Natural variation in condition-dependent display colour does not predict male courtship success in a jumping spider

In many animals, males display costly, condition-dependent ornaments to choosy females. Indicator models of sexual selection predict that females should choose mates based on natural variation in such traits. In Habronattus pyrrithrix jumping spiders, males have conspicuous, condition-dependent red faces and green legs that they display to cryptically coloured females during courtship. In a correlational study using field-collected spiders, we paired individual males with virgin females in the laboratory and found that natural variation in male coloration did not predict mating success (likelihood of copulation) or levels of female aggression. Rather, mating success was best predicted by male body condition. We then conducted an outdoor experiment under natural sunlight where we gave both virgin and mated females the choice between two simultaneously courting males, one with his facial coloration experimentally reduced and the other that received a sham treatment. Again, we found no relationship between male coloration and courtship success. Our previous studies have shown that the presence (versus absence) of red facial coloration improves courtship success, but here we found no evidence that more subtle natural variation in this trait has any effect on success. We discuss these findings in the context of complex signalling and species recognition in Habronattus. While many studies report negative results for condition-dependent quality signalling alongside positive ones, few discuss the implications of negative results. We argue that, as empirical data accumulate, we should move towards asking why some condition-dependent traits are consistently important to females while other equally condition-dependent traits are either ignored, or only matter in certain contexts.