or damage intensity among tomato varieties and solanaceous host plants could be due to the genetic diversity of the associated mite populations. The genetic evidence, along with the history of spread of cultivated tomato, corroborates the hypothesis of a South American origin of TRM.
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Affiliation(s)
- Mercia Elias Duarte
- Federal University of Piauí, Campus Amilcar Ferreira Sobral, Floriano, PI, CEP: 64808-605, Brazil
| | - Mariusz Lewandowski
- Section of Applied Entomology, Department of Plant Protection, Institute of Horticultural Sciences, Warsaw University of Life Sciences, ul. Nowoursynowska 159, 02-776, Warsaw, Poland
| | - Renata Santos de Mendonça
- Faculty of Agronomy and Veterinary Medicine, University of Brasília, ICC Sul Campus Darcy Ribeiro, Brasília, DF, CEP 70910-970, Brazil
| | - Sauro Simoni
- CREA - DC Council for Agricultural Research and Economics-Research Centre for Plant Protection and Certification, Via di Lanciola12/a, 50125, Florence, Italy
| | - Denise Navia
- CBGP, Institut Agro, CIRAD, INRAE, IRD, Univ Montpellier, Centre de Biologie pour la Gestion des Populations, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), 755 Avenue du Campus Agropolis, CS 30016, 34988, Montferrier sur Lez Cedex, France.
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Miller WL, Walter WD. Can genetic assignment tests provide insight on the influence of captive egression on the epizootiology of chronic wasting disease? Evol Appl 2020; 13:715-726. [PMID: 32211062 PMCID: PMC7086050 DOI: 10.1111/eva.12895] [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: 03/15/2019] [Revised: 10/23/2019] [Accepted: 10/24/2019] [Indexed: 01/23/2023] Open
Abstract
Identifying the sources of ongoing and novel disease outbreaks is critical for understanding the diffusion of epizootic diseases. Identifying infection sources is difficult when few physical differences separate individuals with different origins. Genetic assignment procedures show great promise for assessing transmission dynamics in such situations. Here, we use genetic assignment tests to determine the source of chronic wasting disease infections in free-ranging white-tailed deer (Odocoileus virginianus) populations. Natural dispersal is thought to facilitate the geographic diffusion of chronic wasting disease, but egression from captive cervid populations represents an alternative source of infection that is difficult to detect due to physical similarities with wild deer. Simulated reference populations were created based on allele frequencies from 1,912 empirical microsatellite genotypes collected in four sampling subregions and five captive facilities. These reference populations were used to assess the likelihood of ancestry and assignment of 1,861 free-ranging deer (1,834 noninfected and 27 infected) and 51 captive individuals to captive or wild populations. The ancestry (Q) and assignment scores (A) for free-ranging deer to wild populations were high (average Q wild = 0.913 and average A wild = 0.951, respectively), but varied among subregions (Q wild = 0.800-0.947, A wild = 0.857-0.976). These findings suggest that captive egression and admixture are rare, but risk may not be spatially uniform. Ancestry and assignment scores for two free-ranging deer with chronic wasting disease sampled in an area where chronic wasting disease was previously unobserved in free-ranging herds indicated a higher likelihood of assignment and proportion of ancestry attributable to captive populations. While we cannot directly assign these individuals to infected facilities, these findings suggest that rare egression events may influence the epizootiology of chronic wasting disease in free-ranging populations. Continued disease surveillance and genetic analyses may further elucidate the relative disease risk attributable to captive and wild sources.
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Affiliation(s)
- William L. Miller
- Pennsylvania Cooperative Fish and Wildlife Research UnitDepartment of Ecosystem Science and ManagementIntercollege Graduate Degree Program in EcologyThe Pennsylvania State UniversityUniversity ParkPAUSA
| | - W. David Walter
- U.S. Geological SurveyPennsylvania Cooperative Fish and Wildlife Research UnitThe Pennsylvania State UniversityUniversity ParkPAUSA
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Daversa DR, Fenton A, Dell AI, Garner TWJ, Manica A. Infections on the move: how transient phases of host movement influence disease spread. Proc Biol Sci 2018; 284:rspb.2017.1807. [PMID: 29263283 PMCID: PMC5745403 DOI: 10.1098/rspb.2017.1807] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 11/20/2017] [Indexed: 11/12/2022] Open
Abstract
Animal movement impacts the spread of human and wildlife diseases, and there is significant interest in understanding the role of migrations, biological invasions and other wildlife movements in spatial infection dynamics. However, the influence of processes acting on infections during transient phases of host movement is poorly understood. We propose a conceptual framework that explicitly considers infection dynamics during transient phases of host movement to better predict infection spread through spatial host networks. Accounting for host transient movement captures key processes that occur while hosts move between locations, which together determine the rate at which hosts spread infections through networks. We review theoretical and empirical studies of host movement and infection spread, highlighting the multiple factors that impact the infection status of hosts. We then outline characteristics of hosts, parasites and the environment that influence these dynamics. Recent technological advances provide disease ecologists unprecedented ability to track the fine-scale movement of organisms. These, in conjunction with experimental testing of the factors driving infection dynamics during host movement, can inform models of infection spread based on constituent biological processes.
