Do asymmetric sticklebacks make better fathers?

Lateral plate number phenotypes in the low morph of the threespine stickleback, Gasterosteus aculeatus, are under strong genetic control and display fluctuating asymmetry. Results of a survey of a natural population show the nests of asymmetric males were more likely to contain fry than nests of symmetric males. This suggests asymmetric males were more reproductively successful than symmetric males. There is little or no possibility that plate number symmetry can be directly assessed by either potential mates or rival males which compete for mates and attack clutches. Asymmetric males may be slightly larger than symmetric males.