INTERACTIVE EFFECTS OF DISTURBANCE AND DISPERSAL ON COMMUNITY ASSEMBLY

Abstract

The traditional debate on alternative community states has been over whether or not they exist. Recent studies have focused on the role of assembly history in dictating community divergence, but the context in which assembly history becomes important is a continued topic of interest. In this study, we created communities of bacterivorous ciliated protists in laboratory microcosms and manipulated assembly history, disturbance frequency, and the presence of dispersal among local communities to investigate the mechanisms behind community divergence. Specifically, we sought to understand how the role of assembly history changed in response to disturbance, dispersal, and the combination of the two. Assembly history determined the identity of the dominant species through priority effects, and dispersal and disturbance showed interactive effects on both alpha and beta diversity. Dispersal increased alpha diversity, but only in the absence of disturbance, and it reduced beta diversity, but not in the presence of low or mixed disturbance treatments. These results show that the role of assembly history and the strength of priority effects are dependent on community context. Each factor cannot be viewed in isolation, and understanding the interaction between them is important for understanding how communities assemble, which lends insight into how ecological restoration should be approached.