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Affiliation(s)
- D R Daversa
- Institute of Integrative Biology, Biosciences Building, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK .,Institute of Zoology, Zoological Society of London, Regents Park, London NW1 4RY, UK.,Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - A Fenton
- Institute of Integrative Biology, Biosciences Building, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - A I Dell
- National Great Rivers Research and Education Centre (NGRREC), East Alton, IL 62024, USA.,Department of Biology, Washington University in St Louis, 1 Brookings Dr, St Louis, MO 63130, USA
| | - T W J Garner
- Institute of Zoology, Zoological Society of London, Regents Park, London NW1 4RY, UK
| | - A Manica
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
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Luo Y, Agnarsson I. Global mtDNA genetic structure and hypothesized invasion history of a major pest of citrus, Diaphorina citri (Hemiptera: Liviidae). Ecol Evol 2017; 8:257-265. [PMID: 29321868 PMCID: PMC5756889 DOI: 10.1002/ece3.3680] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 10/19/2017] [Accepted: 11/08/2017] [Indexed: 11/23/2022] Open
Abstract
The Asian citrus psyllid Diaphorina citri Kuwayama is a key pest of citrus as the vector of the bacterium causing the “huanglongbing” disease (HLB). To assess the global mtDNA population genetic structure, and possible dispersal history of the pest, we investigated genetic variation at the COI gene collating newly collected samples with all previously published data. Our dataset consists of 356 colonies from 106 geographic sites worldwide. High haplotype diversity (H‐mean = 0.702 ± 0.017), low nucleotide diversity (π‐mean = 0.003), and significant positive selection (Ka/Ks = 32.92) were observed. Forty‐four haplotypes (Hap) were identified, clustered into two matrilines: Both occur in southeastern and southern Asia, North and South America, and Africa; lineages A and B also occur in eastern and western Asia, respectively. The most abundant haplotypes were Hap4 in lineage A (35.67%), and Hap9 in lineage B (41.29%). The haplotype network identified them as the ancestral haplotypes within their respective lineages. Analysis of molecular variance showed significant genetic structure (FST = 0.62, p < .0001) between the lineages, and population genetic analysis suggests geographic structuring. We hypothesize a southern and/or southeastern Asia origin, three dispersal routes, and parallel expansions of two lineages. The hypothesized first route involved the expansion of lineage B from southern Asia into North America via West Asia. The second, the expansion of some lineage A individuals from Southeast Asia into East Asia, and the third involved both lineages from Southeast Asia spreading westward into Africa and subsequently into South America. To test these hypotheses and gain a deeper understanding of the global history of D. citri, more data‐rich approaches will be necessary from the ample toolkit of next‐generation sequencing (NGS). However, this study may serve to guide such sampling and in the development of biological control programs against the global pest D. citri.
