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Niche Specificity, Polygeny, and Pleiotropy in Herbivorous Insects
The American Naturalist
|February 27, 2023
Summary
Pleiotropy is not always necessary for herbivorous insects to specialize on specific hosts. Simulation models show specialization can evolve without pleiotropy, especially with rapid environmental change or unequal host productivity.
Area of Science:
- Ecology
- Evolutionary Biology
- Genetics
Background:
- Herbivorous insects often exhibit host use specificity, a phenomenon crucial for understanding insect-host interactions.
- Existing population genetic models suggest specialization arises from habitat preference evolution and antagonistic pleiotropy, but empirical evidence in insects is limited.
- Antagonistic pleiotropy, where a gene affects multiple traits negatively, appears rare in insect host use, prompting further investigation.
Purpose of the Study:
- To investigate the role of pleiotropy in the evolution of sympatric host use specialization in herbivorous insects using simulation models.
- To explore how quantitative genetic traits of performance and preference interact with pleiotropy under varying environmental conditions.
Main Methods:
- Individual-based quantitative genetic simulation models were employed to simulate the evolution of host use specialization.
- Models explored pleiotropies affecting host use performance and those affecting both performance and preference.
- Scenarios included varying rates of environmental change and host species productivity asymmetries.
Main Results:
- Host use specialization can evolve without pleiotropy, particularly under rapid environmental change or when host species have unequal productivity.
- High levels of antagonistic pleiotropy are required for specialization in slowly changing environments without other factors.
- When pleiotropy affects both preference and performance, it can lead to fluctuating host use breadth and increased specificity with greater pleiotropy.
Conclusions:
- Pleiotropy is not a prerequisite for the evolution of host use specialization in herbivorous insects.
- Environmental factors like rapid change and host productivity differences can drive specialization independently of pleiotropy.
- Extensive or multifarious pleiotropy can be sufficient, but not necessary, for achieving host use specialization.
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