Genetic population structure of Neptune whelk in northern Japan inferred from microsatellite DNA variation

Abstract

Genetic population structure of the Neptune whelk (Neptunea arthritica) in northern Japan was estimated from six samples collected from Hokkaido and one sample from Aomori, in northernmost Honshu, using five polymorphic microsatellite DNA loci. Pairwise F ST estimates indicated a genetic cline from eastern and northeastern Hokkaido to southern Hokkaido and northernmost Honshu. The individual-based assignment method and analyses of molecular variance suggested three geographic groups within this cline. The observed population structure was most likely influenced by isolation-by-distance with restricted gene flow, as suggested by the significant correlation between genetic and geographic distance for the entire region examined. The inferred restriction of gene flow is likely due to the poor dispersal ability of this species, which has a benthic, sedentary life history and passive dispersal along the coasts. The observed genetic structure of N. arthritica will be useful for conservation and fisheries management of this species.

Phylogeography of Neptune whelk (Neptunea arthritica) suggests sex-biased impact of tributyltin pollution and overfishing around northern Japan

“…Using five loci of microsatellite DNA markers in seven populations of N. arthritica around Hokkaido, we suggested the restricted gene flow among populations with increasing genetic differentiation among populations separated by increasing geographic distances, i.e. following the isolation-by-distance model (Azuma et al, 2011). The observed restricted gene flow between local populations was most probably influenced by the balance of the transport force of sea water and the low level of dispersal potential of this species (Azuma et al, 2011).…”

“…Hereafter, the term 'sample' is used for a group of individuals collected from each of the abovementioned localities, as representative of the local population. The samples were identical to those used for our previous microsatellite DNA analysis (Azuma et al, 2011), except for RU, which was recruited in the present study. Genomic DNA of the RU sample was extracted using the Pure Gene Kit (Qiagen)…”

“…following the isolation-by-distance model (Azuma et al, 2011). The observed restricted gene flow between local populations was most probably influenced by the balance of the transport force of sea water and the low level of dispersal potential of this species (Azuma et al, 2011). Therefore, the suggested genetic structure was considered to be a result of natural distribution without strong anthropogenic disturbance.…”

“…Sea snails, including N. artheritica, have been a food resource and commercially important in the coastal fisheries in northern Japan (Mizushima & Torisawa, 2003); thus, several biological studies of N. arthritica have been mainly conducted for resource management (Kawai et al, 1994;Fujinaga & Nakao, 1996;Suzuki et al, 2002;Fujinaga, 2003;Fujinaga et al, 2006;Miranda et al, 2007Miranda et al, & 2009Miranda, Fujinaga & Nakao, 2008;Lombardo & Goshima, 2010). However, none of the population genetic studies had appeared before our recent microsatellite DNA analysis in N. arthritica around Hokkaido (Azuma et al, 2011). Using five loci of microsatellite DNA markers in seven populations of N. arthritica around Hokkaido, we suggested the restricted gene flow among populations with increasing genetic differentiation among populations separated by increasing geographic distances, i.e.…”

“…This indicates that mtDNA has sufficient sensitivity for detecting past population declines. Previous microsatellite DNA analyses for N. arthritica did not reveal any evidence of a recent decline in each population (Azuma et al, 2011). However, around Hokkaido, N. arthritica showed a severe decline during the 1970s and 1980s, possibly because of overfishing, imposex caused by tributyltin (TBT) pollution and parasite infection (Kawai et al, 1994;Fujinaga et al, 2006;Miranda et al, 2007Miranda et al, & 2009.…”