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Affiliation(s)
- Yufa Luo
- School of Life and Environmental Sciences Gannan Normal University Ganzhou China
| | - Ingi Agnarsson
- Department of Biology University of Vermont Burlington VT USA.,Department of Entomology National Museum of Natural History Washington DC USA
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Head JR, Chang H, Li Q, Hoover CM, Wilke T, Clewing C, Carlton EJ, Liang S, Lu D, Zhong B, Remais JV. Genetic Evidence of Contemporary Dispersal of the Intermediate Snail Host of Schistosoma japonicum: Movement of an NTD Host Is Facilitated by Land Use and Landscape Connectivity. PLoS Negl Trop Dis 2016; 10:e0005151. [PMID: 27977674 PMCID: PMC5157946 DOI: 10.1371/journal.pntd.0005151] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 11/01/2016] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND While the dispersal of hosts and vectors-through active or passive movement-is known to facilitate the spread and re-emergence of certain infectious diseases, little is known about the movement ecology of Oncomelania spp., intermediate snail host of the parasite Schistosoma japonicum, and its consequences for the spread of schistosomiasis in East and Southeast Asia. In China, despite intense control programs aimed at preventing schistosomiasis transmission, there is evidence in recent years of re-emergence and persistence of infection in some areas, as well as an increase in the spatial extent of the snail host. A quantitative understanding of the dispersal characteristics of the intermediate host can provide new insights into the spatial dynamics of transmission, and can assist public health officials in limiting the geographic spread of infection. METHODOLOGY/PRINCIPAL FINDINGS Oncomelania hupensis robertsoni snails (n = 833) were sampled from 29 sites in Sichuan, China, genotyped, and analyzed using Bayesian assignment to estimate the rate of recent snail migration across sites. Landscape connectivity between each site pair was estimated using the geographic distance distributions derived from nine environmental models: Euclidean, topography, incline, wetness, land use, watershed, stream use, streams and channels, and stream velocity. Among sites, 14.4% to 32.8% of sampled snails were identified as recent migrants, with 20 sites comprising >20% migrants. Migration rates were generally low between sites, but at 8 sites, over 10% of the overall host population originated from one proximal site. Greater landscape connectivity was significantly associated with increased odds of migration, with the minimum path distance (as opposed to median or first quartile) emerging as the strongest predictor across all environmental models. Models accounting for land use explained the largest proportion of the variance in migration rates between sites. A greater number of irrigation channels leading into a site was associated with an increase in the site's propensity to both attract and retain snails. CONCLUSIONS/SIGNIFICANCE Our findings have important implications for controlling the geographic spread of schistosomiasis in China, through improved understanding of the dispersal capacity of the parasite's intermediate host.
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Affiliation(s)
- Jennifer R. Head
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America
| | - Howard Chang
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America
| | - Qunna Li
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America
| | - Christopher M. Hoover
- Environmental Health Sciences, School of Public Health, University of California, Berkeley, California, United States of America
| | - Thomas Wilke
- Department of Animal Ecology and Systematics, Justus Liebig University, Giessen, Germany
| | - Catharina Clewing
- Department of Animal Ecology and Systematics, Justus Liebig University, Giessen, Germany
| | - Elizabeth J. Carlton
- Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado, Anschutz, Aurora, Colorado, United States of America
| | - Song Liang
- Department of Environmental & Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, Florida, United States of America
| | - Ding Lu
- Institute of Parasitic Diseases, Sichuan Center for Disease Control and Prevention, Chengdu, China
| | - Bo Zhong
- Institute of Parasitic Diseases, Sichuan Center for Disease Control and Prevention, Chengdu, China
| | - Justin V. Remais
- Environmental Health Sciences, School of Public Health, University of California, Berkeley, California, United States of America
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Blanchong JA, Robinson SJ, Samuel MD, Foster JT. Application of genetics and genomics to wildlife epidemiology. J Wildl Manage 2016. [DOI: 10.1002/jwmg.1064] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Julie A. Blanchong
- Department of Natural Resource Ecology and Management; Iowa State University; 339 Science II Ames IA 50011 USA
| | | | - Michael D. Samuel
- U.S. Geological Survey, Wisconsin Cooperative Wildlife Research Unit; University of Wisconsin; 204 Russell Labs, 1630 Linden Dr. Madison WI 53706 USA
| | - Jeffrey T. Foster
- Department of Molecular, Cellular and Biomedical Sciences; University of New Hampshire; 291 Rudman Hall Durham NH 03824 USA
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Guidolin AS, Fresia P, Cônsoli FL. The genetic structure of an invasive pest, the Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae). PLoS One 2014; 9:e115749. [PMID: 25545788 PMCID: PMC4278764 DOI: 10.1371/journal.pone.0115749] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 12/01/2014] [Indexed: 11/19/2022] Open
Abstract
The Asian citrus psyllid Diaphorina citri is currently the major threat to the citrus industry as it is the vector of Candidatus Liberibacter, the causal agent of huanglongbing disease (HLB). D. citri is native to Asia and now colonizes the Americas. Although it has been known in some countries for a long time, invasion routes remain undetermined. There are no efficient control methods for the HLB despite the intensive management tools currently in use. We investigated the genetic variability and structure of populations of D. citri to aid in the decision making processes toward sustainable management of this species/disease. We employed different methods to quantify and compare the genetic diversity and structure of D. citri populations among 36 localities in Brazil, using an almost complete sequence of the cytochrome oxidase I (COI) gene. Our analyses led to the identification of two geographically and genetically structured groups. The indices of molecular diversity pointed to a recent population expansion, and we discuss the role of multiple invasion events in this scenario. We also argue that such genetic diversity and population structure may have implications for the best management strategies to be adopted for controlling this psyllid and/or the disease it vectors in Brazil.
