101
|
Tack AJM, Laine AL, Burdon JJ, Bissett A, Thrall PH. Below-ground abiotic and biotic heterogeneity shapes above-ground infection outcomes and spatial divergence in a host-parasite interaction. THE NEW PHYTOLOGIST 2015; 207:1159-1169. [PMID: 25872137 PMCID: PMC4523403 DOI: 10.1111/nph.13408] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 03/13/2015] [Indexed: 05/29/2023]
Abstract
We investigated the impact of below-ground and above-ground environmental heterogeneity on the ecology and evolution of a natural plant-pathogen interaction. We combined field measurements and a reciprocal inoculation experiment to investigate the potential for natural variation in abiotic and biotic factors to mediate infection outcomes in the association between the fungal pathogen Melampsora lini and its wild flax host, Linum marginale, where pathogen strains and plant lines originated from two ecologically distinct habitat types that occur in close proximity ('bog' and 'hill'). The two habitat types differed strikingly in soil moisture and soil microbiota. Infection outcomes for different host-pathogen combinations were strongly affected by the habitat of origin of the plant lines and pathogen strains, the soil environment and their interactions. Our results suggested that tradeoffs play a key role in explaining the evolutionary divergence in interaction traits among the two habitat types. Overall, we demonstrate that soil heterogeneity, by mediating infection outcomes and evolutionary divergence, can contribute to the maintenance of variation in resistance and pathogenicity within a natural host-pathogen metapopulation.
Collapse
Affiliation(s)
- Ayco J. M. Tack
- Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014 University of Helsinki, Finland
| | - Anna-Liisa Laine
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014 University of Helsinki, Finland
| | - Jeremy J. Burdon
- CSIRO Agriculture Flagship, GPO Box 1600, Canberra, A.C.T. 2601, Australia
| | - Andrew Bissett
- CSIRO Agriculture Flagship, GPO Box 1600, Canberra, A.C.T. 2601, Australia
| | - Peter H. Thrall
- CSIRO Agriculture Flagship, GPO Box 1600, Canberra, A.C.T. 2601, Australia
| |
Collapse
|
102
|
Delmas CEL, Mazet ID, Jolivet J, Delière L, Delmotte F. Simultaneous quantification of sporangia and zoospores in a biotrophic oomycete with an automatic particle analyzer: disentangling dispersal and infection potentials. J Microbiol Methods 2015; 107:169-75. [PMID: 25448022 DOI: 10.1016/j.mimet.2014.10.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 10/20/2014] [Accepted: 10/22/2014] [Indexed: 10/24/2022]
Abstract
Quantitative pathogenicity traits drive the fitness and dynamics of pathogens in agricultural ecosystems and are key determinants of the correct management of crop production over time. However, traits relating to infection potential (i.e. zoospore production) have been less thoroughly investigated in oomycetes than traits relating to dispersal (i.e. sporangium production). We simultaneously quantified sporangium and zoospore production in a biotrophic oomycete, for the joint assessment of life-cycle traits relating to dispersal and infection potentials. We used an automatic particle analyzer to count and size the sporangia and/or zoospores produced at t = 0 min (no zoospore release) and t = 100 min (zoospore release) in 43 Plasmopara viticola isolates growing on the susceptible Vitis vinifera cv. Cabernet Sauvignon. We were able to differentiate and quantify three types of propagules from different stages of the pathogen life cycle: full sporangia, empty sporangia and zoospores. The method was validated by comparing the sporangium and zoospore counts obtained with an automatic particle analyzer and under a stereomicroscope (manual counting). Each isolate produced a mean of 5.8 ± 1.9 (SD) zoospores per sporangium. Significant relationships were found between sporangium production and sporangium size (negative) and between sporangium size and the number of zoospores produced per sporangium (positive). However, there was a significant positive correlation between total sporangium production and total zoospore production. This procedure can provide a valid quantification of the production of both sporangia and zoospores by oomycetes in large numbers of samples, facilitating joint estimation of the dispersal and infection potentials of plant pathogens in various agro-ecological contexts.
Collapse
Affiliation(s)
- Chloé E L Delmas
- INRA, UMR1065 Santé et Agroécologie du Vignoble, Villenave d'Ornon, France.
| | | | | | | | | |
Collapse
|
103
|
Hesse E, Best A, Boots M, Hall AR, Buckling A. Spatial heterogeneity lowers rather than increases host-parasite specialization. J Evol Biol 2015; 28:1682-90. [PMID: 26135011 PMCID: PMC4973826 DOI: 10.1111/jeb.12689] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 06/19/2015] [Accepted: 06/24/2015] [Indexed: 11/26/2022]
Abstract
Abiotic environmental heterogeneity can promote the evolution of diverse resource specialists, which in turn may increase the degree of host-parasite specialization. We coevolved Pseudomonas fluorescens and lytic phage ϕ2 in spatially structured populations, each consisting of two interconnected subpopulations evolving in the same or different nutrient media (homogeneous and heterogeneous environments, respectively). Counter to the normal expectation, host-parasite specialization was significantly lower in heterogeneous compared with homogeneous environments. This result could not be explained by dispersal homogenizing populations, as this would have resulted in the heterogeneous treatments having levels of specialization equal to or greater than that of the homogeneous environments. We argue that selection for costly generalists is greatest when the coevolving species are exposed to diverse environmental conditions and that this can provide an explanation for our results. A simple coevolutionary model of this process suggests that this can be a general mechanism by which environmental heterogeneity can reduce rather than increase host-parasite specialization.
Collapse
Affiliation(s)
- E Hesse
- ESI, Biosciences, University of Exeter, Penryn, UK
| | - A Best
- School of Mathematics and Statistics, University of Sheffield, Sheffield, UK
| | - M Boots
- CLES, Biosciences, University of Exeter, Penryn, UK
| | | | - A Buckling
- ESI, Biosciences, University of Exeter, Penryn, UK
| |
Collapse
|
104
|
Abstract
The consequences of host–parasite coevolution are highly contingent on the qualitative coevolutionary dynamics: whether selection fluctuates (fluctuating selection dynamic; FSD), or is directional towards increasing infectivity/resistance (arms race dynamic; ARD). Both genetics and ecology can play an important role in determining whether coevolution follows FSD or ARD, but the ecological conditions under which FSD shifts to ARD, and vice versa, are not well understood. The degree of population mixing is thought to increase host exposure to parasites, hence selecting for greater resistance and infectivity ranges, and we hypothesize this promotes ARD. We tested this by coevolving bacteria and viruses in soil microcosms and found that population mixing shifted bacteria–virus coevolution from FSD to ARD. A simple theoretical model produced qualitatively similar results, showing that mechanisms that increase host exposure to parasites tend to push dynamics towards ARD. The shift from FSD to ARD with increased population mixing may help to explain variation in coevolutionary dynamics between different host–parasite systems, and more specifically the observed discrepancies between laboratory and field bacteria–virus coevolutionary studies.
Collapse
Affiliation(s)
- Pedro Gómez
- Department of Biosciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| | - Ben Ashby
- Department of Biosciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Angus Buckling
- Department of Biosciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| |
Collapse
|
105
|
Brockhurst MA, Chapman T, King KC, Mank JE, Paterson S, Hurst GDD. Running with the Red Queen: the role of biotic conflicts in evolution. Proc Biol Sci 2015; 281:rspb.2014.1382. [PMID: 25355473 PMCID: PMC4240979 DOI: 10.1098/rspb.2014.1382] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
What are the causes of natural selection? Over 40 years ago, Van Valen proposed the Red Queen hypothesis, which emphasized the primacy of biotic conflict over abiotic forces in driving selection. Species must continually evolve to survive in the face of their evolving enemies, yet on average their fitness remains unchanged. We define three modes of Red Queen coevolution to unify both fluctuating and directional selection within the Red Queen framework. Empirical evidence from natural interspecific antagonisms provides support for each of these modes of coevolution and suggests that they often operate simultaneously. We argue that understanding the evolutionary forces associated with interspecific interactions requires incorporation of a community framework, in which new interactions occur frequently. During their early phases, these newly established interactions are likely to drive fast evolution of both parties. We further argue that a more complete synthesis of Red Queen forces requires incorporation of the evolutionary conflicts within species that arise from sexual reproduction. Reciprocally, taking the Red Queen's perspective advances our understanding of the evolution of these intraspecific conflicts.
