title: Genetic differentiation and phylogeography of partially sympatric species complex Rhizophora mucronata Lam. and R. stylosa Griff. using SSR markers.
abstract: BACKGROUND
  Mangrove forests are ecologically important but globally threatened intertidal plant communities. Effective mangrove conservation requires the determination of species identity, management units, and genetic structure. Here, we investigate the genetic distinctiveness and genetic structure of an iconic but yet taxonomically confusing species complex Rhizophora mucronata and R. stylosa across their distributional range, by employing a suite of 20 informative nuclear SSR markers.
  
  
  RESULTS
  Our results demonstrated the general genetic distinctiveness of R. mucronata and R. stylosa, and potential hybridization or introgression between them. We investigated the population genetics of each species without the putative hybrids, and found strong genetic structure between oceanic regions in both R. mucronata and R. stylosa. In R. mucronata, a strong divergence was detected between populations from the Indian Ocean region (Indian Ocean and Andaman Sea) and the Pacific Ocean region (Malacca Strait, South China Sea and Northwest Pacific Ocean). In R. stylosa, the genetic break was located more eastward, between populations from South and East China Sea and populations from the Southwest Pacific Ocean. The location of these genetic breaks coincided with the boundaries of oceanic currents, thus suggesting that oceanic circulation patterns might have acted as a cryptic barrier to gene flow.
  
  
  CONCLUSIONS
  Our findings have important implications on the conservation of mangroves, especially relating to replanting efforts and the definition of evolutionary significant units in Rhizophora species. We outlined the genetic structure and identified geographical areas that require further investigations for both R. mucronata and R. stylosa. These results serve as the foundation for the conservation genetics of R. mucronata and R. stylosa and highlighted the need to recognize the genetic distinctiveness of closely-related species, determine their respective genetic structure, and avoid artificially promoting hybridization in mangrove restoration programmes.
authors.affiliation: Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan. alisonwks@xtbg.ac.cn.|Present Address: Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China. alisonwks@xtbg.ac.cn.
authors.forename: Alison K S
authors.initials: AK
authors.lastname: Wee
authors.affiliation: The University Museum, The University of Tokyo, Hongo 7-3-1, Tokyo, 113-0033, Japan. gen33takayama@gmail.com.
authors.forename: Koji
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authors.lastname: Takayama
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore. rehsaj@gmail.com.
authors.forename: Jasher L
authors.initials: JL
authors.lastname: Chua
authors.affiliation: Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan. asakawa@faculty.chiba-u.jp.
authors.forename: Takeshi
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authors.lastname: Asakawa
authors.affiliation: Biotechnology Programme, M.S. Swaminathan Research Foundation, Chennai, India. justforscience@gmail.com.
authors.forename: Sankararamasubramanian H
authors.initials: SH
authors.lastname: Meenakshisundaram
authors.affiliation: Forestry Sciences Department, Universitas Sumatera Utara, Medan, Indonesia. onrizal@gmail.com.
authors.lastname: Onrizal
authors.affiliation: Bali Botanical Garden, Indonesian Institute of Sciences, Bali, Indonesia. biobayu@gmail.com.
authors.forename: Bayu
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authors.lastname: Adjie
authors.affiliation: Faculty of Biology, Jenderal Soedirman University, Purwokerto, Indonesia. eriantoo@yahoo.com.
authors.forename: Erwin Riyanto
authors.initials: ER
authors.lastname: Ardli
authors.affiliation: Forest Biology Department, Faculty of Forestry, Kasetsart University, Bangkok, Thailand. sungkaes@tcd.ie.
authors.forename: Sarawood
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authors.affiliation: Institute for Tropical Biology and Conservation, Universiti Malaysia Kota Kinabalu, Kota Kinabalu, Malaysia. lyenda85@gmail.com.
authors.forename: Norhaslinda Binti
authors.initials: NB
authors.lastname: Malekal
authors.affiliation: Mangrove Ecosystem Research Centre, Hanoi National University of Education, Hanoi, Vietnam. xt_xuthanh@yahoo.com.
authors.forename: Nguyen Xuan
authors.initials: NX
authors.lastname: Tung
authors.affiliation: Department of Environmental Science, School of Science and Engineering, Ateneo de Manila University, Quezon City, Philippines. ssalmo@ateneo.edu.
authors.forename: Severino G
authors.initials: SG
authors.lastname: Salmo
authors.affiliation: Biology Department, College of Science and Technology, Adventist University of the Philippines, Silang, 4118, Cavite, Philippines. obyupd@yahoo.com.
authors.forename: Orlex Baylen
authors.initials: OB
authors.lastname: Yllano
authors.affiliation: Department of Forest Production, Faculty of Forestry, Universiti Putra Malaysia, Serdang, Malaysia. mnazre@gmail.com.
authors.forename: M Nazre
authors.initials: MN
authors.lastname: Saleh
authors.affiliation: Department of Botany, University of Yangon, Yangon, Myanmar. khinkhinsoe9@googlemail.com.
authors.forename: Khin Khin
authors.initials: KK
authors.lastname: Soe
authors.affiliation: Faculty of Education, University of the Ryukyus, Senbaru, Okinawa, Japan. mame@edu.u-ryukyu.ac.jp.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Tateishi
authors.affiliation: Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan. watano@faculty.chiba-u.jp.
authors.forename: Yasuyuki
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authors.lastname: Watano
authors.affiliation: Tropical Biosphere Research Center, University of the Ryukyus, Iriomote, Okinawa, Japan. babasan@lab.u-ryukyu.ac.jp.|International Society for Mangrove Ecosystems (ISME), c/o Faculty of Agriculture, University of the Ryukyus, Senbaru, Okinawa, 903-0129, Japan. babasan@lab.u-ryukyu.ac.jp.
authors.forename: Shigeyuki
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authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore. ted.webb@nus.edu.sg.
authors.forename: Edward L
authors.initials: EL
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authors.affiliation: Department of Biology, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan. tkaji@faculty.chiba-u.jp.
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mesh_terms: D001210:Asia, Southeastern; D051456:Gene Flow; D040961:Genetic Drift; D018895:Microsatellite Repeats; D058974:Phylogeography; D043982:Rhizophoraceae / Q000145:classification* / Q000235:genetics*; D061350:Sympatry