Composition of subspecies, head spot types and genetic types of charr distributed in the Hino River, Japan

鳥取県日野川水系におけるイワナ属魚類について，ゴギとニッコウイワナ，頭部斑紋型，遺伝子型の組成を調べた。計19の支流から38個体のサンプルが採集され，支流はその発する山塊ごとにグループ化された。ニッコウイワナは水系東部の大山・二子・花見山塊から発する支流に分布したが西部5山塊からの支流には分布せず，対照的にゴギは水系西部の鬼林・道後・三国・船通・鷹入山塊に分布したが東部3山塊には分布しなかった。斑紋型では東部3山塊ではＣ・Ｅ・Ｆ・Ｇ・Ｈは記録されたがＡ・Ｂ・Ｄ型は記録されなかった。一方，西部5山塊ではすべての型が記録された。遺伝子型では6および9つのハプロタイプがそれぞれニッコウイワナおよびゴギ特異的であり，1タイプのみ共通であった。デンドログラムではニッコウイワナおよびゴギそれぞれ5および6つのハプロタイプで構成される亜種特異的なクレードが見られたが，もう一つのクレードは両亜種で形成された。これらの結果は，日野川における両亜種の混棲，ゴギの複数起源性，地形変動等による分布拡大，さらに斑紋の易変異性を示唆する。

Composition of 2 subspecies of white-spotted charr, Salvelinus leucomaenis imbrius (“Gogi”) and S. l. pluvius (“Nikko-iwana”), head spot types and genetic types were investigated for the Hino River, Tottori Prefecture, Japan. A total of 38 charr samples was collected from the 19 branches. All the branches were categorized into 8 groups based on the mountain mass from which the branch originates. Nikko-iwana was distributed in the Daisen, Futago and Hanami mountain masses in the eastern part of the basin and was not distributed in the other 5 mountain masses in the western part. In contrast, Gogi was distributed in the western Onibayashi, Dogo, Mikuni, Senzu and Takairi mountain masses and was not distributed in the 3 eastern mountain masses. For head spot types, C, E, F, G and H were distributed in the 3 eastern masses whereas A, B and D were not recorded from these masses. On the other hand, all the types were distributed in the 5 western masses. For genetic types, 6 and 9 haplotypes were Nikko-iwana- and Gogi-specific, respectively. Only a haplotype comprised both subspecies. In the dendrogram, 5 haplotypes constructed an exclusive clade of Nikko-iwana whereas 6 haplotypes constructed an exclusive clade of Gogi. However, the remaining clade was constructed by both subspecies. These results suggest the co-existence of both subspecies in the Hino River, multiple origins of Gogi, movements of charr by topographic events and plasticity of the head spots.