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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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2
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Leung TLF. Economies of parasite body size. Curr Biol 2022; 32:R645-R649. [PMID: 35728546 DOI: 10.1016/j.cub.2022.01.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Parasitism has independently evolved multiple times across the entire tree of life, and there are numerous parasitic representatives from every major eukaryote kingdom. In animals alone, parasitism has independently evolved at least 200 times. If there are any organisms that one might think would have access to limitless resources, it would be parasites. You would think that living in or on the body of their host, which serves as both a habitat and a food source, would provide parasites with bountiful resources to maximise every aspect of their existence, especially reproduction. But parasitism is not a loophole out of life history trade-offs. There is still a finite amount of resources that a parasite can obtain and allocate to its many needs. Living in a resource-rich environment has allowed many parasites to grow to sizes that are of multiple orders of magnitude larger than their free-living relatives. But that does not mean that the underlying economy of nature and its limitations are inapplicable to parasites.
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Affiliation(s)
- Tommy L F Leung
- Zoology, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia.
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3
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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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4
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Albecker MA, Wilkins LGE, Krueger-Hadfield SA, Bashevkin SM, Hahn MW, Hare MP, Kindsvater HK, Sewell MA, Lotterhos KE, Reitzel AM. Does a complex life cycle affect adaptation to environmental change? Genome-informed insights for characterizing selection across complex life cycle. Proc Biol Sci 2021; 288:20212122. [PMID: 34847763 PMCID: PMC8634620 DOI: 10.1098/rspb.2021.2122] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Complex life cycles, in which discrete life stages of the same organism differ in form or function and often occupy different ecological niches, are common in nature. Because stages share the same genome, selective effects on one stage may have cascading consequences through the entire life cycle. Theoretical and empirical studies have not yet generated clear predictions about how life cycle complexity will influence patterns of adaptation in response to rapidly changing environments or tested theoretical predictions for fitness trade-offs (or lack thereof) across life stages. We discuss complex life cycle evolution and outline three hypotheses—ontogenetic decoupling, antagonistic ontogenetic pleiotropy and synergistic ontogenetic pleiotropy—for how selection may operate on organisms with complex life cycles. We suggest a within-generation experimental design that promises significant insight into composite selection across life cycle stages. As part of this design, we conducted simulations to determine the power needed to detect selection across a life cycle using a population genetic framework. This analysis demonstrated that recently published studies reporting within-generation selection were underpowered to detect small allele frequency changes (approx. 0.1). The power analysis indicates challenging but attainable sampling requirements for many systems, though plants and marine invertebrates with high fecundity are excellent systems for exploring how organisms with complex life cycles may adapt to climate change.
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Affiliation(s)
- Molly A Albecker
- Department of Biology, Utah State University, Logan, UT 84321, USA
| | - Laetitia G E Wilkins
- Max Planck Institute for Marine Microbiology (MPIMM), Celsiusstrasse 1, 28209 Bremen, Germany
| | - Stacy A Krueger-Hadfield
- Department of Biology, University of Alabama at Birmingham, 1300 University Blvd, Birmingham, AL 35294, USA
| | - Samuel M Bashevkin
- Delta Science Program, Delta Stewardship Council, 715 P Street 15-300, Sacramento, CA 95814, USA
| | - Matthew W Hahn
- Department of Biology and Department of Computer Science, Indiana University, 1001 E. 3rd St., Bloomington, IN 47405, USA
| | - Matthew P Hare
- Department of Natural Resources and the Environment, Cornell University, 205 Fernow Hall, Ithaca, NY 14853, USA
| | - Holly K Kindsvater
- Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Mary A Sewell
- School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand
| | - Katie E Lotterhos
- Northeastern University Marine Science Center, 430 Nahant Rd., Nahant, MA 01918, USA
| | - Adam M Reitzel