Collapse
Affiliation(s)
| | - Tracey Chapman
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Kayla C King
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Judith E Mank
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Steve Paterson
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Gregory D D Hurst
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| |
Collapse
|
106
|
Zhan J, Thrall PH, Papaïx J, Xie L, Burdon JJ. Playing on a pathogen's weakness: using evolution to guide sustainable plant disease control strategies. ANNUAL REVIEW OF PHYTOPATHOLOGY 2015; 53:19-43. [PMID: 25938275 DOI: 10.1146/annurev-phyto-080614-120040] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Wild plants and their associated pathogens are involved in ongoing interactions over millennia that have been modified by coevolutionary processes to limit the spatial extent and temporal duration of disease epidemics. These interactions are disrupted by modern agricultural practices and social activities, such as intensified monoculture using superior varieties and international trading of agricultural commodities. These activities, when supplemented with high resource inputs and the broad application of agrochemicals, create conditions uniquely conducive to widespread plant disease epidemics and rapid pathogen evolution. To be effective and durable, sustainable disease management requires a significant shift in emphasis to overtly include ecoevolutionary principles in the design of adaptive management programs aimed at minimizing the evolutionary potential of plant pathogens by reducing their genetic variation, stabilizing their evolutionary dynamics, and preventing dissemination of pathogen variants carrying new infectivity or resistance to agrochemicals.
Collapse
Affiliation(s)
- Jiasui Zhan
- Key Laboratory for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, 350002, China;
| | | | | | | | | |
Collapse
|
107
|
Carlsson-Granér U, Thrall PH. Host resistance and pathogen infectivity in host populations with varying connectivity. Evolution 2015; 69:926-38. [DOI: 10.1111/evo.12631] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 02/18/2015] [Indexed: 01/28/2023]
Affiliation(s)
- Ulla Carlsson-Granér
- Department of Ecology and Environmental Sciences; University of Umeå; S-90187 Umeå Sweden
| | - Peter H. Thrall
- CSIRO Agriculture Flagship GPO Box 1600; Canberra ACT 2601 Australia
| |
Collapse
|
108
|
Abstract
Hosts strongly influence parasite fitness. However, it is challenging to disentangle host effects on genetic vs plasticity-driven traits of parasites, since parasites can evolve quickly. It remains especially difficult to determine the causes and magnitude of parasite plasticity. In successive generations, parasites may respond plastically to better infect their current type of host, or hosts may produce generally 'good' or 'bad' quality parasites. Here, we characterized parasite plasticity by taking advantage of a system in which the parasite (the yeast Metschnikowia bicuspidata, which infects Daphnia) has no detectable heritable variation, preventing rapid evolution. In experimental infection assays, we found an effect of rearing host genotype on parasite infectivity, where host genotypes produced overall high or low quality parasite spores. Additionally, these plastically induced differences were gained or lost in just a single host generation. Together, these results demonstrate phenotypic plasticity in infectivity driven by the within-host rearing environment. Such plasticity is rarely investigated in parasites, but could shape epidemiologically important traits.
Collapse
|
109
|
Laine AL, Burdon JJ, Nemri A, Thrall PH. Host ecotype generates evolutionary and epidemiological divergence across a pathogen metapopulation. Proc Biol Sci 2015; 281:rspb.2014.0522. [PMID: 24870042 DOI: 10.1098/rspb.2014.0522] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The extent and speed at which pathogens adapt to host resistance varies considerably. This presents a challenge for predicting when--and where--pathogen evolution may occur. While gene flow and spatially heterogeneous environments are recognized to be critical for the evolutionary potential of pathogen populations, we lack an understanding of how the two jointly shape coevolutionary trajectories between hosts and pathogens. The rust pathogen Melampsora lini infects two ecotypes of its host plant Linum marginale that occur in close proximity yet in distinct populations and habitats. In this study, we found that within-population epidemics were different between the two habitats. We then tested for pathogen local adaptation at host population and ecotype level in a reciprocal inoculation study. Even after controlling for the effect of spatial structure on infection outcome, we found strong evidence of pathogen adaptation at the host ecotype level. Moreover, sequence analysis of two pathogen infectivity loci revealed strong genetic differentiation by host ecotype but not by distance. Hence, environmental variation can be a key determinant of pathogen population genetic structure and coevolutionary dynamics and can generate strong asymmetry in infection risks through space.
Collapse
Affiliation(s)
- Anna-Liisa Laine
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, PO Box 65, Helsinki 00014, Finland
| | - Jeremy J Burdon
- CSIRO Plant Industry, GPO Box 1600, Canberra, Australian Capital Territory 2601, Australia
| | - Adnane Nemri
- CSIRO Plant Industry, GPO Box 1600, Canberra, Australian Capital Territory 2601, Australia
| | - Peter H Thrall
- CSIRO Plant Industry, GPO Box 1600, Canberra, Australian Capital Territory 2601, Australia
| |
Collapse
|
110
|
Bruns E, Hood ME, Antonovics J. Rate of resistance evolution and polymorphism in long- and short-lived hosts. Evolution 2015; 69:551-60. [DOI: 10.1111/evo.12577] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 11/13/2014] [Indexed: 01/05/2023]
Affiliation(s)
- Emily Bruns
- Department of Biology; University of Virginia; Charlottesville Virginia 22903
| | - Michael E. Hood
- Department of Biology; Amherst College; Amherst Massachusetts 01002
| | - Janis Antonovics
- Department of Biology; University of Virginia; Charlottesville Virginia 22903
| |
Collapse
|
111
|
Lankau RA, Strauss SY. Newly rare or newly common: evolutionary feedbacks through changes in population density and relative species abundance, and their management implications. Evol Appl 2015; 4:338-53. [PMID: 25567977 PMCID: PMC3352561 DOI: 10.1111/j.1752-4571.2010.00173.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Accepted: 11/18/2010] [Indexed: 11/26/2022] Open
Abstract
Environmental management typically seeks to increase or maintain the population sizes of desirable species and to decrease population sizes of undesirable pests, pathogens, or invaders. With changes in population size come long-recognized changes in ecological processes that act in a density-dependent fashion. While the ecological effects of density dependence have been well studied, the evolutionary effects of changes in population size, via changes in ecological interactions with community members, are underappreciated. Here, we provide examples of changing selective pressures on, or evolution in, species as a result of changes in either density of conspecifics or changes in the frequency of heterospecific versus conspecific interactions. We also discuss the management implications of such evolutionary responses in species that have experienced rapid increases or decreases in density caused by human actions.
Collapse
Affiliation(s)
- Richard A Lankau
- Illinois Natural History Survey, University of Illinois Urbana-Champaign, IL, USA ; Department of Evolution and Ecology UC Davis, Davis, CA, USA
| | - Sharon Y Strauss
- Illinois Natural History Survey, University of Illinois Urbana-Champaign, IL, USA ; Department of Evolution and Ecology UC Davis, Davis, CA, USA
| |
Collapse
|
112
|
Burdon JJ, Thrall PH. Pathogen evolution across the agro-ecological interface: implications for disease management. Evol Appl 2015; 1:57-65. [PMID: 25567491 PMCID: PMC3352394 DOI: 10.1111/j.1752-4571.2007.00005.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 11/26/2007] [Indexed: 11/29/2022] Open
Abstract
Infectious disease is a major causal factor in the demography of human, plant and animal populations. While it is generally accepted in medical, veterinary and agricultural contexts that variation in host resistance and pathogen virulence and aggressiveness is of central importance to understanding patterns of infection, there has been remarkably little effort to directly investigate causal links between population genetic structure and disease dynamics, and even less work on factors influencing host–pathogen coevolution. The lack of empirical evidence is particularly surprising, given the potential for such variation to not only affect disease dynamics and prevalence, but also when or where new diseases or pathotypes emerge. Increasingly, this lack of knowledge has led to calls for an integrated approach to disease management, incorporating both ecological and evolutionary processes. Here, we argue that plant pathogens occurring in agro-ecosystems represent one clear example where the application of evolutionary principles to disease management would be of great benefit, as well as providing model systems for advancing our ability to generalize about the long-term coevolutionary dynamics of host–pathogen systems. We suggest that this is particularly the case given that agro-ecological host–pathogen interactions represent a diversity of situations ranging from those that only involve agricultural crops through to those that also include weedy crop relatives or even unrelated native plant communities. We begin by examining some of the criteria that are important in determining involvement in agricultural pathogen evolution by noncrop plants. Throughout we use empirical examples to illustrate the fact that different processes may dominate in different systems, and suggest that consideration of life history and spatial structure are central to understanding dynamics and direction of the interaction. We then discuss the implications that such interactions have for disease management in agro-ecosystems and how we can influence those outcomes. Finally, we identify several major gaps where future research could increase our ability to utilize evolutionary principles in managing disease in agro-ecosystems.
