One quantitative trait locus for intra‐ and interspecific variation in a sex pheromone

Abstract

Even though premating isolation is hypothesized to be a major driving force in speciation, its genetic basis is poorly known. In the noctuid moth Heliothis subflexa, one group of sex pheromone components, the acetates, emitted by the female, plays a crucial isolating role in preventing interspecific matings to males of the closely related Heliothis virescens, in which females do not produce acetates and males are repelled by them. We previously found intraspecific variation in acetates in H. subflexa: females in eastern North America contain significantly more acetates than females in Western Mexico. Here we describe the persistence of this intraspecific variation in laboratory-reared strains and the identification of one major quantitative trait locus (QTL), explaining 40% of the variance in acetate amounts. We homologized this intraspecific QTL to our previously identified interspecific QTL using restriction-associated DNA (RAD) tags. We found that a major intraspecific QTL overlaps with one of the two major interspecific QTL. To identify candidate genes underlying the acetate variation, we investigated a number of gene families with known or suspected acetyl- or acyltransferase activity. The most likely candidate genes did not map to our QTL, so that we currently hypothesize that a transcription factor underlies this QTL. Finding a single, large QTL that impacts variation in pheromone blends between and within species is, to our knowledge, the first such example for traits that have been demonstrated to affect premating isolation.

Genetic basis of allochronic differentiation in the fall armyworm

“…To identify candidate genes on the QTC, the linkage map was homologized to the reference genome of B. mori, using restriction site associated DNA (RAD) analysis (see Baxter et al [53] and Groot et al [54]). DNA of parents, female grandparents and 11 backcross individuals per backcross family was digested with the Sbf1 restriction enzyme (New England Biolabs, Ipswich, MA, USA), barcoded, pooled, sheared and amplified, following the procedure described in Groot et al [54].…”

“…DNA of parents, female grandparents and 11 backcross individuals per backcross family was digested with the Sbf1 restriction enzyme (New England Biolabs, Ipswich, MA, USA), barcoded, pooled, sheared and amplified, following the procedure described in Groot et al [54]. The pool was paired-end sequenced (50 bp fw, 50 bp rev) by FASTERIS (Geneva, Switzerland) with a HiSeq Illumina sequencer, resulting in 76 million reads.…”

Within-population variability in a moth sex pheromone blend: genetic basis and behavioural consequences

“…A genetic map of H. virescens was created using 258 AFLP markers generated by using 35 primer combinations (see [51] for details). We used paired-end RADtags to homologize the linkage groups to our previously constructed interspecific map and the reference genome of Bombyx mori (see the electronic supplementary material and [52] for more details). As this was a female-informative cross and there is no crossing-over in female Lepidoptera, each linkage group corresponds to a separate chromosome [53].…”

The genetic architecture of sexually selected traits in two natural populations of Drosophila montana

“…One exception, for a pre-mating signal, involves a pheromone QTL in the moth species Heliothis subflexa and H. virescens (Groot et al, 2013). Few studies have compared the magnitude of effect sizes within and between populations in addition to assessing whether the same QTLs are implicated, and it may be that consistent genetic effects are associated with phenotypes where large effect loci are more likely to be found, such as pheromone polymorphisms or genes influencing melanism (Wittkopp et al, 2009).…”