- University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223, USA
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5
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Kapila R, Kashyap M, Gulati A, Narasimhan A, Poddar S, Mukhopadhaya A, Prasad NG. Evolution of sex-specific heat stress tolerance and larval Hsp70 expression in populations of Drosophila melanogaster adapted to larval crowding. J Evol Biol 2021; 34:1376-1385. [PMID: 34197669 DOI: 10.1111/jeb.13897] [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: 04/05/2021] [Revised: 05/31/2021] [Accepted: 06/20/2021] [Indexed: 11/29/2022]
Abstract
The ability to tolerate temperature stress is an important component of adult fitness. In holometabolous insects like Drosophila melanogaster, adult stress resistance can be affected by growth conditions experienced during the larval stages. Although evolution under crowded larval conditions is known to lead to the correlated evolution of many adult traits, its consequences on adult heat stress tolerance have not been investigated. Therefore, in the present study, we assessed the adult heat stress tolerance in populations of D. melanogaster adapted to a stressful larval crowding environment. We used replicate populations of D. melanogaster, selected for adaptation to larval crowding stress (MCUs), for more than 230 generations, and their respective controls (MBs). Larvae from selected and control populations were grown under crowded and uncrowded conditions, and their adult heat shock resistance at two different temperatures was measured. Further, we compared Hsp70 expression in crowded and uncrowded larvae of both populations and also measured the Hsp70 expression after a mild heat treatment in adults of selected and control populations. Our results showed that adaptation to larval crowding leads to the evolution of Hsp70 gene expression in larval stages and improves adult heat stress tolerance ability in males, but not in females.
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Affiliation(s)
- Rohit Kapila
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Mayank Kashyap
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Aakanksha Gulati
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Aaditya Narasimhan
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Soumyadip Poddar
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Arunika Mukhopadhaya
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
| | - Nagaraj Guru Prasad
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Punjab, India
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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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7
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Herrig DK, Vertacnik KL, Kohrs AR, Linnen CR. Support for the adaptive decoupling hypothesis from whole-transcriptome profiles of a hypermetamorphic and sexually dimorphic insect, Neodiprion lecontei. Mol Ecol 2021; 30:4551-4566. [PMID: 34174126 DOI: 10.1111/mec.16041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 12/31/2022]
Abstract
Though seemingly bizarre, the dramatic morphological and ecological transformation that occurs when immature life stages metamorphose into reproductive adults is one of the most successful developmental strategies on the planet. The adaptive decoupling hypothesis (ADH) proposes that metamorphosis is an adaptation for breaking developmental links between traits expressed in different life stages, thereby facilitating their independent evolution when exposed to opposing selection pressures. Here, we draw inspiration from the ADH to develop a conceptual framework for understanding changes in gene expression across ontogeny. We hypothesized that patterns of stage-biased and sex-biased gene expression are the product of both decoupling mechanisms and selection history. To test this hypothesis, we characterized transcriptome-wide patterns of gene-expression traits for three ecologically distinct larval stages (all male) and adult males and females of a hypermetamorphic insect (Neodiprion lecontei). We found that stage-biased gene expression was most pronounced between larval and adult males, which is consistent with the ADH. However, even in the absence of a metamorphic transition, considerable stage-biased expression was observed among morphologically and behaviourally distinct larval stages. Stage-biased expression was also observed across ecologically relevant Gene Ontology categories and genes, highlighting the role of ecology in shaping patterns of gene expression. We also found that the magnitude and prevalence of stage-biased expression far exceeded adult sex-biased expression. Overall, our results highlight how the ADH can shed light on transcriptome-wide patterns of gene expression in organisms with complex life cycles. For maximal insight, detailed knowledge of organismal ecology is also essential.
