Early interactions with adults mediate the development of predator defenses in guppies

Antipredator defenses in many species have been shown to exhibit phenotypic plasticity in response to variable predation risk. Some evidence suggests that in certain species adults act as proxy predators, triggering the development of adaptive defenses in juveniles where interaction with a predator is unlikely to occur. However, almost nothing is known about how adult/juvenile interactions mediate plasticity. Here, we examine the nature of the antipredator defenses that develop in Trinidadian guppies as a function of early social experience and investigate the importance of different types of cue (physical, visual, and olfactory) by rearing juveniles under 3 different social conditions. In the first, only juveniles are present; in the second, only visual and olfactory interaction occurs between adults and juveniles; and in the third, adults physically interact with juveniles. Our analyses show that juveniles reared in the physical presence of adults spend significantly less time shoaling with adults than fish from other treatments in an adult versus juvenile shoal-choice trial. Further, we show that juveniles with experience of adult aggression have a decreased response latency to a simulated avian predation attempt and travel a greater distance in the first 5 frames of movement after the simulated strike. Finally, juveniles reared with physical experience of adults developed relatively deeper bodies and were significantly shorter in standard length than guppies reared without physical experience of adults.