Collapse
|
113
|
Barrett LG, Encinas-Viso F, Burdon JJ, Thrall PH. Specialization for resistance in wild host-pathogen interaction networks. FRONTIERS IN PLANT SCIENCE 2015; 6:761. [PMID: 26442074 PMCID: PMC4585140 DOI: 10.3389/fpls.2015.00761] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 09/04/2015] [Indexed: 05/05/2023]
Abstract
Properties encompassed by host-pathogen interaction networks have potential to give valuable insight into the evolution of specialization and coevolutionary dynamics in host-pathogen interactions. However, network approaches have been rarely utilized in previous studies of host and pathogen phenotypic variation. Here we applied quantitative analyses to eight networks derived from spatially and temporally segregated host (Linum marginale) and pathogen (Melampsora lini) populations. First, we found that resistance strategies are highly variable within and among networks, corresponding to a spectrum of specialist and generalist resistance types being maintained within all networks. At the individual level, specialization was strongly linked to partial resistance, such that partial resistance was effective against a greater number of pathogens compared to full resistance. Second, we found that all networks were significantly nested. There was little support for the hypothesis that temporal evolutionary dynamics may lead to the development of nestedness in host-pathogen infection networks. Rather, the common patterns observed in terms of nestedness suggests a universal driver (or multiple drivers) that may be independent of spatial and temporal structure. Third, we found that resistance networks were significantly modular in two spatial networks, clearly reflecting spatial and ecological structure within one of the networks. We conclude that (1) overall patterns of specialization in the networks we studied mirror evolutionary trade-offs with the strength of resistance; (2) that specific network architecture can emerge under different evolutionary scenarios; and (3) network approaches offer great utility as a tool for probing the evolutionary and ecological genetics of host-pathogen interactions.
Collapse
Affiliation(s)
- Luke G. Barrett
- Commonwealth Scientific and Industrial Research Organization Agriculture FlagshipCanberra, ACT, Australia
- *Correspondence: Luke G. Barrett, Commonwealth Scientific and Industrial Research Organization Agriculture Flagship, GPO Box 1600, Canberra ACT 2601, Australia
| | - Francisco Encinas-Viso
- Centre for Australian National Biodiversity Research, Commonwealth Scientific and Industrial Research OrganizationCanberra, ACT, Australia
| | - Jeremy J. Burdon
- Commonwealth Scientific and Industrial Research Organization Agriculture FlagshipCanberra, ACT, Australia
| | - Peter H. Thrall
- Commonwealth Scientific and Industrial Research Organization Agriculture FlagshipCanberra, ACT, Australia
| |
Collapse
|
114
|
Abstract
This review takes an evolutionary view of breeding crops for durable resistance to disease. An understanding of coevolution between hosts and parasites leads to predictors of potentially durable resistance, such as corresponding virulence having a high fitness cost to the pathogen or resistance being common in natural populations. High partial resistance can also promote durability. Whether or not resistance is actually durable, however, depends on ecological and epidemiological processes that stabilize genetic polymorphism, many of which are absent from intensive agriculture. There continues to be no biological, genetic, or economic model for durable resistance. The analogy between plant breeding and natural selection indicates that the basic requirements are genetic variation in potentially durable resistance, effective and consistent selection for resistance, and an efficient breeding process in which trials of disease resistance are integrated with other traits. Knowledge about genetics and mechanisms can support breeding for durable resistance once these fundamentals are in place.
Collapse
|
115
|
Suzuki RO, Degawa Y, Suzuki SN, Hosoya T. Local-and regional-scale spatial patterns of two fungal pathogens of Miscanthus sinensis in grassland communities. MYCOSCIENCE 2015. [DOI: 10.1016/j.myc.2014.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
116
|
Lane-deGraaf KE, Amish SJ, Gardipee F, Jolles A, Luikart G, Ezenwa VO. Signatures of natural and unnatural selection: evidence from an immune system gene in African buffalo. CONSERV GENET 2014. [DOI: 10.1007/s10592-014-0658-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
117
|
Changes in Population Size and Survival inAtelopus spumarius(Anura: Bufonidae) Are Not Correlated with Chytrid Prevalence. J HERPETOL 2014. [DOI: 10.1670/11-269] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
118
|
Zhan J, Thrall PH, Burdon JJ. Achieving sustainable plant disease management through evolutionary principles. TRENDS IN PLANT SCIENCE 2014; 19:570-5. [PMID: 24853471 DOI: 10.1016/j.tplants.2014.04.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 03/29/2014] [Accepted: 04/25/2014] [Indexed: 05/10/2023]
Abstract
Plants and their pathogens are engaged in continuous evolutionary battles and sustainable disease management requires novel systems to create environments conducive for short-term and long-term disease control. In this opinion article, we argue that knowledge of the fundamental factors that drive host-pathogen coevolution in wild systems can provide new insights into disease development in agriculture. Such evolutionary principles can be used to guide the formulation of sustainable disease management strategies which can minimize disease epidemics while simultaneously reducing pressure on pathogens to evolve increased infectivity and aggressiveness. To ensure agricultural sustainability, disease management programs that reflect the dynamism of pathogen population structure are essential and evolutionary biologists should play an increasing role in their design.
Collapse
Affiliation(s)
- Jiasui Zhan
- Key Laboratory of Integrated Pest Management for Fujian-Taiwan Crops, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, China; Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China.
| | - Peter H Thrall
- CSIRO-Plant Industry, PO Box 1600, Canberra, ACT 2601, Australia
| | - Jeremy J Burdon
- CSIRO-Plant Industry, PO Box 1600, Canberra, ACT 2601, Australia
| |
Collapse
|
119
|
Lopez Pascua L, Hall AR, Best A, Morgan AD, Boots M, Buckling A. Higher resources decrease fluctuating selection during host-parasite coevolution. Ecol Lett 2014; 17:1380-8. [PMID: 25167763 PMCID: PMC4257576 DOI: 10.1111/ele.12337] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 05/29/2014] [Accepted: 07/15/2014] [Indexed: 01/20/2023]
Abstract
We still know very little about how the environment influences coevolutionary dynamics. Here, we investigated both theoretically and empirically how nutrient availability affects the relative extent of escalation of resistance and infectivity (arms race dynamic; ARD) and fluctuating selection (fluctuating selection dynamic; FSD) in experimentally coevolving populations of bacteria and viruses. By comparing interactions between clones of bacteria and viruses both within- and between-time points, we show that increasing nutrient availability resulted in coevolution shifting from FSD, with fluctuations in average infectivity and resistance ranges over time, to ARD. Our model shows that range fluctuations with lower nutrient availability can be explained both by elevated costs of resistance (a direct effect of nutrient availability), and reduced benefits of resistance when population sizes of hosts and parasites are lower (an indirect effect). Nutrient availability can therefore predictably and generally affect qualitative coevolutionary dynamics by both direct and indirect (mediated through ecological feedbacks) effects on costs of resistance.
