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Myrenås E, Näslund J, Persson J, Sundin J. Effects of the invasive swim bladder parasite Anguillicola crassus on health and condition indicators in the European eel. JOURNAL OF FISH DISEASES 2023; 46:1029-1047. [PMID: 37329520 DOI: 10.1111/jfd.13822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 05/30/2023] [Accepted: 05/31/2023] [Indexed: 06/19/2023]
Abstract
Parasites negatively affect biological processes within their hosts, which may alter for example health, growth, and reproductive ability. Non-native invasive parasites, in particular, may have large effects on the endemic hosts, given that the hosts lack evolved specific defences against such parasites. The swim bladder nematode Anguillicola crassus, an invasive parasite originating from Asia, is found in the European eel (Anguilla anguilla, L. 1758), since the 1980s. We investigated whether A. crassus affected several indicators related to health of the European eel (spleen- and liver size, body fat content and relative condition). Our results indicate that during the continental residency of the eels, infection by A. crassus had no major negative impacts on the investigated health indicators at the generally low infection intensities present in this study (median 2-3 visible parasites). Given that many of the adult eels were found to have swim bladder damage, concerns about their spawning migration through deeper oceanic environments can still be raised. To allow further investigations, we suggest that quantification of swim bladder damage should be implemented in eel-monitoring programs. Compared to other parasite pressure parameters, swim bladder damage provides additional information about past infections and future problems.
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Affiliation(s)
- Elin Myrenås
- Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Drottningholm, Sweden
| | - Joacim Näslund
- Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Drottningholm, Sweden
| | - John Persson
- Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Drottningholm, Sweden
| | - Josefin Sundin
- Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, Drottningholm, Sweden
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2
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Ruiz de Ybáñez MR, Del Río L, Flores-Flores C, Muñoz P, Berriatua E, Rubio S, Martínez-Carrasco C. Monitoring for Anguillicoloides crassus, Anguillid herpesvirus 1, aquabirnavirus EVE and rhabdovirus EVEX in the European eel population of southern Spain. JOURNAL OF FISH DISEASES 2023; 46:417-431. [PMID: 36651585 DOI: 10.1111/jfd.13754] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 12/23/2022] [Accepted: 01/09/2023] [Indexed: 06/17/2023]
Abstract
European eel is critically endangered in Europe. Among other stressors, pathogens are well-known to harm eels' fitness. One hundred and eighty-two eels were captured in three Eel Management Units in Andalucía (SE Spain) and analysed for Anguillicoloides crassus, Anguillid herpesvirus 1 (AngHV1), the rhabdovirus Eel Virus European X (EVEX) and the aquabirnavirus Eel Virus European (EVE). A. crassus adults and preadults were isolated and morphometrically identified, and the eel swimbladders were artificially digested to count A. crassus larvae. Also, eel tissues were examined by PCRs for the presence of viruses. EVEX and EVE were not detected in any of the eels. The estimated prevalence (95% confidence limits) was 71 (64-78)% for A. crassus and 35 (28-42)% for AngHV-1, varying these prevalences significantly between and within EMUs. Moreover, A. crassus prevalence was highest in smaller eels, in sites closest to the sea and eels sampled in the autumn. By contrast, AngHV-1 prevalence was highest in biggest eels, in sites far from the sea and sampled in the summer or winter. However, in mixed effects logistic models including site as a random variable, the risk of infection was associated with distance to the sea in both A. crassus and AngHV-1 infections and also to winter sampling in the case of AngHV-1 and not to other variables. These results are evidence that both pathogens are highly endemic in eels from Andalusian habitats. Further studies are needed to better understand the risk factors associated with these pathogens on eel populations.
