title: A chemosynthetic weed: the tubeworm Sclerolinum contortum is a bipolar, cosmopolitan species.
abstract: BACKGROUND
  Sclerolinum (Annelida: Siboglinidae) is a genus of small, wiry deep-sea tubeworms that depend on an endosymbiosis with chemosynthetic bacteria for their nutrition, notable for their ability to colonise a multitude of reducing environments. Since the early 2000s, a Sclerolinum population has been known to inhabit sediment-hosted hydrothermal vents within the Bransfield Strait, Southern Ocean, and whilst remaining undescribed, it has been suggested to play an important ecological role in this ecosystem. Here, we show that the Southern Ocean Sclerolinum population is not a new species, but more remarkably in fact belongs to the species S. contortum, first described from an Arctic mud volcano located nearly 16,000 km away.
  
  
  RESULTS
  Our new data coupled with existing genetic studies extend the range of this species across both polar oceans and the Gulf of Mexico. Our analyses show that the populations of this species are structured on a regional scale, with greater genetic differentiation occurring between rather than within populations. Further details of the external morphology and tube structure of S. contortum are revealed through confocal and SEM imaging, and the ecology of this worm is discussed.
  
  
  CONCLUSIONS
  These results shed further insight into the plasticity and adaptability of this siboglinid group to a range of reducing conditions, and into the levels of gene flow that occur between populations of the same species over a global extent.
authors.affiliation: Life Sciences Department, Natural History Museum, London, UK. eemng@leeds.ac.uk.|School of Earth and Environment, University of Leeds, Leeds, UK. eemng@leeds.ac.uk.
authors.forename: Magdalena N
authors.initials: MN
authors.lastname: Georgieva
authors.affiliation: Life Sciences Department, Natural History Museum, London, UK. h.wiklund@nhm.ac.uk.
authors.forename: Helena
authors.initials: H
authors.lastname: Wiklund
authors.affiliation: Life Sciences Department, Natural History Museum, London, UK. gyjbb@leeds.ac.uk.|School of Geography, University of Leeds, Leeds, UK. gyjbb@leeds.ac.uk.
authors.forename: James B
authors.initials: JB
authors.lastname: Bell
authors.affiliation: Centre for Geobiology, University of Bergen, Bergen, Norway. mari.eilertsen@uib.no.|Department of Biology, University of Bergen, Bergen, Norway. mari.eilertsen@uib.no.
authors.forename: Mari H
authors.initials: MH
authors.lastname: Eilertsen
authors.affiliation: Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK. rachel.mills@soton.ac.uk.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Mills
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds, UK. c.t.s.little@earth.leeds.ac.uk.
authors.forename: Crispin T S
authors.initials: CT
authors.lastname: Little
authors.affiliation: Life Sciences Department, Natural History Museum, London, UK. a.glover@nhm.ac.uk.
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Glover
mesh_terms: D000818:Animals; D000864:Antarctic Regions; D001110:Arctic Regions; D001419:Bacteria / Q000378:metabolism; D051456:Gene Flow; D060086:Hydrothermal Vents; D009792:Oceans and Seas; D011077:Polychaeta / Q000235:genetics* / Q000382:microbiology / Q000502:physiology / Q000648:ultrastructure*; D013559:Symbiosis