Download the full-sized PDF of Effect of fluctuating temperature and propagule flow on invasibility of global marine habitats and species distributionDownload the full-sized PDF



Permanent link (DOI):


Export to: EndNote  |  Zotero  |  Mendeley


This file is in the following communities:

Graduate Studies and Research, Faculty of


This file is in the following collections:

Theses and Dissertations

Effect of fluctuating temperature and propagule flow on invasibility of global marine habitats and species distribution Open Access


Other title
Intrinsic growth rate
Propagule pressure
Net reproductive rate
Marine species
Invasive species
Type of item
Degree grantor
University of Alberta
Author or creator
Rajakaruna, Harshana
Supervisor and department
Lewis, Mark (Mathematics and Statistics, Biological Sciences)
Examining committee member and department
Boyce, Mark (Biological Sciences)
Fangliang, He (Renewable Resources)
Lewis, Mark (Mathematics and Statistics, Biological Sciences)
Morris, R. Flynn (Mechanical Engineering)
Amarasekare, Priyanga (Ecology and Evolutionary Biology)
Department of Biological Sciences
Date accepted
Graduation date
Doctor of Philosophy
Degree level
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.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Rajakaruna, H., Strasser, C., Lewis, M., 2012. Identifying non-invasible habitats for marine copepods using temperature-dependent R0. Biological Invasions 14(3),633-647.Rajakaruna, H., Potapov, A., Lewis, M., 2013. Impact of stochasticity in immigration and reintroductions on colonizing and declining populations. Theoretical Population Biology, 85, 38-48.

File Details

Date Uploaded
Date Modified
Audit Status
Audits have not yet been run on this file.
File format: pdf (Portable Document Format)
Mime type: application/pdf
File size: 3552592
Last modified: 2015:10:12 20:42:52-06:00
Filename: Rajakaruna_Harshana_Fall 2013.pdf
Original checksum: a9e47cdfb768814e046bb592fb923965
Well formed: true
Valid: true
Status message: Too many fonts to report; some fonts omitted. Total fonts = 1093
File author: Harshana
Page count: 229
File language: en-CA
Activity of users you follow
User Activity Date