Predator-induced neophobia in juvenile cichlids
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Predation is an important but often fluctuating selection factor for prey animals. Accordingly, individuals plastically adopt antipredator strategies in response to current predation risk. Recently, it was proposed that predation risk also plastically induces neophobia (an antipredator response towards novel cues). Previous studies, however, do not allow a differentiation between general neophobia and sensory channel-specific neophobic responses. Therefore, we tested the neophobia hypothesis focusing on adjustment in shoaling behavior in response to a novel cue addressing a different sensory channel than the one from which predation risk was initially perceived. From hatching onwards, juveniles of the cichlid Pelvicachromis taeniatus were exposed to different chemical cues in a split-clutch design: conspecific alarm cues which signal predation risk and heterospecific alarm cues or distilled water as controls. At 2 months of age, their shoaling behavior was examined prior and subsequent to a tactical disturbance cue. We found that fish previously exposed to predation risk formed more compact shoals relative to the control groups in response to the novel disturbance cue. Moreover, the relationship between shoal density and shoal homogeneity was also affected by experienced predation risk. Our findings indicate predator-induced, increased cross-sensory sensitivity towards novel cues making neophobia an effective antipredator mechanism.
KeywordsPelvicachromis taeniatus Pelvicachromis kribensis Alarm cues Shoaling Predation risk
We thank the Bakker research group for discussion of the manuscript. Furthermore, we are grateful to Douglas Chivers and two anonymous referees for helpful comments.
Author contribution statement
DM, SAB, TCMB and TT conceived the study; DM, SAB and TT designed the experiments; DM carried out the research; DM and TT analysed the data and wrote the paper. All authors read and improved the manuscript and agreed to the final content.
Compliance with ethical standards
This research was funded by the Deutsche Forschungsgemeinschaft (DFG: BA 2885/5-1, TH 1615/1-1).
Conflict of interest
The authors declare that they have no conflict of interest.
All work reported here was conducted in accordance with § 4, § 8b and § 9(2) of the German animal welfare act (BGB l. I S. 1207, 1313) which constitute all applicable institutional and national guidelines for the care and use of animals.
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