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Loss of Dynamic Stability in a Host-Parasitoid System is Related to the Magnitude and Temporal Scale of Trend in Environmental change. / BRETT PETERSEN

Swansea University Author: BRETT PETERSEN

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Abstract

Climate change is driving changes to populations leading to biodiversity crises. Knowledge is increasing on how populations are changing with research predicting how future population dynamics may predict population dynamics. Mathematical models have been an important tool to predict how biodiversit...

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Published: Swansea University, Wales, UK 2024
Institution: Swansea University
Degree level: Master of Research
Degree name: MA by Research
Supervisor: Fowler, M., and Coste, C.
URI: https://cronfa.swan.ac.uk/Record/cronfa66251
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Abstract: Climate change is driving changes to populations leading to biodiversity crises. Knowledge is increasing on how populations are changing with research predicting how future population dynamics may predict population dynamics. Mathematical models have been an important tool to predict how biodiversity may change as the climate changes. Much research has concentrated on a ‘step change’ of the environment, but research on the effects of a gradual increase in the environmental parameters, whereby these parameters gradually increase or decrease over time, has been underexplored.To address this gap, I used a version of the Nicholson-Bailey model that has been modified to include an environmental trend, whereby, over time, the environment increases the response of the host and parasitoids intrinsic growth rate across each time step over a temporal scale, to show how this could affect population dynamics within a discrete-time host-parasitoid system and how this differs to a constant environment. I further change the magnitude and temporal scale of the trend of the environment to establish their effects on population dynamics and try to analyse the dynamics.The constant environment became unstable after an initial transient phase, when the environmental effect on the system caused the host population growth rate to reach 115% of the current population size, showing cyclic/chaotic dynamics. The trend in the environment contrasted this by almost always having stability after the initial transient phase, sometimes becoming cyclic/chaotic at a certain environmental value within the trend when population growth rate became higher than 115% of the current population size. At smaller speeds of environmental change, the population started oscillating at lower environmental parameter values than for faster speeds. This was dependent on an increase in temporal scale, causing rate of increase from one environmental value to the next to become smaller, allowing for populations to track the environmental change and shift from stability to instability at an earlier stage, whereas larger rates of increase at smaller temporal scales rather abruptly shifted from stability to sudden amplified instability.This research emphasises the need to study the effects of a trend in the environment with more intricacy and detail, to predict the future of population dynamics under different climate change scenarios.
Item Description: A selection of content is redacted or is partially redacted from this thesis to protect sensitive and personal information.
Keywords: Trend in environment, host-parasitoid model, climate change, stability-instability
College: Faculty of Science and Engineering