351
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Raeymaekers JA, Wegner K, Huyse T, Volckaert FA. Infection dynamics of the monogenean parasite Gyrodactylus gasterostei on sympatric and allopatric populations of the three-spined stickleback Gasterosteus aculeatus. Folia Parasitol (Praha) 2011; 58:27-34. [DOI: 10.14411/fp.2011.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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352
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Yin M, Laforsch C, Lohr JN, Wolinska J. Predator-induced defense makes Daphnia more vulnerable to parasites. Evolution 2011; 65:1482-8. [PMID: 21521197 DOI: 10.1111/j.1558-5646.2011.01240.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Inducible defensive traits against herbivores or predators are widespread in plants and animals. Theory predicts that defended morphs have greater fitness in the presence of predators, but lower fitness than undefended morphs in the absence of predators. If such costs did not exist, then a constitutively defended morph would be favored by natural selection; yet, evidence for such costs has been elusive. Our current work reveals a significant cost to inducible defenses. Using the waterflea (Daphnia) model system, we show that induced defended morphs are significantly more vulnerable to infection by a virulent yeast parasite than undefended morphs. In two independent experiments, the proportion of successful infections and the number of parasite spores were higher among defended versus undefended Daphnia. Thus, by demonstrating a previously unknown and environmentally relevant cost to inducible defenses, this study enhances our understanding of adaptive phenotypic plasticity and its evolution.
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Affiliation(s)
- Mingbo Yin
- Ludwig-Maximilians University Munich, Department Biology II, Grosshaderner Str. 2, D-82152 Planegg-Martinsried, Germany
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353
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Duneau D, Luijckx P, Ben-Ami F, Laforsch C, Ebert D. Resolving the infection process reveals striking differences in the contribution of environment, genetics and phylogeny to host-parasite interactions. BMC Biol 2011; 9:11. [PMID: 21342515 PMCID: PMC3052238 DOI: 10.1186/1741-7007-9-11] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 02/22/2011] [Indexed: 11/30/2022] Open
Abstract
Background Infection processes consist of a sequence of steps, each critical for the interaction between host and parasite. Studies of host-parasite interactions rarely take into account the fact that different steps might be influenced by different factors and might, therefore, make different contributions to shaping coevolution. We designed a new method using the Daphnia magna - Pasteuria ramosa system, one of the rare examples where coevolution has been documented, in order to resolve the steps of the infection and analyse the factors that influence each of them. Results Using the transparent Daphnia hosts and fluorescently-labelled spores of the bacterium P. ramosa, we identified a sequence of infection steps: encounter between parasite and host; activation of parasite dormant spores; attachment of spores to the host; and parasite proliferation inside the host. The chances of encounter had been shown to depend on host genotype and environment. We tested the role of genetic and environmental factors in the newly described activation and attachment steps. Hosts of different genotypes, gender and species were all able to activate endospores of all parasite clones tested in different environments; suggesting that the activation cue is phylogenetically conserved. We next established that parasite attachment occurs onto the host oesophagus independently of host species, gender and environmental conditions. In contrast to spore activation, attachment depended strongly on the combination of host and parasite genotypes. Conclusions Our results show that different steps are influenced by different factors. Host-type-independent spore activation suggests that this step can be ruled out as a major factor in Daphnia-Pasteuria coevolution. On the other hand, we show that the attachment step is crucial for the pronounced genetic specificities of this system. We suggest that this one step can explain host population structure and could be a key force behind coevolutionary cycles. We discuss how different steps can explain different aspects of the coevolutionary dynamics of the system: the properties of the attachment step, explaining the rapid evolution of infectivity and the properties of later parasite proliferation explaining the evolution of virulence. Our study underlines the importance of resolving the infection process in order to better understand host-parasite interactions.
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Affiliation(s)
- David Duneau
- University of Basel, Zoological Institute, Vesalgasse 1, Basel, Switzerland.
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354
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Affiliation(s)
- Dieter Ebert
- Universität Basel, Zoological Institute, Vesalgasse 1, 4059 Basel, Switzerland.
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355
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Schulte RD, Makus C, Hasert B, Michiels NK, Schulenburg H. Host-parasite local adaptation after experimental coevolution of Caenorhabditis elegans and its microparasite Bacillus thuringiensis. Proc Biol Sci 2011; 278:2832-9. [PMID: 21307053 DOI: 10.1098/rspb.2011.0019] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Coevolving hosts and parasites can adapt to their local antagonist. In studies on natural populations, the observation of local adaptation patterns is thus often taken as indirect evidence for coevolution. Based on this approach, coevolution was previously inferred from an overall pattern of either parasite or host local adaptation. Many studies, however, failed to detect such a pattern. One explanation is that the studied system was not subject to coevolution. Alternatively, coevolution occurred, but remained undetected because it took different routes in different populations. In some populations, it is the host that is locally adapted, whereas in others it is the parasite, leading to the absence of an overall local adaptation pattern. Here, we test for overall as well as population-specific patterns of local adaptation using experimentally coevolved populations of the nematode Caenorhabditis elegans and its bacterial microparasite Bacillus thuringiensis. Furthermore, we assessed the importance of random interaction effects using control populations that evolved in the absence of the respective antagonist. Our results demonstrate that experimental coevolution produces distinct local adaptation patterns in different replicate populations, including host, parasite or absence of local adaptation. Our study thus provides experimental evidence of the predictions of the geographical mosaic theory of coevolution, i.e. that the interaction between parasite and host varies across populations.
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Affiliation(s)
- Rebecca D Schulte
- Institute for Evolution and Biodiversity, Westphalian Wilhelms-University Muenster, Huefferstrasse 1, 48149 Muenster, Germany.
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356
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Stelzer CP. The Cost of Sex and Competition between Cyclical and Obligate Parthenogenetic Rotifers. Am Nat 2011; 177:E43-53. [DOI: 10.1086/657685] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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357
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Hall SR, Becker CR, Duffy MA, Cáceres CE. Variation in resource acquisition and use among host clones creates key epidemiological trade‐offs. Am Nat 2011; 176:557-65. [PMID: 20887188 DOI: 10.1086/656523] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Parasites can certainly harm host fitness. Given such virulence, hosts should evolve strategies to resist or tolerate infection. But what governs those strategies and the costs that they incur? This study illustrates how a fecundity‐susceptibility trade‐off among clonally reared genotypes of a zooplankton (Daphnia dentifera) infected by a fungal parasite (Metschnikowia) arises due to variation in resource acquisition and use by hosts. To make these connections, we used lab experiments and theoretical models that link feeding with susceptibility, energetics, and fecundity of hosts. These feeding‐based mechanisms also produced a fecundity‐survivorship trade‐off. Meanwhile, a parasite spore yield–fecundity trade‐off arose from variation in juvenile growth rate among host clones (another index of resource use), a result that was readily anticipated and explained by the models. Thus, several key epidemiological trade‐offs stem from variation in resource acquisition and use among clones. This connection should catalyze the creation of new theory that integrates resource‐ and gene‐based responses of hosts to disease.
