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Scholz C, Jarquín-Díaz VH, Planillo A, Radchuk V, Scherer C, Schulze C, Ortmann S, Kramer-Schadt S, Heitlinger E. Host weight, seasonality and anthropogenic factors contribute to parasite community differences between urban and rural foxes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 936:173355. [PMID: 38796016 DOI: 10.1016/j.scitotenv.2024.173355] [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: 02/13/2024] [Revised: 05/15/2024] [Accepted: 05/17/2024] [Indexed: 05/28/2024]
Abstract
Pathogens often occur at different prevalence along environmental gradients. This is of particular importance for gradients of anthropogenic impact such as rural-urban transitions presenting a changing interface between humans and wildlife. The assembly of parasite communities is affected by both the external environmental conditions and individual host characteristics. Hosts with low body weight (smaller individuals or animals with poor body condition) might be more susceptible to infection. Furthermore, parasites' mode of transmission might affect their occurrence: rural environments with better availability of intermediate hosts might favour trophic transmission, while urban environments, typically with dense definitive host populations, might favour direct transmission. We here study helminth communities (141 intestinal samples) within the red fox (Vulpes vulpes), a synanthropic host, using DNA metabarcoding of multiple marker genes. We analysed the effect of urbanisation, seasonality and host-intrinsic (weight, sex) variables on helminth communities. Helminth species richness increased in foxes with lower body weight and in winter and spring. Season and urbanisation, however, had strong effects on the community composition, i.e., on the identity of the detected species. Surprisingly, transmission in two-host life cycles (trophic transmission) was more pronounced in urban Berlin than in rural Brandenburg. This disagrees with the prevailing hypothesis that trophically transmitted helminths are less prevalent in urban areas than in rural areas. Generally, co-infestations with multiple helminths and high infection intensity are associated with lighter (younger, smaller or low body condition) animals. Both host-intrinsic traits and environmental drivers together shape parasite community composition and turnover along urban-rural gradients.
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Affiliation(s)
- Carolin Scholz
- Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany
| | - Víctor Hugo Jarquín-Díaz
- Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany; Department of Molecular Parasitology, Institute for Biology, Humboldt University Berlin (HU), Berlin, Germany; Charité - Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Germany; Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Aimara Planillo
- Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany; Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - Viktoriia Radchuk
- Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany
| | - Cédric Scherer
- Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany
| | - Christoph Schulze
- Berlin-Brandenburg State Laboratory (LLBB), Frankfurt (Oder), Germany
| | - Sylvia Ortmann
- Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany
| | - Stephanie Kramer-Schadt
- Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany; Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany; Institute of Ecology, Technische Universität Berlin, Germany
| | - Emanuel Heitlinger
- Leibniz Institute for Zoo and Wildlife Research (IZW) in the Forschungsverbund Berlin e.V., Berlin, Germany; Department of Molecular Parasitology, Institute for Biology, Humboldt University Berlin (HU), Berlin, Germany.
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Benesh DP, Chubb JC, Parker GA. Adaptive division of growth and development between hosts in helminths with two-host life cycles. Evolution 2022; 76:1971-1985. [PMID: 35860949 DOI: 10.1111/evo.14574] [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: 03/07/2022] [Revised: 05/11/2022] [Accepted: 05/25/2022] [Indexed: 01/22/2023]
Abstract
Parasitic worms (helminths) with complex life cycles divide growth and development between successive hosts. Using data from 597 species of acanthocephalans, cestodes, and nematodes with two-host life cycles, we found that helminths with larger intermediate hosts were more likely to infect larger, endothermic definitive hosts, although some evolutionary shifts in definitive host mass occurred without changes in intermediate host mass. Life-history theory predicts parasites to shift growth to hosts in which they can grow rapidly and/or safely. Accordingly, helminth species grew relatively less as larvae and more as adults if they infected smaller intermediate hosts and/or larger, endothermic definitive hosts. Growing larger than expected in one host, relative to host mass/endothermy, was not associated with growing less in the other host, implying a lack of cross-host trade-offs. Rather, some helminth orders had both large larvae and large adults. Within these taxa, however, size at maturity in the definitive host was unaffected by changes to larval growth, as predicted by optimality models. Parasite life-history strategies were mostly (though not entirely) consistent with theoretical expectations, suggesting that helminths adaptively divide growth and development between the multiple hosts in their complex life cycles.
