Data from: Isolation by Resistance Across a Complex Coral Reef Seascape

A detailed understanding of the genetic structure of populations and an accurate interpretation of processes driving contemporary patterns of gene flow are fundamental to successful conservation management. The field of seascape genetics seeks to incorporate environmental variables and processes into analyses of population genetic data to improve our understanding of forces driving genetic divergence in the marine environment. However, the majority of seascape approaches to date have been applied to linear coastal systems or at large spatial scales (> 250 km), with very few applied to complex systems at regional spatial scales (< 100 km), which are more relevant to spatial conservation management. Here, we apply a seascape genetics approach to a peripheral population of the broadcast spawning coral Acropora spicifera across the Houtman Abrolhos Islands, a high-latitude complex coral reef system off the central coast of Western Australia. We coupled population genetic data from a panel of microsatellite DNA markers with a biophysical dispersal model to test whether oceanographic processes could explain patterns of genetic divergence. We identified significant variation in allele frequencies over distances less than 10 km, with significant variation occurring between adjacent sites but not between the most geographically distant ones. Recruitment probabilities between sites based on simulated larval dispersal were projected into a measure of resistance to connectivity that was significantly correlated with patterns of genetic divergence, demonstrating that patterns of spatial genetic structure are a function of restrictions to gene flow imposed by oceanographic currents. This study advances our understanding of the role of larval dispersal on the fine-scale genetic structure of populations across a complex island system and applies a methodological framework that can be tailored to suit a variety of marine organisms with a range of life history characteristics.