Warming-enhanced priority effects at population and community levels in aquatic bacteria

The immigration history of communities can profoundly affect community composition. For instance, early-arriving species can have a lasting effect on community structure by reducing the immigration success of late-arriving ones through priority effects. Warming could possibly enhance priority effects by increasing growth rates of early-arriving species. Here we implemented a full-factorial experiment with aquatic bacteria where both temperature and dispersal rate of a better adapted community were manipulated to test their effects on the importance of priority effects. Our results suggest that priority effects might be strengthened by increasing temperature as warming increased the resistance of recipient communities against dispersal, and decreased the relative abundance of successfully established late-arriving species. However, warming-enhanced priority effects were not always found and their strengths differed between recipient communities and dispersal rates. These findings highlight the importance of context dependent studies of priority effects.