A major locus controls a biologically active pheromone component in Heliconius melpomene
Kelsey J R P Byers1,2, Kathy Darragh1,2, Jamie Musgrove2
1Department of Zoology, University of Cambridge, Cambridge, CB2 3EJ, United Kingdom.
Evolution; International Journal of Organic Evolution
|January 9, 2020
Summary
Butterfly sex pheromones, like octadecanal, play a role in mate choice and evolution. Genetic mapping reveals a single locus controls octadecanal production, suggesting its importance in butterfly speciation.
Area of Science:
- Evolutionary biology
- Chemical ecology
- Genetics
Background:
- Mate choice signals are crucial for understanding reproductive isolation and speciation.
- The role of sex pheromones in butterfly courtship and mate choice is not well understood.
- Butterflies utilize complex blends of wing-based chemical compounds for courtship.
Purpose of the Study:
- To investigate the role of wing androconial compounds in Heliconius butterfly mate choice.
- To identify the genetic basis of pheromone production in Heliconius.
- To assess the potential contribution of pheromones to speciation in Heliconius.
Main Methods:
- Electroantennography was used to assess olfactory responses to androconial extracts in Heliconius melpomene and Heliconius cydno.
- Quantitative trait locus (QTL) mapping was employed to identify genetic loci controlling pheromone production.
- Experimental manipulation of octadecanal levels on male wings was performed to test its bioactivity.
Main Results:
- Responses to androconial extracts were not species-specific, indicating conserved olfactory mechanisms.
- Octadecanal, a major component of the H. melpomene blend, significantly influenced mating time, demonstrating its bioactivity.
- A single QTL on chromosome 20 accounted for 41% of the variation in octadecanal production between species, containing candidate fatty acid biosynthesis genes.
Conclusions:
- Sex pheromones in Heliconius butterflies carry significant information for mate choice.
- The production of key pheromones like octadecanal is under simple genetic control.
- Pheromonal signals, due to their genetic basis, may play a substantial role in the speciation process of Heliconius butterflies.
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