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The role of embryonic risk cues on the life history, morphology and behaviour of the wood frog Lithobates sylvaticus



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Predation is an important selective force that can influence prey life history, morphology, physiology, and behaviour. For prey to accurately mitigate their current predation risk, it is vital that they obtain reliable and updated information from their environment. Chemical information, such as alarm cues and disturbance cues, are known to play an important role in risk assessment for aquatic species and stimulates phenotypic plasticity. Alarm cues are chemicals released by a prey that have been attacked by a predator, while disturbance cues are released by uninjured, distressed prey prior to an attack or during a missed predation event. Both cues are detected during the embryonic and post embryonic stages. Alarm cues can be produced in the embryonic stage and can affect the morphology and hatching time of embryos. However, the way in which alarm cue exposure at this early stage impacts post-embryonic behaviour is unknown. In addition, it is unknown if embryos can produce disturbance cues. Using wood frog (Lithobates sylvaticus) embryos, I explored the existence of embryonic disturbance cues and their effects on hatching time, morphology, post-embryonic behaviour and growth during the larval stage, as well as the effect of embryonic alarm cues. Embryonic disturbance cues and embryonic alarm cues caused delayed hatching, and decreased size of tadpoles. Embryonic disturbance cues also caused a decrease in response to larval alarm cues. Neither cue caused a change in morphology. Wood frog embryos can produce disturbance cues. These cues as well as embryonic alarm cues are used by embryos to assess the risk in their environment and produce a response according to the risk. This study is the first to examine the production of embryonic disturbance cues and their effects, providing data to better understand the ecological implications of disturbance cues during the embryonic stage, and contribute to our understanding of how much prey rely on disturbance cues to assess risk.



embryonic disturbance cues, embryonic alarm cues, predation risk, Lithobates sylvaticus, antipredator response



Master of Science (M.Sc.)






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