窪地の埋め戻し場所に出現したアマモの遺伝的多様性と種子供給源

摘要

The objective of this study is to clarify the genetic diversity and seed sources of the Zostera marina population colonizing the habitat constructed in a depression on the coast of Iwakuni in Hiroshima Bay. We investigated Zostera beds in Hiroshima Bay and conducted genetic analysis of 30 samples collected at each of the six beds, using five microsatellite markers. Our results are as follows. The major seed production areas were considered to be Nomijima, Obatake-Kojiro and Miyajima. The mean numbers of alleles per locus and heterozygosities were almost the same between the constructed and natural habitats. The pairwise Fst ranged from 0.000 to 0.037; suggesting a high gene flow among populations in Hiroshima Bay. Assignment test showed the maximum likelihood values between the samples of the constructed habitat and distant populations (more than 15-20 km away) as well as of neighboring populations. These results suggested that the Z. marina population colonizing the constructed habitat had almost the same genetic diversity as the natural population, and that distant populations as well as neighboring populations in Hiroshima Bay can serve a seed supply source.%本研究では，窪地の埋め專し場所に出現したアマモの遺伝的多様性と種子供給源の解明を目的に，岩国市地先及び広島湾周辺海域においてアマモの生育状況調査とマイクロサテライトマーカーによる遺伝子解析を行った。その結果，主な種子生産区域は能美島，大畠-神代，宮島地区と考えられた。1遺伝子座当たりの平均アレル数と平均へテロ接合率を比較すると，埋め戻し場所のアマモは天然アマモ場と比較して大きな差はなかった。ペアワイズFstは0·000～0.037の範囲にあり,アマモ場相互の盛んな遺伝的交流が考えられた。アサインメントテストでは，埋め戻し場所のアマモは近隣のアマモ集団だけでなく，15km以上離れたアマモ集団との間でも最大尤度を示した。以上の結果から，埋め戻し場所のアマモは天然アマモ場と同様な遺伝的多様性をもち，種子供給源として近隣のアマモ場だけでなく，広島湾内にある遠方のアマモ場も寄与することが考えられた。