TITLE:
Dispersal Ability and Genetic Structure in Mytilid Mussels of Whale-Fall Communities
AUTHORS:
Youki Fukasawa, Haruna Kobayashi-Iwatani, Masaru Kawato, Hideki Kobayashi, Yoshihiro Fujiwara, Jun-Ichi Miyazaki
KEYWORDS:
Chemosynthesis-Based Community, Mitochondrial DNA, Organic Falls, Stepping Stone Hypothesis
JOURNAL NAME:
Open Journal of Marine Science,
Vol.5 No.3,
July
23,
2015
ABSTRACT: Since organic falls are
ephemeral and distributed sporadically, organisms in organic-fall communities
must acquire high dispersal ability to migrate from one organic fall to
another. However, the dispersal ability of obligate organic-fall organisms has
not been investigated thoroughly and the stability of the genetic structure of
their communities is unknown. In this study, in order to elucidate the dispersal
ability and genetic structure in the organic-fall communities, we carried out
population genetic analyses based on sequences of mitochondrial NADH
dehydrogenase subunit 4 in two mytilid mussels.Adipicola pacifica was obtained from whale and cow bones
artificially settled in Japanese waters off Cape Noma (CN) and in the
Nansei-Shoto Trench (NS) and Sagami Bay (SB), and Benthomodiolus geikotsucola from natural whale bones in the
Torishima Seamount (TS); both species are symbiotic with chemoautotrophic
bacteria. Genetic differentiation (Fst) indicated almost no
annual change in genetic structure between 2003, 2004, 2005, and 2007
collections of A. pacificafrom CN (depth 225 -
229 m), although the 2010 collection had somewhat different genetic structure
from the others. Similarly, there was not significant genetic differentiation
between 1993 and 2005 collections of B.geikotsucola from TS (depth 4020 m). The Fst and gene bidirectional mean rate of
gene flow (Nm) indicated high gene flow and no significant genetic
differentiation between A. pacifica specimens collected from CN, NS, and
SB. The results suggest that the genetic structure is stable and A. pacifica has high dispersal ability. The
mismatch distribution suggests that A. pacificaexpanded their
distribution from SB to NS via CN, as expansion time (τ = 2ut) decreased
from SB to CN and NS.