Sign Stimuli in the Threespine Stickleback (Gasterosteus Aculeatus): a Re-Examination and Extension of Some Classic Experiments

Abstract

1. Both Long Island and Dutch territorial male Gasterosteus aculeatus exhibited considerable variation in their responses to dummies. Such responses were generally consistent within the same individual presented with the same dummy: male dummies evoked primarily aggressive behavior and female dummies evoked primarily courtship. However, males from both Long Island and Dutch populations sometimes directed courtship to male dummies and aggression to female dummies. 2. Males from both populations generally directed more aggression (bites) to the silver male dummy than to the dummy male bearing red undersides and blue eyes (i.e. , nuptial coloration). However, exceptional males from both populations showed the opposite trend. In trials with Dutch males in which backoffs could be measured, this behavior was more often directed to the nuptially colored dummy male than to the silver one. 3. Males from the Long Island population directed more activities, especially bites, to the horizontal dummy male than to either the headup or headdown dummy male. These males exhibited no difference in frequencies of behaviors directed to headup and headdown dummy males. Dutch males were only tested with headup vs horizontal dummy males and they too directed more activities, especially bites, to the latter. 4. Males from the Long Island population directed more courtship (zigzags and leads) and aggression (bites) to the dummy female with the greater abdominal distention, even when such distention was extreme (supernormal). Dutch males were only tested with (normally) gravid vs supergravid dummy females and they directed more activities, especially zigzags, to the latter. 5. Males from the Long Island population directed more courtship (zigzags and leads) and aggression (bites) to the horizontal dummy female than to either the headup or headdown one. Dutch males were only tested with headup vs horizontal dummy females and directed more courtship to the latter.