UBC Theses and Dissertations

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UBC Theses and Dissertations

The thermal ecology of populations and ecosystem services in a changing world Bernhardt, Joanna Robin


A central goal of ecology is to understand what drives the abundance, distribution and diversity of life on Earth. For centuries, biologists have been addressing these questions from a variety of perspectives, and yet we still lack a coherent and mechanistic understanding of what drives these patterns. One process that is shared by all of life on Earth is metabolism. The development and testing of metabolic scaling theory (MST), which formalizes relationships between body size, temperature and metabolism, has revealed remarkable generality in the way that organisms respond to the environment. In spite of extensive documentation of cross-species metabolic patterns, we still lack evidence for how metabolic constraints propagate from the fine to the broad organizational scales. The large gap in our understanding at the level of populations presents a critical challenge for MST. I have combined theory, experiments and data synthesis to test the metabolic underpinnings of biodiversity and its implications for human well-being. Results showed that the temperature-dependence of population dynamics can be predicted from the temperature-dependence of individual metabolism, thus lending strong support for the role of energetic constraints in governing population growth and abundance. Further, I showed that variation in ecologically important traits such as body size has important implications for the nutritional value of aquatic species assemblages, thus linking the processes that structure ecosystems with the benefits they provide. This approach has revealed that understanding what generates and maintains aquatic biodiversity has direct and immediate consequences for human well-being.

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