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Affiliation(s)
- M Rocío Ruiz de Ybáñez
- Departamento de Sanidad Animal, Facultad de Veterinaria, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Universidad de Murcia, Murcia, Spain
| | - Laura Del Río
- Departamento de Sanidad Animal, Facultad de Veterinaria, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Universidad de Murcia, Murcia, Spain
| | - César Flores-Flores
- Sección de Biología Molecular, Área Científica y Técnica de Investigación, Universidad de Murcia, Murcia, Spain
| | - Pilar Muñoz
- Departamento de Sanidad Animal, Facultad de Veterinaria, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Universidad de Murcia, Murcia, Spain
| | - Eduardo Berriatua
- Departamento de Sanidad Animal, Facultad de Veterinaria, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Universidad de Murcia, Murcia, Spain
| | - Silvia Rubio
- Planificación Cinegética y Piscícola, Agencia de Medio Ambiente y Agua, Junta de Andalucía, Granada, Spain
| | - Carlos Martínez-Carrasco
- Departamento de Sanidad Animal, Facultad de Veterinaria, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Universidad de Murcia, Murcia, Spain
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3
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Parchemin C, Tapissier-Bontemps N, Sasal P, Faliex E. Anguilla sp. diseases diagnoses and treatments: The ideal methods at the crossroads of conservation and aquaculture purposes. JOURNAL OF FISH DISEASES 2022; 45:943-969. [PMID: 35526273 DOI: 10.1111/jfd.13634] [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: 02/24/2022] [Revised: 04/20/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
Anguilla anguilla, A. japonica and A. rostrata are the most fished and consumed eel species. However, these species are Critically Endangered, Endangered and Endangered, respectively. A combination of factors is thought to be responsible for their decline including fisheries, climate change, habitat destruction, barriers to migration, pollution and pathogens. Among them, viruses, bacteria and parasites are causing weakening of wild eels and serious economic losses for fishermen and eel farmers. Early detection of pathogens is essential to provide appropriate responses both for conservation reasons and to limit economic losses. Classic diagnosis approaches are time consuming and invasive and usual treatments, for example, antipathogenic substances are becoming obsolete because of pathogen resistance and environmental impact problems. The need for early and non-invasive diagnostic methods as well as effective and environmentally friendly treatments has increased. Vaccine development and diet supplementation have known a growing interest since their use could allow prevention of diseases. In this review, we summarize the main pathogens-viruses, bacteria and parasites-of the three northern temperate eel species, the methods used to detect these pathogens and the different treatments used. We discussed and highlighted the need for non-invasive, rapid and efficient detection methods, as well as effective and environmentally friendly treatments for both conservation and aquaculture purposes.
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Affiliation(s)
- Christelle Parchemin
- Centre de Recherches Insulaires et Observatoire de l'Environnement (CRIOBE), Université de Perpignan, Perpignan Cedex, France
- Centre de Formation et de Recherche sur les Environnements Méditerranéens (CEFREM), Université de Perpignan, Perpignan Cedex, France
| | - Nathalie Tapissier-Bontemps
- Centre de Recherches Insulaires et Observatoire de l'Environnement (CRIOBE), Université de Perpignan, Perpignan Cedex, France
| | - Pierre Sasal
- Centre de Recherches Insulaires et Observatoire de l'Environnement (CRIOBE), Université de Perpignan, Perpignan Cedex, France
| | - Elisabeth Faliex
- Centre de Formation et de Recherche sur les Environnements Méditerranéens (CEFREM), Université de Perpignan, Perpignan Cedex, France
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4
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Context-dependent parasite infection affects trophic niche in populations of sympatric stickleback species. Parasitology 2022; 149:1164-1172. [PMID: 35570701 PMCID: PMC10090597 DOI: 10.1017/s0031182022000531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
How parasites alter host feeding ecology remains elusive in natural populations. A powerful approach to investigate the link between infection and feeding ecology is quantifying unique and shared responses to parasite infection in related host species within a common environment. Here, 9 pairs of sympatric populations of the three-spined and nine-spined stickleback fishes were sampled across a range of freshwater and brackish habitats to investigate how parasites alter host feeding ecology: (i) biotic and abiotic determinants of parasite community composition, and (ii) to what extent parasite infection correlates with trophic niche specialization of the 2 species, using stable isotope analyses (δ15N and δ13C). It was determined that parasite community composition and host parasite load varied among sites and species and were correlated with dissolved oxygen. It was also observed that the digenean Cyathocotyle sp.'s abundance, a common directly infecting parasite with a complex life cycle, correlated with host δ13C in a fish species-specific manner. In 6 sites, correlations were found between parasite abundance and their hosts' feeding ecology. These effects were location-specific and occasionally host species or host size-specific. Overall, the results suggest a relationship between parasite infection and host trophic niche which may be an important and largely overlooked ecological factor. The population specificity and variation in parasite communities also suggest this effect is multifarious and context-dependent.
