Coral reef fish rapidly learn to identify multiple unknown predators upon recruitment to the reef.

Matthew D Mitchell,Maud C O Ferrari,Douglas P Chivers,Mark I Mccormick,Brock Fenton

doi:10.1371/journal.pone.0015764

Abstract

Organisms often undergo shifts in habitats as their requirements change with ontogeny.Upon entering a new environment, it is vitally important to be able to rapidly assess predation risk. Predation pressure should selectively promote mechanisms that enable the rapid identification of novel predators. Here we tested the ability of a juvenile marine fish to simultaneously learn the identity of multiple previously unknown predators. Individuals were conditioned with a ‘cocktail’ of novel odours (from two predators and two non-predators) paired with either a conspecific alarm cue or a saltwater control and then tested for recognition of the four odours individually and two novel odours (one predator and one non-predator) the following day. Individuals conditioned with the ‘cocktail’ and alarm cue responded to the individual ‘cocktail’ odours with an antipredator response compared to controls. These results demonstrate that individuals acquire recognition of novel odours and that the responses were not due to innate recognition of predators or due to a generalised response to novel odours. Upon entering an unfamiliar environment prey species are able to rapidly assess the risk of predation, enhancing their chances of survival, through the assessment of chemical stimuli.

Highlights

Most organisms live under the constant threat of predation throughout their lives [1]
The 2-factor MANOVA revealed a significant interaction between conditioning cues and testing odours on the behavioural response of P. moluccensis
The 2-factor ANOVAs performed on the ‘cocktail’ odours only revealed a significant effect of conditioning (F1,112 = 116.0, p,0.0001), but no effect of species (F3,112 = 0.2, p = 0.880) and no interaction between the two factors (F3,112 = 0.2, p = 0.910) on the foraging behaviour of P. moluccensis, indicating that the fish learned to recognize the four cocktail species as threatening, and responded to all four with the same intensity

Summary

Introduction

Most organisms live under the constant threat of predation throughout their lives [1]. Antipredator behaviours are energetically expensive and reduce time available for other important activities such as foraging, mating and resource defence [1,2]. The risks associated with predation vary with both time and space and will change throughout a prey’s life [5]. Most organisms undergo ontogenetic shifts during their development, often resulting in individuals switching habitats in order to exploit superior food resources, shelter and establish or enhance mating opportunities [6]. The composition of potential predators within a given habitat will change as fish grow and switch prey guilds [9,10], or as environmental changes introduce new predators [11]. Predators themselves are highly variable in space and time, ensuring that the risk of predation is in constant flux. Prey should be dynamic and flexible in their antipredator behaviour

Methods

Results

Conclusion