Collapse
Affiliation(s)
- Laura Lopez Pascua
- Oxford Regional Molecular Genetics Laboratory, Oxford University Hospitals NHS Trust, Oxford, UK
| | | | | | | | | | | |
Collapse
|
120
|
Bruns E, Carson ML, May G. The jack of all trades is master of none: a pathogen's ability to infect a greater number of host genotypes comes at a cost of delayed reproduction. Evolution 2014; 68:2453-66. [PMID: 24890322 DOI: 10.1111/evo.12461] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 05/20/2014] [Indexed: 01/16/2023]
Abstract
A trade-off between a pathogen's ability to infect many hosts and its reproductive capacity on each host genotype is predicted to limit the evolution of an expanded host range, yet few empirical results provide evidence for the magnitude of such trade-offs. Here, we test the hypothesis for a trade-off between the number of host genotypes that a fungal pathogen can infect (host genotype range) and its reproductive capacity on susceptible plant hosts. We used strains of the oat crown rust fungus that carried widely varying numbers of virulence (avr) alleles known to determine host genotype range. We quantified total spore production and the expression of four pathogen life-history stages: infection efficiency, time until reproduction, pustule size, and spore production per pustule. In support of the trade-off hypothesis, we found that virulence level, the number of avr alleles per pathogen strain, was correlated with significant delays in the onset of reproduction and with smaller pustule sizes. Modeling from our results, we conclude that trade-offs have the capacity to constrain the evolution of host genotype range in local populations. In contrast, long-term trends in virulence level suggest that the continued deployment of resistant host lines over wide regions of the United States has generated selection for increased host genotype range.
Collapse
Affiliation(s)
- Emily Bruns
- Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, Minnesota, 55108; Department of Biology, University of Virginia, Charlottesville, Virginia, 22904.
| | | | | |
Collapse
|
121
|
Betts A, Kaltz O, Hochberg ME. Contrasted coevolutionary dynamics between a bacterial pathogen and its bacteriophages. Proc Natl Acad Sci U S A 2014; 111:11109-14. [PMID: 25024215 PMCID: PMC4121802 DOI: 10.1073/pnas.1406763111] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Many antagonistic interactions between hosts and their parasites result in coevolution. Although coevolution can drive diversity and specificity within species, it is not known whether coevolutionary dynamics differ among functionally similar species. We present evidence of coevolution within simple communities of Pseudomonas aeruginosa PAO1 and a panel of bacteriophages. Pathogen identity affected coevolutionary dynamics. For five of six phages tested, time-shift assays revealed temporal peaks in bacterial resistance and phage infectivity, consistent with frequency-dependent selection (Red Queen dynamics). Two of the six phages also imposed additional directional selection, resulting in strongly increased resistance ranges over the entire length of the experiment (ca. 60 generations). Cross-resistance to these two phages was very high, independent of the coevolutionary history of the bacteria. We suggest that coevolutionary dynamics are associated with the nature of the receptor used by the phage for infection. Our results shed light on the coevolutionary process in simple communities and have practical application in the control of bacterial pathogens through the evolutionary training of phages, increasing their virulence and efficacy as therapeutics or disinfectants.
Collapse
Affiliation(s)
- Alex Betts
- Institut des Sciences de l'Evolution, Université Montpellier II, Unité Mixte de Recherche 5554, 34095 Montpellier Cedex 05, France;Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom
| | - Oliver Kaltz
- Institut des Sciences de l'Evolution, Université Montpellier II, Unité Mixte de Recherche 5554, 34095 Montpellier Cedex 05, France
| | - Michael E Hochberg
- Institut des Sciences de l'Evolution, Université Montpellier II, Unité Mixte de Recherche 5554, 34095 Montpellier Cedex 05, France;Santa Fe Institute, Santa Fe, NM 87501; andWissenschaftskolleg zu Berlin, 14193 Berlin, Germany
| |
Collapse
|
122
|
Ashby B, Gupta S, Buckling A. Effects of epistasis on infectivity range during host-parasite coevolution. Evolution 2014; 68:2972-82. [PMID: 24957848 PMCID: PMC4261995 DOI: 10.1111/evo.12479] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 06/11/2014] [Indexed: 12/18/2022]
Abstract
Understanding how parasites adapt to changes in host resistance is crucial to evolutionary epidemiology. Experimental studies have demonstrated that parasites are more capable of adapting to gradual, rather than sudden changes in host phenotype, as the latter may require multiple mutations that are unlikely to arise simultaneously. A key, but as yet unexplored factor is precisely how interactions between mutations (epistasis) affect parasite evolution. Here, we investigate this phenomenon in the context of infectivity range, where parasites may experience selection to infect broader sets of genotypes. When epistasis is strongly positive, we find that parasites are unlikely to evolve broader infectivity ranges if hosts exhibit sudden, rather than gradual changes in phenotype, in close agreement with empirical observations. This is due to a low probability of fixing multiple mutations that individually confer no immediate advantage. When epistasis is weaker, parasites are more likely to evolve broader infectivity ranges if hosts make sudden changes in phenotype, which can be explained by a balance between mutation supply and selection. Thus, we demonstrate that both the rate of phenotypic change in hosts and the form of epistasis between mutations in parasites are crucial in shaping the evolution of infectivity range.
Collapse
Affiliation(s)
- Ben Ashby
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, United Kingdom.
| | | | | |
Collapse
|
123
|
Dybdahl MF, Jenkins CE, Nuismer SL. Identifying the Molecular Basis of Host-Parasite Coevolution: Merging Models and Mechanisms. Am Nat 2014; 184:1-13. [DOI: 10.1086/676591] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
124
|
Van Tyne D, Gilmore MS. Friend turned foe: evolution of enterococcal virulence and antibiotic resistance. Annu Rev Microbiol 2014; 68:337-56. [PMID: 25002090 DOI: 10.1146/annurev-micro-091213-113003] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The enterococci are an ancient genus that evolved along with the tree of life. These intrinsically rugged bacteria are highly adapted members of the intestinal consortia of a range of hosts that spans the animal kingdom. Enterococci are also leading opportunistic hospital pathogens, causing infections that are often resistant to treatment with most antibiotics. Despite the importance of enterococci as hospital pathogens, the vast majority live outside of humans, and nearly all of their evolutionary history took place before the appearance of modern humans. Because hospital infections represent evolutionary end points, traits that exacerbate human infection are unlikely to have evolved for that purpose. However, clusters of traits have converged in specific lineages that are well adapted to colonize the antibiotic-perturbed gastrointestinal tracts of patients and that thrive in the hospital environment. Here we discuss these traits in an evolutionary context, as well as how comparative genomics is providing new insights into the evolution of the enterococci.
Collapse
Affiliation(s)
- Daria Van Tyne
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
| | | |
Collapse
|
125
|
Burdon JJ, Barrett LG, Rebetzke G, Thrall PH. Guiding deployment of resistance in cereals using evolutionary principles. Evol Appl 2014; 7:609-24. [PMID: 25067946 PMCID: PMC4105914 DOI: 10.1111/eva.12175] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 05/14/2014] [Indexed: 11/28/2022] Open
Abstract
Genetically controlled resistance provides plant breeders with an efficient means of controlling plant disease, but this approach has been constrained by practical difficulties associated with combining many resistance genes together and strong evolutionary responses from pathogen populations leading to subsequent resistance breakdown. However, continuing advances in molecular marker technologies are revolutionizing the ability to rapidly and reliably manipulate resistances of all types - major gene, adult plant and quantitative resistance loci singly or multiply into individual host lines. Here, we argue that these advances provide major opportunities to deliberately design deployment strategies in cereals that can take advantage of the evolutionary pressures faced by target pathogens. Different combinations of genes deployed either within single host individuals or between different individuals within or among crops, can be used to reduce the size of pathogen populations and generate patterns of disruptive selection. This will simultaneously limit immediate epidemic development and reduce the probability of subsequent evolutionary change in the pathogen for broader infectivity or increased aggressiveness. The same general principles are relevant to the control of noncereal diseases, but the most efficacious controls will vary reflecting the range of genetic options available and their fit with specific ecology and life-history combinations.
