Dispersal in Stream Networks: Meta-populations and Meta-communities

Abstract

Meta-approaches to understanding diversity, including meta-populations and meta-communities, have created a paradigm shift in ecological research, including in stream ecosystems. Both of these frameworks emphasize the major role that organismal dispersal plays in generating and maintaining biodiversity patterns because dispersal links processes at local scales to processes at larger spatial scales. Fundamental to the application of meta-approaches is an understanding of dispersal. Ecologists working in stream systems use various methods to measure or estimate the dispersal of aquatic organisms. More direct measures include mark-recapture techniques and the use of various nets and traps. Due to the difficulty of directly monitoring the dispersal of aquatic organisms, particularly smaller taxa, organismal-based dispersal proxies such as traits-based approaches and population genetics can be used to infer dispersal patterns. Graph-based proxies that rely on the spatial distribution of sampling sites can also be used to infer dispersal in stream networks. While experimental approaches—including the direct manipulation of dispersal—have been employed less often than observational approaches, they have been able to mechanistically link dispersal rates and patterns to patterns in observed biodiversity. Likewise, theoretical approaches that include mathematical and simulation modeling have been able to conduct in silico experiments to test scenarios that are impractical or impossible to conduct in real-world systems. Here we provide a brief introduction to these techniques, highlight some of the insights that they have enabled, and discuss their importance in bringing meta-approaches to the study of stream ecosystems.