Frederik Hendrickx, Bram Vanthournout, and Michael Taborsky (2015)
Selection for costly traits result in a vacant mating niche and in the evolution of a genetic male dimorphism
Evolution, 69(8):2105-2117.
The expected strong directional selection for traits that increase a male’s mating ability conflicts with the frequent observation that
within species, males may show extreme variation in sexual traits. These male reproductive polymorphisms are usually attributed
to direct male–male competition. It is currently unclear, however, how directional selection for sexually selected traits may convert
into disruptive selection, and if female preference for elaborate traits may be an alternative mechanism driving the evolution
of male polymorphism. Here, we explore this mechanism using the polyandric dwarf spider Oedothorax gibbosus as a model.
We first show that males characterized by conspicuous cephalic structures serving as a nuptial feeding device (“gibbosus males”)
significantly outperform other males in siring offspring of previously fertilized females. However, significant costs in terms of
development time of gibbosus males open a mating niche for an alternative male type lacking expensive secondary sexual traits.
These “tuberosus males” obtain virtually all fertilizations early in the breeding season. Individual-based simulations demonstrate
a hitherto unknown general principle, by which males selected for high investment to attract females suffer constrained mating
opportunities. This creates a vacant mating
Peer Review, International Redaction Board, Impact Factor
Sex Characteristics, Evolutionary Biology, Adaptation
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