bric à brac controls sex pheromone choice by male European corn borer moths

Abstract

The sex pheromone system of ~160,000 moth species acts as a powerful form of assortative mating whereby females attract conspecific males with a species-specific blend of volatile compounds. Understanding how female pheromone production and male preference coevolve to produce this diversity requires knowledge of the genes underlying change in both traits. In the European corn borer moth, pheromone blend variation is controlled by two alleles of an autosomal fatty-acyl reductase gene expressed in the female pheromone gland (pgFAR). Here we show that asymmetric male preference is controlled by cis-acting variation in a sex-linked transcription factor expressed in the developing male antenna, bric à brac (bab). A genome-wide association study of preference using pheromone-trapped males implicates variation in the 293 kb bab intron 1, rather than the coding sequence. Linkage disequilibrium between bab intron 1 and pgFAR further validates bab as the preference locus, and demonstrates that the two genes interact to contribute to assortative mating. Thus, lack of physical linkage is not a constraint for coevolutionary divergence of female pheromone production and male behavioral response genes, in contrast to what is often predicted by evolutionary theory.

A single point mutation causes one-way alteration of pheromone receptor function in two Heliothis species

“…Based on the typical roles of female moths as signal producers and male moths as signal receivers in the sex pheromone system, several evolutionary hypotheses, such as the stasis hypothesis, asymmetric tracking hypothesis, and wallflower hypothesis, have been proposed ( Allison and Cardé, 2016 ; Cardé and Baker, 1984 ; Groot et al., 2006 ; Roelofs et al., 2002 ); however there is no consensus. This is mainly because existing studies show that the synthesis of sex pheromones in females and the perception of sex information in males are regulated by different genes and under independent genetic control ( Gould et al., 2009 , 2010 ; Löfstedt et al., 1989 ; Dopman et al., 2004 ; Unbehend et al., 2021 ). Although the contributions of male and female traits to the evolution of sex pheromone communication remain controversial, it is undeniable that male moths' perception of sex pheromone is one of the key steps.…”

A genetic switch for male UV iridescence in an incipient species pair of sulphur butterflies

“…In Drosophila , linkage mapping studies have shown that regulatory alleles of the bab locus ( bab1/2 recent paralogs) explain natural variation in dimorphic pigmentation and ovariole number ( 23 , 26 , 40 ). In corn borer moths ( Ostrinia nubilalis ), male response to a polymorphic female pheromone blend is driven by a Z-linked regulatory variation in the first intron of bab ( 41 ). This same intron is within the Colias U -locus interval.…”

Elevated temperature increases reproductive investment in less preferred mates in the invasive European corn borer moth

“…We calculated likelihood ratio chi-square statistics for factors in the car package (Fox & Weisberg, 2019) and performed Tukey-corrected pairwise comparisons using emmeans (Lenth, 2019). To further analyze and visualize effects, we used several other R packages: dplyr (Wickham et al, 2018), ggplot2 (Wickham, 2016), MASS (Venables & Ripley, 2002), plyr (Wickham, 2011), survival (Therneau, 2020), and survminer (Kassambara et al, 2019). The standard error (SE) for the proportion producing eggs was calculated using the equation Havel et al, 2019).…”