Invasion sequence affects predator-prey dynamics in a multi-species interaction

Ecologists seek to understand the rules that govern the assembly, coexistence and persistence of communities of interacting species. There is, however, a variety of sequences in which a multi-species community can be assembled-unlike more familiar one- and two-species systems. Ecological systems can exhibit contrasting dynamics depending on initial conditions(1), but studies have been focused on simple communities initiated at different densities, not on multi-species communities constructed in different sequences. Investigations of permanence and convergence in ecological communities(2-4) have been concerned with the flux of whole species (presence or absence)(4) but have not addressed the central issues concerning the dynamics exhibited by individual species in particular interactions. Here we examine data for replicated three-species systems and demonstrate that the dynamic trajectories of both a predator and its prey within the system are determined by the sequence in which it is constructed, and that for one construction-sequence alternative dynamic patterns are possible.