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Affiliation(s)
- Daniel P Benesh
- Department of Molecular Parasitology, Humboldt University, 10115, Berlin, Germany.,Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), 12587, Berlin, Germany
| | - James C Chubb
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, L69 7ZB, United Kingdom
| | - Geoff A Parker
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, L69 7ZB, United Kingdom
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Okamura B, Gruhl A, De Baets K. Evolutionary transitions of parasites between freshwater and marine environments. Integr Comp Biol 2022; 62:345-356. [PMID: 35604852 DOI: 10.1093/icb/icac050] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 05/11/2022] [Accepted: 05/19/2022] [Indexed: 11/14/2022] Open
Abstract
Evolutionary transitions of organisms between environments have long fascinated biologists but attention has focused almost exclusively on free-living organisms and challenges to achieve such transitions. This bias requires addressing because parasites are a major component of biodiversity. We address this imbalance by focusing on transitions of parasitic animals between marine and freshwater environments. We highlight parasite traits and processes that may influence transition likelihood (e.g. transmission mode, life cycle, host use), and consider mechanisms and directions of transitions. Evidence for transitions in deep time and at present are described, and transitions in our changing world are considered. We propose that environmental transitions may be facilitated for endoparasites because hosts reduce exposure to physiologically challenging environments and argue that adoption of an endoparasitic lifestyle entails an equivalent transitioning process as organisms switch from living in one environment (e.g. freshwater, seawater, or air) to living symbiotically within hosts. Environmental transitions of parasites have repeatedly resulted in novel forms and diversification, contributing to the tree of life. Recognising the potential processes underlying present-day and future environmental transitions is crucial in view of our changing world and the current biodiversity crisis.
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Affiliation(s)
- Beth Okamura
- Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom
| | | | - Kenneth De Baets
- Institute of Evolutionary Biology, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, Warsaw 02-089, Poland
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Phillips JA, Vargas Soto JS, Pawar S, Koprivnikar J, Benesh DP, Molnár PK. The effects of phylogeny, habitat and host characteristics on the thermal sensitivity of helminth development. Proc Biol Sci 2022; 289:20211878. [PMID: 35135354 PMCID: PMC8825990 DOI: 10.1098/rspb.2021.1878] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Helminth parasites are part of almost every ecosystem, with more than 300 000 species worldwide. Helminth infection dynamics are expected to be altered by climate change, but predicting future changes is difficult owing to lacking thermal sensitivity data for greater than 99.9% of helminth species. Here, we compiled the largest dataset to date on helminth temperature sensitivities and used the Metabolic Theory of Ecology to estimate activation energies (AEs) for parasite developmental rates. The median AE for 129 thermal performance curves was 0.67, similar to non-parasitic animals. Although exceptions existed, related species tended to have similar thermal sensitivities, suggesting some helminth taxa are inherently more affected by rising temperatures than others. Developmental rates were more temperature-sensitive for species from colder habitats than those from warmer habitats, and more temperature sensitive for species in terrestrial than aquatic habitats. AEs did not depend on whether helminth life stages were free-living or within hosts, whether the species infected plants or animals, or whether the species had an endotherm host in its life cycle. The phylogenetic conservatism of AE may facilitate predicting how temperature change affects the development of helminth species for which empirical data are lacking or difficult to obtain.
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Affiliation(s)
- Jessica Ann Phillips
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.,Department of Zoology, Oxford University, Oxford, UK
| | - Juan S Vargas Soto
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.,Laboratory of Quantitative Global Change Ecology, Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Samraat Pawar
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, UK
| | - Janet Koprivnikar
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Daniel P Benesh
- Molecular Parasitology, Humboldt University, Philippstr. 13, Haus 14, 10115 Berlin, Germany.,Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587 Berlin, Germany
| | - Péter K Molnár
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.,Laboratory of Quantitative Global Change Ecology, Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
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Benesh DP, Chubb JC, Lafferty KD, Parker GA. Complex life-cycles in trophically transmitted helminths: Do the benefits of increased growth and transmission outweigh generalism and complexity costs? CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2022; 2:100085. [PMID: 35310018 PMCID: PMC8928126 DOI: 10.1016/j.crpvbd.2022.100085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 02/24/2022] [Accepted: 02/24/2022] [Indexed: 12/01/2022]
Abstract
Why do so many parasitic worms have complex life-cycles? A complex life-cycle has at least two hypothesized costs: (i) worms with longer life-cycles, i.e. more successive hosts, must be generalists at the species level, which might reduce lifetime survival or growth, and (ii) each required host transition adds to the risk that a worm will fail to complete its life-cycle. Comparing hundreds of trophically transmitted acanthocephalan, cestode, and nematode species with different life-cycles suggests these costs are weaker than expected. Helminths with longer cycles exhibit higher species-level generalism without impaired lifetime growth. Further, risk in complex life-cycles is mitigated by increasing establishment rates in each successive host. Two benefits of longer cycles are transmission and production. Longer cycles normally include smaller (and thus more abundant) first hosts that are likely to consume parasite propagules, as well as bigger (and longer-lived) definitive hosts, in which adult worms grow to larger and presumably more fecund reproductive sizes. Additional factors, like host immunity or dispersal, may also play a role, but are harder to address. Given the ubiquity of complex life-cycles, the benefits of incorporating or retaining hosts in a cycle must often exceed the costs. Comparing helminth species hints at the costs and benefits of complex life-cycles. Generalism and survival costs in longer life-cycles are weaker than expected. Longer life-cycles have growth and transmission benefits. The benefits of a complex life-cycle must often exceed the costs.