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Affiliation(s)
- Danielle K Herrig
- Department of Biology, University of Kentucky, Lexington, Kentucky, USA
| | - Kim L Vertacnik
- Department of Biology, University of Kentucky, Lexington, Kentucky, USA
| | - Anna R Kohrs
- Department of Biology, University of Kentucky, Lexington, Kentucky, USA
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8
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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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9
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Benesh DP, Parker GA, Chubb JC, Lafferty KD. Trade-Offs with Growth Limit Host Range in Complex Life-Cycle Helminths. Am Nat 2020; 197:E40-E54. [PMID: 33523790 DOI: 10.1086/712249] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractParasitic worms with complex life cycles have several developmental stages, with each stage creating opportunities to infect additional host species. Using a data set for 973 species of trophically transmitted acanthocephalans, cestodes, and nematodes, we confirmed that worms with longer life cycles (i.e., more successive hosts) infect a greater diversity of host species and taxa (after controlling for study effort). Generalism at the stage level was highest for middle life stages, the second and third intermediate hosts of long life cycles. By simulating life cycles in real food webs, we found that middle stages had more potential host species to infect, suggesting that opportunity constrains generalism. However, parasites usually infected fewer host species than expected from simulated cycles, suggesting that generalism has costs. There was no trade-off in generalism from one stage to the next, but worms spent less time growing and developing in stages where they infected more taxonomically diverse hosts. Our results demonstrate that life-cycle complexity favors high generalism and that host use across life stages is determined by both ecological opportunity and life-history trade-offs.
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10
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Chubb JC, Benesh D, Parker GA. Ungulate Helminth Transmission and Two Evolutionary Puzzles. Trends Parasitol 2020; 36:64-79. [DOI: 10.1016/j.pt.2019.10.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/22/2019] [Accepted: 10/22/2019] [Indexed: 11/17/2022]
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11
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Birget PLG, Schneider P, O’Donnell AJ, Reece SE. Adaptive phenotypic plasticity in malaria parasites is not constrained by previous responses to environmental change. EVOLUTION MEDICINE AND PUBLIC HEALTH 2019; 2019:190-198. [PMID: 31660151 PMCID: PMC6805783 DOI: 10.1093/emph/eoz028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/25/2019] [Indexed: 01/12/2023]
Abstract
Background and objectives Phenotypic plasticity enables organisms to maximize fitness by matching trait values to different environments. Such adaptive phenotypic plasticity is exhibited by parasites, which experience frequent environmental changes during their life cycle, between individual hosts and also in within-host conditions experienced during infections. Life history theory predicts that the evolution of adaptive phenotypic plasticity is limited by costs and constraints, but tests of these concepts are scarce. Methodology Here, we induce phenotypic plasticity in malaria parasites to test whether mounting a plastic response to an environmental perturbation constrains subsequent plastic responses to further environmental change. Specifically, we perturb red blood cell resource availability to induce Plasmodium chabaudi to alter the trait values of several phenotypes underpinning within-host replication and between-host transmission. We then transfer parasites to unperturbed hosts to examine whether constraints govern the parasites’ ability to alter these phenotypes in response to their new in-host environment. Results Parasites alter trait values in response to the within-host environment they are exposed to. We do not detect negative consequences, for within-host replication or between-host transmission, of previously mounting a plastic response to a perturbed within-host environment. Conclusions and implications We suggest that malaria parasites are highly plastic and adapted to adjusting their phenotypes in response to the frequent changes in the within-host conditions they experience during infections. Our findings support the growing body of evidence that medical interventions, such as anti-parasite drugs, induce plastic responses that are adaptive and can facilitate the survival and potentially, drug resistance of parasites. Lay Summary Malaria parasites have evolved flexible strategies to cope with the changing conditions they experience during infections. We show that using such flexible strategies does not impact upon the parasites’ ability to grow (resulting in disease symptoms) or transmit (spreading the disease).