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Affiliation(s)
- Aline S. Guidolin
- Lab de Interações em Insetos, Depto de Entomologia & Acarologia, ESALQ, Univ de São Paulo, Av. Pádua Dias 11, 13418-900, Piracicaba, São Paulo, Brasil
| | - Pablo Fresia
- Lab de Resistência de Artrópodes a Táticas de Controle, Depto de Entomologia & Acarologia, ESALQ, Univ de São Paulo, Av. Pádua Dias 11, 13418-900, Piracicaba, São Paulo, Brasil
| | - Fernando L. Cônsoli
- Lab de Interações em Insetos, Depto de Entomologia & Acarologia, ESALQ, Univ de São Paulo, Av. Pádua Dias 11, 13418-900, Piracicaba, São Paulo, Brasil
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Rebaudo F, Costa J, Almeida CE, Silvain JF, Harry M, Dangles O. Simulating population genetics of pathogen vectors in changing landscapes: guidelines and application with Triatoma brasiliensis. PLoS Negl Trop Dis 2014; 8:e3068. [PMID: 25102068 PMCID: PMC4125301 DOI: 10.1371/journal.pntd.0003068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 06/21/2014] [Indexed: 11/28/2022] Open
Abstract
Background Understanding the mechanisms that influence the population dynamics and spatial genetic structure of the vectors of pathogens infecting humans is a central issue in tropical epidemiology. In view of the rapid changes in the features of landscape pathogen vectors live in, this issue requires new methods that consider both natural and human systems and their interactions. In this context, individual-based model (IBM) simulations represent powerful yet poorly developed approaches to explore the response of pathogen vectors in heterogeneous social-ecological systems, especially when field experiments cannot be performed. Methodology/Principal Findings We first present guidelines for the use of a spatially explicit IBM, to simulate population genetics of pathogen vectors in changing landscapes. We then applied our model with Triatoma brasiliensis, originally restricted to sylvatic habitats and now found in peridomestic and domestic habitats, posing as the most important Trypanosoma cruzi vector in Northeastern Brazil. We focused on the effects of vector migration rate, maximum dispersal distance and attraction by domestic habitat on T. brasiliensis population dynamics and spatial genetic structure. Optimized for T. brasiliensis using field data pairwise fixation index (FST) from microsatellite loci, our simulations confirmed the importance of these three variables to understand vector genetic structure at the landscape level. We then ran prospective scenarios accounting for land-use change (deforestation and urbanization), which revealed that human-induced land-use change favored higher genetic diversity among sampling points. Conclusions/Significance Our work shows that mechanistic models may be useful tools to link observed patterns with processes involved in the population genetics of tropical pathogen vectors in heterogeneous social-ecological landscapes. Our hope is that our study may provide a testable and applicable modeling framework to a broad community of epidemiologists for formulating scenarios of landscape change consequences on vector dynamics, with potential implications for their surveillance and control. Worldwide, humans are modifying landscapes at an unprecedented rate. These modifications have an influence on the ecology of pathogen vectors, yet this issue has received relatively little input from modeling research. The current study presents guidelines for the use of a modeling framework for the representation of the dynamics and spatial genetic structure of pathogen vectors. It allows considering spatiotemporal landscape modifications explicitly, to represent human-altered modifications and consequences. We applied this modeling framework to Triatoma brasiliensis, vector of the pathogen Trypanosoma cruzi responsible for the Chagas disease, in the semi-arid Northeastern Brazil. Using field data of pairwise fixation index (FST) from microsatellite loci, we found that migration rate, maximum dispersal distance and attraction by domestic habitat were all key parameters to understand vector spatial genetic structure at the landscape level. At the interface across disciplines, this study provides to the community of epidemiologists a testable and applicable framework to foresee landscape modification consequences on vector dynamics and genetic structure, with potential implications for their surveillance and control.