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Affiliation(s)
- Daniel P. Benesh
- Humboldt University of Berlin, Molecular Parasitology, Philippstr. 13, Haus 14, 10115, Berlin, Germany
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587, Berlin, Germany
- Corresponding author. Humboldt University of Berlin, Molecular Parasitology, Philippstr. 13, Haus 14, 10115, Berlin, Germany.
| | - James C. Chubb
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Kevin D. Lafferty
- Western Ecological Research Center, U.S. Geological Survey, at Marine Science Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Geoff A. Parker
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, L69 7ZB, UK
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6
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Benesh DP, Parker G, Chubb JC. Life-cycle complexity in helminths: What are the benefits? Evolution 2021; 75:1936-1952. [PMID: 34184269 DOI: 10.1111/evo.14299] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/23/2021] [Accepted: 06/06/2021] [Indexed: 12/22/2022]
Abstract
Parasitic worms (i.e., helminths) commonly infect multiple hosts in succession. With every transmission step, they risk not infecting the next host and thus dying before reproducing. Given this risk, what are the benefits of complex life cycles? Using a dataset for 973 species of trophically transmitted acanthocephalans, cestodes, and nematodes, we tested whether hosts at the start of a life cycle increase transmission and whether hosts at the end of a life cycle enable growth to larger, more fecund sizes. Helminths with longer life cycles, that is, more successive hosts, infected conspicuously smaller first hosts, slightly larger final hosts, and exploited trophic links with lower predator-prey mass ratios. Smaller first hosts likely facilitate transmission because of their higher abundance and because parasite propagules were the size of their normal food. Bigger definitive hosts likely increase fecundity because parasites grew larger in big hosts, particularly endotherms. Helminths with long life cycles attained larger adult sizes through later maturation, not faster growth. Our results indicate that complex helminth life cycles are ubiquitous because growth and reproduction are highest in large, endothermic hosts that are typically only accessible via small intermediate hosts, that is, the best hosts for growth and transmission are not the same.
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Affiliation(s)
- Daniel P Benesh
- Molecular Parasitology, Humboldt University, Berlin, Germany.,Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
| | - Geoff Parker
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, UK
| | - James C Chubb
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, UK
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Froelick S, Gramolini L, Benesh DP. Comparative analysis of helminth infectivity: growth in intermediate hosts increases establishment rates in the next host. Proc Biol Sci 2021; 288:20210142. [PMID: 33726588 DOI: 10.1098/rspb.2021.0142] [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] [Indexed: 01/07/2023] Open
Abstract
Parasitic worms (i.e. helminths) commonly infect multiple hosts in succession before reproducing. At each life cycle step, worms may fail to infect the next host, and this risk accumulates as life cycles include more successive hosts. Risk accumulation can be minimized by having high establishment success in the next host, but comparisons of establishment probabilities across parasite life stages are lacking. We compiled recovery rates (i.e. the proportion of parasites recovered from an administered dose) from experimental infections with acanthocephalans, cestodes and nematodes. Our data covered 127 helminth species and 16 913 exposed hosts. Recovery rates increased with life cycle progression (11%, 29% and 46% in first, second and third hosts, respectively), because larger worm larvae had higher recovery, both within and across life stages. Recovery declined in bigger hosts but less than it increased with worm size. Higher doses were used in systems with lower recovery, suggesting that high doses are chosen when few worms are expected to establish infection. Our results indicate that growing in the small and short-lived hosts at the start of a complex life cycle, though dangerous, may substantially improve parasites' chances of completing their life cycles.
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Affiliation(s)
- Spencer Froelick
- Molecular Parasitology, Humboldt University, Philippstr. 13, Haus 14, 10115 Berlin, Germany
| | - Laura Gramolini
- Molecular Parasitology, Humboldt University, Philippstr. 13, Haus 14, 10115 Berlin, Germany.,Department of Ecophysiology and Aquaculture, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587 Berlin, Germany
| | - Daniel P Benesh
- Molecular Parasitology, Humboldt University, Philippstr. 13, Haus 14, 10115 Berlin, Germany.,Department of Ecophysiology and Aquaculture, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Müggelseedamm 310, 12587 Berlin, Germany
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