Title: Universal fitness dynamics through an adaptive resource utilization model,
Abstract: The fitness of a species determines its abundance and survival in an
ecosystem. At the same time, species take up resources for growth, so their
abundance affects the availability of resources in an ecosystem. We show here
that such species-resource coupling can be used to assign a quantitative metric
for fitness to each species. This fitness metric also allows for the modeling
of drift in species composition, and hence ecosystem evolution through
speciation and adaptation. Our results provide a foundation for an entirely
computational exploration of evolutionary ecosystem dynamics on any length or
time scale. For example, we can evolve ecosystem dynamics even by initiating
dynamics out of a single primordial ancestor and show that there exists a well
defined ecosystem-averaged fitness dynamics that is resilient against resource
shocks.