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Affiliation(s)
- Francois Rebaudo
- BEI-UR072, IRD, Gif-sur-Yvette, France
- LEGS-UPR9034, CNRS-UPSud11, Gif-sur-Yvette, France
- * E-mail:
| | - Jane Costa
- Laboratório de Biodiversidade Entomológica, Instituto Oswaldo Cruz - Fiocruz, Rio de Janeiro, Rio de Janeiro, Brasil
| | - Carlos E. Almeida
- Departamento de Ciências Biológicas, Faculdade de Ciências Farmacêuticas, UNESP, Araraquara, Sao Paolo, Brasil
| | - Jean-Francois Silvain
- BEI-UR072, IRD, Gif-sur-Yvette, France
- LEGS-UPR9034, CNRS-UPSud11, Gif-sur-Yvette, France
| | - Myriam Harry
- LEGS-UPR9034, CNRS-UPSud11, Gif-sur-Yvette, France
| | - Olivier Dangles
- BEI-UR072, IRD, Gif-sur-Yvette, France
- LEGS-UPR9034, CNRS-UPSud11, Gif-sur-Yvette, France
- Instituto de Ecología, Campus Cotacota, Universidad Mayor San Andrés, La Paz, Bolivia
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Tack AJM, Hakala J, Petäjä T, Kulmala M, Laine AL. Genotype and spatial structure shape pathogen dispersal and disease dynamics at small spatial scales. Ecology 2014; 95:703-14. [DOI: 10.1890/13-0518.1] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Vander Wal E, Edye I, Paquet PC, Coltman DW, Bayne E, Brook RK, Andrés JA. Juxtaposition between host population structures: implications for disease transmission in a sympatric cervid community. Evol Appl 2013; 6:1001-11. [PMID: 24187583 PMCID: PMC3804234 DOI: 10.1111/eva.12065] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 01/29/2013] [Indexed: 12/03/2022] Open
Abstract
Sympatric populations of phylogenetically related species are often vulnerable to similar communicable diseases. Although some host populations may exhibit spatial structure, other hosts within the community may have unstructured populations. Thus, individuals from unstructured host populations may act as interspecific vectors among discrete subpopulations of sympatric alternate hosts. We used a cervid-bovine tuberculosis (Mycobacterium bovis) system to investigate the landscape-scale potential for bovine tuberculosis transmission within a nonmigratory white-tailed deer (Odocoileus virginianus) and elk (Cervus canadensis) community. Using landscape population genetics, we tested for genetic and spatial structure in white-tailed deer. We then compared these findings with the sympatric elk population that is structured and which has structure that correlates spatially and genetically to physiognomic landscape features. Despite genetic structure that indicates the white-tailed deer population forms three sympatric clusters, the absence of spatial structure suggested that intraspecific pathogen transmission is not likely to be limited by physiognomic landscape features. The potential for intraspecific transmission among subpopulations of elk is low due to spatial population structure. Given that white-tailed deer are abundant, widely distributed, and exhibit a distinct lack of spatial population structure, white-tailed deer likely pose a greater threat as bovine tuberculosis vectors among elk subpopulations than elk.
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Affiliation(s)
- Eric Vander Wal
- Department of Biology, University of Saskatchewan Saskatoon, SK, Canada
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Xiao N, Remais JV, Brindley PJ, Qiu DC, Carlton EJ, Li RZ, Lei Y, Blair D. Approaches to genotyping individual miracidia of Schistosoma japonicum. Parasitol Res 2013; 112:3991-9. [PMID: 24013341 DOI: 10.1007/s00436-013-3587-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 08/22/2013] [Indexed: 10/26/2022]
Abstract
Molecular genetic tools are needed to address questions as to the source and dynamics of transmission of the human blood fluke Schistosoma japonicum in regions where human infections have reemerged, and to characterize infrapopulations in individual hosts. The life stage that interests us as a target for collecting genotypic data is the miracidium, a very small larval stage that consequently yields very little DNA for analysis. Here, we report the successful development of a multiplex format permitting genotyping of 17 microsatellite loci in four sequential multiplex reactions using a single miracidium held on a Whatman Classic FTA indicating card. This approach was successful after short storage periods, but after long storage (>4 years), considerable difficulty was encountered in multiplex genotyping, necessitating the use of whole genome amplification (WGA) methods. WGA applied to cards stored for long periods of time resulted in sufficient DNA for accurate and repeatable genotyping. Trials and tests of these methods, as well as application to some field-collected samples, are reported, along with the discussion of the potential insights to be gained from such techniques. These include recognition of sibships among miracidia from a single host, and inference of the minimum number of worm pairs that might be present in a host.
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Affiliation(s)
- Ning Xiao
- Institute of Parasitic Diseases, Sichuan Center for Disease Control and Prevention, Chengdu, Sichuan, 610041, People's Republic of China,
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