Abstract

Ecologists seek to understand the rules that govern the assembly, coexistence and persistence of communities of interacting species. Commonly, they focus on conditions for coexistence and equilibrium dynamics, implicitly assuming that transient dynamics is less important. There is, however, a variety of sequences in which a multi-species community can be assembled – unlike more familiar one- and two-species systems. Strikingly, empirical ecologists have collected empirical data for a multi-species system (a lepidopteran host and two of its natural enemies: a viral pathogen and a parasitoid wasp) which shows that the dynamic trajectories are determined by the sequence in which it is constructed, and that for one construction-sequence alternative dynamic patterns are possible. For instance, the three-species system constructed by adding the parasitoid to an established host-virus system (HVP) exhibits dynamics strikingly different from those of its two-species counterparts as well as from those of the three-species system obtained by adding first the virus to established host-parasitoid populations (HPV). Understanding the population dynamic consequences of the sequence in which a multi-species interaction is assembled will be essential for predicting the outcome of invasions, and that the ‘‘transient’’ behaviour of such systems following an invasion may be as, or more, important than equilibrium states that are effectively never attained over the timescales observed in complex natural systems. The goal of the project is to understand what biological mechanisms could underlie the contrasting dynamics in these experimental systems. Along the way, the candidate will have the opportunity to familiarize with stochastic Turing patterns, which may be important in the modelling part of the dissertation. Prerequisites are a good grasp of the main stochastic processes.

Possible collaboration with the owner of the empirical data (S.M. Sait).

References

• Sait, S.M., Liu, W.C., Thompson, D.J., Godfray, H.C.J. and Begon, M., 2000. ‘‘Invasion sequence affects predator–prey dynamics in a multi-species interaction’’. Nature, 405(6785), p.448.
• Karig, D., Martini, K.M., Lu, T., DeLateur, N.A., Goldenfeld, N. and Weiss, R., 2018. ‘‘Stochastic Turing patterns in a synthetic bacterial population’’. Proceedings of the National Academy of Sciences, 115(26), pp.6572-6577.