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Sökning: WFRF:(Ehrlén Johan)

  • Resultat 181-190 av 212
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181.
  • van Dijk, Laura J. A, et al. (författare)
  • Direct and insect-mediated effects of pathogens on plant growth and fitness
  • 2021
  • Ingår i: Journal of Ecology. - : British Ecological Society. - 0022-0477 .- 1365-2745. ; 109:7, s. 2769-2779
  • Tidskriftsartikel (refereegranskat)abstract
    • 1. Plants are attacked by a large diversity of pathogens. These pathogens can affectplant growth and fitness directly but also indirectly by inducing changes in the host plant that affect interactions with beneficial and antagonistic insects. Yet, we lack insights into the relative importance of direct and indirect effects of pathogens on their host plants, and how these effects differ among pathogen species.2. In this study, we examined four fungal pathogens on the wood anemone Anemone nemorosa. We used field observations to record the impacts of each pathogen species on plant growth and fitness throughout the season, and experimental hand pollination and insect feeding trials to assess whether fitness impacts were mediated by pathogen-induced changes in plant–pollinator and plant–herbivore interactions.3. Three out of four pathogens negatively affected plant size, and pathogens differed strongly in their effect on plant architecture. Infected plants had lower fitness, but this effect was not mediated by pollinators or herbivores. Even so, two out of four pathogens reduced herbivory on anemones in the field, and we found negative effects of pathogen infection on herbivore preference and performance in feeding trials.4. Synthesis. Our results are of broader significance in two main respects. First, we demonstrated that pathogens negatively affected plant growth and fitness, and that the magnitude of these effects varied among pathogen species, suggesting that pathogens constitute important selective agents that differ in strength. Second, direct effects on plant fitness were more important than effects mediatedby beneficial and antagonistic insects. In addition, although we did not detect insect-mediated effects on plant fitness, the negative effects of some pathogens on herbivore preference and performance indicate that pathogen communities influence the distribution and abundance of herbivores.
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182.
  • van Dijk, Laura J. A., 1990-, et al. (författare)
  • Single, but not dual, attack by a biotrophic pathogen and a sap-sucking insect affects the oak leaf metabolome
  • 2022
  • Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 13
  • Tidskriftsartikel (refereegranskat)abstract
    • Plants interact with a multitude of microorganisms and insects, both below- and above ground, which might influence plant metabolism. Despite this, we lack knowledge of the impact of natural soil communities and multiple aboveground attackers on the metabolic responses of plants, and whether plant metabolic responses to single attack can predict responses to dual attack. We used untargeted metabolic fingerprinting (gas chromatography-mass spectrometry, GC-MS) on leaves of the pedunculate oak, Quercus robur, to assess the metabolic response to different soil microbiomes and aboveground single and dual attack by oak powdery mildew (Erysiphe alphitoides) and the common oak aphid (Tuberculatus annulatus). Distinct soil microbiomes were not associated with differences in the metabolic profile of oak seedling leaves. Single attacks by aphids or mildew had pronounced but different effects on the oak leaf metabolome, but we detected no difference between the metabolomes of healthy seedlings and seedlings attacked by both aphids and powdery mildew. Our findings show that aboveground attackers can have species-specific and non-additive effects on the leaf metabolome of oak. The lack of a metabolic signature detected by GC-MS upon dual attack might suggest the existence of a potential negative feedback, and highlights the importance of considering the impacts of multiple attackers to gain mechanistic insights into the ecology and evolution of species interactions and the structure of plant-associated communities, as well as for the development of sustainable strategies to control agricultural pests and diseases and plant breeding.
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183.
  • van Dijk, Laura J. A., 1990-, et al. (författare)
  • Soil microbiomes drive aboveground plant–pathogen–insect interactions
  • 2022
  • Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 2022:12
  • Tidskriftsartikel (refereegranskat)abstract
    • Plants interact with a large diversity of microbes and insects, both below and above ground. While studies have shown that belowground microbes affect the performance of plants and aboveground organisms, we lack insights into how belowground microbial communities may shape interactions between aboveground pathogens and insects. We investigated how soil microbiomes and aboveground organisms affect plant growth and development, and whether differences in soil microbiomes influence interactions between aboveground organisms. We conducted a growth-chamber experiment with oak seedlings Quercus robur growing in three soils with similar abiotic soil properties but with distinct natural soil microbiomes. Seedlings were subjected to single or dual attack by powdery mildew Erysiphe alphitoides and aphids Tuberculatus annulatus, either in the presence or absence of prior attack by a free-feeding caterpillar Phalera bucephala. Soil microbiomes were associated with differences in seedling height, and seedlings with multiple aboveground organisms had more but smaller leaves than healthy seedlings. The soil microbiome affected the severity of powdery mildew infection, and mediated the impact of co-occurring aboveground organisms on aphid population size. Our study highlights that plant performance is affected by natural soil microbiomes as well as aboveground organisms, and that natural soil microbiomes can affect interactions between pathogens and insects. These findings are important to understand species interactions in natural systems, as well as for practical applications, such as manipulation of soil microbiomes to manage agricultural pests and diseases.
