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Effect of fluctuating temperature and propagule flow on invasibility of global marine habitats and species distribution
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- Author / Creator
- Rajakaruna, Harshana
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Invasive colonizers propagated through human-mediated vectors are bio-homogenizing the world’s oceans and impacting the ecological structures and functions. Where do they come from, and where do they go? What bio-physical mechanisms drive them to do what they do? Can we control the human-mediated spread? In this thesis I focus on how seasonal fluctuation of habitat temperature impacts persistence, range expansion and distribution of invasive marine species by developing simple biologically meaningful metrics and producing results consistent with advanced mathematical methods. First, I show how the ambient temperature impacts the net reproductive rate of invasive marine calanoid copepod Pseudodiaptomous marinus, thereby, the invasibility of habitats to P. marinus. I extend this approach to include periodic fluctuations of habitat temperature by defining a new weighted net reproductive rate, which is a measure of the cross-periodic growth of a population. I use this and other metrics I developed to understand the bio-geographical structure of invasion dynamics of P. marinus. In general, the trend for marine invasives is to progress from ecoregions with high-amplitude periodic temperature (APT) to ecoregions with low APT within a range of optimal mean temperatures. This optimal immigration may increase their cross-periodic fitness suggesting an existence of a conveyor belt of invasive marine species generation driven by large gradients of temperature-amplitudes across global ecoregions. For further understanding of marine processes, I investigate the Metabolic Theory of Ecology (MTE) models that describe species (taxonomic) richness, and show that such models perform better for marine taxa, calanoid copepods, copepods and tunicates when periodic fluctuations of temperature are taken into account. The major conclusion in this thesis is that annual temperature cycles and their amplitude-gradients across ecoregions may drive species invasion dynamics and diversity distribution. A large potential of the conveyor belt together with the escalated human-mediated propagule flow may suggest that there would be high-degree invasions in the future across the world’s ecoregions. Finally, I show how stochasticity in propagule flow of species introduced to variable environments can be managed cost-effectively through stochastic control methods to reduce the probability of invasions.
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- Graduation date
- Fall 2013
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.