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Bracamonte SE, Knopf K, Monaghan MT. Encapsulation of Anguillicola crassus reduces the abundance of adult parasite stages in the European eel (Anguilla anguilla). JOURNAL OF FISH DISEASES 2021; 44:771-782. [PMID: 33270932 DOI: 10.1111/jfd.13301] [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: 08/04/2020] [Revised: 10/23/2020] [Accepted: 10/25/2020] [Indexed: 06/12/2023]
Abstract
Encapsulation of the parasitic nematode Anguillicola crassus Kuwahara, Niimi & Hagaki is commonly observed in its native host, the Japanese eel (Anguilla japonica Temminck & Schlegel). Encapsulation has also been described in a novel host, the European eel (A. anguilla L.), and there is evidence that encapsulation frequency has increased since the introduction of A. crassus. We examined whether encapsulation of A. crassus provides an advantage to its novel host in Lake Müggelsee, NE Germany. We provide the first evidence that encapsulation was associated with reduced abundance of adult A. crassus. This pattern was consistent in samples taken 3 months apart. There was no influence of infection on the expression of the two metabolic genes studied, but the number of capsules was negatively correlated with the expression of two mhc II genes of the adaptive immune response, suggesting a reduced activation. Interestingly, eels that encapsulated A. crassus had higher abundances of two native parasites compared with non-encapsulating eels. We propose that the response of A. anguilla to infection by A. crassus may interfere with its reaction to other co-occurring parasites.
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Affiliation(s)
- Seraina E Bracamonte
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
- Berlin Center for Genomics in Biodiversity Research, Berlin, Germany
- Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany
- Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain
| | - Klaus Knopf
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
- Faculty of Life Sciences, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Michael T Monaghan
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
- Berlin Center for Genomics in Biodiversity Research, Berlin, Germany
- Institut für Biologie, Freie Universität Berlin, Berlin, Germany
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6
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Jousseaume T, Roussel JM, Beaulaton L, Bardonnet A, Faliex E, Amilhat E, Acou A, Feunteun E, Launey S. Molecular detection of the swim bladder parasite Anguillicola crassus (Nematoda) in fecal samples of the endangered European eel Anguilla anguilla. Parasitol Res 2021; 120:1897-1902. [PMID: 33674925 DOI: 10.1007/s00436-021-07100-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 02/22/2021] [Indexed: 11/29/2022]
Abstract
The European eel Anguilla anguilla is listed as critically endangered by the IUCN. Among many threats, the introduced parasitic nematode Anguillicola crassus is suspected to alter the eels' swim bladder and jeopardize their reproductive oceanic migration. To date, gaining knowledge about the distribution and prevalence of A. crassus requires individual sacrifice (over 50,000 eels were sacrificed for epidemiology studies since 2010). This paper describes a non-lethal molecular protocol for identifying prevalence of A. crassus in A. anguilla, based on searching for A. crassus DNA in the feces of eels. Tests using three DNA microsatellite markers specific to the nematode showed that molecular detection provided similar results to visual examination of the swim bladder in up to 80% of the cases, and allowed for comparison of prevalence among sites. Easy to implement, this non-lethal protocol for detecting A. crassus could be valuable for management plans of this endangered species.
