Sexual conflict and intrasexual polymorphism promote assortative mating and halt population differentiation

• Sexual conflict is thought to be an important evolutionary force in drivingphenotypic diversification, population divergence, and speciation. However,empirical evidence is inconsistent with the generality that sexual conflictenhances population divergence. Here, we demonstrate an alternativeevolutionary outcome in which sexual conflict plays a conservative role inmaintaining male and female polymorphisms locally, rather than promotingpopulation divergence. In diving beetles, female polymorphisms haveevolved in response to male mating harassment and sexual conflict. We presentthe first empirical evidence that this female polymorphism is associatedwith (i) two distinct and sympatric male morphological mating clusters(morphs) and (ii) assortative mating between male and female morphs.Changes in mating traits in one sex led to a predictable change in the othersex which leads to predictable within-population evolutionary dynamics inmale and female morph frequencies. Our results reveal that sexual conflictcan lead to assortative mating between male offence and female defencetraits, if a stable male and female mating polymorphisms are maintained.Stable male and female mating polymorphisms are an alternative outcometo an accelerating coevolutionary arms race driven by sexual conflict. Suchstable polymorphisms challenge the common view of sexual conflict as anengine of rapid speciation via exaggerated coevolution between sexes.

Subject headings

NATURVETENSKAP  -- Biologi -- Evolutionsbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Evolutionary Biology (hsv//eng)

Keyword

coevolution

sexual antagonism

sympatric speciation

population variation

spatial structure

Diversity of life

Livets mångfald

coevolution

population variation

sexual antagonism

spatial structure

sympatric speciation

Publication and Content Type

ref (subject category)

art (subject category)