Stimulus-specific and response-specific habituation in courting stickleback: Developmental and functional considerations

Male threespine stickleback, Gasterosteus aculeatus, from a marine populati on on Long Island, New York were presented simultaneously with two dummies, one simulating a normally distended ('thinner') gravid female and the othe r a highly distended ('fatter') one. Males initially courted the dummies mu ch as they do real females, but showed stimulus-specific and response-speci fic habituation to the dummies. Males initially courted the fatter dummy sl ightly more than the thinner one but showed clear signs of habituation towa rd the thinner dummy after about 4 min while courtship to the fatter one co ntinued throughout the 1 hr presentation period. Thus, within 1? min males were directing a much greater proportion of courtship tc, the fatter dummy, and this difference increased over time. Males also attacked both dummies and, in contrast to their courtship response, divided biting equally betwee n the two dummies. Moreover, bite rates to the thinner and the fatter dummy doubled within the first 12 min and then fluctuated around that level for the remainder of the trial. The stimulus-specific and response-specific nat ure of habituation may be adaptive for male mating success because it leads the mule to focus courtship on the preferred female and to direct attack a gainst the fish presenting a greater threat to the nest but a lower potenti al reproductive payoff.