Does Invasion Sequence Affect Community Structure?

The effects of invasion sequence on community structure were evaluated using aquatic microcosms. Thirty 400—mL beakers were inoculated with replicated subsets of species from a species pool consisting of green, blue—green, and golden algae, ciliates, a rotifer, a dinoflagellate, and euglenoids. These species were added according to four distinct sequences and two different rates over a 23—wk period, resulting in four replicated sets of insular communities. Significant differences in community structure and species richness could be attributed to both sequence of invasion and distance effects. "Priority" effects were found to be important in some but not all instances. Communities could be divided into two primary types that are similar to the two community types previously reported to arise from the assembly of these same taxa according to different invasions schedules.