Browsing by Author "Neale, Zoey R"

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    Temperature-dependent predator-prey dynamics: unveiling complexities across species and contexts in a warming world
    (2023-11-01) Neale, Zoey R; Rudolf, Volker
    Rising global temperatures have profound influences on natural ecosystems. Direct effects of environmental warming on individual metabolic rates scale up to influence every level of biological organization. Past studies examine direct effects of temperature on individual and population performances, but less attention has been paid to indirect effects on species interactions such as predation. In this thesis I investigate how predator thermal responses differ across species and contexts and the implications this can have on prey communities. In my first chapter, I experimentally tested and compared thermal responses of feeding rates of six predators collected from the same habitat to determine how species experiencing similar climatic conditions can vary in respond to temperature changes. I found large disparities in the thermal responses across species. Notably, the differences were large enough to shift the hierarchy of predators feeding on a shared prey along a temperature gradient. In my second chapter I examined whether local historic climate regimes influence thermal responses of species by experimentally comparing thermal responses of predators of the same species collected at different sites spanning a latitudinal gradient of 11°C. I found that thermal responses of populations can differ substantially across latitudes. Predators at higher latitudes demonstrated stronger sensitivities to temperature than predators collected from the lowest latitude. Moreover, differences in the shape of the response curves resulted in range-specific warming effects, with higher latitude predators increasing more than lower latitude predators along one portion of the gradient but decreasing more than lower latitudes along another portion. In my third chapter I explored how thermal responses of intraspecific demographic rates, predation, and interspecific competition among prey interact to influence population dynamics in a three-species food web. I found warming had opposing effects on prey population sizes independent of interspecific interactions, increasing population sizes at colder temperatures but suppressing them at warmer temperatures. Additionally, top-down control was dependent on temperature, with predators suppressing prey population sizes at intermediate-warm temperatures but not cold. Overall, these results highlight the context-dependence of predator-prey interactions to temperature and the need to consider these contexts when predicting and mitigating the effects of climate change.