Sire attractiveness influences offspring performance in guppies

According to the good-genes hypothesis, females choose among males to ensure the inheritance of superior paternal genes by their offspring. Despite increasing support for this prediction, in some cases differential (non-genetic) maternal effects may obscure or amplify the relationship between paternal attractiveness and offspring quality. Artificial insemination controls such effects because it uncouples mate choice from copulation, therefore denying females the opportunity of assessing male attractiveness. We adopted this technique in the live-bearing fish Poecilia reticulata and examined whether paternal coloration was associated with the behavioural performance of newborn offspring. Sexually receptive virgin females were inseminated with sperm taken individually from donor males that exhibited high variation in the area of orange pigmentation, a trait known to influence female choice in the study population. Our analysis of offspring performance focused on the anti-predator behaviour of newborn fish, including schooling by sibling pairs, the response (swimming speed) of these fishes to a simulated avian predator, and the time taken for a naive investigator to capture the offspring. Although we found no significant effect of sire coloration on either schooling or swimming speed, our analysis revealed a significant positive association between sire coloration and the ability of newborn offspring to evade capture. This finding supports the view that at least one aspect of anti-predator behaviour in newborn offspring is influenced by sire genotype, which in turn is revealed by the expression of secondary sexual traits.