An individual-based simulation model to link population, community, and metacommunity dynamics

Introduction The dynamical behavior of individuals in ecosystems involves a multifaceted set of interaction types and processes that take place at different hierarchical levels. We present an individual-based, stochastic model that considers species dynamics at three hierarchical levels: population, community, and metacommunity. We use an individual-based model to show how the consequences of mechanisms that are specific to each hierarchical level may interact with processes that belong to other hierarchical levels. The strength of these effects is quantified in terms of impacts on metapopulation sizes and spatial distribution of populations. Results indicate the following: (1) the cohesion of the social network structure among conspecific individuals heavily affects their feeding efficiency at food-web level; (2) more generalist feeding habits trigger homogeneous spatial distribution of species at the landscape scale; and (3) high frequency of migration movements limits the local success of a generalist species thus leading to small metapopulation sizes. We illustrate how such a hierarchical framework may contribute to understanding the emergence of macroscopic patterns (i.e., metapopulation size and spatial heterogeneity) starting from elementary, bottom–up rules defined at the individual level. Hierarchical Organization and Individual-Based Modeling in Ecology Concurrent processes and interactions occur at different hierarchical levels in ecosystems (i.e., individual, population, community, and metapopulation/metacommunity) and do often spread their effects beyond the levels in which they actually originate. Some studies describe how ecological dynamics involving two hierarchical layers may interplay with each other. Social interactions among conspecific individuals may be regulated by metapopulation and community dynamics, community composition may be molded by landscape fragmentation, and species coexistence in metacommunities may result from the trade-off between spatial dispersal and multiple interaction types in food webs. Association rates in a population of wild Asian elephants depend on environmental conditions and seasonality (de Silva et al., 2011). The rates at which social ties are formed peak in dry periods and resident elephants tend to maintain over time a stable pool of interactions with the same individuals. The cohesion of social groups of baboons may vary in response to predation pressure or spatial food distribution (Barton et al., 1996). When predation pressure is high, the distances between conspecific individuals are smaller and social groups are more cohesive; this raises the chances of contest competition.