UBC Theses and Dissertations
Some factors affecting the development and expression of escape behavior in the guppy (Poecilia reticulata) Goodey, Wayne
Adult guppies (Poecilia reticulata) frequently chase, but only infrequently capture and eat, young conspecifics. On average, young in planted tanks containing 6-14 adults and 1-4 young experienced over 270 chases per individual per day. Does the experience of being chased affect escape behavior? I tested this in two experiments on individual guppies. In the first, the escape behavior of three groups of guppies - control fish (those chased by adults in the first 48 hr of life), partially experienced fish (exposed to chemical cues from chasing adults, visual cues from chasing adults, or chemical cues from predatory fish), and inexperienced fish - was compared for their response to an aerial predator stimulus. Response intensity varied among the treatments, but deprivation had no effect on the appearance of stereotyped escape behaviors. Deprivation had no influence on the drop response elicited by the aerial stimulus, but it caused a general increase in the length of time spent freezing in response to the stimulus. Fish exposed to chemical cues from adult guppies, on the other hand, developed a near-control response. In the second experiment, I exposed guppies from the same experience groups to predation to see if long freezing times were selected against. Controls were not attacked with greater latency nor did they survive longer than any deprived group, but it took more attacks to kill control fish than to kill any deprived fish. I propose that chasing by adults is an ontogenetic mechanism for conditioning the young to avoid predation. This is selected for because guppies which are chased as juveniles survive better than those not chased as juveniles.