title: A new barrier to dispersal trapped old genetic clines that escaped the Easter Microplate tension zone of the Pacific vent mussels.
abstract: Comparative phylogeography of deep-sea hydrothermal vent species has uncovered several genetic breaks between populations inhabiting northern and southern latitudes of the East Pacific Rise. However, the geographic width and position of genetic clines are variable among species. In this report, we further characterize the position and strength of barriers to gene flow between populations of the deep-sea vent mussel Bathymodiolus thermophilus. Eight allozyme loci and DNA sequences of four nuclear genes were added to previously published sequences of the cytochrome c oxidase subunit I gene. Our data confirm the presence of two barriers to gene flow, one located at the Easter Microplate (between 21°33'S and 31°S) recently described as a hybrid zone, and the second positioned between 7°25'S and 14°S with each affecting different loci. Coalescence analysis indicates a single vicariant event at the origin of divergence between clades for all nuclear loci, although the clines are now spatially discordant. We thus hypothesize that the Easter Microplate barrier has recently been relaxed after a long period of isolation and that some genetic clines have escaped the barrier and moved northward where they have subsequently been trapped by a reinforcing barrier to gene flow between 7°25'S and 14°S.
authors: Université Pierre et Marie Curie-Paris 6, Laboratoire Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France ; CNRS UMR 7144, Station Biologique de Roscoff, Roscoff, France ; Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, North Carolina, United States of America.
authors: Sophie
authors: S
authors: Plouviez
authors: Baptiste
authors: B
authors: Faure
authors: Dominique
authors: D
authors: Le Guen
authors: François H
authors: FH
authors: Lallier
authors: Nicolas
authors: N
authors: Bierne
authors: Didier
authors: D
authors: Jollivet
mesh_terms: D043383:Adenosylhomocysteinase / Q000235:genetics; D063147:Animal Distribution; D000818:Animals; D001483:Base Sequence; D049872:Bivalvia / Q000166:cytology / Q000201:enzymology / Q000235:genetics* / Q000502:physiology*; D002467:Cell Nucleus / Q000235:genetics; D019143:Evolution, Molecular; D006239:Haplotypes; D060086:Hydrothermal Vents; D007527:Isoenzymes / Q000235:genetics; D008928:Mitochondria / Q000235:genetics; D010140:Pacific Ocean; D011110:Polymorphism, Genetic; D012641:Selection, Genetic
chemical_list: D007527:Isoenzymes; D043383:Adenosylhomocysteinase