Individual-based models (IBMs) are developed whenever we believe that intraspecific trait variations, local interactions, heterogeneous environments, and adaptive behavior are essential to understand and predict the dynamics of populations, communities, and ecosystems. Therefore, in Individual-Based Ecology, we try to build theory on the individual perspective, complementing more aggregated approaches. However, until recently IBMs seemed to be too complex and case-specific to address the community level. Theoretical development in community ecology has therefore focused on the coexistence of dominant species, while the typically long tail of rank abundance curves has remained largely unexplored.
Results/Conclusions
In the last decade, individual-based modeling has made great progress: by linking the behavior of individuals to first principles such as energy budgets, photosynthesis, or fitness seeking, IBMs have been able to predict the response to new conditions; by modeling trait-based functional types instead of species, diversity has been represented in a manageable way; by using multiple patterns observed at different levels of organization and scales, parameterization has become efficient and structural realism has been achieved. This development of IBM methodology is now beginning to influence ecological theory development, which in turn brings new challenges for individual-based modelling. As a recent example of this co-evolution, I will present Coviability Analysis (CVA), which combines concepts of Population Viability Analysis and individual-based modelling to better understand the viability of the many low abundance species. CVA links individuals, small populations and communities and explicitly takes into account: environmental and demographic stochasticity that affect small populations, intraspecific trait variations and behavioral plasticity, as well as local heterogeneities, interactions and feedback. CVA is a framework to complement modern coexistence theory and links individual-based modelling and ecological theory development.