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Eco-evolutionary modelling, fitness and Lotka's mass conjectures
1School of Environment and Science, Griffith University, Nathan, 4111, Queensland, Australia.
Abstract:
We consider the results of an eco-evolutionary model of mutualism to test the role of three metrics of evolution: total fitness and Lotka's conjectures that ecosystems may evolve to maximise their total biomass and the total flux of mass through them. Analytic arguments to support the fitness and biomass metrics are provided. Our results suggest that total fitness and Lotka's total mass conjectures are useful indicators of the evolutionary outcomes of the mutualism model. The maximisation of these ecosystem-level properties is consistent with each population maximising the metrics within the constraints imposed upon them by the evolution of the other population. We note that the metrics are not necessarily global properties, as unique ecological outcomes can be achieved by multiple evolutionary outcomes, each of which maximises biomass, cycling and fitness within its own domain. We provide an example where the solution space of the model is divided into distinct regions that each has a stable eco-evolutionary equilibrium at its maximum. Each region represents a different combination of facultative and/or obligate mutualism, but are all associated with the same ecological outcome. In our simple model, which one of these solutions is achieved depends on the initial evolutionary state of the populations.
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