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Affiliation(s)
- Philip L G Birget
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Petra Schneider
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Aidan J O’Donnell
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Sarah E Reece
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
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12
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Franke F, Raifarth N, Kurtz J, Scharsack JP. Consequences of divergent temperature optima in a host–parasite system. OIKOS 2019. [DOI: 10.1111/oik.05864] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Frederik Franke
- Inst. for Evolution and Biodiversity, Univ. of Münster Hüfferstrasse 1, DE‐48149 Münster Germany
| | - Nadja Raifarth
- Inst. for Evolution and Biodiversity, Univ. of Münster Hüfferstrasse 1, DE‐48149 Münster Germany
| | - Joachim Kurtz
- Inst. for Evolution and Biodiversity, Univ. of Münster Hüfferstrasse 1, DE‐48149 Münster Germany
| | - Jörn P. Scharsack
- Inst. for Evolution and Biodiversity, Univ. of Münster Hüfferstrasse 1, DE‐48149 Münster Germany
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13
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Kasl EL, Font WF, Criscione CD. Resolving evolutionary changes in parasite life cycle complexity: Molecular phylogeny of the trematode genus Alloglossidium indicates more than one origin of precociousness. Mol Phylogenet Evol 2018; 126:371-381. [DOI: 10.1016/j.ympev.2018.04.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 03/17/2018] [Accepted: 04/17/2018] [Indexed: 10/17/2022]
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14
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Hébert FO, Grambauer S, Barber I, Landry CR, Aubin-Horth N. Major host transitions are modulated through transcriptome-wide reprogramming events in Schistocephalus solidus, a threespine stickleback parasite. Mol Ecol 2017; 26:1118-1130. [PMID: 27997044 DOI: 10.1111/mec.13970] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 12/02/2016] [Accepted: 12/06/2016] [Indexed: 12/26/2022]
Abstract
Parasites with complex life cycles have developed numerous phenotypic strategies, closely associated with developmental events, to enable the exploitation of different ecological niches and facilitate transmission between hosts. How these environmental shifts are regulated from a metabolic and physiological standpoint, however, still remain to be fully elucidated. We examined the transcriptomic response of Schistocephalus solidus, a trophically transmitted parasite with a complex life cycle, over the course of its development in an intermediate host, the threespine stickleback, and the final avian host. Results from our differential gene expression analysis show major reprogramming events among developmental stages. The final host stage is characterized by a strong activation of reproductive pathways and redox homoeostasis. The attainment of infectivity in the fish intermediate host-which precedes sexual maturation in the final host and is associated with host behaviour changes-is marked by transcription of genes involved in neural pathways and sensory perception. Our results suggest that un-annotated and S. solidus-specific genes could play a determinant role in host-parasite molecular interactions required to complete the parasite's life cycle. Our results permit future comparative analyses to help disentangle species-specific patterns of infection from conserved mechanisms, ultimately leading to a better understanding of the molecular control and evolution of complex life cycles.
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Affiliation(s)
- François Olivier Hébert
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, 1030 avenue de la Médecine, Québec, QC, G1V 0A6, Canada
| | - Stephan Grambauer
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Adrian Building, University Road, Leicester, LE1 7RH, UK
| | - Iain Barber
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Adrian Building, University Road, Leicester, LE1 7RH, UK
| | - Christian R Landry
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, 1030 avenue de la Médecine, Québec, QC, G1V 0A6, Canada
| | - Nadia Aubin-Horth
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, 1030 avenue de la Médecine, Québec, QC, G1V 0A6, Canada
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15
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Caddigan SC, Pfenning AC, Sparkes TC. Competitive growth, energy allocation, and host modification in the acanthocephalan Acanthocephalus dirus: field data. Parasitol Res 2016; 116:199-206. [DOI: 10.1007/s00436-016-5279-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 09/28/2016] [Indexed: 11/24/2022]
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16
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Abstract
SUMMARYComplex life cycles are common in free-living and parasitic organisms alike. The adaptive decoupling hypothesis postulates that separate life cycle stages have a degree of developmental and genetic autonomy, allowing them to be independently optimized for dissimilar, competing tasks. That is, complex life cycles evolved to facilitate functional specialization. Here, I review the connections between the different stages in parasite life cycles. I first examine evolutionary connections between life stages, such as the genetic coupling of parasite performance in consecutive hosts, the interspecific correlations between traits expressed in different hosts, and the developmental and functional obstacles to stage loss. Then, I evaluate how environmental factors link life stages through carryover effects, where stressful larval conditions impact parasites even after transmission to a new host. There is evidence for both autonomy and integration across stages, so the relevant question becomes how integrated are parasite life cycles and through what mechanisms? By highlighting how genetics, development, selection and the environment can lead to interdependencies among successive life stages, I wish to promote a holistic approach to studying complex life cycle parasites and emphasize that what happens in one stage is potentially highly relevant for later stages.
