Why are females still choosing male sticklebacks based on ornaments?
The nest of a male stickleback is not a limiting resource. A male stickleback builds a nest, but nest size is not all that limiting. A male stickleback can still attract many females to his nest and thus, sexually selected traits might be strongly favored. In addition, a male that is successful and vigorous in defending his nest from rivals may also become a good parent in that he must aggressively defend his nest and offspring from rivals and predators. The conditions for the evolution of male choice are not quite met in sticklebacks because males are not the limiting sex, female egg production might still be limiting for males. The idea of operational sex ratio (Emlen and Oring) explains why male stickleback are under strong sexual selection and females still choose males on the basis of their bright red coloration. The reproductive rate of the population is still limited by females which must yolk up additional eggs for subsequent clutches. At any point during the breeding season, t