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Affiliation(s)
- Spencer R Hall
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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358
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Affiliation(s)
- Raoul K. Boughton
- Avian Ecology, Archbold Biological Station, 123 Main Drive, Venus, Florida, USA
| | - Gerrit Joop
- Institute of Integrative Biology,
Experimental Ecology, ETH Zürich, CH‐8092 Zürich, Switzerland
| | - Sophie A.O. Armitage
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasse 1, D‐48149 Münster, Germany
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359
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Brown JKM, Tellier A. Plant-parasite coevolution: bridging the gap between genetics and ecology. ANNUAL REVIEW OF PHYTOPATHOLOGY 2011; 49:345-67. [PMID: 21513455 DOI: 10.1146/annurev-phyto-072910-095301] [Citation(s) in RCA: 157] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We review current ideas about coevolution of plants and parasites, particularly processes that generate genetic diversity. Frequencies of host resistance and parasite virulence alleles that interact in gene-for-gene (GFG) relationships coevolve in the familiar boom-and-bust cycle, in which resistance is selected when virulence is rare, and virulence is selected when resistance is common. The cycle can result in stable polymorphism when diverse ecological and epidemiological factors cause negative direct frequency-dependent selection (ndFDS) on host resistance, parasite virulence, or both, such that the benefit of a trait to fitness declines as its frequency increases. Polymorphism can also be stabilized by overdominance, when heterozygous hosts have greater resistance than homozygotes to diverse pathogens. Genetic diversity can also persist in the form of statistical polymorphism, sustained by random processes acting on gene frequencies and population size. Stable polymorphism allows alleles to be long-lived and genetic variation to be detectable in natural populations. In agriculture, many of the factors promoting stability in host-parasite interactions have been lost, leading to arms races of host defenses and parasite effectors.
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Affiliation(s)
- James K M Brown
- Department of Disease and Stress Biology, John Innes Center, Colney, Norwich, NR4 7UH, United Kingdom.
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360
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Abstract
The surface coat (SC) of the plant-parasitic nematode cuticle is an understudied area of current research, even though it likely plays key roles in both nematode-plant and nematode-microbe interactions. Although in several ways Caenorhabditis elegans is a poor model for plant-parasitic nematodes, it is a useful starting point for investigations of the cuticle and its SC, especially in the light of recent work using this species as a model for innate immunity and the generic biology underpinning much host-parasite biology. We review the research focused on the involvement of the SC of plant-parasitic nematodes. Using the insights gained from animal-parasitic nematodes and other sequenced nematodes, we discuss the key roles that the SC may play.
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Affiliation(s)
- Keith G Davies
- Plant Pathology and Microbiology, Rothamsted Research, Hertfordshire AL5 2JQ, United Kingdom
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361
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Abstract
Recombination hotspots are small chromosomal regions, where meiotic crossover events happen with high frequency. Recombination is initiated by a double-strand break (DSB) that requires the intervention of the molecular repair mechanism. The DSB repair mechanism may result in the exchange of homologous chromosomes (crossover) and the conversion of the allelic sequence that breaks into the one that does not break (biased gene conversion). Biased gene conversion results in a transmission advantage for the allele that does not break, thus preventing recombination and rendering recombination hotspots transient. How is it possible that recombination hotspots persist over evolutionary time (maintaining the average chromosomal crossover rate) when they are self-destructive? This fundamental question is known as the recombination hotspot paradox and has attracted much attention in recent years. Yet, that attention has not translated into a fully satisfactory answer. No existing model adequately explains all aspects of the recombination hotspot paradox. Here, we formulate an intragenomic conflict model resulting in Red Queen dynamics that fully accounts for all empirical observations regarding the molecular mechanisms of recombination hotspots, the nonrandom targeting of the recombination machinery to hotspots and the evolutionary dynamics of hotspot turnover.
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Affiliation(s)
- F Ubeda
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA.
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362
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363
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Miller WJ, Ehrman L, Schneider D. Infectious speciation revisited: impact of symbiont-depletion on female fitness and mating behavior of Drosophila paulistorum. PLoS Pathog 2010; 6:e1001214. [PMID: 21151959 PMCID: PMC2996333 DOI: 10.1371/journal.ppat.1001214] [Citation(s) in RCA: 146] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 10/27/2010] [Indexed: 11/18/2022] Open
Abstract
The neotropical Drosophila paulistorum superspecies, consisting of at least six geographically overlapping but reproductively isolated semispecies, has been the object of extensive research since at least 1955, when it was initially trapped mid-evolution in flagrant statu nascendi. In this classic system females express strong premating isolation patterns against mates belonging to any other semispecies, and yet uncharacterized microbial reproductive tract symbionts were described triggering hybrid inviability and male sterility. Based on theoretical models and limited experimental data, prime candidates fostering symbiont-driven speciation in arthropods are intracellular bacteria belonging to the genus Wolbachia. They are maternally inherited symbionts of many arthropods capable of manipulating host reproductive biology for their own benefits. However, it is an ongoing debate as to whether or not reproductive symbionts are capable of driving host speciation in nature and if so, to what extent. Here we have reevaluated this classic case of infectious speciation by means of present day molecular approaches and artificial symbiont depletion experiments. We have isolated the α-proteobacteria Wolbachia as the maternally transmitted core endosymbionts of all D. paulistorum semispecies that have coevolved towards obligate mutualism with their respective native hosts. In hybrids, however, these mutualists transform into pathogens by overreplication causing embryonic inviability and male sterility. We show that experimental reduction in native Wolbachia titer causes alterations in sex ratio, fecundity, and mate discrimination. Our results indicate that formerly designated Mycoplasma-like organisms are most likely Wolbachia that have evolved by becoming essential mutualistic symbionts in their respective natural hosts; they have the potential to trigger pre- and postmating isolation. Furthermore, in light of our new findings, we revisit the concept of infectious speciation and discuss potential mechanisms that can restrict or promote symbiont-induced speciation at post- and prezygotic levels in nature and under artificial laboratory conditions.
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Affiliation(s)
- Wolfgang J Miller
- Laboratories of Genome Dynamics, Center of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria.
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364
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Eizaguirre C, Lenz TL. Major histocompatibility complex polymorphism: dynamics and consequences of parasite-mediated local adaptation in fishes. JOURNAL OF FISH BIOLOGY 2010; 77:2023-2047. [PMID: 21133915 DOI: 10.1111/j.1095-8649.2010.02819.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Parasitism is a common form of life and represents a strong selective pressure for host organisms. In response to this evolutionary pressure, vertebrates have developed genetically coded defences such as the major histocompatibility complex (MHC). Mechanisms of parasite-mediated selection not only maintain outstanding polymorphism in these genes but have also been proposed to further promote host population divergence and ultimately speciation because it can drive evolution of local adaptation in which MHC genes play a crucial role. This review first highlights the dynamics and complexity of parasite-mediated selection in natural systems, which not only depends on dominating parasite strategies and on the taxonomic diversity of the parasite community but also includes the differences in parasite communities between habitats and niches, creating divergent selection on locally adapted populations. Then the different ways in which MHC genes potentially allow vertebrates to respond to these dynamics and to adapt locally are outlined. Finally, it is proposed that varying selection strength in time and space may lead to variation in the strength of precopulatory reproductive isolation which has evolved to maintain local adaptation.
