Dispersal Across Headwaters Determines Fish Population Structure Between Interdigitating River Systems in the Guiana...

Area of Science:

• Ecology
• Evolutionary Biology
• Genetics

Background:

• Riverine population structure models typically assume longitudinal dispersal within dendritic river networks.
• Dynamic river configurations can lead to seasonal or long-term hydrologic connections, enabling poorly understood out-of-network dispersal.
• Existing models may not adequately capture the population structure of riverine taxa due to violations of dispersal assumptions.

Purpose of the Study:

• To investigate the prevalence and impact of out-of-network dispersal in riverine species.
• To test for connectivity between adjacent river systems not explained by contemporary river configurations.
• To assess if alternative dispersal routes influence population structure, genetic diversity, and differentiation in riverine fishes.

Main Methods:

• Genetic population structure analysis of *Krobia potaroensis*, a cichlid fish endemic to the Pakaraima Mountains, Guyana.
• Analysis focused on detecting genetic associations between populations in interdigitating river systems.
• Comparison of genetic data with contemporary river network configurations.

Main Results:

• Genetic associations were detected among populations that did not align with current river configurations.
• Evidence suggests historical or ongoing dispersal between adjacent river systems.
• Findings indicate that longitudinal dispersal within river networks is not always the sole factor shaping population structure.

Conclusions:

• Out-of-network dispersal is a significant factor in shaping riverine population structure and genetic diversity.
• Existing population structure models for riverine taxa may need revision to incorporate non-longitudinal dispersal routes.
• Understanding alternative dispersal pathways is crucial for effective conservation and management of riverine species.