Collapse
Affiliation(s)
- Jeremy J Burdon
- CSIRO, Plant Industry Canberra, ACT, Australia ; CSIRO Biosecurity Flagship Canberra, ACT, Australia
| | | | | | | |
Collapse
|
126
|
Boots M, White A, Best A, Bowers R. How specificity and epidemiology drive the coevolution of static trait diversity in hosts and parasites. Evolution 2014; 68:1594-606. [PMID: 24593303 PMCID: PMC4257575 DOI: 10.1111/evo.12393] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 02/21/2014] [Indexed: 12/19/2022]
Abstract
There is typically considerable variation in the level of infectivity of parasites and the degree of resistance of hosts within populations. This trait variation is critical not only to the evolutionary dynamics but also to the epidemiology, and potentially the control of infectious disease. However, we lack an understanding of the processes that generate and maintain this trait diversity. We examine theoretically how epidemiological feedbacks and the characteristics of the interaction between host types and parasites strains determine the coevolution of host-parasite diversity. The interactions include continuous characterizations of the key phenotypic features of classic gene-for-gene and matching allele models. We show that when there are costs to resistance in the hosts and infectivity in the parasite, epidemiological feedbacks may generate diversity but this is limited to dimorphism, often of extreme types, in a broad range of realistic infection scenarios. For trait polymorphism, there needs to be both specificity of infection between host types and parasite strains as well as incompatibility between particular strains and types. We emphasize that although the high specificity is well known to promote temporal "Red Queen" diversity, it is costs and combinations of hosts and parasites that cannot infect that will promote static trait diversity.
Collapse
Affiliation(s)
- Mike Boots
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10 9EZ, United Kingdom.
| | | | | | | |
Collapse
|
127
|
Ashby B, Gupta S. PARASITIC CASTRATION PROMOTES COEVOLUTIONARY CYCLING BUT ALSO IMPOSES A COST ON SEX. Evolution 2014; 68:2234-44. [DOI: 10.1111/evo.12425] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 03/29/2014] [Indexed: 01/23/2023]
Affiliation(s)
- Ben Ashby
- Department of Zoology; University of Oxford; Oxford OX1 3PS United Kingdom
| | - Sunetra Gupta
- Department of Zoology; University of Oxford; Oxford OX1 3PS United Kingdom
| |
Collapse
|
128
|
Papaïx J, Burdon JJ, Lannou C, Thrall PH. Evolution of pathogen specialisation in a host metapopulation: joint effects of host and pathogen dispersal. PLoS Comput Biol 2014; 10:e1003633. [PMID: 24853675 PMCID: PMC4031062 DOI: 10.1371/journal.pcbi.1003633] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 04/08/2014] [Indexed: 11/22/2022] Open
Abstract
Metapopulation processes are important determinants of epidemiological and evolutionary dynamics in host-pathogen systems, and are therefore central to explaining observed patterns of disease or genetic diversity. In particular, the spatial scale of interactions between pathogens and their hosts is of primary importance because migration rates of one species can affect both spatial and temporal heterogeneity of selection on the other. In this study we developed a stochastic and discrete time simulation model to specifically examine the joint effects of host and pathogen dispersal on the evolution of pathogen specialisation in a spatially explicit metapopulation. We consider a plant-pathogen system in which the host metapopulation is composed of two plant genotypes. The pathogen is dispersed by air-borne spores on the host metapopulation. The pathogen population is characterised by a single life-history trait under selection, the infection efficacy. We found that restricted host dispersal can lead to high amount of pathogen diversity and that the extent of pathogen specialisation varied according to the spatial scale of host-pathogen dispersal. We also discuss the role of population asynchrony in determining pathogen evolutionary outcomes.
Collapse
Affiliation(s)
- Julien Papaïx
- INRA, UMR 1290 BIOGER, Thiverval-Grignon, France
- INRA, UR 341 MIA, Jouy-en-Josas, France
- CSIRO Plant Industry, Canberra, Australia
| | | | | | | |
Collapse
|
129
|
Fraile A, Hily JM, Pagán I, Pacios LF, García-Arenal F. Host resistance selects for traits unrelated to resistance-breaking that affect fitness in a plant virus. Mol Biol Evol 2014; 31:928-39. [PMID: 24441034 DOI: 10.1093/molbev/msu045] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
The acquisition by parasites of the capacity to infect resistant host genotypes, that is, resistance-breaking, is predicted to be hindered by across-host fitness trade-offs. All analyses of costs of resistance-breaking in plant viruses have focused on within-host multiplication without considering other fitness components, which may limit understanding of virus evolution. We have reported that host range expansion of tobamoviruses on L-gene resistant pepper genotypes was associated with severe within-host multiplication penalties. Here, we analyze whether resistance-breaking costs might affect virus survival in the environment by comparing tobamovirus pathotypes differing in infectivity on L-gene resistance alleles. We predicted particle stability from structural models, analyzed particle stability in vitro, and quantified virus accumulation in different plant organs and virus survival in the soil. Survival in the soil differed among tobamovirus pathotypes and depended on differential stability of virus particles. Structure model analyses showed that amino acid changes in the virus coat protein (CP) responsible for resistance-breaking affected the strength of the axial interactions among CP subunits in the rod-shaped particle, thus determining its stability and survival. Pathotypes ranked differently for particle stability/survival and for within-host accumulation. Resistance-breaking costs in survival add to, or subtract from, costs in multiplication according to pathotype. Hence, differential pathotype survival should be considered along with differential multiplication to understand the evolution of the virus populations. Results also show that plant resistance, in addition to selecting for resistance-breaking and for decreased multiplication, also selects for changes in survival, a trait unrelated to the host-pathogen interaction that may condition host range expansion.
Collapse
Affiliation(s)
- Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA) and E.T.S.I. Agrónomos, Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| | | | | | | | | |
Collapse
|
130
|
Ashby B, Gupta S, Buckling A. Spatial structure mitigates fitness costs in host-parasite coevolution. Am Nat 2014; 183:E64-74. [PMID: 24561607 DOI: 10.1086/674826] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The extent of population mixing is known to influence the coevolutionary outcomes of many host and parasite traits, including the evolution of generalism (the ability to resist or infect a broad range of genotypes). While the segregation of populations into interconnected demes has been shown to influence the evolution of generalism, the role of local interactions between individuals is unclear. Here, we combine an individual-based model of microbial communities with a well-established framework of genetic specificity that matches empirical observations of bacterium-phage interactions. We find the evolution of generalism in well-mixed populations to be highly sensitive to the severity of associated fitness costs, but the constraining effect of costs on the evolution of generalism is lessened in spatially structured populations. The contrasting outcomes between the two environments can be explained by different scales of competition (i.e., global vs. local). These findings suggest that local interactions may have important effects on the evolution of generalism in host-parasite interactions, particularly in the presence of high fitness costs.
Collapse
Affiliation(s)
- Ben Ashby
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
| | | | | |
Collapse
|
131
|
Leroy T, Le Cam B, Lemaire C. When virulence originates from non-agricultural hosts: new insights into plant breeding. INFECTION GENETICS AND EVOLUTION 2014; 27:521-9. [PMID: 24412509 DOI: 10.1016/j.meegid.2013.12.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 12/11/2013] [Accepted: 12/30/2013] [Indexed: 12/27/2022]
Abstract
Monogenic plant resistance breakdown is a model for testing evolution in action in pathogens. As a rule, plant pathologists argue that virulence - the allele that allows pathogens to overcome resistance - is due to a new mutation at the avirulence locus within the native/endemic population that infects susceptible crops. In this article, we develop an alternative and neglected scenario where a given virulence pre-exists in a non-agricultural host and might be accidentally released or introduced on the matching resistant cultivar in the field. The main difference between the two scenarios is the divergence time expected between the avirulent and the virulent populations. As a consequence, population genetic approaches such as genome scans and Approximate Bayesian Computation methods allow explicit testing of the two scenarios by timing the divergence. This review then explores the fundamental implications of this alternative scenario for plant breeding, including the invasion of virulence or the evolution of more aggressive hybrids, and proposes concrete solutions to achieve a sustainable resistance.