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Affiliation(s)
- C Eizaguirre
- Leibniz Institute for Marine Sciences (IFM GEOMAR), Department of Evolutionary Ecology of Marine Fishes, Düsternbrooker Weg 20, 24105, Kiel, Germany.
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365
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Luijckx P, Ben-Ami F, Mouton L, Du Pasquier L, Ebert D. Cloning of the unculturable parasite Pasteuria ramosa and its Daphnia host reveals extreme genotype-genotype interactions. Ecol Lett 2010; 14:125-31. [PMID: 21091597 DOI: 10.1111/j.1461-0248.2010.01561.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The degree of specificity in host-parasite interactions has important implications for ecology and evolution. Unfortunately, specificity can be difficult to determine when parasites cannot be cultured. In such cases, studies often use isolates of unknown genetic composition, which may lead to an underestimation of specificity. We obtained the first clones of the unculturable bacterium Pasteuria ramosa, a parasite of Daphnia magna. Clonal genotypes of the parasite exhibited much more specific interactions with host genotypes than previous studies using isolates. Clones of P. ramosa infected fewer D. magna genotypes than isolates and host clones were either fully susceptible or fully resistant to the parasite. Our finding enhances our understanding of the evolution of virulence and coevolutionary dynamics in this system. We recommend caution when using P. ramosa isolates as the presence of multiple genotypes may influence the outcome and interpretation of some experiments.
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Affiliation(s)
- Pepijn Luijckx
- Institut of Zoology, Evolutionsbiologie, University of Basel, Basel, Switzerland.
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366
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Hoebe PN, Stift M, Holub EB, Mable BK. The effect of mating system on growth of Arabidopsis lyrata in response to inoculation with the biotrophic parasite Albugo candida. J Evol Biol 2010; 24:391-401. [PMID: 21091813 DOI: 10.1111/j.1420-9101.2010.02177.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The effects of variation in host reproductive systems on response to pathogens are not well understood. We inoculated individuals from outcrossing and inbreeding populations of North American Arabidopsis lyrata with Albugo candida (white blister rust) to test the effect of mating system and heterozygosity on disease response. We observed three host infection phenotypes, classified as fully resistant, partially resistant and fully susceptible. Overall, inbreeding populations had more susceptible and fewer partially resistant individuals than outcrossing populations, but the highest proportion of resistant individuals was found in two of the inbreeding populations. Mating system did not affect relative growth rate of inoculated plants, but there were strong effects of population and infection phenotype. We conclude that mating system per se does not determine the resistance of natural A. lyrata populations to infection by Albugo, but that the increased variability in responses among inbreeding populations may be due to reduced effective population size.
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Affiliation(s)
- P N Hoebe
- Division of Ecology and Evolutionary Biology, University of Glasgow, Glasgow, UK
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367
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Antonovics J, Thrall PH, Burdon JJ, Laine AL. Partial resistance in the Linum-Melampsora host-pathogen system: does partial resistance make the red queen run slower? Evolution 2010; 65:512-22. [PMID: 21029078 DOI: 10.1111/j.1558-5646.2010.01146.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Five levels of disease expression were scored in a cross-inoculation study of 120 host and 60 pathogen lines of wild flax Linum marginale and its rust fungus Melampsora lini sampled from six natural populations. Patterns of partial resistance showed clear evidence of gene-for-gene interactions, with particular levels of partial resistance occurring in specific host-pathogen combinations. Sympatric and putatively more highly coevolved host-pathogen combinations had a lower frequency of partial resistance types relative to allopatric combinations. Sympatric host-pathogen combinations also showed a lower diversity of resistance responses, but there was a trend toward a greater fraction of this variance being determined by pathogen-genotype × host-genotype interactions. In this system, there was no evidence that partial resistances slow host-pathogen coevolution. The analyses show that if variation is generated by among population host or pathogen dispersal, then coevolution occurs largely by pathogens overcoming the partial resistances that are generated.
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Affiliation(s)
- Janis Antonovics
- Department of Biology, University of Virginia, Charlottesville, Virginia 22904, USA.
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368
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Wolinska J, Spaak P, Koerner H, Petrusek A, Seda J, Giessler S. Transmission mode affects the population genetic structure of Daphnia parasites. J Evol Biol 2010; 24:265-73. [PMID: 21044206 DOI: 10.1111/j.1420-9101.2010.02163.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Parasite life cycle variation can shape parasite evolution, by predisposing them towards different population genetic structures. We compared the population genetic structure of two co-occurring parasite species of Daphnia, to collect evidence for their expected transmission modes. The ichthyosporean Caullerya mesnili has a direct life cycle, whereas the microsporidian Berwaldia schaefernai is hypothesized to require passage through a secondary host. The parasites were collected from three geographically isolated Daphnia populations. The nucleotide variation in the internal transcribed spacer (ITS) region was assessed at the within-individual, within-population and among-population levels, using amova. We detected significant partitioning at all levels, except for a lack of among-population variation in Berwaldia. This was confirmed by neighbour-joining and principal component analyses; Caullerya populations were distinct from each other, while there was much overlap among parasite isolates representing different populations of Berwaldia. This all implies a higher amount of gene flow for Berwaldia, consistent with the hypothesized transmission mode.
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Affiliation(s)
- J Wolinska
- Department Biologie II, Evolutionsökologie, Ludwig-Maximilians-Universität, München, Germany.
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369
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Abstract
The Red Queen hypothesis is based on the assumption that parasites must genetically match their hosts to infect them successfully. If the parasites fail, they are assumed to be killed by the host's immune system. Here, we tested this using sympatric (mostly susceptible) and allopatric (mostly resistant) populations of a freshwater snail and its trematode parasite. We determined whether parasites which do not infect are either killed or passed through the host's digestive tract and remain infectious. Our results show that parasites do not get a second chance: they either infect or are killed by the host. The results suggest strong selection against parasites that are not adapted to local host genotypes.
