Hox genes mediate the escalation of sexually antagonistic traits in water striders.

Antonin Jean Johan Crumière,Abderrahman Khila

doi:10.1098/rsbl.2018.0720

Abstract

Sexual conflict occurs when traits favoured in one sex impose fitness costs on the other sex. In the case of sexual conflict over mating rate, the sexes often undergo antagonistic coevolution and escalation of traits that enhance females' resistance to superfluous mating and traits that increase males' persistence. How this escalation in sexually antagonistic traits is established during ontogeny remains unclear. In the water strider Rhagovelia antilleana, male persistence traits consist of sex combs on the forelegs and multiple rows of spines and a thick femur in the rear legs. Female resistance traits consist of a prominent spike-like projection of the pronotum. RNAi knockdown against the Hox gene Sex Combs Reduced resulted in the reduction in both the sex comb in males and the pronotum projection in females. RNAi against the Hox gene Ultrabithorax resulted in the complete loss or reduction of all persistence traits in male rear legs. These results demonstrate that Hox genes can be involved in intra- and inter-locus sexual conflict and mediate escalation of sexually antagonistic traits.

Highlights

The evolutionary interests of males and females during mating interactions often diverge, leading to the coevolution of sexually antagonistic traits that are favoured in one sex at a fitness cost to the other [1,2]
These results demonstrate that Hox genes can be involved in intra- and inter-locus sexual conflict and mediate escalation of sexually antagonistic traits
In females, Sex Combs Reduced (Scr) RNAi resulted in a reduction in the size and disruption of the shape of the pronotum projection. These results demonstrate that the same Hox gene, Scr, is involved in the development of both male persistence and female resistance traits that are located in its domain of action, i.e. the first thoracic segment

Summary

Evolutionary developmental biology

Hox genes mediate the escalation of sexually antagonistic traits in water striders Antonin Jean Johan Crumiere† and Abderrahman Khila. In the case of sexual conflict over mating rate, the sexes often undergo antagonistic coevolution and escalation of traits that enhance females’ resistance to superfluous mating and traits that increase males’ persistence. RNAi knockdown against the Hox gene Sex Combs Reduced resulted in the reduction in both the sex comb in males and the pronotum projection in females. RNAi against the Hox gene Ultrabithorax resulted in the complete loss or reduction of all persistence traits in male rear legs. These results demonstrate that Hox genes can be involved in intra- and inter-locus sexual conflict and mediate escalation of sexually antagonistic traits

Introduction

Results

Discussion