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Published on: August 12, 2019
Host-race formation: promoted by phenology, constrained by heritability
A V Whipple1, W G Abrahamson, M A Khamiss
1Department of Biology, Bucknell University, Lewisburg, PA, USA. amy.whipple@nau.edu
Journal of Evolutionary Biology
|February 20, 2009
Summary
Phenological differences in host plants create a trade-off for the goldenrod gall fly, potentially driving host-race formation. However, limited genetic variation for emergence time may impede this evolutionary process.
Area of Science:
- Evolutionary Biology
- Ecology
- Entomology
Background:
- Host-race formation in herbivores is often linked to genetic trade-offs in utilizing different host plants.
- Differential timing of host-plant availability (phenology) can impose these trade-offs, influencing herbivore specialization.
- The goldenrod gall fly (Eurosta solidaginis) is a model system for studying host-race formation.
Purpose of the Study:
- To investigate the role of phenology in limiting host-plant use in the goldenrod gall fly.
- To determine if phenological constraints lead to a trade-off promoting divergent selection on fly emergence time.
- To assess the genetic capacity of the fly to respond to selection on emergence time amidst environmental variation.
Main Methods:
- Experimental manipulation of host-plant age for oviposition and gall induction.
- Assessment of oviposition and gall induction success on young and intermediate-aged Solidago canadensis and Solidago gigantea.
- Estimation of heritability for emergence time using parent-offspring regression.
Main Results:
- Oviposition and gall induction on the alternate host (S. canadensis) were highest on young plants.
- Gall induction on the primary host (S. gigantea) was highest on intermediate-aged plants.
- Heritability estimates suggest that genetic variation for emergence time is limited relative to environmental variation.
Conclusions:
- A phenological trade-off exists for goldenrod gall fly host-plant use, creating potential for divergent selection on emergence time.
- The observed genetic variation for emergence time may impede rapid host-race formation.
- Environmental variation plays a significant role in the emergence timing of the goldenrod gall fly.
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