北海道礼文華峠におけるブナ分布北限域孤立個体群の立地と植生

筆者らはブナの分布北限域における最前線孤立個体群を太平洋から水平距離で2.5km内陸に位置する豊浦町礼文華峠の岩峰上及びその周辺で発見した．これはブナの天然分布個体群の中でも太平洋側における最北限の個体群であると考えられた。付近のアメダスのデータによれば，年平均気温7.3 ℃，年降水量1,198 mm，最大積雪深85cmであった．現地の暖かさの指数WIは52.5℃・月と推定された．ブナの分布，植生と立地の状況を明らかにするために現地調査を行った結果，以下の知見を得た．（1）岩峰上に生育する胸高以上のブナは約1.7 haの範囲（標高196 ～ 275 m）に39本生育し，胸高直径階分布は緩やかなL字型を示し，10 cm以下の個体が最多であった．（2） 岩峰のブナは主にミズナラ，ホオノキ，シラカンバと混生し，競合する針葉樹は記録されなかった．（3） 植物群落の種構成は日本海側に成立するブナ林に類似していた．（4） 土壌pHはやや酸性で5.4 ～ 5.5であり，無機態窒素は全国のブナ林の値と大きな違いはなかった．以上の知見から，礼文華峠の岩峰上のブナ個体群は，その生育に適した気候条件に加え，本州の岩峰などでしばしば優占する針葉樹類が不在であるなどの条件が重なって成立したと考えられた

Biology of the Spotted-Wing Drosophila suzukii (Diptera: Drosophilidae) in Hokkaido, Northern Japan. III. Breeding on Blueberries

Breeding of Drosophila (Sophophora) suzukii on blueberries was studied during the entire ripening season from July to October in Hokkaido, northern Japan. The species began to use blueberries from late July in the years 2016, 2017, and 2018 and from early August in 2019; about 95% of the fruits were infected by D. suzukii females from late August to late September. The active breeding of D. suzukii on blueberries peaked in late August, and number of adults that emerged from a single blueberry fruit was 4.2±2.1 (n=20), with the maximum number being 9. For breeding of D. suzukii on cherry fruits, the damage ratio was quite low, because of its fruiting period being about 1 month earlier than the appearance of D. suzukii in Hokkaido

DataSheet_1_Possible northern persistence of Siebold’s beech, Fagus crenata, at its northernmost distribution limit on an island in Japan Sea: Okushiri Island, Hokkaido.pdf

Siebold’s beech, Fagus crenata, is widely distributed across the Japanese Archipelago and islands in Japan Sea. Similar to the northern limit of the geographical distribution of F. crenata on the mainland of Hokkaido, the northern limit of the distribution of F. crenata on islands in the Japan Sea is observed on Okushiri Island (ca 42°N). To understand the genetic relationships of F. crenata on Okushiri Island, we examined chloroplast (cp) DNA haplotypes and 11 nuclear microsatellite (SSR) loci among 1,838 individuals from 44 populations from Okushiri Island, mainland Hokkaido, and the northern part of the Tohoku region on Honshu Island. We identified 2 cpDNA haplotypes, which represent not only populations on the Japan Sea coast but also those on the Pacific coast and this suggested the Okushiri Island populations might not be formed by single colonization. Genetic diversity of the Okushiri Island populations of nuclear SSR was not lower than the mainland and the STRUCTURE analysis revealed the Okushiri Island individuals were admixed between Hokkaido and Tohoku clusters. Approximate Bayesian computation inferred that divergence between Tohoku and Hokkaido, and admixture between two populations which generated Okushiri populations occurred before the last glacial maximum (LGM), that is, 7,890 (95% hyper probability density (HPD): 3,420 – 9,910) and 3,870 (95% HPD: 431– 8,540) generations ago, respectively. These inferences were well supported by a geological history which suggested an isolation of Okushiri Island from Hokkaido started prior to the Middle Pleistocene. We discuss the possible persistence of F. crenata during the last glacial maximum on northern islands in the Japan Sea such as Okushiri Island.</p

DataSheet_2_Possible northern persistence of Siebold’s beech, Fagus crenata, at its northernmost distribution limit on an island in Japan Sea: Okushiri Island, Hokkaido.pdf

Siebold’s beech, Fagus crenata, is widely distributed across the Japanese Archipelago and islands in Japan Sea. Similar to the northern limit of the geographical distribution of F. crenata on the mainland of Hokkaido, the northern limit of the distribution of F. crenata on islands in the Japan Sea is observed on Okushiri Island (ca 42°N). To understand the genetic relationships of F. crenata on Okushiri Island, we examined chloroplast (cp) DNA haplotypes and 11 nuclear microsatellite (SSR) loci among 1,838 individuals from 44 populations from Okushiri Island, mainland Hokkaido, and the northern part of the Tohoku region on Honshu Island. We identified 2 cpDNA haplotypes, which represent not only populations on the Japan Sea coast but also those on the Pacific coast and this suggested the Okushiri Island populations might not be formed by single colonization. Genetic diversity of the Okushiri Island populations of nuclear SSR was not lower than the mainland and the STRUCTURE analysis revealed the Okushiri Island individuals were admixed between Hokkaido and Tohoku clusters. Approximate Bayesian computation inferred that divergence between Tohoku and Hokkaido, and admixture between two populations which generated Okushiri populations occurred before the last glacial maximum (LGM), that is, 7,890 (95% hyper probability density (HPD): 3,420 – 9,910) and 3,870 (95% HPD: 431– 8,540) generations ago, respectively. These inferences were well supported by a geological history which suggested an isolation of Okushiri Island from Hokkaido started prior to the Middle Pleistocene. We discuss the possible persistence of F. crenata during the last glacial maximum on northern islands in the Japan Sea such as Okushiri Island.</p

