Abstract
Phenotypic plasticity in defensive traits is an appropriate mechanism to cope with the variable hazard of a frequently changing predator spectrum. In the animal kingdom these so-called inducible defences cover the entire taxonomic range from protozoans to vertebrates. The inducible defensive traits range from behaviour, morphology, and life-history adaptations to the activation of specific immune systems in vertebrates. Inducible defences in prey species play important roles in the dynamics and functioning of food webs. Freshwater zooplankton show the most prominent examples of inducible defences triggered by chemical cues, so-called kairomones, released by predatory invertebrates and fish. The objective of this review is to highlight recent progress in research on inducible defences in freshwater zooplankton concerning behaviour, morphology, and life-history, as well as difficulties of studies conducted in a multipredator set up. Furthermore, we outline costs associated with the defences and discuss difficulties as well as the progress made in characterizing defence-inducing cues. Finally, we aim to indicate further possible routes in this field of research and provide a comprehensive table of inducible defences with respect to both prey and predator species.
Highlights
Community diversity is greatly influenced by a variety of selection pressures, one of which is predation (e.g., [1,2,3,4])
Winder et al [60] proposed that temperature and food abundance modulate the depth selection in Daphnia, while predator kairomones and UV-radiation modulate the timing of the diel vertical migration (DVM), emphasizing the importance of considering these factors in experiments
While morphological defences in other groups of zooplankton can vary over developmental stages, the morphology of rotifers is determined at birth, and could be understood as a maternal-induced defence [19]
Summary
Community diversity is greatly influenced by a variety of selection pressures, one of which is predation (e.g., [1,2,3,4]) To increase their fitness, prey species have evolved a variety of defensive mechanisms [5,6,7,8,9]. Relevant for the induction of defences are chemical cues, so-called kairomones These are semiochemicals, which predators release unintentionally, signalling the presence of a respective predator to its prey. The phenomenon of thusly induced defences is expressed in fascinating and often striking changes in morphology, life history, and behaviour of various zooplankton species (e.g., [24,25,26,27,28,29,30,31]). We point out possible future directions of research and provide a comprehensive table of recent studies (since 2003) on inducible defences in zooplankton (Table A1)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
