Dynamics of life - self-organisation, co-adaptation & the evolution of resilience in complex ecosystems

Ecosystems are highly ordered, non-random systems, yet neither are they designed from a specific construction plan determining their structure and composition, nor are they directly predictable from the traits and behaviour of the species they are comprised of. The order arises from self-organising forces stemming from the interactions between individuals - yet the concrete principles behind self-organisation, the role of community integrity versus single species traits and the feedbacks between species and the systems they form are largely unknown. In this thesis, complex-systems modelling is used as a tool to bridge the gap between microscopic behaviour and emergent macroscopic systems and concepts from information theory are applied to quantify the arising, development and evolution of order within ecological communities. Generally, the information content within an ecosystem, the information content the ecosystem has about itself and its future states as well as the general coadaptation and organisation tend to increase with advanced developmental state. This goes along with a shift from bottom-up control from micro- to the macrolevel in earlier developmental stages to top-down control the system tends to impose on its species and individuals in late-successional stages. Coadaptation, next to individual fitness, also plays a role for species abundance and survival in communities undergoing disturbances, emphasizing the role of community integrity for its persistence. Overall, the results illustrate that species interactions are the guiding force behind ecosystem organisation, that coadaptation shapes functionality, stability and resilience and that ecosystem development is not either guided by fundamental laws \emph{or} global optimisation criteria, but by both - individual fitness and the system's state determine ecosystem development in a dialogue of bottom-up and top-down control.Open Acces