Collapse
Affiliation(s)
- Thibault Leroy
- Université d'Angers, IRHS, PRES LUNAM, SFR QUASAV, Boulevard Lavoisier, 49045 Angers, France; INRA, IRHS, PRES LUNAM, SFR QUASAV, Rue Georges Morel, 49071 Beaucouzé, France; Agrocampus Ouest, IRHS, PRES LUNAM, SFR QUASAV, Rue Le Nôtre, 49045 Angers, France
| | - Bruno Le Cam
- Université d'Angers, IRHS, PRES LUNAM, SFR QUASAV, Boulevard Lavoisier, 49045 Angers, France; INRA, IRHS, PRES LUNAM, SFR QUASAV, Rue Georges Morel, 49071 Beaucouzé, France; Agrocampus Ouest, IRHS, PRES LUNAM, SFR QUASAV, Rue Le Nôtre, 49045 Angers, France
| | - Christophe Lemaire
- Université d'Angers, IRHS, PRES LUNAM, SFR QUASAV, Boulevard Lavoisier, 49045 Angers, France; INRA, IRHS, PRES LUNAM, SFR QUASAV, Rue Georges Morel, 49071 Beaucouzé, France; Agrocampus Ouest, IRHS, PRES LUNAM, SFR QUASAV, Rue Le Nôtre, 49045 Angers, France.
| |
Collapse
|
132
|
Feng H, Wang X, Zhang Q, Fu Y, Feng C, Wang B, Huang L, Kang Z. Monodehydroascorbate reductase gene, regulated by the wheat PN-2013 miRNA, contributes to adult wheat plant resistance to stripe rust through ROS metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:1-12. [DOI: 10.1016/j.bbagrm.2013.11.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 11/06/2013] [Accepted: 11/12/2013] [Indexed: 12/27/2022]
|
133
|
Kasuga T, Gijzen M. Epigenetics and the evolution of virulence. Trends Microbiol 2013; 21:575-82. [DOI: 10.1016/j.tim.2013.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/03/2013] [Accepted: 09/05/2013] [Indexed: 12/21/2022]
|
134
|
Sympatric inhibition and niche differentiation suggest alternative coevolutionary trajectories among Streptomycetes. ISME JOURNAL 2013; 8:249-56. [PMID: 24152720 DOI: 10.1038/ismej.2013.175] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/30/2013] [Accepted: 09/03/2013] [Indexed: 11/08/2022]
Abstract
Soil bacteria produce a diverse array of antibiotics, yet our understanding of the specific roles of antibiotics in the ecological and evolutionary dynamics of microbial interactions in natural habitats remains limited. Here, we show a significant role for antibiotics in mediating antagonistic interactions and nutrient competition among locally coexisting Streptomycete populations from soil. We found that antibiotic inhibition is significantly more intense among sympatric than allopatric Streptomycete populations, indicating local selection for inhibitory phenotypes. For sympatric but not allopatric populations, antibiotic inhibition is significantly positively correlated with niche overlap, indicating that inhibition is targeted toward bacteria that pose the greatest competitive threat. Our results support the hypothesis that antibiotics serve as weapons in mediating local microbial interactions in soil and suggest that coevolutionary niche displacement may reduce the likelihood of an antibiotic arms race. Further insight into the diverse roles of antibiotics in microbial ecology and evolution has significant implications for understanding the persistence of antibiotic inhibitory and resistance phenotypes in environmental microbes, optimizing antibiotic drug discovery and developing strategies for managing microbial coevolutionary dynamics to enhance inhibitory phenotypes.
Collapse
|
135
|
Susi H, Laine AL. Pathogen life-history trade-offs revealed in allopatry. Evolution 2013; 67:3362-70. [PMID: 24152013 PMCID: PMC4208680 DOI: 10.1111/evo.12182] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 05/29/2013] [Indexed: 11/29/2022]
Abstract
Trade-offs in life-history traits is a central tenet in evolutionary biology, yet their ubiquity and relevance to realized fitness in natural populations remains questioned. Trade-offs in pathogens are of particular interest because they may constrain the evolution and epidemiology of diseases. Here, we studied life-history traits determining transmission in the obligate fungal pathogen, Podosphaera plantaginis, infecting Plantago lanceolata. We find that although traits are positively associated on sympatric host genotypes, on allopatric host genotypes relationships between infectivity and subsequent transmission traits change shape, becoming even negative. The epidemiological prediction of this change in life-history relationships in allopatry is lower disease prevalence in newly established pathogen populations. An analysis of the natural pathogen metapopulation confirms that disease prevalence is lower in newly established pathogen populations and they are more prone to go extinct during winter than older pathogen populations. Hence, life-history trade-offs mediated by pathogen local adaptation may influence epidemiological dynamics at both population and metapopulation levels.
Collapse
Affiliation(s)
- Hanna Susi
- Metapopulation Research Group, PO Box 65 (Viikinkaari 1), Department of Biosciences, FI-00014 University of Helsinki, Finland
| | | |
Collapse
|
136
|
Chakraborty S. Migrate or evolve: options for plant pathogens under climate change. GLOBAL CHANGE BIOLOGY 2013; 19:1985-2000. [PMID: 23554235 DOI: 10.1111/gcb.12205] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 03/12/2013] [Indexed: 05/21/2023]
Abstract
Findings on climate change influence on plant pathogens are often inconsistent and context dependent. Knowledge of pathogens affecting agricultural crops and natural plant communities remains fragmented along disciplinary lines. By broadening the perspective beyond agriculture, this review integrates cross-disciplinary knowledge to show that at scales relevant to climate change, accelerated evolution and changing geographic distribution will be the main implications for pathogens. New races may evolve rapidly under elevated temperature and CO2 , as evolutionary forces act on massive pathogen populations boosted by a combination of increased fecundity and infection cycles under favourable microclimate within enlarged canopy. Changing geographic distribution will bring together diverse lineages/genotypes that do not share common ecological niche, potentially increasing pathogen diversity. However, the uncertainty of model predictions and a lack of synthesis of fragmented knowledge remain as major deficiencies in knowledge. The review contends that the failure to consider scale and human intervention through new technology are major sources of uncertainty. Recognizing that improved biophysical models alone will not reduce uncertainty, it proposes a generic framework to increase focus and outlines ways to integrate biophysical elements and technology change with human intervention scenarios to minimize uncertainty. To synthesize knowledge of pathogen biology and life history, the review borrows the concept of 'fitness' from population biology as a comprehensive measure of pathogen strengths and vulnerabilities, and explores the implications of pathogen mode of nutrition to fitness and its interactions with plants suffering chronic abiotic stress under climate change. Current and future disease management options can then be judged for their ability to impair pathogenic and saprophytic fitness. The review pinpoints improving confidence in model prediction by minimizing uncertainty, developing management strategies to reduce overall pathogen fitness, and finding new sources of data to trawl for climate signatures on pathogens as important challenges for future research.
Collapse
Affiliation(s)
- Sukumar Chakraborty
- CSIRO Plant Industry, Queensland Bioscience Precinct, St. Lucia, Queensland, Australia.
| |
Collapse
|
137
|
Barclay VC. Variation in host resistance could limit the spread of more broadly virulent pathogens. Virulence 2013; 4:347-9. [PMID: 23689611 PMCID: PMC3714125 DOI: 10.4161/viru.25061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
138
|
Bockelmann AC, Tams V, Ploog J, Schubert PR, Reusch TBH. Quantitative PCR reveals strong spatial and temporal variation of the wasting disease pathogen, Labyrinthula zosterae in northern European eelgrass (Zostera marina) beds. PLoS One 2013; 8:e62169. [PMID: 23658711 PMCID: PMC3642213 DOI: 10.1371/journal.pone.0062169] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 03/18/2013] [Indexed: 11/18/2022] Open
Abstract
Seagrass beds are the foundation species of functionally important coastal ecosystems worldwide. The world’s largest losses of the widespread seagrass Zostera marina (eelgrass) have been reported as a consequence of wasting disease, an infection with the endophytic protist Labyrinthula zosterae. During one of the most extended epidemics in the marine realm, ∼90% of East and Western Atlantic eelgrass beds died-off between 1932 and 1934. Today, small outbreaks continue to be reported, but the current extent of L. zosterae in European meadows is completely unknown. In this study we quantify the abundance and prevalence of the wasting disease pathogen among 19 Z. marina populations in northern European coastal waters, using quantitative PCR (QPCR) with primers targeting a species specific portion of the internally transcribed spacer (ITS1) of L. zosterae. Spatially, we found marked variation among sites with abundances varying between 0 and 126 cells mg−1Z. marina dry weight (mean: 5.7 L. zosterae cells mg−1Z. marina dry weight ±1.9 SE) and prevalences ranged from 0–88.9%. Temporarily, abundances varied between 0 and 271 cells mg−1Z. marina dry weight (mean: 8.5±2.6 SE), while prevalences ranged from zero in winter and early spring to 96% in summer. Field concentrations accessed via bulk DNA extraction and subsequent QPCR correlated well with prevalence data estimated via isolation and cultivation from live plant tissue. L. zosterae was not only detectable in black lesions, a sign of Labyrinthula-induced necrosis, but also occurred in green, apparently healthy tissue. We conclude that L. zosterae infection is common (84% infected populations) in (northern) European eelgrass populations with highest abundances during the summer months. In the light of global climate change and increasing rate of marine diseases our data provide a baseline for further studies on the causes of pathogenic outbreaks of L. zosterae.
