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Explain the concept of host range in the context of plant virus emergence and evolution.
The host range refers to the number of host species used by a pathogen. It is a key factor in understanding pathogen epidemiology and pathogenicity. However, it is not an immutable trait and is influenced by ecological factors such as species distribution and interaction.
Why is estimating a virus host range difficult, especially for plant viruses?
Estimating a virus host range is difficult because identifying all 'non-hosts' is practically impossible. This task is particularly challenging for plant viruses, and knowledge on host ranges may be limited, especially in wild ecosystems.
How does host range evolution contribute to plant virus emergence?
Host range evolution may result in a shift or change between hosts, or in the acquisition of new hosts or loss of existing ones. This contributes to the ability of the virus to encounter new hosts and adapt to ensure effective between-host transmission.
What ecological factors influence the host range of a virus?
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Why have studies on host ranges of plant viruses strongly favored those causing diseases in crops, and what remains relatively unexplored?
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What are some of the traits quantified in ecological and evolutionary studies related to disease risk?
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How does connectivity affect virus expansion or host range alteration?
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What are some of the factors hypothesized to play a role in infection distribution?
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What does the conceptual framework highlight in terms of disease spread?
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How are prevalence-diversity relationships affected in a given habitat?
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How does co-infection affect the pleiotropic effects of resistance-breaking mutations on plant virus multiplication?
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What environmental factors may modulate across-host fitness trade-offs in the evolution of host range for plant viruses?
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What are some conflicting trade-offs that may constrain the evolution of organisms, including plant viruses?
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How is selection for a broader host range in plant viruses manifested in terms of traits unrelated to the plant-virus interaction?
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What influences the evolution of a species' resource breadth, including plant viruses?
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What are the major intrinsic and extrinsic factors influencing host range evolution in viruses?
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Explain the gene-for-gene (GFG) and matching-alleles (MA) co-evolutionary models and their application in analyzing plant virus host range evolution.
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Describe the structure of virus-host interaction networks and how it can vary depending on geographical and taxonomical scales.
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What role does specificity of infection play in the evolution of virus host range?
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How do resistance-breaking mutations in viruses affect virus multiplication and host range?
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Study Notes
Host Range Evolution in Viruses
- Host range evolution is influenced by both intrinsic factors (genetic traits) and extrinsic factors (ecology and epidemiology).
- Genetic specificity is a major intrinsic determinant of host range, with some viruses and genotypes only able to infect specific hosts.
- The gene-for-gene (GFG) and matching-alleles (MA) co-evolutionary models have been applied to analyze plant virus host range evolution.
- The structure of virus-host interaction networks can be modular or nested, depending on geographical and taxonomical scales.
- A study of a virus-plant species infection matrix revealed a nested network with significant modules corresponding to viruses infecting particular plant families.
- Specificity of infection leads to adaptive trade-offs among hosts, hindering host range expansion and favoring the evolution of specialism rather than generalism.
- Across-host fitness trade-offs affect transmission across host species and can result from antagonistic pleiotropy of host-range mutations and epistatic interactions among them.
- Evidence of across-host fitness trade-offs mostly comes from experiments, which may complicate predictions on host range evolution when a higher number of interactions are examined.
- Adaptation to a new host may result in adaptation to closely related hosts, favoring virus jumps to related species.
- Resistance-breaking mutations in viruses can have pleiotropic effects on virus multiplication, depending on the specific mutation and the susceptible host genotype.
- The distribution of effects of host range mutations may depend on demographic factors of the virus population associated with the host genotype.
- Predicting host range evolution in genetically heterogeneous, susceptible host populations is difficult due to the complex effects of host-range mutations modulated by extrinsic environmental factors.
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Description
Explore the factors influencing the evolution of host range in viruses, from genetic specificity to virus-host interaction networks and adaptation to new hosts. Understand the impact of across-host fitness trade-offs and resistance-breaking mutations on virus multiplication and transmission.