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184.
  • van Dijk, Laura J. A., et al. (författare)
  • The relationship between pathogen life history traits and metapopulation dynamics
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Life-history traits of plant pathogens, such as transmission mode and overwintering strategy, may drive disease dynamics. Still, we lack empirical insights into how life-history traits influence spatiotemporal disease dynamics. We first investigated life history traits in terms of infectivity and overwintering strategy of four fungal pathogens (two rust fungi, one chytrid fungus and one smut fungus) on the forest herb Anemone nemorosa, and then used these traits to make predictions about pathogen metapopulation dynamics that were tested in an extensive field study over four growing seasons. Pathogens infecting new plants mostly via spores (the chytrid and smut fungus) had higher patch occupancies and colonization rates than pathogens that mainly caused systemic infections and overwintered in the rhizomes (the rust fungi). While the rust fungi more often occupied well-connected plant patches, the chytrid and smut fungus were equally or more common in isolated patches. Patch size was positively related to patch occupancy and colonization rates for all pathogens. Predicting disease dynamics is crucial to understand the ecological and evolutionary dynamics of host-pathogen interactions, and to prevent disease outbreaks. Our results suggest that life-history traits are linked to metapopulation dynamics, and can thus be used to improve predictions of disease dynamics. 
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185.
  • van Dijk, Laura J. A., et al. (författare)
  • The relationship between pathogen life-history traits and metapopulation dynamics
  • 2022
  • Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 233:6, s. 2585-2598
  • Tidskriftsartikel (refereegranskat)abstract
    • Plant pathogen traits, such as transmission mode and overwintering strategy, may have important effects on dispersal and persistence, and drive disease dynamics. Still, we lack insights into how life-history traits influence spatiotemporal disease dynamics.We adopted a multifaceted approach, combining experimental assays, theory and field surveys, to investigate whether information about two pathogen life-history traits – infectivity and overwintering strategy – can predict pathogen metapopulation dynamics in natural systems. For this, we focused on four fungal pathogens (two rust fungi, one chytrid fungus and one smut fungus) on the forest herb Anemone nemorosa.Pathogens infecting new plants mostly via spores (the chytrid and smut fungi) had higher patch occupancies and colonization rates than pathogens causing mainly systemic infections and overwintering in the rhizomes (the two rust fungi). Although the rust fungi more often occupied well-connected plant patches, the chytrid and smut fungi were equally or more common in isolated patches. Host patch size was positively related to patch occupancy and colonization rates for all pathogens.Predicting disease dynamics is crucial for understanding the ecological and evolutionary dynamics of host–pathogen interactions, and to prevent disease outbreaks. Our study shows that combining experiments, theory and field observations is a useful way to predict disease dynamics.
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186.
  • van Dijk, Laura J. A., et al. (författare)
  • The timing and asymmetry of plant-pathogen-insect interactions
  • 2020
  • Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 287:1935
  • Tidskriftsartikel (refereegranskat)abstract
    • Insects and pathogens frequently exploit the same host plant and can potentially impact each other's performance. However, studies on plant-pathogen-insect interactions have mainly focused on a fixed temporal setting or on a single interaction partner. In this study, we assessed the impact of time of attacker arrival on the outcome and symmetry of interactions between aphids (Tuberculatus annulatus), powdery mildew (Erysiphe alphitoides), and caterpillars (Phalera bucephala) feeding on pedunculate oak,Quercus robur, and explored how single versus multiple attackers affect oak performance. We used a multifactorial greenhouse experiment in which oak seedlings were infected with either zero, one, two, or three attackers, with the order of attacker arrival differing among treatments. The performances of all involved organisms were monitored throughout the experiment. Overall, attackers had a weak and inconsistent impact on plant performance. Interactions between attackers, when present, were asymmetric. For example, aphids performed worse, but powdery mildew performed better, when co-occurring. Order of arrival strongly affected the outcome of interactions, and early attackers modified the strength and direction of interactions between later-arriving attackers. Our study shows that interactions between plant attackers can be asymmetric, time-dependent, and species specific. This is likely to shape the ecology and evolution of plant-pathogen-insect interactions.
