The evolution of conspicuous coloration in male three-spined sticklebacks: Contradictory results and conflicting studies

The three-spined stickleback (Gasterosteus aculeatus L.) is perhaps one of the most studied species of fish with respect to its mating behavior and reproductive biology. This paper reviews several well-known experimental studies which have focused on the adaptive significance of the bright-red breeding coloration of male sticklebacks including the maintenance and loss of red coloration with respect to predation pressure, and the role of parasites in affecting coloration and mate choice. However, results from some recent studies tend to refute or draw into question these original results. The main reason for these conflicting and contradictory findings is not only because stickleback populations show a high degree of variability, as is often argued by stickleback biologists, but appears to be due to a lack of correspondence between laboratory and field work. It is proposed that factors affecting the mating and reproductive biology of three-spined sticklebacks in the wild may be much more complex than previous, single-variable laboratory experiments have suggested.