Ocean circulation model predicts high genetic structure observed in a long-lived pelagic developer.

Area of Science:

• Marine Ecology
• Population Genetics
• Oceanography

Background:

• Understanding gene flow across marine seascapes is crucial for marine ecology, informing local adaptation and population persistence.
• Oceanic gene flow is often inferred from population genetics and species' life histories, but genetic structure reflects past processes and may not indicate current connectivity.
• Larval dispersal patterns are key to marine population connectivity, but are challenging to predict in complex coastal environments.

Purpose of the Study:

• To predict larval dispersal patterns using a high-resolution oceanographic model along the complex coastline of western Canada.
• To test the model's predictions against observed genetic structure in a benthic sea star species.
• To investigate the role of ocean circulation in shaping genetic structure despite a long pelagic larval phase.

Main Methods:

• Utilized a high-resolution oceanographic circulation model to simulate larval dispersal.
• Simulated dispersal for a benthic sea star with a 6-10 week pelagic larval duration.
• Validated model predictions against existing genetic data and conducted new genetic sampling within a known phylogeographic break.

Main Results:

• The coupled genetic and circulation model successfully predicted the observed high degree of genetic structure in the sea star population.
• Ocean circulation patterns were found to retain passive larvae within 20-50 km of their source.
• Despite a long pelagic larval phase, significant genetic structure was evident, explained by localized retention.

Conclusions:

• Ocean circulation patterns are a primary driver of genetic structure in marine populations along complex coastlines.
• The findings suggest that marine populations can maintain high genetic structure even with long larval dispersal phases.
• Effective marine conservation strategies, such as Marine Protected Area networks, require designs that account for localized larval retention.