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Affiliation(s)
- Kayla C King
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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370
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Graham AL, Shuker DM, Pollitt LC, Auld SKJR, Wilson AJ, Little TJ. Fitness consequences of immune responses: strengthening the empirical framework for ecoimmunology. Funct Ecol 2010. [DOI: 10.1111/j.1365-2435.2010.01777.x] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Andrea L. Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, 08 544, USA
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3JT, UK
- Centre for Immunity, Infection, and Evolution; School of Biological Sciences, University of Edinburgh, EH9 3JT, UK
| | | | - Laura C. Pollitt
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3JT, UK
| | - Stuart K. J. R. Auld
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3JT, UK
| | - Alastair J. Wilson
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3JT, UK
| | - Tom J. Little
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3JT, UK
- Centre for Immunity, Infection, and Evolution; School of Biological Sciences, University of Edinburgh, EH9 3JT, UK
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371
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Pauwels K, De Meester L, Decaestecker E, Stoks R. Phenoloxidase but not lytic activity reflects resistance against Pasteuria ramosa in Daphnia magna. Biol Lett 2010; 7:156-9. [PMID: 20810432 DOI: 10.1098/rsbl.2010.0634] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The field of ecological immunology strongly relies on indicators of immunocompetence. Two major indicators in invertebrates, the activity of phenoloxidase (PO) and lytic activity have recently been questioned in studies showing that, across a natural range of baseline levels, these indicators did not predict resistance against a manipulated challenge with natural parasites. We confirmed this finding by showing that baseline levels of PO and lytic activity in the host Daphnia magna were not related to spore load of the parasite Pasteuria ramosa. Yet, PO levels in infected hosts did predict spore load, indicating PO activity can be useful as an indicator of immunocompetence in this model parasite-host system.
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Affiliation(s)
- Kevin Pauwels
- Laboratory of Aquatic Ecology and Evolutionary Biology, K.U. Leuven, Charles Deberiotstraat 32, B-3000 Leuven, Belgium.
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372
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Orsini L, Decaestecker E, De Meester L, Pfrender ME, Colbourne JK. Genomics in the ecological arena. Biol Lett 2010; 7:2-3. [PMID: 20702453 DOI: 10.1098/rsbl.2010.0629] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This meeting report presents the cutting-edge research that is developing around the waterflea Daphnia, an emerging model system in environmental genomics. Daphnia has been a model species in ecology, toxicology and evolution for many years and is supported by a large community of ecologists, evolutionary biologists and ecotoxicologists. Thanks to new advances in genomics and transciptomics and to the sustained efforts of the Daphnia Genomics Consortium (DGC), Daphnia is also rapidly developing as a model system in environmental genomics. Advances in this emerging field were presented at the DGC 2010, held for the first time in a European University. During the meeting, a plethora of elegant studies were presented on the mechanisms of responses to environmental challenges using recently developed genomic tools. The DGC 2010 is a concrete example of the new trends in ecology and evolution. The times are mature for the application of innovative genomic and transcriptomic tools for studies of environmental genomics in non-model organisms.
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Affiliation(s)
- Luisa Orsini
- Laboratory of Aquatic Ecology and Evolutionary Biology, , K.U. Leuven, Ch. Deberiotstraat 32, 3000 Leuven, Belgium.
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373
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Schoebel CN, Tellenbach C, Spaak P, Wolinska J. Temperature effects on parasite prevalence in a natural hybrid complex. Biol Lett 2010; 7:108-11. [PMID: 20702454 DOI: 10.1098/rsbl.2010.0616] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Both host susceptibility and parasite infectivity commonly have a genetic basis, and can therefore be shaped by coevolution. However, these traits are often sensitive to environmental variation, resulting in genotype-by-environment interactions. We tested the influence of temperature on host-parasite genetic specificity in the Daphnia longispina hybrid complex, exposed to the protozoan parasite Caullerya mesnili. Infection rates were higher at low temperature. Furthermore, significant differences between host clones, but not between host taxa, and a host genotype-by-temperature interaction were observed.
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Affiliation(s)
- Corine N Schoebel
- Eawag, Aquatic Ecology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
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374
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Fitness and virulence of a bacterial endoparasite in an environmentally stressed crustacean host. Parasitology 2010; 138:122-31. [DOI: 10.1017/s0031182010000995] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYHost-parasite interactions are shaped by the co-evolutionary arms race of parasite virulence, transmission success as well as host resistance and recovery. The virulence and fitness of parasites may depend on host condition, which is mediated, for instance, by host energy constraints. Here, we investigated to what extent stress imposed by predation threat and environmental pollutants influences host-parasite interactions. We challenged the crustacean hostDaphnia magnawith the sterilizing bacterial endoparasitePasteuria ramosaand simultaneously exposed the host to fish kairomones, the pesticide carbaryl or both stressors. While parasite virulence, measured as impact on host mortality and sterilization, increased markedly after short-term pesticide exposure, it was not influenced by predation threat. Parasite fitness, measured in terms of produced transmission stages, decreased both in fish and pesticide treatments. This effect was much stronger under predation threat than carbaryl exposure, and was attributable to reduced somatic growth of the host, presumably resulting in fewer resources for parasite development. While the indirect impact of both stressors on spore loads provides evidence for host condition-dependent parasite fitness, the finding of increased virulence only under carbaryl exposure indicates a stronger physiological impact of the neurotoxic chemical compared with the effect of a non-toxic fish kairomone.
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375
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Anderson B, Terblanche JS, Ellis AG. Predictable patterns of trait mismatches between interacting plants and insects. BMC Evol Biol 2010; 10:204. [PMID: 20604973 PMCID: PMC2927919 DOI: 10.1186/1471-2148-10-204] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 07/07/2010] [Indexed: 11/10/2022] Open
Abstract
Background There are few predictions about the directionality or extent of morphological trait (mis)matches between interacting organisms. We review and analyse studies on morphological trait complementarity (e.g. floral tube length versus insect mouthpart length) at the population and species level. Results Plants have consistently more exaggerated morphological traits than insects at high trait magnitudes and in some cases less exaggerated traits than insects at smaller trait magnitudes. This result held at the population level, as well as for phylogenetically adjusted analyses at the species-level and for both pollination and host-parasite interactions, perhaps suggesting a general pattern. Across communities, the degree of trait mismatch between one specialist plant and its more generalized pollinator was related to the level of pollinator specialization at each site; the observed pattern supports the "life-dinner principle" of selection acting more strongly on species with more at stake in the interaction. Similarly, plant mating system also affected the degree of trait correspondence because selfing reduces the reliance on pollinators and is analogous to pollination generalization. Conclusions Our analyses suggest that there are predictable "winners" and "losers" of evolutionary arms races and the results of this study highlight the fact that breeding system and the degree of specialization can influence the outcome.