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17
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Benesh DP, Kalbe M. Experimental parasite community ecology: intraspecific variation in a large tapeworm affects community assembly. J Anim Ecol 2016; 85:1004-13. [DOI: 10.1111/1365-2656.12527] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 04/01/2016] [Indexed: 12/27/2022]
Affiliation(s)
- Daniel P. Benesh
- Max Planck Institute for Evolutionary Biology; August-Thienemann-Str. 2 24306 Plön Germany
- Marine Science Institute; University of California; Santa Barbara CA 93106-6150 USA
| | - Martin Kalbe
- Max Planck Institute for Evolutionary Biology; August-Thienemann-Str. 2 24306 Plön Germany
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Kalbe M, Eizaguirre C, Scharsack JP, Jakobsen PJ. Reciprocal cross infection of sticklebacks with the diphyllobothriidean cestode Schistocephalus solidus reveals consistent population differences in parasite growth and host resistance. Parasit Vectors 2016; 9:130. [PMID: 26951744 PMCID: PMC4782366 DOI: 10.1186/s13071-016-1419-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/02/2016] [Indexed: 11/19/2022] Open
Abstract
Background In host-parasite evolutionary arms races, parasites are generally expected to adapt more rapidly, due to their large population sizes and short generation times. There exist systems, though, where parasites cannot outpace their hosts because of similar generation times in both antagonists. In those cases concomitant adaptation is expected. Methods We tested this hypothesis in the three-spined stickleback-Schistocephalus solidus tapeworm system, where generation times are comparable in both organisms. We chose two populations of sticklebacks which differ prominently in the prevalence of S. solidus and consequently in its level of selective pressure. We performed a full factorial common garden experiment. Particularly, Norwegian (NO) and German (DE) sticklebacks, as well as hybrids between both stickleback populations and in both parental combinations, were exposed each to a single S. solidus originating from the same two host populations. Results We found the infection phenotype to depend on the host population, the parasite population, but not their interaction. NO-parasites showed higher infectivity than DE-parasites, with NO-sticklebacks also being more resistant to DE-parasites than to the sympatric NO-parasite. Reciprocally, DE-hosts were more susceptible to the allopatric NO-parasite while DE-parasites grew less than NO-parasites in all stickleback groups. Despite this asymmetry, the ratio of worm to host weight, an indicator of parasite virulence, was identical in both sympatric combinations, suggesting an optimal virulence as a common outcome of parallel coevolved systems. In hybrid sticklebacks, intermediate infection rates and growth of S. solidus from either origin suggests a simple genetic basis of resistance. However, comparison of infection phenotypes in NO-maternal and DE-maternal hybrid sticklebacks indicates local adaptation to the sympatric counterpart in both the host and the parasite. Conclusions Host-parasite systems with similar generation time show evidence for concomitant reciprocal adaptation resulting in parasite optimal virulence and host parasite specific resistance. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1419-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Martin Kalbe
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306, Plön, Germany.
| | - Christophe Eizaguirre
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306, Plön, Germany. .,School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
| | - Jörn P Scharsack
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306, Plön, Germany. .,Department of Animal Evolutionary Ecology, Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, 48149, Münster, Germany.
| | - Per J Jakobsen
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306, Plön, Germany. .,Institute for Biology, University of Bergen, Thor Møhlensgt. 55, 5020, Bergen, Norway.
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19
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Kasl EL, McAllister CT, Robison HW, Connior MB, Font WF, Criscione CD. Evolutionary consequence of a change in life cycle complexity: A link between precocious development and evolution toward female-biased sex allocation in a hermaphroditic parasite. Evolution 2015; 69:3156-70. [PMID: 26508113 DOI: 10.1111/evo.12805] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 10/02/2015] [Accepted: 10/10/2015] [Indexed: 11/29/2022]
Abstract
The evolutionary consequences of changes in the complex life cycles of parasites are not limited to the traits that directly affect transmission. For instance, mating systems that are altered due to precocious sexual maturation in what is typically regarded as an intermediate host may impact opportunities for outcrossing. In turn, reproductive traits may evolve to optimize sex allocation. Here, we test the hypothesis that sex allocation evolved toward a more female-biased function in populations of the hermaphroditic digenean trematode Alloglossidium progeneticum that can precociously reproduce in their second hosts. In these precocious populations, parasites are forced to self-fertilize as they remain encysted in their second hosts. In contrast, parasites in obligate three-host populations have more opportunities to outcross in their third host. We found strong support that in populations with precocious development, allocation to male resources was greatly reduced. We also identified a potential phenotypically plastic response in a body size sex allocation relationship that may be driven by the competition for mates. These results emphasize how changes in life cycle patterns that alter mating systems can impact the evolution of reproductive traits in parasites.
