title: Isolation by resistance across a complex coral reef seascape.
abstract: 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.
authors.affiliation: The UWA Oceans Institute, School of Plant Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia luke.thomas@live.com.au.
authors.forename: Luke
authors.initials: L
authors.lastname: Thomas
authors.affiliation: Centre for Evolutionary Biology, School of Animal Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia.
authors.forename: W Jason
authors.initials: WJ
authors.lastname: Kennington
authors.affiliation: Trace and Environmental DNA (TrEnD) Laboratory, Department of Environment and Agriculture, Curtin University, Bentley, Western Australia 6102, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Stat
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand.
authors.forename: Shaun P
authors.initials: SP
authors.lastname: Wilkinson
authors.affiliation: Geoscience Australia, Symonston, Australian Capital Territory 2601, Australia.
authors.forename: Johnathan T
authors.initials: JT
authors.lastname: Kool
authors.affiliation: The UWA Oceans Institute, School of Plant Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Kendrick
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000235:genetics*; D057894:Coral Reefs; D051456:Gene Flow; D005819:Genetic Markers; D007814:Larva / Q000235:genetics; D018895:Microsatellite Repeats; D008954:Models, Biological; D014872:Water Movements; D014904:Western Australia
chemical_list: D005819:Genetic Markers
keywords: Acropora spicifera; connectivity; dispersal; spatial conservation management