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187.
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188.
  • Vanhoenacker, Didrik, et al. (författare)
  • Morph-specific selection on floral traits in a polymorphic plant
  • 2010
  • Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 23:6, s. 1251-1260
  • Tidskriftsartikel (refereegranskat)abstract
    • Correlations between phenotypic traits are common in many organisms, but the relative importance of nonadaptive mechanisms and selection for the evolution and maintenance of such correlations are poorly understood. In polymorphic species, morphs may evolve quantitative differences in additional characters as a result of morph-specific selection. The perennial rosette herb Primula farinosa is polymorphic for scape length. The short-scaped morph is less damaged by grazers and seed predators but is more strongly pollen limited than the long-scaped morph. We examined whether morph-specific differences in biotic interactions are associated with differences in selection on two other traits affecting floral display (number of flowers and petal size) and on one trait likely to affect pollination efficiency (corolla tube width) in three P. farinosa populations. Differences in selection between morphs were detected in one population. In this population, selection for more flowers and larger petals was stronger in the short-scaped than in the long-scaped morph, and although there was selection for narrower corolla tubes in the short-scaped morph, no statistically significant selection on corolla tube width could be detected in the long-scaped morph. In the study populations, the short-scaped morph produced more and larger flowers and wider corolla tubes. Current morph-specific selection was thus only partly consistent with trait differences between morphs. The results provide evidence of morph-specific selection on traits associated with floral display and pollination efficiency, respectively.
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189.
  • Vanhoenacker, Didrik, et al. (författare)
  • Non-linear relationship between intensity of plant-animal interactions and selection strength
  • 2013
  • Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 16:2, s. 198-205
  • Tidskriftsartikel (refereegranskat)abstract
    • The shape of the relationship between intensity of biotic interactions and strength of selection is important for spatial variation in selection, but is little explored. We quantified interactions and selection in 69 populations of the short-lived herb Primula farinosa. As predicted because of saturation and depletion effects, the strength of selection on a discrete and on a continuously varying floral display trait were in several cases significantly non-linearly related to the mean intensity of mutualistic and antagonistic interactions. Strength of selection was strongest at low levels of fruit initiation and at high intensities of seed predation. Seed predation varied more among populations than did fruit initiation and could explain a larger proportion of the among-population variation in strength of selection. Our results support the contention that interaction intensity affects selection strength, and suggests that for mutualistic and antagonistic interactions that can be saturated or depleted, this relationship is sometimes non-linear.
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190.
  • Vanhoenacker, Didrik, 1971- (författare)
  • Selection on floral traits in Primula farinosa
  • 2008
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Flowers and inflorescences have evolved in relation to animals for at least 100 million years. Plants attract pollinators with large, conspicuous, bright-coloured or scented flowers. These display attributes, however, also attract herbivores. Optimal conspicuousness may therefore represent a trade-off between attractiveness to pollinators and vulnerability to herbivores. In a heterogenic landscape, the abundances of pollinators and herbivores vary, and this variation should cause the local net selection on floral traits to vary as well. This thesis investigates how pollinators and herbivores select for floral traits, how this selection is linked to interaction intensities, and what factors determine spatial variation in interaction intensity. I have studied the small perennial herb, Primula farinosa, and its interactions with pollinators, a seed predator moth, and grazers. The plant varies in several floral traits; most notably it displays a polymorphism in scape length. Results showed that pollinators selected for long scape, while the seed predator and grazers selected against long scape. Local net selection on scape length depended on interaction intensities of all three interactions. Scape morph also affected selection on number and size of flowers. We hypothesised that intensity of seed predation should depend on local population history of the specialised moth. However, the results from a 5-year survey suggests that patches were recolonized every year, and that the most important patch choice criteria were plant characteristics, such as mean inflorescence size and scape morph frequency. Within a geographic selection mosaic, local hot spots of plant evolution may not be random patches, but patches chosen by the agent of selection based on plant trait values. This thesis shows how spatial population ecology and herbivore dispersal behaviour are linked to mosaic interactions and trait evolution.
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