Experience With Chemical Cues Influences Subsequent Behavior of Rainbow Darters, Etheostoma Caeruleum


Angela Gibson

Date of Graduation

Spring 2004


Master of Science in Biology



Committee Chair

Alicia Mathis


I performed two sets of experiments to determine whether rainbow darters, Etheostoma caeruleum, alter their behavior following experience with predatory and conspecific stimuli. First, I tested whether darters could learn to associate the color of a predator model with danger. In one experiment, I used standard associative protocols where I simultaneously exposed darters to red predator models and to either an alarm chemical (unconditioned fright stimulus) or blank water (control), and then subsequently tested the responses of the darters (number of hops) to the models (either red or blue) alone. The results of the study are ambiguous with respect to learning because darters in the alarm treatment showed significant reductions in baseline activity (number of hops) before the presentation of the models. However, the finding that exposure to alarm pheromones can affect rainbow darter behavior several days following exposure has not been reported before. In a second associative learning experiment, I paired a red or blue model with either the alarm pheromone or a blank control. In subsequent tests, darters did not appear to associate danger with the color of their training model. In a second set of experiments, I tested whether experience with conspecific and heterospecific stimuli influenced habitat choice of darters. Darters were initially exposed to the stimuli in one of the two habitats (woody debris and rocks). The results were: (a) Darters exposed to chemical cues from predators (in both habitats) preferred to occupy the rock substrate when tested 24 hours after removal of the stimulus; in contrast, exposure to nonpredatory control stimuli (stoneroller and blank) resulted in random habitat choice after 24 hours. (b) Habitat choice of darters exposed to conspecific alarm pheromones (in either habitat) was random after 24 hours. (c) Darters were attracted to the rock habitat (but not the woody debris) if it had previously contained social pheromones.


rainbow darters, aversive learning, chemical cues, alarm pheromone, fright responses

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© Angela Gibson