What influences community composition – assembly history, environmental change or both?

Background/Question/Methods

Both the order in which species arrive in a community, and local environmental conditions, such as temperature, are known to affect community structure. Little is known, however, about the potential for, and occurrence of, interactions between assembly history and the environment. Here we explore the influence of assembly history-temperature interactions (and main effects) on the structure of communities of competitors, using a combination of theoretical modelling and experimentation with small-scale protozoa communities.

Results/Conclusions

Heuristic modelling suggests that there is the potential for temperature and assembly order to interact to influence community composition and, in addition, that priority effects are unlikely to play an important role in shaping communities under a changing environment. We show the major driver of long-term abundance was temperature, however there are long lasting, species-specific, assembly order effects that significantly altered the effect of temperature on abundances. Priority effects proved, in general, to be short lived, and after the initial assembly phase there was rarely any advantage to colonising a habitat before other species. The results presented here suggest that even small environmental change could interact with the stochastic nature of community assembly to alter future community composition.