Individual Variability

Pettorelli, Nathalie; Hilborn, Anne; Duncan, Clare; Durant, Sarah M.

doi:10.1016/bs.aecr.2015.01.001

Cited by 43 publications

(23 citation statements)

References 141 publications

(128 reference statements)

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“…Previous studies demonstrating density-dependent effects may therefore have captured the effects of natural selection. Indeed, intraspecific variation in foraging traits is emerging as a potentially key factor shaping the strength of trophic cascades (Bolnick et al, 2011;Pettorelli, Hilborn, Duncan, & Durant, 2015;Sih, Cote, Evans, Fogarty, & Pruitt, 2012;Start & Gilbert, 2017). Moreover, the strength of selection imposed by predators should also vary with their densities, as the strength of selection for predator-prey interactions is expected to increase with greater prey mortality (Benkman, 2013).…”

Section: Introductionmentioning

confidence: 99%

Past selection impacts the strength of an aquatic trophic cascade

et al. 2018

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In complex food webs, interactions among species in different trophic levels can generate cascading indirect effects that couple top predators with primary producers, thereby affecting ecosystem functioning. Natural selection imposed by top predators on intermediate predators may play a role in shaping the strength of these trophic cascades, but this conjecture remains largely untested. To determine the effects of natural selection on the strength of trophic cascades, we conducted a two‐part experiment in a four‐level aquatic trophic system involving a top predator (fish), an intermediate predator (damselflies), herbivores (zooplankton) and primary producers (algae). We first quantified how predation by fish generated selection on damselfly activity levels after controlling for phenotypic plasticity. We then measured the indirect effects of this selection on primary production (phytoplankton biomass). In both experiments, we varied the density of predators, allowing us to elucidate both trait‐mediated and density‐mediated indirect effects. We found that as fish density increased, damselfly survivorship declined, which generated natural selection favouring less active damselflies. These results are robust after taking into account latent effects of plasticity in response to fish predator cues. The surviving damselflies likely foraged less, freeing herbivores from predation, which in turn reduced primary production. This selection‐driven trait‐mediated indirect effect was only apparent at low damselfly densities, because the consumptive effect of damselflies at high densities overwhelmed the effects of past selection. These results demonstrate how the past action of natural selection imposed by predators affects the phenotypes of prey that consume herbivores, which ultimately influences primary productivity—a selective trophic cascade. Natural selection can therefore act as a mechanism coupling ecological dynamics across trophic levels, which ultimately influences ecosystem functioning. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13102/suppinfo is available for this article.

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Section: Introductionmentioning

confidence: 99%

Past selection impacts the strength of an aquatic trophic cascade

et al. 2018

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“…Predicting ecological dynamics and supporting management decisions depend on our understanding of how individuals interact. It is, thus, crucial to use functional response models that fit the best with data and with mechanisms underlying interactions [6]. However, functional response models are hardly identifiable: often, different functional responses fit well to data and inferences show no or little statistical power [14,15].…”

Section: Dealing With Identifiabilitymentioning

confidence: 99%

“…The last perspective of this work is about how individual interactions translate into birth and death; in other words how functional responses are related to numerical responses [6]. As most population and community dynamics models are systems of differential equations, functional responses and numerical responses are generally assumed to play at similar time scales (except when slow/fast processes are explicitly assumed).…”

Section: Assumptions and Time Scalesmentioning

confidence: 99%

Rejuvenating functional responses with renewal theory

Billiard

Bansaye

Chazottes

2018

J. R. Soc. Interface.

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Functional responses are widely used to describe interactions and resource exchange between individuals in ecology. The form given to functional responses dramatically affects the dynamics and stability of populations and communities. Despite their importance, functional responses are generally considered with a phenomenological approach, without clear mechanistic justifications from individual traits and behaviours. Here, we develop a bottom-up stochastic framework grounded in renewal theory that shows how functional responses emerge from the level of the individuals through the decomposition of interactions into different activities. Our framework has many applications for conceptual, theoretical and empirical purposes. First, we show how the mean and variance of classical functional responses are obtained with explicit ecological assumptions, for instance regarding foraging behaviours. Second, we give examples in specific ecological contexts, such as in nuptial-feeding species or size-dependent handling times. Finally, we demonstrate how to analyse data with our framework, especially highlighting that observed variability in the number of interactions can be used to infer parameters and compare functional response models.

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“…Research has previously focussed on the responses of prey in predator-prey interactions [4, 5, 6]. However, there is burgeoning interest in how the behaviour of predators influences population dynamics [7, 8]. There is ample evidence that both within and between-individual variation in predator behaviour influences predator-prey dynamics (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…[9, 10, 5, 6]. Our understanding of the degree and forms of influence is still in its infancy despite long recognition of the importance of individual variation [11, 10, 7, 12]. One major source of variation in predator behaviour and hence predation success and population dynamics is individual foraging strategy.…”

Section: Introductionmentioning

confidence: 99%

On the innovation and evolution of predatory tactics

Gokhale

Wignall

2019

Preprint

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Predator-prey systems are ubiquitous across ecological systems. Typical ecological models focus on the dynamics of predator-prey populations. Eco-evolutionary models integrate arms race or Red-Queen like dynamics. The roles of the predator and prey species are always assumed to be static. Nevertheless, sometimes predators can bite off more than they can chew. For example, predators that encounter multiple or dangerous prey types may need to develop new predatory tactics to capture prey. We explore the dynamics of predator-prey dynamics when the prey can injure or kill the predator. This common ecological scenario places pressure on the predator to develop novel predatory tactics to both capture prey and avoid counter-attack from prey. Taking a bottom-up approach, we develop the Holling function mechanistically and then implement it in a model of innovationselection dynamics inspired by economic theory. We show how an interdisciplinary approach can be used to explain the emergence of complex predatory behaviours. Notably, our study shows why predators may hunt dangerous prey even when safe prey are available. In a broader context, we demonstrate how a multidisciplinary approach combining ecology, evolution and economics improves our understanding of a complex behavioural trait.

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Individual Variability

Cited by 43 publications

References 141 publications

Past selection impacts the strength of an aquatic trophic cascade

Past selection impacts the strength of an aquatic trophic cascade

Rejuvenating functional responses with renewal theory

On the innovation and evolution of predatory tactics

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