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Affiliation(s)
- Bruce Anderson
- Plant Animal Interactions, Botany and Zoology Department, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
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376
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Jansen M, Stoks R, Decaestecker E, Coors A, Van De Meutter F, De Meester L. Local exposure shapes spatial patterns in infectivity and community structure of Daphnia parasites. J Anim Ecol 2010; 79:1023-33. [PMID: 20584096 DOI: 10.1111/j.1365-2656.2010.01718.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
1. Spatial patterns in parasite community structure are probably driven by the availability of infectious stages. This is because hosts become infected through picking up infectious stages from their environment. Several studies have, however, reported strong genotype by genotype interactions and parasite-mediated selection in hosts. This leads to the prediction of a parasite by host population interaction with respect to infection rates and intensities, which may also shape spatial patterns in parasite community structure. 2. Using the water flea Daphnia magna and its microparasites as a model, we carried out a laboratory experiment to test explicitly to what extent parasite community structure in host populations is determined by the availability of infectious stages in the sediment they are exposed to, and to what extent host population identity and location play a role. 3. We exposed 10 D. magna host populations each to sediment of their own habitat and sediment of the other nine habitats, and monitored the parasite community of the resulting experimental populations. 4. Sediment seems to be a strong determinant of parasite infection rates, while there was no overall effect of host population. Sympatric parasite and host population combinations did in most cases not result in significantly different infection rates than allopatric parasite and host combinations. Our results indicate that spore availability could be the key variable determining parasite community structure in natural Daphnia populations.
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Affiliation(s)
- Mieke Jansen
- Laboratory of Aquatic Ecology and Evolutionary Biology, K.U.Leuven, Ch. Deberiotstraat 32, 3000 Leuven, Belgium.
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377
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Strong effects of amoebae grazing on the biomass and genetic structure of a Microcystis bloom (Cyanobacteria). Environ Microbiol 2010; 12:2797-813. [DOI: 10.1111/j.1462-2920.2010.02249.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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378
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Abstract
The Red Queen hypothesis posits a promising way to explain the widespread existence of sexual reproduction despite the cost of producing males. The essence of the hypothesis is that coevolutionary interactions between hosts and parasites select for the genetic diversification of offspring via cross-fertilization. Here, I relax a common assumption of many Red Queen models that each host is exposed to one parasite. Instead, I assume that the number of propagules encountered by each host depends on the number of infected hosts in the previous generation, which leads to additional complexities. The results suggest that epidemiological feedbacks, combined with frequency-dependent selection, could lead to the long-term persistence of sex under biologically reasonable conditions.
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Affiliation(s)
- C M Lively
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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379
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Lively CM. A Review of Red Queen Models for the Persistence of Obligate Sexual Reproduction. J Hered 2010; 101 Suppl 1:S13-20. [DOI: 10.1093/jhered/esq010] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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380
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Multiple reciprocal adaptations and rapid genetic change upon experimental coevolution of an animal host and its microbial parasite. Proc Natl Acad Sci U S A 2010; 107:7359-64. [PMID: 20368449 DOI: 10.1073/pnas.1003113107] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The coevolution between hosts and parasites is predicted to have complex evolutionary consequences for both antagonists, often within short time periods. To date, conclusive experimental support for the predictions is available mainly for microbial host systems, but for only a few multicellular host taxa. We here introduce a model system of experimental coevolution that consists of the multicellular nematode host Caenorhabditis elegans and the microbial parasite Bacillus thuringiensis. We demonstrate that 48 host generations of experimental coevolution under controlled laboratory conditions led to multiple changes in both parasite and host. These changes included increases in the traits of direct relevance to the interaction such as parasite virulence (i.e., host killing rate) and host resistance (i.e., the ability to survive pathogens). Importantly, our results provide evidence of reciprocal effects for several other central predictions of the coevolutionary dynamics, including (i) possible adaptation costs (i.e., reductions in traits related to the reproductive rate, measured in the absence of the antagonist), (ii) rapid genetic changes, and (iii) an overall increase in genetic diversity across time. Possible underlying mechanisms for the genetic effects were found to include increased rates of genetic exchange in the parasite and elevated mutation rates in the host. Taken together, our data provide comprehensive experimental evidence of the consequences of host-parasite coevolution, and thus emphasize the pace and complexity of reciprocal adaptations associated with these antagonistic interactions.
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381
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Dercole F, Ferriere R, Rinaldi S. Chaotic Red Queen coevolution in three-species food chains. Proc Biol Sci 2010; 277:2321-30. [PMID: 20356888 DOI: 10.1098/rspb.2010.0209] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Coevolution between two antagonistic species follows the so-called 'Red Queen dynamics' when reciprocal selection results in an endless series of adaptation by one species and counteradaptation by the other. Red Queen dynamics are 'genetically driven' when selective sweeps involving new beneficial mutations result in perpetual oscillations of the coevolving traits on the slow evolutionary time scale. Mathematical models have shown that a prey and a predator can coevolve along a genetically driven Red Queen cycle. We found that embedding the prey-predator interaction into a three-species food chain that includes a coevolving superpredator often turns the genetically driven Red Queen cycle into chaos. A key condition is that the prey evolves fast enough. Red Queen chaos implies that the direction and strength of selection are intrinsically unpredictable beyond a short evolutionary time, with greatest evolutionary unpredictability in the superpredator. We hypothesize that genetically driven Red Queen chaos could explain why many natural populations are poised at the edge of ecological chaos. Over space, genetically driven chaos is expected to cause the evolutionary divergence of local populations, even under homogenizing environmental fluctuations, and thus to promote genetic diversity among ecological communities over long evolutionary time.
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Affiliation(s)
- Fabio Dercole
- DEI, Politecnico di Milano, Via Ponzio 34/5, 20133 Milan, Italy
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382
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Abstract
The past is never dead. It's not even past William Faulkner (1951)
Bacteria can acquire heritable immunity to viral (phage) enemies by incorporating phage DNA into their own genome. This mechanism of anti-viral defence, known by the acronym CRISPR, simultaneously stores detailed information about current and past enemies and the evolved resistance to them. As a high-resolution genetic marker that is intimately tied with the host–pathogen interaction, the CRISPR system offers a unique, and relatively untapped, opportunity to study epidemiological and coevolutionary dynamics in microbial communities that were previously neglected because they could not be cultured in the laboratory. We briefly review the molecular mechanisms of CRISPR-mediated host–pathogen resistance, before assessing their potential importance for coevolution in nature, and their utility as a means of studying coevolutionary dynamics through metagenomics and laboratory experimentation.
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Affiliation(s)
- Pedro F Vale
- Institute of Evolutionary Biology, University of Edinburgh, The Kings Buildings, West Mains Road, Edinburgh EH9 3JT, UK.