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Affiliation(s)
- Thibaut Jousseaume
- ESE, Ecology and Ecosystems Health, Agrocampus Ouest, INRAE, Rennes, France.,Management of Diadromous Fish in their Environment, OFB, INRAE, Agrocampus Ouest, Univ Pau Pays Adour, 65 rue de Saint-Brieuc, 35042, Rennes, France
| | - Jean-Marc Roussel
- ESE, Ecology and Ecosystems Health, Agrocampus Ouest, INRAE, Rennes, France.,Management of Diadromous Fish in their Environment, OFB, INRAE, Agrocampus Ouest, Univ Pau Pays Adour, 65 rue de Saint-Brieuc, 35042, Rennes, France
| | - Laurent Beaulaton
- Management of Diadromous Fish in their Environment, OFB, INRAE, Agrocampus Ouest, Univ Pau Pays Adour, 65 rue de Saint-Brieuc, 35042, Rennes, France.,OFB, Direction de la Recherche et de l'Appui Scientifique, Rennes, France
| | - Agnès Bardonnet
- Management of Diadromous Fish in their Environment, OFB, INRAE, Agrocampus Ouest, Univ Pau Pays Adour, 65 rue de Saint-Brieuc, 35042, Rennes, France.,INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, Collège STE, Ecobiop, St-Pée-sur-Nivelle, France
| | - Elisabeth Faliex
- Centre de Formation et de Recherche sur les Environnements Méditerranéens (Cefrem), UMR 5110 CNRS-Université de Perpignan, Perpignan, France
| | - Elsa Amilhat
- Centre de Formation et de Recherche sur les Environnements Méditerranéens (Cefrem), UMR 5110 CNRS-Université de Perpignan, Perpignan, France
| | - Anthony Acou
- Management of Diadromous Fish in their Environment, OFB, INRAE, Agrocampus Ouest, Univ Pau Pays Adour, 65 rue de Saint-Brieuc, 35042, Rennes, France.,MNHN-Station de Biologie Marine de Dinard, CRESCO, Dinard, France
| | - Eric Feunteun
- MNHN-Station de Biologie Marine de Dinard, CRESCO, Dinard, France.,Biologie des Organismes et Ecosystèmes Aquatiques, MNHN, CNRS, Sorbonne Université, IRD, Université Caen Normandie, Université des Antilles, Station Marine, Dinard, France
| | - Sophie Launey
- ESE, Ecology and Ecosystems Health, Agrocampus Ouest, INRAE, Rennes, France. .,Management of Diadromous Fish in their Environment, OFB, INRAE, Agrocampus Ouest, Univ Pau Pays Adour, 65 rue de Saint-Brieuc, 35042, Rennes, France.
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7
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Currie HAL, Flores Martin N, Espindola Garcia G, Davis FM, Kemp PS. A mechanical approach to understanding the impact of the nematode Anguillicoloides crassus on the European eel swimbladder. J Exp Biol 2020; 223:jeb219808. [PMID: 32748794 DOI: 10.1242/jeb.219808] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 06/30/2020] [Indexed: 11/20/2022]
Abstract
One of the most detrimental factors in the drastic decline of the critically endangered European eel (Anguilla anguilla) was the inadvertent introduction of the invasive nematode Anguillicoloides crassus Infection primarily affects the swimbladder, a gas-filled organ that enables the eel to control its depth in the water. A reduction in swimbladder function may be fatal for eel undergoing their spawning migration to the Sargasso Sea, a journey of over 5000 km. Although the physiological damage caused by this invasive parasite is well studied through the use of quantifiable gross pathological indices, providing a good measure of the swimbladder health status, they cannot separate the role of mechanical and morphological damage. Our study examined the appropriateness of three commonly used indices as a measure of mechanical damage by performing uniaxial tensile tests on swimbladder specimens obtained from an infected eel population. When the test results were compared with the gross pathological indices it was found that thickness correlated most strongly with mechanical damage, both confirming and, more importantly, explaining the counterintuitive findings of earlier work. In a damaged swimbladder, the immune response leads to a trade-off; increasing wall thickness raises the pressure required for organ rupture but decreases strength. The results indicate that for moderate infection the mechanical integrity of the swimbladder can be maintained. For severe infection, however, a reduction in mechanical integrity may reach a tipping point, thereby affecting the successful completion of their oceanic migration.