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Affiliation(s)
- Emily L Kasl
- Department of Biology, Texas A&M University, College Station, Texas.
| | - Chris T McAllister
- Science and Mathematics Division, Eastern Oklahoma State College, Idabel, Oklahoma
| | - Henry W Robison
- Department of Biology, Southern Arkansas University, Magnolia, Arkansas
| | - Matthew B Connior
- Life Sciences, Northwest Arkansas Community College, Bentonville, Arkansas
| | - William F Font
- Department of Biological Sciences, Southeastern Louisiana University, Hammond, Louisiana
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20
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Parker GA, Ball MA, Chubb JC. Evolution of complex life cycles in trophically transmitted helminths. II. How do life-history stages adapt to their hosts? J Evol Biol 2015; 28:292-304. [DOI: 10.1111/jeb.12576] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 12/15/2014] [Indexed: 01/20/2023]
Affiliation(s)
- G. A. Parker
- Department of Evolution, Ecology and Behaviour; Institute of Integrative Biology; University of Liverpool; Liverpool UK
| | - M. A. Ball
- Mathematical Sciences; University of Liverpool; Liverpool UK
| | - J. C. Chubb
- Department of Evolution, Ecology and Behaviour; Institute of Integrative Biology; University of Liverpool; Liverpool UK
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21
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Parker GA, Ball MA, Chubb JC. Evolution of complex life cycles in trophically transmitted helminths. I. Host incorporation and trophic ascent. J Evol Biol 2015; 28:267-91. [PMID: 25625702 DOI: 10.1111/jeb.12575] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 12/12/2014] [Accepted: 12/15/2014] [Indexed: 01/18/2023]
Abstract
Links between parasites and food webs are evolutionarily ancient but dynamic: life history theory provides insights into helminth complex life cycle origins. Most adult helminths benefit by sexual reproduction in vertebrates, often high up food chains, but direct infection is commonly constrained by a trophic vacuum between free-living propagules and definitive hosts. Intermediate hosts fill this vacuum, facilitating transmission to definitive hosts. The central question concerns why sexual reproduction, and sometimes even larval growth, is suppressed in intermediate hosts, favouring growth arrest at larval maturity in intermediate hosts and reproductive suppression until transmission to definitive hosts? Increased longevity and higher growth in definitive hosts can generate selection for larger parasite body size and higher fecundity at sexual maturity. Life cycle length is increased by two evolutionary mechanisms, upward and downward incorporation, allowing simple (one-host) cycles to become complex (multihost). In downward incorporation, an intermediate host is added below the definitive host: models suggest that downward incorporation probably evolves only after ecological or evolutionary perturbations create a trophic vacuum. In upward incorporation, a new definitive host is added above the original definitive host, which subsequently becomes an intermediate host, again maintained by the trophic vacuum: theory suggests that this is plausible even under constant ecological/evolutionary conditions. The final cycle is similar irrespective of its origin (upward or downward). Insights about host incorporation are best gained by linking comparative phylogenetic analyses (describing evolutionary history) with evolutionary models (examining selective forces). Ascent of host trophic levels and evolution of optimal host taxa ranges are discussed.