Collapse
|
139
|
Kubinak JL, Potts WK. Host resistance influences patterns of experimental viral adaptation and virulence evolution. Virulence 2013; 4:410-8. [PMID: 23645287 DOI: 10.4161/viru.24724] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Infectious diseases are major threats to all living systems, so understanding the forces of selection that limit the evolution of more virulent pathogens is of fundamental importance; this includes the practical application of identifying possible mitigation strategies for at-risk host populations. The evolution of more virulent pathogens has been classically understood to be limited by the tradeoff between within-host growth rate and transmissibility. Importantly, heterogeneity among hosts can influence both of these factors. However, despite our substantial understanding of how the immune system operates to control pathogen replication during infection, we have only a limited appreciation of how variability in intrinsic (i.e., genetically determined) levels of host resistance influences patterns of pathogen adaptation and virulence evolution. Here, we describe results from experimental evolution studies using a model host-pathogen (virus-mammal) system; we demonstrate that variability in intrinsic levels of resistance among host genotypes can have significant effects on patterns of pathogen adaptation and virulence evolution during serial passage. Both the magnitude of adaptive response as well as the degree of pathogen specialization was positively correlated with host resistance, while mean overall virulence of post-passage virus was negatively correlated with host resistance. These results are consistent with a model whereby resistant host genotypes impose stronger selection on adapting pathogen populations, which in turn leads to the evolution of more specialized pathogen variants whose overall (i.e., mean) virulence across host genotypes is reduced.
Collapse
Affiliation(s)
- Jason L Kubinak
- Division of Microbiology and Immunology, Department of Pathology; School of Medicine, University of Utah; Salt Lake City, UT USA.
| | | |
Collapse
|
140
|
Van AL, Caffier V, Lasserre-Zuber P, Chauveau A, Brunel D, Le Cam B, Durel CE. Differential selection pressures exerted by host resistance quantitative trait loci on a pathogen population: a case study in an apple × Venturia inaequalis pathosystem. THE NEW PHYTOLOGIST 2013; 197:899-908. [PMID: 23278324 DOI: 10.1111/nph.12086] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 10/29/2012] [Indexed: 06/01/2023]
Abstract
Understanding how pathogens evolve according to pressures exerted by their plant hosts is essential for the derivation of strategies aimed at the durable management of resistant cultivars. The spectrum of action of the resistance factors in the partially resistant cultivars is thought to be an important determinant of resistance durability. However, it has not yet been demonstrated whether the pressures exerted by quantitative resistance are different according to their spectrum of action. To investigate selection pressures exerted by apple genotypes harbouring various resistance quantitative trait loci (QTLs) on a mixed inoculum of the scab disease agent, Venturia inaequalis, we monitored V. inaequalis isolate proportions on diseased apple leaves of an F1 progeny using quantitative pyrosequencing technology and QTL mapping. Broad-spectrum resistances did not exert any differential selection pressures on the mixed inoculum, whereas narrow-spectrum resistances decreased the frequencies of some isolates in the mixture relative to the susceptible host genotypes. Our results suggest that the management of resistant cultivars should be different according to the spectrum of action of their resistance factors. The pyramiding of broad-spectrum factors or the use of a mixture of apple genotypes that carry narrow-spectrum resistance factors are two possible strategies for the minimization of resistance erosion.
Collapse
Affiliation(s)
- Amandine Lê Van
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, SFR 4207 QUASAV, PRES L'UNAM, 42 rue Georges Morel, F-49071, Beaucouzé Cedex, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
- Université d'Angers, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
| | - Valérie Caffier
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, SFR 4207 QUASAV, PRES L'UNAM, 42 rue Georges Morel, F-49071, Beaucouzé Cedex, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
- Université d'Angers, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
| | - Pauline Lasserre-Zuber
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, SFR 4207 QUASAV, PRES L'UNAM, 42 rue Georges Morel, F-49071, Beaucouzé Cedex, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
- Université d'Angers, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
| | - Aurélie Chauveau
- INRA, US1279 Etude du Polymorphisme des Génomes Végétaux - EPGV, Centre National de Génotypage, 2 rue Gaston Crémieux, F-91057, Évry Cedex, France
| | - Dominique Brunel
- INRA, US1279 Etude du Polymorphisme des Génomes Végétaux - EPGV, Centre National de Génotypage, 2 rue Gaston Crémieux, F-91057, Évry Cedex, France
| | - Bruno Le Cam
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, SFR 4207 QUASAV, PRES L'UNAM, 42 rue Georges Morel, F-49071, Beaucouzé Cedex, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
- Université d'Angers, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
| | - Charles-Eric Durel
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, SFR 4207 QUASAV, PRES L'UNAM, 42 rue Georges Morel, F-49071, Beaucouzé Cedex, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
- Université d'Angers, UMR1345 Institut de Recherche en Horticulture et Semences - IRHS, F-49045, Angers, France
| |
Collapse
|
141
|
Zhan J, McDonald BA. Experimental measures of pathogen competition and relative fitness. ANNUAL REVIEW OF PHYTOPATHOLOGY 2013; 51:131-53. [PMID: 23767846 DOI: 10.1146/annurev-phyto-082712-102302] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Competition among pathogen strains for limited host resources can have a profound effect on pathogen evolution. A better understanding of the principles and consequences of competition can be useful in designing more sustainable disease management strategies. The competitive ability and relative fitness of a pathogen strain are determined by its intrinsic biological properties, the resistance and heterogeneity of the corresponding host population, the population density and genetic relatedness of the competing strains, and the physical environment. Competitive ability can be inferred indirectly from fitness components, such as basic reproduction rate or transmission rate. However, pathogen strains that exhibit higher fitness components when they infect a host alone may not exhibit a competitive advantage when they co-infect the same host. The most comprehensive measures of competitive ability and relative fitness come from calculating selection coefficients in a mixed infection in a field setting. Mark-release-recapture experiments can be used to estimate fitness costs associated with unnecessary virulence and fungicide resistance.
Collapse
Affiliation(s)
- Jiasui Zhan
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
| | | |
Collapse
|
142
|
Loeuille N, Barot S, Georgelin E, Kylafis G, Lavigne C. Eco-Evolutionary Dynamics of Agricultural Networks. ADV ECOL RES 2013. [DOI: 10.1016/b978-0-12-420002-9.00006-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
143
|
Characterization and inheritance of resistance to stripe rust in the wheat line Guinong775. YI CHUAN = HEREDITAS 2012; 34:1607-13. [DOI: 10.3724/sp.j.1005.2012.01607] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
144
|
Poullain V, Nuismer SL. Infection Genetics and the Likelihood of Host Shifts in Coevolving Host-Parasite Interactions. Am Nat 2012; 180:618-28. [DOI: 10.1086/667889] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
145
|
Zhan G, Zhuang H, Wang F, Wei G, Huang L, Kang Z. Population genetic diversity of Puccinia striiformis f. sp. tritici on different wheat varieties in Tianshui, Gansu Province. World J Microbiol Biotechnol 2012; 29:173-81. [PMID: 23054697 DOI: 10.1007/s11274-012-1170-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 09/12/2012] [Indexed: 10/27/2022]
Abstract
Population genetic diversity in Tianshui city was analyzed with SSR markers in 605 single-pustule isolates of the stripe rust pathogen, Puccinia striiformis f. sp. tritici (Pst), obtained from 19 varieties of wheat. Significant differences in genetic diversity among populations were defected. Genetic diversity was highest in population on Tian 863-13, a highly resistant variety, whereas genetic diversity was lowest in population on Huixianhong, a highly susceptible variety. Seven populations from seven varieties that carried the common Yr18 resistance gene were clustered as one sub-group at 0.88 similarity coefficient, which showed that resistance gene selection had close relation with pathogen's component. The results of present study can provide a theoretical basis for integrated management of wheat stripe rust and effective deployment of resistance genes in Pst over-summering zones in China.
