title: Phylogeographic data revealed shallow genetic structure in the kelp Saccharina japonica (Laminariales, Phaeophyta).
abstract: BACKGROUND
  Population structure and genetic diversity of marine organisms in the Northwestern Pacific Ocean exhibited complex patterns. Saccharina japonica is a commercially and ecologically important kelp species widely distributed along the coast of Japan Sea. However, it is still poorly known about population genetics and phylogeographic patterns of wild S. japonica populations on a large geographic scale, which is an important contribution to breeding and conservation of this marine crop.
  
  
  RESULTS
  We collected 612 mitochondrial COI and trnW-trnL sequences. Diversity indices suggested that S. japonica populations along the coast of Hokkaido exhibited the highest genetic diversity. Bayesian Analysis of Population Structure (BAPS) revealed four clusters in the kelp species (cluster 1: Hokkaido and South Korea; cluster 2: northwestern Hokkaido; cluster 3: Far Eastern Russia; cluster 4: China). The network inferred from concatenated data exhibited two shallow genealogies corresponding to two BAPS groups (cluster 2 and cluster 3). We did not detect gene flow between the two shallow genealogies, but populations within genealogy have asymmetric gene exchange. Bayesian skyline plots and neutrality tests suggested that S. japonica experienced postglacial expansion around 10.45 ka.
  
  
  CONCLUSIONS
  The coast of Hokkaido might be the origin and diversification center of S. japonica. Gene exchange among S. japonica populations could be caused by anthropogenic interference and oceanographic regimes. Postglacial expansions and gene exchange apparently led to more shared haplotypes and less differentiation that in turn led to the present shallow phylogeographical patterns in S. japonica.
authors.affiliation: Key Lab of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. zhangjie0616@126.com.|Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China. zhangjie0616@126.com.|University of Chinese Academy of Sciences, Beijing, 100049, China. zhangjie0616@126.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Lab of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. yaojianting@qdio.ac.cn.|Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China. yaojianting@qdio.ac.cn.
authors.forename: Jian-Ting
authors.initials: JT
authors.lastname: Yao
authors.affiliation: Key Lab of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. zhmsun@hotmail.com.
authors.forename: Zhong-Min
authors.initials: ZM
authors.lastname: Sun
authors.affiliation: Key Lab of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. gfu@brandeis.edu.|Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, 051-0013, Hokkaido, Japan. gfu@brandeis.edu.
authors.forename: Gang
authors.initials: G
authors.lastname: Fu
authors.affiliation: Sakhalin Scientific Research Institute of Fisheries and Oceanology, Yuzhno-Sakhalinsk, 693023, Russia. dgalanin@yandex.ru.
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Galanin
authors.affiliation: Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, 051-0013, Hokkaido, Japan. nagasato@fsc.hokudai.ac.jp.
authors.forename: Chikako
authors.initials: C
authors.lastname: Nagasato
authors.affiliation: Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, 051-0013, Hokkaido, Japan. motomura@fsc.hokudai.ac.jp.
authors.forename: Taizo
authors.initials: T
authors.lastname: Motomura
authors.affiliation: Key Lab of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. huzimin9712@163.com.|Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China. huzimin9712@163.com.
authors.forename: Zi-Min
authors.initials: ZM
authors.lastname: Hu
authors.affiliation: Key Lab of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China. dlduan@qdio.ac.cn.|Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China. dlduan@qdio.ac.cn.
authors.forename: De-Lin
authors.initials: DL
authors.lastname: Duan
mesh_terms: D001499:Bayes Theorem; D051456:Gene Flow; D014644:Genetic Variation; D006239:Haplotypes; D044423:Kelp / Q000145:classification / Q000235:genetics*; D010140:Pacific Ocean; D058974:Phylogeography