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Affiliation(s)
- G A Parker
- Department of Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
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22
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Auld SKJR, Tinsley MC. The evolutionary ecology of complex lifecycle parasites: linking phenomena with mechanisms. Heredity (Edinb) 2014; 114:125-32. [PMID: 25227255 DOI: 10.1038/hdy.2014.84] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 07/09/2014] [Accepted: 08/12/2014] [Indexed: 11/09/2022] Open
Abstract
Many parasitic infections, including those of humans, are caused by complex lifecycle parasites (CLPs): parasites that sequentially infect different hosts over the course of their lifecycle. CLPs come from a wide range of taxonomic groups-from single-celled bacteria to multicellular flatworms-yet share many common features in their life histories. Theory tells us when CLPs should be favoured by selection, but more empirical studies are required in order to quantify the costs and benefits of having a complex lifecycle, especially in parasites that facultatively vary their lifecycle complexity. In this article, we identify ecological conditions that favour CLPs over their simple lifecycle counterparts and highlight how a complex lifecycle can alter transmission rate and trade-offs between growth and reproduction. We show that CLPs participate in dynamic host-parasite coevolution, as more mobile hosts can fuel CLP adaptation to less mobile hosts. Then, we argue that a more general understanding of the evolutionary ecology of CLPs is essential for the development of effective frameworks to manage the many diseases they cause. More research is needed identifying the genetics of infection mechanisms used by CLPs, particularly into the role of gene duplication and neofunctionalisation in lifecycle evolution. We propose that testing for signatures of selection in infection genes will reveal much about how and when complex lifecycles evolved, and will help quantify complex patterns of coevolution between CLPs and their various hosts. Finally, we emphasise four key areas where new research approaches will provide fertile opportunities to advance this field.
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Affiliation(s)
- S K J R Auld
- Division of Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling, UK
| | - M C Tinsley
- Division of Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling, UK
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Benesh DP, Chubb JC, Parker GA. The trophic vacuum and the evolution of complex life cycles in trophically transmitted helminths. Proc Biol Sci 2014; 281:rspb.2014.1462. [PMID: 25209937 DOI: 10.1098/rspb.2014.1462] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Parasitic worms (helminths) frequently have complex life cycles in which they are transmitted trophically between two or more successive hosts. Sexual reproduction often takes place in high trophic-level (TL) vertebrates, where parasites can grow to large sizes with high fecundity. Direct infection of high TL hosts, while advantageous, may be unachievable for parasites constrained to transmit trophically, because helminth propagules are unlikely to be ingested by large predators. Lack of niche overlap between propagule and definitive host (the trophic transmission vacuum) may explain the origin and/or maintenance of intermediate hosts, which overcome this transmission barrier. We show that nematodes infecting high TL definitive hosts tend to have more successive hosts in their life cycles. This relationship was modest, though, driven mainly by the minimum TL of hosts, suggesting that the shortest trophic chains leading to a host define the boundaries of the transmission vacuum. We also show that alternative modes of transmission, like host penetration, allow nematodes to reach high TLs without intermediate hosts. We suggest that widespread omnivory as well as parasite adaptations to increase transmission probably reduce, but do not eliminate, the barriers to the transmission of helminths through the food web.
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Affiliation(s)
- Daniel P Benesh
- Marine Science Institute, University of California, Santa Barbara, CA 93106-6150, USA Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, August-Thienemann-Strasse 2, 24306 Plön, Germany
| | - James C Chubb
- Department of Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Geoff A Parker
- Department of Evolution, Ecology and Behaviour, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
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Weinreich F, Kalbe M, Benesh DP. Making the in vitro breeding of Schistocephalus solidus more flexible. Exp Parasitol 2014; 139:1-5. [PMID: 24560832 DOI: 10.1016/j.exppara.2014.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 12/16/2013] [Accepted: 02/09/2014] [Indexed: 11/19/2022]
Abstract
Schistocephalus solidus is one of the few cestodes that can be bred in vitro. Worms have typically been bred in pairs, so the parents of each offspring can clearly be assigned. From a genetic perspective, it would be useful to be able to mate an individual worm to multiple partners while still being able to distinguish among different parents. As each adult S. solidus possesses numerous reproductive complexes, cutting worms and breeding the pieces separately would facilitate such breeding designs. We halved worms before in vitro breeding and evaluated whether this affected outcrossing rates and reproductive output. Cutting did not influence clutch mass, i.e. egg number and size, or outcrossing rates, but eggs from cut worms had a lower hatching rate than eggs from uncut worms. We found that when two anterior worm halves were bred together, they produced fewer, smaller eggs with higher hatching rates, compared to two posterior halves. Moreover, once we controlled for this effect of 'worm half', the two halves of an individual worm tended to reproduce similarly under comparable circumstances. We conclude that cutting plerocercoids increases the flexibility with which this tapeworm can be experimentally bred without dramatically affecting the production of viable, outcrossed eggs.
