@article{VelzenGaedkeKlauschies2022,
  author    = {Velzen, Ellen van and Gaedke, Ursula and Klauschies, Toni},
  title     = {Quantifying the capacity for contemporary trait changes to drive intermittent predator-prey cycles},
  series = {Ecological monographs : a publication of the Ecological Society of America},
  volume    = {92},
  journal   = {Ecological monographs : a publication of the Ecological Society of America},
  number    = {2},
  publisher = {Wiley},
  address   = {New York},
  issn      = {1557-7015},
  doi       = {10.1002/ecm.1505},
  pages     = {29},
  year      = {2022},
  abstract  = {A large and growing body of theory has demonstrated how the presence of trait variation in prey or predator populations may affect the amplitude and phase of predator-prey cycles. Less attention has been given to so-called intermittent cycles, in which predator-prey oscillations recurrently disappear and re-appear, despite such dynamics being observed in empirical systems and modeling studies. A comprehensive understanding of the conditions under which trait changes may drive intermittent predator-prey dynamics, as well as their potential ecological implications, is therefore missing. Here we provide a first systematic analysis of the eco-evolutionary conditions that may give rise to intermittent predator-prey cycles, investigating 16 models that incorporate different types of trait variation within prey, predators, or both. Our results show that intermittent dynamics often arise through predator-prey coevolution, but only very rarely when only one trophic level can adapt. Additionally, the frequency of intermittent cycles depends on the source of trait variation (genetic variation or phenotypic plasticity) and the genetic architecture (Mendelian or quantitative traits), with intermittency occurring most commonly through Mendelian evolution, and very rarely through phenotypic plasticity. Further analysis identified three necessary conditions for when trait variation can drive intermittent cycles. First, the intrinsic stability of the predator-prey system must depend on the traits of prey, predators, or both. Second, there must be a mechanism causing the recurrent alternation between stable and unstable states, leading to a "trait" cycle superimposed on the population dynamics. Finally, these trait dynamics must be significantly slower than the predator-prey cycles. We show how these conditions explain all the abovementioned patterns. We further show an important unexpected consequence of these necessary conditions: they are most easily met when intraspecific trait variation is at high risk of being lost. As trait diversity is positively associated with ecosystem functioning, this can have potentially severe negative consequences. This novel result highlights the importance of identifying and understanding intermittent cycles in theoretical studies and natural systems. The new approach for detecting and quantifying intermittency we develop here will be instrumental in enabling future study.},
  language  = {en}
}
@misc{YamamichiKlauschiesMineretal.2019,
  author    = {Yamamichi, Masato and Klauschies, Toni and Miner, Brooks E. and van Velzen, Ellen},
  title     = {Modelling inducible defences in predator-prey interactions},
  series = {Ecology letters},
  volume    = {22},
  journal   = {Ecology letters},
  number    = {2},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {1461-023X},
  doi       = {10.1111/ele.13183},
  pages     = {390 -- 404},
  year      = {2019},
  abstract  = {Inducible defences against predation are widespread in the natural world, allowing prey to economise on the costs of defence when predation risk varies over time or is spatially structured. Through interspecific interactions, inducible defences have major impacts on ecological dynamics, particularly predator-prey stability and phase lag. Researchers have developed multiple distinct approaches, each reflecting assumptions appropriate for particular ecological communities. Yet, the impact of inducible defences on ecological dynamics can be highly sensitive to the modelling approach used, making the choice of model a critical decision that affects interpretation of the dynamical consequences of inducible defences. Here, we review three existing approaches to modelling inducible defences: Switching Function, Fitness Gradient and Optimal Trait. We assess when and how the dynamical outcomes of these approaches differ from each other, from classic predator-prey dynamics and from commonly observed eco-evolutionary dynamics with evolving, but non-inducible, prey defences. We point out that the Switching Function models tend to stabilise population dynamics, and the Fitness Gradient models should be carefully used, as the difference with evolutionary dynamics is important. We discuss advantages of each approach for applications to ecological systems with particular features, with the goal of providing guidelines for future researchers to build on.},
  language  = {en}
}