Concerted evolution of male and female display traits in the European corn borer, Ostrinia nubilalis

Jean-Marc Lassance,Christer Löfstedt

doi:10.1186/1741-7007-7-10

Abstract

BackgroundSexual reproduction entails the encounter of the sexes and the multiplicity of rituals is parallel to the diversity of mating systems. Evolutionary mechanisms such as sexual selection and sexual conflict have led to the elaboration of traits to gain attention and favours from potential partners. A paradox exists about how coordinated systems can evolve and diverge when there would seem to be a stabilising selection acting. Moth display traits – pheromones – constitute an advantageous model with which to address questions about the evolution of mating systems in animals. Both males and females can possess pheromones that are involved either in close- or long-range communication. Female and male pheromones appear to have different origins and to be under different evolutionary constraints, thus they might be envisioned as independently evolving traits. We conducted laboratory experiments to explore the role of scents released during courtship by males of the European corn borer, Ostrinia nubilalis.ResultsInformation provided by the male pheromone appears critical for female acceptance. The composition of this male pheromone varies in an age-dependent manner and females show mating preference towards older males in choice experiments. Furthermore, male signals may allow species discrimination and reinforce reproductive isolation. Finally, we found evidence for a genetic correlation between male and female signals, the evolution of which is best explained by the constraints and opportunities resulting from the sharing of gene products.ConclusionIn this study we used an integrative approach to characterise the male sex pheromone in a moth. Interestingly, the male chemical signal is analogous to the female signal in that structurally similar compounds are being used by both sexes. Hence, in systems where both sexes possess display traits, the pleiotropy of genes generating the traits could influence the evolutionary trajectories of sexual signals and lead to their divergence, with speciation being the ultimate result.

Highlights

Sexual reproduction entails the encounter of the sexes and the multiplicity of rituals is parallel to the diversity of mating systems
Mating experiments We examined whether European corn borer (ECB) female mating preference is associated with male age by exposing them to males from three age classes (0, 2- and 4-day-old males)
Behavioural observations throughout the reported experiments provide evidence for the ability of ECB females to distinguish between males, and that male pheromone is a secondary sexual trait associated with female mating preference

Summary

Introduction

Sexual reproduction entails the encounter of the sexes and the multiplicity of rituals is parallel to the diversity of mating systems Evolutionary mechanisms such as sexual selection and sexual conflict have led to the elaboration of traits to gain attention and favours from potential partners. Moth display traits – pheromones – constitute an advantageous model with which to address questions about the evolution of mating systems in animals. Both males and females can possess pheromones that are involved either in close- or longrange communication. Species-specific sex pheromones emitted by female moths mediate long-range mate attraction of males and play an important role in species recognition [2,5,10,11]. Authors have proposed explanations as to why females might make mate choice decisions [16,17,18,19,20], but few studies have addressed which sensory cues mediate female choice

Methods

Results

Discussion

Conclusion