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Affiliation(s)
- Helen A L Currie
- International Centre for Ecohydraulics Research, Faculty of Engineering and Physical Sciences, Boldrewood Innovation Campus, University of Southampton, Southampton SO16 7QF, UK
| | - Nicholas Flores Martin
- International Centre for Ecohydraulics Research, Faculty of Engineering and Physical Sciences, Boldrewood Innovation Campus, University of Southampton, Southampton SO16 7QF, UK
| | - Gerardo Espindola Garcia
- International Centre for Ecohydraulics Research, Faculty of Engineering and Physical Sciences, Boldrewood Innovation Campus, University of Southampton, Southampton SO16 7QF, UK
| | - Frances M Davis
- International Centre for Ecohydraulics Research, Faculty of Engineering and Physical Sciences, Boldrewood Innovation Campus, University of Southampton, Southampton SO16 7QF, UK
| | - Paul S Kemp
- International Centre for Ecohydraulics Research, Faculty of Engineering and Physical Sciences, Boldrewood Innovation Campus, University of Southampton, Southampton SO16 7QF, UK
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Gomez SR, Morgans S, Kristan DM. Rapamycin exposure to host and to adult worms affects life history traits of Heligmosomoides bakeri. Exp Parasitol 2019; 204:107720. [PMID: 31279929 DOI: 10.1016/j.exppara.2019.107720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 03/26/2019] [Accepted: 07/03/2019] [Indexed: 01/24/2023]
Abstract
Parasite life history can be affected by conditions of the host and of the external environment. Rapamycin, a known immunosuppressant of mammals, was fed to laboratory mice that were then infected with the Trichostrongylid nematode Heligmosomoides bakeri to determine if host rapamycin exposure would affect parasite survival, growth, and reproduction. In addition, adult worms from control fed mice were directly exposed to rapamycin to assess if rapamycin would affect worm viability and ex vivo reproduction. We found that host ingestion of rapamycin did not affect H. bakeri survival or growth for male or female worms, but female worms had increased reproduction both in vivo and when removed from the host and cultured ex vivo. After direct rapamycin exposure, motility of female worms was greater at low levels of rapamycin compared to high levels of rapamycin or high levels of DMSO (the vehicle used to solubilize rapamycin) in control media, but was similar to females in low levels of DMSO in control media. Male motility was not affected by the presence of rapamycin or DMSO in the media. Ex vivo egg deposition was higher when exposed to rapamycin than when cultured in control media that contained DMSO, regardless of DMSO dose. Overall, we conclude that host ingestion of rapamycin or direct exposure to rapamycin was generally favorable or neutral for parasite life history traits.
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Affiliation(s)
- Sarah R Gomez
- Department of Biological Sciences, 333 S. Twin Oaks Valley Rd, California State University San Marcos, San Marcos, CA, 92096, USA
| | - Scott Morgans
- Department of Biological Sciences, 333 S. Twin Oaks Valley Rd, California State University San Marcos, San Marcos, CA, 92096, USA
| | - Deborah M Kristan
- Department of Biological Sciences, 333 S. Twin Oaks Valley Rd, California State University San Marcos, San Marcos, CA, 92096, USA.
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9
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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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10
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Jacobs A, Hughes MR, Robinson PC, Adams CE, Elmer KR. The Genetic Architecture Underlying the Evolution of a Rare Piscivorous Life History Form in Brown Trout after Secondary Contact and Strong Introgression. Genes (Basel) 2018; 9:genes9060280. [PMID: 29857499 PMCID: PMC6026935 DOI: 10.3390/genes9060280] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/16/2018] [Accepted: 05/17/2018] [Indexed: 01/17/2023] Open
Abstract
Identifying the genetic basis underlying phenotypic divergence and reproductive isolation is a longstanding problem in evolutionary biology. Genetic signals of adaptation and reproductive isolation are often confounded by a wide range of factors, such as variation in demographic history or genomic features. Brown trout (Salmo trutta) in the Loch Maree catchment, Scotland, exhibit reproductively isolated divergent life history morphs, including a rare piscivorous (ferox) life history form displaying larger body size, greater longevity and delayed maturation compared to sympatric benthivorous brown trout. Using a dataset of 16,066 SNPs, we analyzed the evolutionary history and genetic architecture underlying this divergence. We found that ferox trout and benthivorous brown trout most likely evolved after recent secondary contact of two distinct glacial lineages, and identified 33 genomic outlier windows across the genome, of which several have most likely formed through selection. We further identified twelve candidate genes and biological pathways related to growth, development and immune response potentially underpinning the observed phenotypic differences. The identification of clear genomic signals divergent between life history phenotypes and potentially linked to reproductive isolation, through size assortative mating, as well as the identification of the underlying demographic history, highlights the power of genomic studies of young species pairs for understanding the factors shaping genetic differentiation.
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Affiliation(s)
- Arne Jacobs
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
| | - Martin R Hughes
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
- Scottish Centre for Ecology and the Natural Environment, University of Glasgow, Rowardennan, Loch Lomond, Glasgow G63 0AW, Scotland, UK.
| | - Paige C Robinson
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
| | - Colin E Adams
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
- Scottish Centre for Ecology and the Natural Environment, University of Glasgow, Rowardennan, Loch Lomond, Glasgow G63 0AW, Scotland, UK.
| | - Kathryn R Elmer
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
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