James Maino
Scaling of metabolic traits between species of different body size
Our ability to predict variation in ecosystem processes is currently limited by our ability to mechanistically link biological processes across both spatial and temporal scales (Enquist et al, 2003).
As outlined in Brown et. al (2004)'s seminal work, metabolism provides a basis for using the first principles of physics, chemistry, and biology to link the biology of individual organisms to the ecology of populations, communities, and ecosystems.
Metabolic rate is the rate at which organisms take up, transform, and expend energy and materials and provides a window into a fundamental constraint by which ecological processes are governed.
Organism size and temperature influence metabolic rate in profound ways that have long been appreciated in the scientific community, though the underlying mechanism for this relationship is still the subject of intense debate.
So far, the study of metabolic scaling has largely been based on comparative and theoretical approaches.
These approaches are necessary and important, but they are poor at establishing cause and effect relationships (Glazier, 2005).
At the same time, many of these theories claiming a mechanistic basis make similar predictions that tend to align very well with empirical patterns. To move forward in this field it will be necessary to
- acknowledge where competing theories make parallel and divergent predictions and
- to disentangle cause from effect through experimental testing of these divergent predictions.
Ultimately, illuminating the universal physicochemical constraints mechanisms underlying metabolic scaling both within and among species will have profound implications for our understanding of the key processes constraining phenomena across all levels of biological organisation.
Such research will progress the development of ecology as a predictive science.
In hopes of demonstrating the importance of the testing and direct comparison of competing metabolic theories, my project contrasts two well established conceptual frameworks.
The first of these are derived from the resource-distribution network line of thinking (WBE);
the second is Dynamic Energy Budget.
It is important to add that this project is concerned with encouraging the direct contrasting of theories in general and that these two particular theories where chosen due to academic attention they have received independently of each other.
Furthermore, these two quantitative theories are also likely to represent the two most developed and elaborated mechanistic theories for the metabolic organisation of organisms.
My project will contribute to this field by:
- reviewing competing theories in order to show numerical similarities in quantitative structure, while highlighting key areas where predictions for how metabolic traits vary across taxa most strongly diverge
- use the much neglected animal group of terrestrial invertebrates to experimentally assess the underlying assumptions of each respective theory
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