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Affiliation(s)
- Friederike Weinreich
- Department of Evolutionary Ecology, Max-Planck-Institute for Evolutionary Biology, August-Thienemann-Strasse 2, 24306 Plön, Germany
| | - Martin Kalbe
- Department of Evolutionary Ecology, Max-Planck-Institute for Evolutionary Biology, August-Thienemann-Strasse 2, 24306 Plön, Germany
| | - Daniel P Benesh
- Department of Evolutionary Ecology, Max-Planck-Institute for Evolutionary Biology, August-Thienemann-Strasse 2, 24306 Plön, Germany.
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Benesh DP. Parental effects on the larval performance of a tapeworm in its copepod first host. J Evol Biol 2013; 26:1625-33. [PMID: 23859276 DOI: 10.1111/jeb.12165] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 03/19/2013] [Accepted: 03/26/2013] [Indexed: 01/08/2023]
Abstract
Parents can influence the phenotype of their offspring through various mechanisms, besides the direct effect of heredity. Such parental effects are little explored in parasitic organisms, perhaps because in many parasites, per capita investment into offspring is low. I investigated whether parental identity, beyond direct genetic effects, could explain variation in the performance of the tapeworm Schistocephalus solidus in its first intermediate host, a copepod. I first determined that two breeding worms could be separated from one another after ~48 h of in vitro incubation and that the isolated worms continued producing outcrossed eggs, that is, rates self-fertilization did not increase after separation. Thus, from a breeding pair, two sets of genetically comparable eggs can be collected that have unambiguous parental identities. In an infection experiment, I found that the development of larval worms tended to vary between the two parental worms within breeding pairs, but infection success and growth rate in copepods did not. Accounting for this parental effect decreased the estimated heritability for development by nearly half. These results suggest that larval performance is not simply a function of a worm's genotype; who mothered or fathered an offspring can also affect offspring fitness, contradicting the perhaps naïve idea that parasites simply produce large quantities of uniformly low-quality offspring.
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Affiliation(s)
- D P Benesh
- Department of Evolutionary Ecology, Max-Planck-Institute for Evolutionary Biology, Plön, Germany.
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26
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Henrich T, Benesh DP, Kalbe M. Hybridization between two cestode species and its consequences for intermediate host range. Parasit Vectors 2013; 6:33. [PMID: 23390985 PMCID: PMC3584927 DOI: 10.1186/1756-3305-6-33] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/01/2013] [Indexed: 11/29/2022] Open
Abstract
Background Many parasites show an extraordinary degree of host specificity, even though a narrow range of host species reduces the likelihood of successful transmission. In this study, we evaluate the genetic basis of host specificity and transmission success of experimental F1 hybrids from two closely related tapeworm species (Schistocephalus solidus and S. pungitii), both highly specific to their respective vertebrate second intermediate hosts (three- and nine-spined sticklebacks, respectively). Methods We used an in vitro breeding system to hybridize Schistocephalus solidus and S. pungitii; hybridization rate was quantified using microsatellite markers. We measured several fitness relevant traits in pure lines of the parental parasite species as well as in their hybrids: hatching rates, infection rates in the copepod first host, and infection rates and growth in the two species of stickleback second hosts. Results We show that the parasites can hybridize in the in vitro system, although the proportion of self-fertilized offspring was higher in the heterospecific breeding pairs than in the control pure parental species. Hybrids have a lower hatching rate, but do not show any disadvantages in infection of copepods. In fish, hybrids were able to infect both stickleback species with equal frequency, whereas the pure lines were only able to infect their normal host species. Conclusions Although not yet documented in nature, our study shows that hybridization in Schistocephalus spp. is in principle possible and that, in respect to their expanded host range, the hybrids are fitter. Further studies are needed to find the reason for the maintenance of the species boundaries in wild populations.
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Affiliation(s)
- Tina Henrich
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary, Biology, August-Thienemann-Strasse 2, Plön 24306, Germany
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