Item – Thèses Canada

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Numéro d'OCLC
948509893
Lien(s) vers le texte intégral
Exemplaire de BAC
Exemplaire de BAC
Auteur
Thompson, Patrick,
Titre
The structure and functioning of metacommunities in changing environments
Diplôme
Ph. D. -- McGill University, 2015
Éditeur
[Montreal] : McGill University Libraries, [2015]
Description
1 online resource
Notes
Thesis supervisor: Andrew Gonzalez (Supervisor).
Includes bibliographical references.
Résumé
"Landscape fragmentation limits the ability of species to disperse between habitats and shift their distributions in response to changing environmental conditions. Because of habitat fragmentation, many species will be unable to keep pace with climate change, and this is expected to greatly impact the diversity, functioning, and stability of future ecosystems. Conserving habitat connectivity is expected to mitigate some of these impacts. But there are also concerns that the complexity of ecological responses will compromise our ability to predict future community structure and functioning. The spatial insurance hypothesis extends connectivity science to show how dispersal between local habitats maintains biodiversity and ecosystem functioning when environmental conditions are changing. However, complex issues remain, such as whether dispersal can simultaneously provide stability for the full range of ecosystem functions produced by a community, and how regional climate warming will impact the strength of spatial insurance provided by biological diversity. In this thesis, I extend research on the spatial insurance hypothesis with a combination of field surveys, experimentation, and theoretical simulations. I first conducted a field survey to determine how the composition and function of pond zooplankton communities was structured by the local environmental conditions of ponds on Mont St. Hilaire, QC. I found that measures of zooplankton functional and phylogenetic diversity outperformed species richness in explaining variation in two types of zooplankton ecosystem functions. Furthermore, the composition of these communities was determined by the local environmental conditions in the ponds, suggesting that dispersal could potentially provide spatial insurance if these conditions were to change. I then tested this experimentally, asking whether dispersal could preserve diversity and provide stability to metacommunities under ambient and warmed conditions. I found that dispersal preserved biodiversity and stabilized metacommunity biomass in ambient conditions, but that this benefit was lost with warming. This suggests that the stabilizing effects of dispersal may be eroded by directional environmental change, such as climate warming. I then returned to the spatial insurance model, extending the theory by incorporating multiple ecosystem functions. I showed that changing the rate at which species disperse dramatically alters the number, identity, and stability of functions that are produced both locally and regionally. Intermediate dispersal rates result in the greatest simultaneous production of functions across spatial scales and stabilize the temporal production of each function at the regional scale. However, this results in great local variability of each function, which differs from the stabilizing effect previously reported when only one function is considered. Finally, I used a theoretical simulation to test how biotic interactions and the rate of species dispersal interact to affect the predictability of multispecies range shifts under directional climate change. I showed how biotic interactions result in differences in the ability of species to track changes in climate, resulting in novel and unpredictable community compositions. Yet, when dispersal rates are not limiting, these differences are minimized and species track changes in climate at the same speed as their neighbours, leading to predictable range shifts. As a whole, my thesis tests and extends the spatial insurance hypothesis, demonstrating the conditions under which dispersal maintains the composition, functioning, stability, and predictability of ecological communities. These findings give support to the strategy of managing landscapes to maintain connectivity as a way to mitigate the joint impacts of habitat fragmentation and climate change."--
Autre lien(s)
digitool.Library.McGill.CA
digitool.library.mcgill.ca
escholarship.mcgill.ca
escholarship.mcgill.ca
Sujet
Biology