Exaptation as a Criterion for Modelling Complex Ecosystems. The Case of the Venice Lagoon

Abstract

In their celebrated essay on the spandrels of St Mark’s Basilica in Venice, Gould and Lewontin criticised the adaptationist tendency to interpret every form as the optimal outcome of a function. With the concept of exaptation, Gould and Vrba subsequently proposed an evolutionary perspective based on contingent processes of co-option and re-functionalisation. Transposed to the modelling of complex ecosystems, this perspective makes it possible to overcome the idea that systems such as the Venice Lagoon evolve towards determined equilibrium states, inviting instead an interpretation of them as emerging configurations produced by functional reuses and multi-level interactions. In a lagoon system, hydraulic infrastructures, salinity gradients, plant communities and anthropogenic pressures do not organise themselves according to linear trajectories, but generate side effects that become conditions for new forms of stability: salt marshes arising from altered sedimentary processes, species colonising artificial habitats, and technical devices modifying ecological niches. Exaptation thus becomes not only an interpretative category but a methodological criterion: it guides the construction of models capable of detecting emerging patterns at different scales and of integrating mechanistic description and statistical learning without reducing complexity to pure prediction. Contemporary hybrid approaches – combining process-based simulation and physics-informed neural networks – can be reread as exploratory rather than predictive devices: tools for probing scenarios in which functions, relationships and ecological roles are redefined over time. From this perspective, modelling Venice means designing a field of possibilities, rather than optimising an outcome. Exaptation operates as a principle of validation and generation: it invites comparison of models with multiple and unexpected patterns, recognising that ecological innovation – like technical innovation – often emerges from unintended deviations and reuses. Adopting exaptation as an operative criterion therefore entails a specific epistemic stance: replacing the search for equilibrium with the analysis of contingent transformations, and understanding artificial intelligence not as a tool of control, but as a means of making visible the lateral trajectories of lagoon evolution.