Data from: Sexual conflict and antagonistic coevolution across water strider populations

Microevolutionary studies have demonstrated sexually antagonistic
selection on sexual traits, and existing evidence supports a
macroevolutionary pattern of sexually antagonistic coevolution. Two
current questions are how antagonistic selection within populations scales
to divergence among populations, and to what extent intraspecific
divergence matches species-level patterns. To address these questions, we
conducted an intraspecific comparative study of sexual armaments and
mating behaviours in a water strider (Gerris incognitus) in which male
genitals grasp resistant females and female abdominal structures help ward
off males. The degree of exaggeration of these armaments coevolves across
species. We found a similar strong pattern of antagonistic coevolution
among populations, suggesting that sexual conflict drives population
differentiation in morphology. Furthermore, relative exaggeration in
armaments was closely related to mating outcomes in a common environment.
Interestingly, the effect of armaments on mating was mediated by
population sexual size dimorphism. When females had a large size
advantage, mating activity was low and independent of armaments, but when
males had a relative size advantage, mating activity depended on which sex
had relatively exaggerated armaments. Thus, a strong signal of sexually
antagonistic coevolution is apparent even among populations. These results
open opportunities to understand links between sexual arms races,
ecological variation and reproductive isolation.