Abstract
Predator–prey relationships are a central component of community dynamics. Classic approaches have tried to understand and predict these relationships in terms of consumptive interactions between predator and prey species, but characterizing the interaction this way is insufficient to predict the complexity and context dependency inherent in predator–prey relationships. Recent approaches have begun to explore predator–prey relationships in terms of an evolutionary-ecological game in which predator and prey adapt to each other through reciprocal interactions involving context-dependent expression of functional traits that influence their biomechanics. Functional traits are defined as any morphological, behavioral, or physiological trait of an organism associated with a biotic interaction. Such traits include predator and prey body size, predator and prey personality, predator hunting mode, prey mobility, prey anti-predator behavior, and prey physiological stress. Here, I discuss recent advances in this functional trait approach. Evidence shows that the nature and strength of many interactions are dependent upon the relative magnitude of predator and prey functional traits. Moreover, trait responses can be triggered by non-consumptive predator–prey interactions elicited by responses of prey to risk of predation. These interactions in turn can have dynamic feedbacks that can change the context of the predator–prey interaction, causing predator and prey to adapt their traits—through phenotypically plastic or rapid evolutionary responses—and the nature of their interaction. Research shows that examining predator–prey interactions through the lens of an adaptive evolutionary-ecological game offers a foundation to explain variety in the nature and strength of predator–prey interactions observed in different ecological contexts.
Highlights
Most animal species are engaged in a predator–prey relationship by consuming prey or falling victim to predators or both
There is growing appreciation that variety in the structure and functioning of ecological communities and ecosystems can be strongly dependent upon the evolutionary history of the interacting predator and prey species[67,68,69,70,71,72,73,74,79,80,81,82]
The extent to which this reflects variation in the expression of species functional traits that can change via plasticity or rapid evolution in response to the changing ecological conditions created by their interactions[44,67,71] remains to be seen, and it will likely be difficult to explain context dependency in the absence of taking an adaptive functional trait approach[40,44]
Summary
Most animal species are engaged in a predator–prey relationship by consuming prey or falling victim to predators or both. One historical environmental condition that changes is the presence/absence of fish predators, which can be used to evaluate how Daphnia vulnerability traits (for example, body size and shape, length of defensive spines, alertness, and movement in water column) change in response to fish presence (plasticity due to non-consumptive effects) and fish consumption (selection and adaptive evolution)[69]. The degree of plasticity expressed by hatched individuals varied depending on the historical association with fish predators[69] This again underscores the need to examine traits in action, including how different evolutionary processes drive the trait changes as environmental context changes in order to enhance predictive understanding of complexity underlying predator–prey dynamics and interactions. If this capacity is found to be widespread across predator and prey species, it could change our outlook on the fate of species in a rapidly changing world
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