title: Historical processes and contemporary ocean currents drive genetic structure in the seagrass Thalassia hemprichii in the Indo-Australian Archipelago.
abstract: Understanding spatial patterns of gene flow and genetic structure is essential for the conservation of marine ecosystems. Contemporary ocean currents and historical isolation due to Pleistocene sea level fluctuations have been predicted to influence the genetic structure in marine populations. In the Indo-Australian Archipelago (IAA), the world's hotspot of marine biodiversity, seagrasses are a vital component but population genetic information is very limited. Here, we reconstructed the phylogeography of the seagrass Thalassia hemprichii in the IAA based on single nucleotide polymorphisms (SNPs) and then characterized the genetic structure based on a panel of 16 microsatellite markers. We further examined the relative importance of historical isolation and contemporary ocean currents in driving the patterns of genetic structure. Results from SNPs revealed three population groups: eastern Indonesia, western Indonesia (Sunda Shelf) and Indian Ocean; while the microsatellites supported five population groups (eastern Indonesia, Sunda Shelf, Lesser Sunda, Western Australia and Indian Ocean). Both SNPs and microsatellites showed asymmetrical gene flow among population groups with a trend of southwestward migration from eastern Indonesia. Genetic diversity was generally higher in eastern Indonesia and decreased southwestward. The pattern of genetic structure and connectivity is attributed partly to the Pleistocene sea level fluctuations modified to a smaller level by contemporary ocean currents.
authors.affiliation: School of Science and Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup, WA, 6027, Australia.|UPT. LKBL-Tual, Research Centre for Oceanography (P2O), Indonesian Institute of Sciences (LIPI), Ancol Timur, Jakarta, 14430, Indonesia.
authors.forename: Udhi E
authors.initials: UE
authors.lastname: Hernawan
authors.affiliation: School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia.
authors.forename: Kor-Jent
authors.initials: KJ
authors.lastname: van Dijk
authors.affiliation: School of Plant Biology and The Ocean Institute, The University of Western Australia, Crawley, WA, 6009, Australia.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Kendrick
authors.affiliation: CSIRO Ocean and Atmosphere, Centre for Environment and Life Sciences, Floreat, WA, 6014, Australia.
authors.forename: Ming
authors.initials: M
authors.lastname: Feng
authors.affiliation: School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia.
authors.forename: Edward
authors.initials: E
authors.lastname: Biffin
authors.affiliation: School of Science and Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup, WA, 6027, Australia.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Lavery
authors.affiliation: School of Science and Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup, WA, 6027, Australia.
authors.forename: Kathryn
authors.initials: K
authors.lastname: McMahon
mesh_terms: D001315:Australia; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population; D031321:Hydrocharitaceae / Q000235:genetics*; D019156:Indian Ocean; D007214:Indonesia; D018895:Microsatellite Repeats; D010140:Pacific Ocean; D058974:Phylogeography; D020641:Polymorphism, Single Nucleotide; D014872:Water Movements; D014904:Western Australia
keywords: gene flow; geological history; microsatellite; ocean current; single nucleotide polymorphisms