title: High connectivity of animal populations in deep-sea hydrothermal vent fields in the Central Indian Ridge relevant to its geological setting.
abstract: Dispersal ability plays a key role in the maintenance of species in spatially and temporally discrete niches of deep-sea hydrothermal vent environments. On the basis of population genetic analyses in the eastern Pacific vent fields, dispersal of animals in the mid-oceanic ridge systems generally appears to be constrained by geographical barriers such as trenches, transform faults, and microplates. Four hydrothermal vent fields (the Kairei and Edmond fields near the Rodriguez Triple Junction, and the Dodo and Solitaire fields in the Central Indian Ridge) have been discovered in the mid-oceanic ridge system of the Indian Ocean. In the present study, we monitored the dispersal of four representative animals, Austinograea rodriguezensis, Rimicaris kairei, Alviniconcha and the scaly-foot gastropods, among these vent fields by using indirect methods, i.e., phylogenetic and population genetic analyses. For all four investigated species, we estimated potentially high connectivity, i.e., no genetic difference among the populations present in vent fields located several thousands of kilometers apart; however, the direction of migration appeared to differ among the species, probably because of different dispersal strategies. Comparison of the intermediate-spreading Central Indian Ridge with the fast-spreading East Pacific Rise and slow-spreading Mid-Atlantic Ridge revealed the presence of relatively high connectivity in the intermediate- and slow-spreading ridge systems. We propose that geological background, such as spreading rate which determines distance among vent fields, is related to the larval dispersal and population establishment of vent-endemic animal species, and may play an important role in controlling connectivity among populations within a biogeographical province.
authors.affiliation: Mauritius Oceanography Institute, Quatre-Bornes, Mauritius.
authors.forename: Girish
authors.initials: G
authors.lastname: Beedessee
authors.affiliation: Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Watanabe
authors.affiliation: Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan ; Graduate School of Marine Science and Technoloy, Tokyo University of Marine Science and Technology, Minato, Tokyo, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Ogura
authors.affiliation: Enoshima Aquarium, Fujisawa, Kanagawa, Japan.
authors.forename: Suguru
authors.initials: S
authors.lastname: Nemoto
authors.affiliation: Atmosphere and Ocean Research Institute, the University of Tokyo, Kashiwa, Chiba, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Yahagi
authors.affiliation: Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakagawa
authors.affiliation: Precambrian Ecosystem Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan ; Precambrian Ecosystem Laboratory, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Takai
authors.affiliation: Albion Fisheries Research Centre, Ministry of Fisheries, Petite Rivière, Mauritius.
authors.forename: Meera
authors.initials: M
authors.lastname: Koonjul
authors.affiliation: Mauritius Oceanography Institute, Quatre-Bornes, Mauritius.
authors.forename: Daniel E P
authors.initials: DE
authors.lastname: Marie
mesh_terms: D063147:Animal Distribution; D000818:Animals; D033364:Decapoda; D017753:Ecosystem; D004777:Environment; D049851:Gastropoda; D005828:Genetics, Population; D060086:Hydrothermal Vents; D019156:Indian Ocean; D012623:Seawater