Within-population variability in a moth sex pheromone blend: genetic basis and behavioural consequences.
Evolutionary diversification of sexual communication systems in moths is perplexing because signal and response are under stabilizing selection in many species, and this is expected to constrain evolutionary change. In the moth Heliothis virescens, we consistently found high phenotypic variability in the female sex pheromone blend within each of four geographically distant populations. Here, we assess the heritability, genetic basis and behavioural consequences of this variation. Artificial selection with field-collected moths dramatically increased the relative amount of the saturated compound 16:Ald and decreased its unsaturated counterpart Z11-16:Ald, the major sex pheromone component (high line). In a cross between the high- and low-selected lines, one quantitative trait locus (QTL) explained 11-21% of the phenotypic variance in the 16:Ald/Z11-16:Ald ratio. Because changes in activity of desaturase enzymes could affect this ratio, we measured their expression levels in pheromone glands and mapped desaturase genes onto our linkage map. A delta-11-desaturase had lower expression in females producing less Z11-16:Ald; however, this gene mapped to a different chromosome than the QTL. A model in which the QTL is a trans-acting repressor of delta-11 desaturase expression explains many features of the data. Selection favouring heterozygotes which produce more unsaturated components could maintain a polymorphism at this locus.
IBED, University of Amsterdam, , Science Park 904, 1098 XH Amsterdam, The Netherlands, Department Entomology, Max Planck Institute for Chemical Ecology, , Hans Knöll Strasse 8, Jena 07745, Germany, Leibniz Institute for Natural Product Research and Infection Biology, , Beutenbergstrasse 11A, Jena 07745, Germany, Department Entomology, North Carolina State University, , 100 Derieux Place, Raleigh, NC 27695-7613, USA, W. M. Keck Center for Behavioral Biology, North Carolina State University, , Raleigh, NC 27695-7617, USA.
Astrid T
AT
Groot
Gerhard
G
Schöfl
Ollie
O
Inglis
Susanne
S
Donnerhacke
Alice
A
Classen
Antje
A
Schmalz
Richard G
RG
Santangelo
Jennifer
J
Emerson
Fred
F
Gould
Coby
C
Schal
David G
DG
Heckel
D000818:Animals; D014644:Genetic Variation; D007178:Inbreeding; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D009036:Moths / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D010641:Phenotype; D040641:Quantitative Trait Loci; D012724:Sex Attractants / Q000737:chemistry / Q000235:genetics*; D012726:Sexual Behavior, Animal
D019476:Insect Proteins; D012724:Sex Attractants
Heliothis virescens; Lepidoptera; balancing selection; delta-11-desaturase; heterozygote advantage; quantitative trait locus analysis