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383
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Mauchline TH, Mohan S, Davies KG, Schaff JE, Opperman CH, Kerry BR, Hirsch PR. A method for release and multiple strand amplification of small quantities of DNA from endospores of the fastidious bacterium Pasteuria penetrans. Lett Appl Microbiol 2010; 50:515-21. [PMID: 20302597 DOI: 10.1111/j.1472-765x.2010.02830.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS To establish a reliable protocol to extract DNA from Pasteuria penetrans endospores for use as template in multiple strand amplification, thus providing sufficient material for genetic analyses. To develop a highly sensitive PCR-based diagnostic tool for P. penetrans. METHODS AND RESULTS An optimized method to decontaminate endospores, release and purify DNA enabled multiple strand amplification. DNA purity was assessed by cloning and sequencing gyrB and 16S rRNA gene fragments obtained from PCR using generic primers. Samples indicated to be 100%P. penetrans by the gyrB assay were estimated at 46% using the 16S rRNA gene. No bias was detected on cloning and sequencing 12 housekeeping and sporulation gene fragments from amplified DNA. The detection limit by PCR with Pasteuria-specific 16S rRNA gene primers following multiple strand amplification of DNA extracted using the method was a single endospore. CONCLUSIONS Generation of large quantities DNA will facilitate genomic sequencing of P. penetrans. Apparent differences in sample purity are explained by variations in 16S rRNA gene copy number in Eubacteria leading to exaggerated estimations of sample contamination. Detection of single endospores will facilitate investigations of P. penetrans molecular ecology. SIGNIFICANCE AND IMPACT OF THE STUDY These methods will advance studies on P. penetrans and facilitate research on other obligate and fastidious micro-organisms where it is currently impractical to obtain DNA in sufficient quantity and quality.
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Affiliation(s)
- T H Mauchline
- Nematode Interactions Unit, Department of Plant Pathology and Microbiology, Rothamsted Research, Harpenden, Hertfordshire, UK.
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384
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Affiliation(s)
- Curtis M Lively
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
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385
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Abstract
Populations living in a spatially and temporally changing environment can adapt to the changing optimum and/or migrate toward favorable habitats. Here we extend previous analyses with a static optimum to allow the environment to vary in time as well as in space. The model follows both population dynamics and the trait mean under stabilizing selection, and the outcomes can be understood by comparing the loads due to genetic variance, dispersal, and temporal change. With fixed genetic variance, we obtain two regimes: (1) adaptation that is uniform along the environmental gradient and that responds to the moving optimum as expected for panmictic populations and when the spatial gradient is sufficiently steep, and (2) a population with limited range that adapts more slowly than the environmental optimum changes in both time and space; the population therefore becomes locally extinct and migrates toward suitable habitat. We also use a population-genetic model with many loci to allow genetic variance to evolve, and we show that the only solution now has uniform adaptation.
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Affiliation(s)
- Jitka Polechová
- Biomathematics and Statistics Scotland, James Clerk Maxwell Building, King's Buildings, Edinburgh EH9 3JZ, Scotland, United Kingdom.
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386
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Tellier A, Brown J. The Influence of Perenniality and Seed Banks on Polymorphism in Plant‐Parasite Interactions. Am Nat 2009; 174:769-79. [DOI: 10.1086/646603] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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387
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Mouton L, Traunecker E, McElroy K, Du Pasquier L, Ebert D. Identification of a polymorphic collagen-like protein in the crustacean bacteria Pasteuria ramosa. Res Microbiol 2009; 160:792-9. [DOI: 10.1016/j.resmic.2009.08.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 08/10/2009] [Accepted: 08/26/2009] [Indexed: 11/24/2022]
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388
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Molecular identification and hidden diversity of novel Daphnia parasites from European lakes. Appl Environ Microbiol 2009; 75:7051-9. [PMID: 19767459 DOI: 10.1128/aem.01306-09] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Parasites play important roles in local population dynamics and genetic structure. However, due to insufficient diagnostic tools, detailed host-parasite interactions may remain concealed by hidden parasite diversity in natural systems. Microscopic examination of 19 European lake Daphnia populations revealed the presence of three groups of parasites: fungi, microsporidia, and oomycetes. For most of these parasites no genetic markers have been described so far. Based on sequence similarities of the nuclear small-subunit and internal transcribed spacer (ITS) rRNA gene regions, one fungus, four microsporidian, and nine oomycete taxa were discovered in 147 infected Daphnia (and/or three other zooplankton crustaceans). Additionally, cloning of rRNA gene regions revealed parasite sequence variation within host individuals. This was most pronounced in the ITS region of one microsporidian taxon, where the within-host sequence variation ranged from 1.7% to 5.3% polymorphic sites for parasite isolates from 14 different geographical locations. Interestingly, the parasite isolates from close locations grouped together based on sequence similarities, suggesting that there was parasite dispersal. Taken together, the data obtained in this study revealed hidden diversity of parasite communities in Daphnia lake populations. Moreover, a higher level of resolution for identifying parasite strains makes it possible to test new hypotheses with respect to parasite dispersal, transmission routes, and coinfection.
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389
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Hornett EA, Charlat S, Wedell N, Jiggins CD, Hurst GDD. Rapidly shifting sex ratio across a species range. Curr Biol 2009; 19:1628-31. [PMID: 19747825 DOI: 10.1016/j.cub.2009.07.071] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 07/14/2009] [Accepted: 07/27/2009] [Indexed: 11/26/2022]
Abstract
Sex ratios are subject to distortion by a range of inherited parasites. Although it has been predicted that the presence of these elements will result in spatial and temporal variation in host sex ratio, testing of this hypothesis has been constrained by availability of historical data. We here determine spatial and temporal variation in sex ratio in a interaction between a butterfly and male-killing Wolbachia bacteria by assaying infection presence in museum specimens, and from this inferring infection prevalence and phenotype in historical populations. Comparison of contemporary and museum samples revealed profound change in four of five populations examined. Two populations become extremely female biased, associated with spread of the male-killer bacterium. One evolved from extremely female biased to a sex ratio near parity, resulting from the infection losing male-killing activity. The final population fluctuated widely in sex ratio, associated with varying frequency of the male killer. We conclude that asynchronous invasion and decline of sex-ratio distorters combines with the evolution of host suppressors to produce a rapidly changing mosaic of sex ratio. As a consequence, the reproductive ecology of the host species is likely to be fundamentally altered over short time scales. Further, the study demonstrates the utility of museum specimens as "silent witnesses" of evolutionary change.
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Affiliation(s)
- Emily A Hornett
- School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, UK.
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390
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Abstract
Why don't asexual females replace sexual females in most natural populations of eukaryotes? One promising explanation is that parasites could counter the reproductive advantages of asexual reproduction by exerting frequency-dependent selection against common clones (the Red Queen hypothesis). One apparent limitation of the Red Queen theory, however, is that parasites would seem to be required by theory to be highly virulent. In the present study, I present a population-dynamic view of competition between sexual females and asexual females that interact with co-evolving parasites. The results show that asexual populations have higher carrying capacities, and more unstable population dynamics, than sexual populations. The results also suggest that the spread of a clone into a sexual population could increase the effective parasite virulence as population density increases. This combination of parasite-mediated frequency-dependent selection, and density-dependent virulence, could lead to the coexistence of sexual and asexual reproductive strategies and the long-term persistence of sex.
