Metacommunity models and empirical data reveal asymmetric network-constrained fish dispersal

Area of Science:

• Ecology
• Freshwater Biology
• Conservation Biology

Background:

• Biodiversity and community composition are shaped by dispersal processes.
• Understanding spatial dispersal networks is crucial but challenging.
• Riverscape connectivity influences species distribution and ecological processes.

Purpose of the Study:

• To infer a spatially explicit dispersal network for fish communities in the Negro River basin.
• To identify key dispersal parameters influencing community assembly.
• To test the influence of riverine features on dispersal patterns.

Main Methods:

• Combined metacommunity modeling with empirical data from 58 fish communities.
• Assessed support for alternative dispersal parameters including sources, asymmetry, distance decay, and barriers.
• Utilized statistical models to identify the most likely dispersal network.

Main Results:

• Fish dispersal is predominantly asymmetric, favoring downstream movement along river branches.
• The river outlet acts as a significant source for upstream dispersal, even over long distances.
• No evidence of dam-induced barriers was found, possibly due to lagged ecological responses.

Conclusions:

• Metacommunity models and empirical data can effectively infer complex dispersal patterns in riverscapes.
• Asymmetric dispersal and outlet-mediated connectivity are key processes structuring fish biodiversity.
• Further research is needed to understand long-term impacts of fragmentation on dispersal.