Isolation by resistance across a complex coral reef seascape

Area of Science:

• Marine Biology
• Population Genetics
• Conservation Science

Background:

• Understanding population genetic structure and gene flow is crucial for effective marine spatial conservation.
• Seascape genetics integrates environmental data to explain genetic divergence in marine populations.
• Previous seascape studies focused on linear coasts or large scales, with few examining complex, regional systems.

Purpose of the Study:

• To apply a seascape genetics approach to a peripheral coral population (Acropora spicifera) in a complex reef system.
• To test if oceanographic processes explain genetic divergence patterns at a regional scale.
• To investigate fine-scale genetic structure and connectivity in a coral reef environment.

Main Methods:

• Coupled population genetic data (microsatellite markers) with a biophysical dispersal model.
• Analyzed genetic variation and allele frequencies across sites within the Houtman Abrolhos Islands.
• Projected simulated larval dispersal into a resistance surface correlated with genetic divergence.

Main Results:

• Significant genetic variation and differentiation were found between adjacent coral sites (less than 10 km apart).
• Oceanographic currents, modeled as larval dispersal, created a resistance surface significantly correlated with genetic divergence.
• Patterns of spatial genetic structure were driven by restrictions to gene flow imposed by ocean currents.

Conclusions:

• Larval dispersal and oceanographic currents play a significant role in shaping fine-scale genetic structure in coral populations.
• This study demonstrates the utility of seascape genetics in complex island systems at regional scales.
• The methodological framework can be adapted for diverse marine organisms and life-history traits.