Linking genotype to phenotype: a modelling framework for investigating individual and interacting mycelia
The central question addressed in this thesis is the origin of complexity in individual and interacting fungal mycelia. A conceptual model identifying the minimal rule set responsible for complexity in terms of exhibited growth patterns is presented. The theoretical results replicate observed colony forms on agar and demonstrate that phenotype is sensitive to both environmental context and genotype. We show that the fungal phenotype may have its origins in the defining characteristic of indeterminate organisms, namely their ability to recycle locally immobilised internal resources into a mobilised form capable of being directed to new internal sinks. We show that phenotype can be modelled as an emergent property resulting from the interplay among simple local processes governing uptake and remobilization of internal resources, and macroscopic processes associated with their transport. The model demonstrates that the recycling process is crucial in soil-like environments where resources are limited and patchy. Theoretical analysis also shows that the recycling mechanism promotes optimised foraging depending on the resource quantity and quality, e.g. exploitative, when resource is plentiful and explorative when resource is scant. The model is extended to represent fungal interactions between two distinct individuals by incorporating an additional inhibitor field. A range of observed interaction outcomes are replicated by modifying the parameters associated with the recycling apparatus only, based on the inhibitor field and trait values of the interaction process. The modelling framework is now in a form where an investigation into the origin of complexity underlying fungal community organisation can be undertaken.
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