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Affiliation(s)
- C M Lively
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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391
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Bérénos C, Schmid-Hempel P, Wegner KM. Evolution of host resistance and trade-offs between virulence and transmission potential in an obligately killing parasite. J Evol Biol 2009; 22:2049-56. [PMID: 19732263 DOI: 10.1111/j.1420-9101.2009.01821.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Standard epidemiological theory predicts that parasites, which continuously release propagules during infection, face a trade-off between virulence and transmission. However, little is known how host resistance and parasite virulence change during coevolution with obligate killers. To address this question we have set up a coevolution experiment evolving Nosema whitei on eight distinct lines of Tribolium castaneum. After 11 generations we conducted a time-shift experiment infecting both the coevolved and the replicate control host lines with the original parasite source, and coevolved parasites from generation 8 and 11. We found higher survival in the coevolved host lines than in the matching control lines. In the parasite populations, virulence measured as host mortality decreased during coevolution, while sporeload stayed constant. Both patterns are compatible with adaptive evolution by selection for resistance in the host and by trade-offs between virulence and transmission potential in the parasite.
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Affiliation(s)
- C Bérénos
- Experimental Ecology, Institute of Integrative Biology, ETH Zürich, 8092 Zürich, Switzerland.
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392
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Zhang QG, Buckling A, Ellis RJ, Godfray HCJ. COEVOLUTION BETWEEN COOPERATORS AND CHEATS IN A MICROBIAL SYSTEM. Evolution 2009; 63:2248-56. [DOI: 10.1111/j.1558-5646.2009.00708.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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393
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Red Queen dynamics with non-standard fitness interactions. PLoS Comput Biol 2009; 5:e1000469. [PMID: 19680432 PMCID: PMC2715217 DOI: 10.1371/journal.pcbi.1000469] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Accepted: 07/15/2009] [Indexed: 12/04/2022] Open
Abstract
Antagonistic coevolution between hosts and parasites can involve rapid fluctuations of genotype frequencies that are known as Red Queen dynamics. Under such dynamics, recombination in the hosts may be advantageous because genetic shuffling can quickly produce disproportionately fit offspring (the Red Queen hypothesis). Previous models investigating these dynamics have assumed rather simple models of genetic interactions between hosts and parasites. Here, we assess the robustness of earlier theoretical predictions about the Red Queen with respect to the underlying host-parasite interactions. To this end, we created large numbers of random interaction matrices, analysed the resulting dynamics through simulation, and ascertained whether recombination was favoured or disfavoured. We observed Red Queen dynamics in many of our simulations provided the interaction matrices exhibited sufficient ‘antagonicity’. In agreement with previous studies, strong selection on either hosts or parasites favours selection for increased recombination. However, fast changes in the sign of linkage disequilibrium or epistasis were only infrequently observed and do not appear to be a necessary condition for the Red Queen hypothesis to work. Indeed, recombination was often favoured even though the linkage disequilibrium remained of constant sign throughout the simulations. We conclude that Red Queen-type dynamics involving persistent fluctuations in host and parasite genotype frequencies appear to not be an artefact of specific assumptions about host-parasite fitness interactions, but emerge readily with the general interactions studied here. Our results also indicate that although recombination is often favoured, some of the factors previously thought to be important in this process such as linkage disequilibrium fluctuations need to be reassessed when fitness interactions between hosts and parasites are complex. The Red Queen has become an eponym for rapid and perpetual evolutionary arms races between hosts and parasites. The Red Queen also lends her name to the idea that such arms races are at the core of the question of why sexual reproduction is so widespread among higher-level organisms. According to this view, recombination provides the hosts with an advantage that allows faster adaptation to the parasite population. To date, mathematical models trying to quantify Red Queen dynamics and the Red Queen hypothesis for the evolution of sex have generally made several simplifying assumptions about how host and parasite genotypes interact with each other (i.e., how they influence each other's fitness). In this article we present a model that allows for arbitrary patterns of fitness interactions between both parties. We demonstrate that the degree of ‘antagonicity’ in these interactions is decisive for whether Red Queen dynamics are observed, and assess the robustness of various previous results concerning the Red Queen hypothesis with respect to fitness interactions. Our results also make clear how difficult predictions of coevolutionary dynamics and selection for recombination are likely to be in real host-parasite systems.
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394
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Trotsenko YA, Medvedkova KA, Khmelenina VN, Eshinimayev BT. Thermophilic and thermotolerant aerobic methanotrophs. Microbiology (Reading) 2009. [DOI: 10.1134/s0026261709040018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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395
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Jokela J, Dybdahl MF, Lively CM. The maintenance of sex, clonal dynamics, and host-parasite coevolution in a mixed population of sexual and asexual snails. Am Nat 2009; 174 Suppl 1:S43-53. [PMID: 19441961 DOI: 10.1086/599080] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Sexual populations should be vulnerable to invasion and replacement by ecologically similar asexual females because asexual lineages have higher per capita growth rates. However, as asexual genotypes become common, they may also become disproportionately infected by parasites. The Red Queen hypothesis postulates that high infection rates in the common asexual clones could periodically favor the genetically diverse sexual individuals and promote the short-term coexistence of sexual and asexual populations. Testing this idea requires comparison of competing sexual and asexual lineages that are attacked by natural parasites. To date no such data have been available. Here, we report on long-term dynamics and parasite coevolution in a "mixed" (sexual and asexual) population of snails (Potamopyrgus antipodarum). We found that, within 7-10 years, the most common clones were almost completely replaced by initially rare clones in two different habitats, while sexuals persisted throughout the study period. The common clones, which were initially more resistant to infection, also became more susceptible to infection by sympatric (but not allopatric) parasites over the course of the study. These results are consistent with the Red Queen hypothesis and show that the coevolutionary dynamics predicted by the theory may also favor sexual reproduction in natural populations.
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Affiliation(s)
- Jukka Jokela
- 1EAWAG, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, 8600 Dübendorf, Switzerland.
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396
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Franco-Paredes C, Bottazzi ME, Hotez PJ. The unfinished public health agenda of chagas disease in the era of globalization. PLoS Negl Trop Dis 2009; 3:e470. [PMID: 19582139 PMCID: PMC2700253 DOI: 10.1371/journal.pntd.0000470] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Carlos Franco-Paredes
- Hospital Infantil de México, Federico
Gómez, México, D.F., México
- Department of Medicine, Emory University, Atlanta,
Georgia, United States of America
- * E-mail:
| | - Maria Elena Bottazzi
- Department of Microbiology, Immunology, and Tropical
Medicine, The George Washington University, Washington, D.C., United States of
America
- Sabin Vaccine Institute, Washington, D.C., United
States of America
| | - Peter J. Hotez
- Department of Microbiology, Immunology, and Tropical
Medicine, The George Washington University, Washington, D.C., United States of
America
- Sabin Vaccine Institute, Washington, D.C., United
States of America
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397
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Davies KG. Understanding the interaction between an obligate hyperparasitic bacterium, Pasteuria penetrans and its obligate plant-parasitic nematode host, Meloidogyne spp. ADVANCES IN PARASITOLOGY 2009; 68:211-45. [PMID: 19289196 DOI: 10.1016/s0065-308x(08)00609-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Pasteuria penetrans is an endospore-forming bacterium, which is a hyperparasite of root-knot nematodes Meloidogyne spp. that are economically important pests of a wide range of crops. The life cycle of the bacterium and nematode are described with emphasis on the bacterium's potential as a biocontrol agent. Two aspects that currently prohibit the commercial development of the bacterium as a biocontrol agent are the inability to culture it outside its host and its host specificity. Vegetative growth of the bacterium is possible in vitro; however, getting the vegetative stages of the bacterium to enter sporogenesis has been problematic. Insights from genomic survey sequences regarding the role of cation concentration and the phosphorylation of Spo0F have proved useful in inducing vegetative bacteria to sporulate. Similarly, genomic data have also proved useful in understanding the attachment of endospores to the cuticle of infective nematode juveniles, and a Velcro-like model of spore attachment is proposed that involves collagen-like fibres on the surface of the endospore interacting with mucins on the nematode cuticle. Ecological studies of the interactions between Daphnia and Pasteuria ramosa are examined and similarities are drawn between the co-evolution of virulence in the Daphnia system and that of plant-parasitic nematodes.
