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 spatial 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. Information about barriers to gene flow (such as ocean
currents) is used to define a resistance surface to predict the spatial
genetic structure of populations and explain deviations from the widely
applied isolation-by-distance model. The majority of seascape approaches
to date have been applied to linear coastal systems or at large spatial
scales (more than 250 km), with very few applied to complex systems at
regional spatial scales (less than 100 km). 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 of less than 10 km, with significant differentiation 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 coral 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.