Collapse
Affiliation(s)
- Gangming Zhan
- College of Plant Protection and State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, P.O. Box 13#, Yangling 712100, Shaanxi Province, China
| | | | | | | | | | | |
Collapse
|
146
|
Agrawal AA, Hastings AP, Johnson MTJ, Maron JL, Salminen JP. Insect Herbivores Drive Real-Time Ecological and Evolutionary Change in Plant Populations. Science 2012; 338:113-6. [DOI: 10.1126/science.1225977] [Citation(s) in RCA: 326] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Insect herbivores are hypothesized to be major factors affecting the ecology and evolution of plants. We tested this prediction by suppressing insects in replicated field populations of a native plant, Oenothera biennis, which reduced seed predation, altered interspecific competitive dynamics, and resulted in rapid evolutionary divergence. Comparative genotyping and phenotyping of nearly 12,000 O. biennis individuals revealed that in plots protected from insects, resistance to herbivores declined through time owing to changes in flowering time and lower defensive ellagitannins in fruits, whereas plant competitive ability increased. This independent real-time evolution of plant resistance and competitive ability in the field resulted from the relaxation of direct selective effects of insects on plant defense and through indirect effects due to reduced herbivory on plant competitors.
Collapse
|
147
|
Tack AJM, Thrall PH, Barrett LG, Burdon JJ, Laine AL. Variation in infectivity and aggressiveness in space and time in wild host-pathogen systems: causes and consequences. J Evol Biol 2012; 25:1918-1936. [PMID: 22905782 DOI: 10.1111/j.1420-9101.2012.02588.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 07/02/2012] [Accepted: 07/05/2012] [Indexed: 12/18/2022]
Abstract
Variation in host resistance and in the ability of pathogens to infect and grow (i.e. pathogenicity) is important as it provides the raw material for antagonistic (co)evolution and therefore underlies risks of disease spread, disease evolution and host shifts. Moreover, the distribution of this variation in space and time may inform us about the mode of coevolutionary selection (arms race vs. fluctuating selection dynamics) and the relative roles of G × G interactions, gene flow, selection and genetic drift in shaping coevolutionary processes. Although variation in host resistance has recently been reviewed, little is known about overall patterns in the frequency and scale of variation in pathogenicity, particularly in natural systems. Using 48 studies from 30 distinct host-pathogen systems, this review demonstrates that variation in pathogenicity is ubiquitous across multiple spatial and temporal scales. Quantitative analysis of a subset of extensively studied plant-pathogen systems shows that the magnitude of within-population variation in pathogenicity is large relative to among-population variation and that the distribution of pathogenicity partly mirrors the distribution of host resistance. At least part of the variation in pathogenicity found at a given spatial scale is adaptive, as evidenced by studies that have examined local adaptation at scales ranging from single hosts through metapopulations to entire continents and - to a lesser extent - by comparisons of pathogenicity with neutral genetic variation. Together, these results support coevolutionary selection through fluctuating selection dynamics. We end by outlining several promising directions for future research.
Collapse
Affiliation(s)
- A J M Tack
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - P H Thrall
- CSIRO-Plant Industry, Canberra, ACT, Australia
| | - L G Barrett
- CSIRO-Plant Industry, Canberra, ACT, Australia
| | - J J Burdon
- CSIRO-Plant Industry, Canberra, ACT, Australia
| | - A-L Laine
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, Helsinki, Finland
| |
Collapse
|
148
|
de Roode JC, Lefèvre T. Behavioral Immunity in Insects. INSECTS 2012; 3:789-820. [PMID: 26466629 PMCID: PMC4553590 DOI: 10.3390/insects3030789] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 07/03/2012] [Accepted: 07/10/2012] [Indexed: 12/29/2022]
Abstract
Parasites can dramatically reduce the fitness of their hosts, and natural selection should favor defense mechanisms that can protect hosts against disease. Much work has focused on understanding genetic and physiological immunity against parasites, but hosts can also use behaviors to avoid infection, reduce parasite growth or alleviate disease symptoms. It is increasingly recognized that such behaviors are common in insects, providing strong protection against parasites and parasitoids. We review the current evidence for behavioral immunity in insects, present a framework for investigating such behavior, and emphasize that behavioral immunity may act through indirect rather than direct fitness benefits. We also discuss the implications for host-parasite co-evolution, local adaptation, and the evolution of non-behavioral physiological immune systems. Finally, we argue that the study of behavioral immunity in insects has much to offer for investigations in vertebrates, in which this topic has traditionally been studied.
Collapse
Affiliation(s)
- Jacobus C de Roode
- Department of Biology, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA.
| | - Thierry Lefèvre
- MIVEGEC (UM1-UM2-CNRS 5290-IRD 224), Centre IRD, 911 Av. Agropolis-BP 64501, Montpellier 34394, France.
| |
Collapse
|
149
|
Bever JD, Platt TG, Morton ER. Microbial population and community dynamics on plant roots and their feedbacks on plant communities. Annu Rev Microbiol 2012; 66:265-83. [PMID: 22726216 PMCID: PMC3525954 DOI: 10.1146/annurev-micro-092611-150107] [Citation(s) in RCA: 228] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The composition of the soil microbial community can be altered dramatically due to association with individual plant species, and these effects on the microbial community can have important feedbacks on plant ecology. Negative plant-soil feedback plays primary roles in maintaining plant community diversity, whereas positive plant-soil feedback may cause community conversion. Host-specific differentiation of the microbial community results from the trade-offs associated with overcoming plant defense and the specific benefits associated with plant rewards. Accumulation of host-specific pathogens likely generates negative feedback on the plant, while changes in the density of microbial mutualists likely generate positive feedback. However, the competitive dynamics among microbes depends on the multidimensional costs of virulence and mutualism, the fine-scale spatial structure within plant roots, and active plant allocation and localized defense. Because of this, incorporating a full view of microbial dynamics is essential to explaining the dynamics of plant-soil feedbacks and therefore plant community ecology.
Collapse
Affiliation(s)
- James D. Bever
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Thomas G. Platt
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Elise R. Morton
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| |
Collapse
|
150
|
Zhan J, Yang L, Zhu W, Shang L, Newton AC. Pathogen populations evolve to greater race complexity in agricultural systems--evidence from analysis of Rhynchosporium secalis virulence data. PLoS One 2012; 7:e38611. [PMID: 22723870 PMCID: PMC3377678 DOI: 10.1371/journal.pone.0038611] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Accepted: 05/08/2012] [Indexed: 11/19/2022] Open
Abstract
Fitness cost associated with pathogens carrying unnecessary virulence alleles is the fundamental assumption for preventing the emergence of complex races in plant pathogen populations but this hypothesis has rarely been tested empirically on a temporal and spatial scale which is sufficient to distinguish evolutionary signals from experimental error. We analyzed virulence characteristics of ≈ 1000 isolates of the barley pathogen Rhynchosporium secalis collected from different parts of the United Kingdom between 1984 and 2005. We found a gradual increase in race complexity over time with a significant correlation between sampling date and race complexity of the pathogen (r(20) = 0.71, p = 0.0002) and an average loss of 0.1 avirulence alleles (corresponding to an average gain of 0.1 virulence alleles) each year. We also found a positive and significant correlation between barley cultivar diversity and R. secalis virulence variation. The conditions assumed to favour complex races were not present in the United Kingdom and we hypothesize that the increase in race complexity is attributable to the combination of natural selection and genetic drift. Host resistance selects for corresponding virulence alleles to fixation or dominant frequency. Because of the weak fitness penalty of carrying the unnecessary virulence alleles, genetic drift associated with other evolutionary forces such as hitch-hiking maintains the frequency of the dominant virulence alleles even after the corresponding resistance factors cease to be used.
Collapse
Affiliation(s)
- Jiasui Zhan
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China.
| | | | | | | | | |
Collapse
|