Open Collections

Stark, Keila

University of British Columbia

Ecologists face the challenge of understanding and predicting how living systems change as thermal regimes change relative to historical norms. To meet this challenge, we require theories that relate temperature change to biological processes influencing biodiversity patterns across levels of organization, from individual organisms to whole ecosystems. Ecological and evolutionary responses to temperature are mediated by its effects on organism growth, survival, reproduction, and other components of fitness, all governed by metabolism. In this thesis, I draw from concepts in metabolic scaling theory and metacommunity theory to better understand and predict how biodiversity and functioning in ecological communities respond to warming. First, I review key concepts in the Metabolic Theory of Ecology (MTE), including its assumptions of steady state conditions in its original models of temperature-dependent biological processes. I suggest extensions to MTE that better capture ecological systems frequently disrupted from steady state under climate change, including transient population dynamics and evolving thermal response curves. Next, using a freshwater mesocosm experiment, I test whether dispersal modifies the temperature dependence of community metabolism. While gross primary productivity and community respiration increase with temperature and biomass, dispersal does not significantly alter their temperature dependence. Instead, successional dynamics drive variation in community metabolism, highlighting the need to account for these dynamics in metabolic theory models. I then develop a temperature-dependent metacommunity model to simulate how warming-driven changes in growth, competition, and dispersal change species richness and abundance. I show that including temperature-dependent competition and dispersal fundamentally alters predictions compared to conventional models, and whether diversity and abundance increase or decrease per degree warming depends on community competition structure and differences in species' thermal response curves. Last, I experimentally estimate thermal response curves for population dispersal rates. I find species-specific thermal response curves for dispersal which differ from those for growth rates; these differences result in different colonization dynamics and regional biodiversity patterns across temperatures. Together, these studies link the conserved temperature dependence of metabolism with the diversity of thermal phenotypes among organisms and resulting biodiversity patterns across space and time.

Text

2025-04-25

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90822

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/