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Affiliation(s)
- Keith G Davies
- Plant Pathology and Microbiology, Rothamsted Research, Harpenden, United Kingdom
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398
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Jones LE, Becks L, Ellner SP, Hairston NG, Yoshida T, Fussmann GF. Rapid contemporary evolution and clonal food web dynamics. Philos Trans R Soc Lond B Biol Sci 2009; 364:1579-91. [PMID: 19414472 PMCID: PMC2690500 DOI: 10.1098/rstb.2009.0004] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Character evolution that affects ecological community interactions often occurs contemporaneously with temporal changes in population size, potentially altering the very nature of those dynamics. Such eco-evolutionary processes may be most readily explored in systems with short generations and simple genetics. Asexual and cyclically parthenogenetic organisms such as microalgae, cladocerans and rotifers, which frequently dominate freshwater plankton communities, meet these requirements. Multiple clonal lines can coexist within each species over extended periods, until either fixation occurs or a sexual phase reshuffles the genetic material. When clones differ in traits affecting interspecific interactions, within-species clonal dynamics can have major effects on the population dynamics. We first consider a simple predator-prey system with two prey genotypes, parametrized with data from a well-studied experimental system, and explore how the extent of differences in defence against predation within the prey population determine dynamic stability versus instability of the system. We then explore how increased potential for evolution affects the community dynamics in a more general community model with multiple predator and multiple prey genotypes. These examples illustrate how microevolutionary 'details' that enhance or limit the potential for heritable phenotypic change can have significant effects on contemporaneous community-level dynamics and the persistence and coexistence of species.
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Affiliation(s)
- Laura E. Jones
- Department of Ecology and Evolutionary Biology, Cornell UniversityCorson Hall, Ithaca, NY 14853-2701, USA
| | - Lutz Becks
- Department of Ecology and Evolutionary Biology, Cornell UniversityCorson Hall, Ithaca, NY 14853-2701, USA
| | - Stephen P. Ellner
- Department of Ecology and Evolutionary Biology, Cornell UniversityCorson Hall, Ithaca, NY 14853-2701, USA
| | - Nelson G. Hairston
- Department of Ecology and Evolutionary Biology, Cornell UniversityCorson Hall, Ithaca, NY 14853-2701, USA
| | - Takehito Yoshida
- Department of General Systems Studies, University of Tokyo3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan
| | - Gregor F. Fussmann
- Department of Biology, McGill University1205 Avenue Docteur-Penfield, Montreal, Quebec H3A 1B1, Canada
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399
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Abstract
1. The idea that parasites can affect host diversity is pervasive, and the possibility that parasites can increase host diversity is of particular interest. In this review, we focus on diversity in the resistance of hosts to their parasites, and on the different ways in which parasites can increase or decrease this resistance diversity. 2. Theoretically, parasites can exert many different types of selection on host populations, which each have consequences for host diversity. Specifically, theory predicts that parasites can exert negative frequency-dependent selection (NFDS) and disruptive selection on resistance, both of which increase host diversity, as well as directional selection and stabilizing selection on resistance, both of which decrease host diversity. 3. Despite these theoretical predictions, most biologists think of only NFDS or directional selection for increased resistance in response to parasitism. Here, we present empirical support for all of these types of selection occurring in natural populations. Interestingly, several recent studies demonstrate that there is spatiotemporal variation in the type of selection that occurs (and, therefore, in the effects of parasitism on host diversity). 4. A key question that remains, then, is: What determines the type of parasite-mediated selection that occurs? Theory demonstrates that the answer to this question lies, at least in part, with trade-offs associated with resistance. Specifically, the type of evolution that occurs depends critically on the strength and shape of these trade-offs. This, combined with empirical evidence for a strong effect of environment on the shape and strength of trade-offs, may explain the observed spatiotemporal variation in parasite-mediated selection. 5. We conclude that spatiotemporal variation in parasite-driven evolution is likely to be common, and that this variation may be driven by ecological factors. We suggest that the feedback between ecological and evolutionary dynamics in host-parasite interactions is likely to be a productive area of research. In particular, studies addressing the role of ecological factors (e.g. productivity and predation regimes) in driving the outcome of parasite-mediated selection on host populations are warranted. Such studies are necessary if we are to understand the mechanisms underlying the observed variation in the effects of parasites on host diversity.
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Affiliation(s)
- Meghan A Duffy
- School of Biology, Georgia Institute of Technology, Atlanta, GA 30332-0230, USA.
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Labbé P, Little TJ. ProPhenolOxidase in Daphnia magna: cDNA sequencing and expression in relation to resistance to pathogens. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2009; 33:674-680. [PMID: 19103220 DOI: 10.1016/j.dci.2008.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 11/27/2008] [Accepted: 11/27/2008] [Indexed: 05/27/2023]
Abstract
Invertebrates utilise the innate immune system when defending against pathogenic attack. However, except for some effectors as proPhenolOxidase (proPO), the innate immune response is less well understood outside model insect species, and its role in natural host-pathogen systems is generally not well documented. We have therefore initiated studies on the immune response of the crustacean Daphnia when exposed to the specialist endobacterial pathogen, Pasteuria ramosa. This study was focused on the proPO gene of Daphnia magna. D. magna possesses a single copy of proPO (as does its congener, D. pulex), but there was some evidence of alternative splicing. Analyses of sequence similarity in a range of arthropod taxa suggested that the proPO gene in Daphnia was as dissimilar to other crustaceans as it was to insects, while analysis on intraspecific variation indicated that the gene is highly conserved. ProPO was found to be significantly up-regulated within 1-4h following exposure to the bacteria. This is the first evidence of a Daphnia immune response, and our observations raise the possibility that the PhenolOxidase (PO) cascade is involved in the defence against pathogenic gram-positive bacteria.
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Affiliation(s)
- Pierrick Labbé
- University of Edinburgh, IEB, Ashworth Laboratory, Kings Buildings, Edinburgh, UK.
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