Disruptive selection on male reproductive polymorphism in a jumping spider, Maevia inclemens

• Females of Maevia inclemens do not show preference for either of the two male morphs.
• Females prefer opposite values of anatomical and behavioural traits for each morph.
• Variation in female preference results in disruptive sexual selection.
• The weak differences between morphs concur with their respective selection pressure.

Genetic polymorphism in males has long been considered paradoxical because sexual selection is expected to deplete additive genetic variation. Although studies have shown how divergent selection between populations can make that work, it is very rare to find disruptive selection within one population. Since intersexual selection can have a significant effect on the phenotypic morphospace of the opposite sex, we analysed the role of female preference as a disruptive selective force. In this study we evaluated how female preference acts on anatomical and sex-related behavioural traits of two male morphs in the jumping spider Maevia inclemens. We used mate choice trials to analyse how female preference for the two morphs varied. The tests indicated that females preferred opposite values of two anatomical and two behavioural traits for each male morph. This study is, to our knowledge, the first to show disruptive sexual selection in Arachnidae and significantly expands the realm of disruptive selection, by adding one more case to the very few documented instances. These processes, which act entirely within a species, are of particular interest because they could contribute to the evolution of reproductive isolation and sympatric speciation by sexual selection, a controversial topic in evolutionary biology.