DataSheet_3_Possible northern persistence of Siebold’s beech, Fagus crenata, at its northernmost distribution limit on an island in Japan Sea: Okushiri Island, Hokkaido.pdf

Siebold’s beech, Fagus crenata, is widely distributed across the Japanese Archipelago and islands in Japan Sea. Similar to the northern limit of the geographical distribution of F. crenata on the mainland of Hokkaido, the northern limit of the distribution of F. crenata on islands in the Japan Sea is observed on Okushiri Island (ca 42°N). To understand the genetic relationships of F. crenata on Okushiri Island, we examined chloroplast (cp) DNA haplotypes and 11 nuclear microsatellite (SSR) loci among 1,838 individuals from 44 populations from Okushiri Island, mainland Hokkaido, and the northern part of the Tohoku region on Honshu Island. We identified 2 cpDNA haplotypes, which represent not only populations on the Japan Sea coast but also those on the Pacific coast and this suggested the Okushiri Island populations might not be formed by single colonization. Genetic diversity of the Okushiri Island populations of nuclear SSR was not lower than the mainland and the STRUCTURE analysis revealed the Okushiri Island individuals were admixed between Hokkaido and Tohoku clusters. Approximate Bayesian computation inferred that divergence between Tohoku and Hokkaido, and admixture between two populations which generated Okushiri populations occurred before the last glacial maximum (LGM), that is, 7,890 (95% hyper probability density (HPD): 3,420 – 9,910) and 3,870 (95% HPD: 431– 8,540) generations ago, respectively. These inferences were well supported by a geological history which suggested an isolation of Okushiri Island from Hokkaido started prior to the Middle Pleistocene. We discuss the possible persistence of F. crenata during the last glacial maximum on northern islands in the Japan Sea such as Okushiri Island.</p

DataSheet_5_Possible northern persistence of Siebold’s beech, Fagus crenata, at its northernmost distribution limit on an island in Japan Sea: Okushiri Island, Hokkaido.pdf

Siebold’s beech, Fagus crenata, is widely distributed across the Japanese Archipelago and islands in Japan Sea. Similar to the northern limit of the geographical distribution of F. crenata on the mainland of Hokkaido, the northern limit of the distribution of F. crenata on islands in the Japan Sea is observed on Okushiri Island (ca 42°N). To understand the genetic relationships of F. crenata on Okushiri Island, we examined chloroplast (cp) DNA haplotypes and 11 nuclear microsatellite (SSR) loci among 1,838 individuals from 44 populations from Okushiri Island, mainland Hokkaido, and the northern part of the Tohoku region on Honshu Island. We identified 2 cpDNA haplotypes, which represent not only populations on the Japan Sea coast but also those on the Pacific coast and this suggested the Okushiri Island populations might not be formed by single colonization. Genetic diversity of the Okushiri Island populations of nuclear SSR was not lower than the mainland and the STRUCTURE analysis revealed the Okushiri Island individuals were admixed between Hokkaido and Tohoku clusters. Approximate Bayesian computation inferred that divergence between Tohoku and Hokkaido, and admixture between two populations which generated Okushiri populations occurred before the last glacial maximum (LGM), that is, 7,890 (95% hyper probability density (HPD): 3,420 – 9,910) and 3,870 (95% HPD: 431– 8,540) generations ago, respectively. These inferences were well supported by a geological history which suggested an isolation of Okushiri Island from Hokkaido started prior to the Middle Pleistocene. We discuss the possible persistence of F. crenata during the last glacial maximum on northern islands in the Japan Sea such as Okushiri Island.</p

Image_2_Possible northern persistence of Siebold’s beech, Fagus crenata, at its northernmost distribution limit on an island in Japan Sea: Okushiri Island, Hokkaido.tiff

Siebold’s beech, Fagus crenata, is widely distributed across the Japanese Archipelago and islands in Japan Sea. Similar to the northern limit of the geographical distribution of F. crenata on the mainland of Hokkaido, the northern limit of the distribution of F. crenata on islands in the Japan Sea is observed on Okushiri Island (ca 42°N). To understand the genetic relationships of F. crenata on Okushiri Island, we examined chloroplast (cp) DNA haplotypes and 11 nuclear microsatellite (SSR) loci among 1,838 individuals from 44 populations from Okushiri Island, mainland Hokkaido, and the northern part of the Tohoku region on Honshu Island. We identified 2 cpDNA haplotypes, which represent not only populations on the Japan Sea coast but also those on the Pacific coast and this suggested the Okushiri Island populations might not be formed by single colonization. Genetic diversity of the Okushiri Island populations of nuclear SSR was not lower than the mainland and the STRUCTURE analysis revealed the Okushiri Island individuals were admixed between Hokkaido and Tohoku clusters. Approximate Bayesian computation inferred that divergence between Tohoku and Hokkaido, and admixture between two populations which generated Okushiri populations occurred before the last glacial maximum (LGM), that is, 7,890 (95% hyper probability density (HPD): 3,420 – 9,910) and 3,870 (95% HPD: 431– 8,540) generations ago, respectively. These inferences were well supported by a geological history which suggested an isolation of Okushiri Island from Hokkaido started prior to the Middle Pleistocene. We discuss the possible persistence of F. crenata during the last glacial maximum on northern islands in the Japan Sea such as Okushiri Island.</p

DataSheet_4_Possible northern persistence of Siebold’s beech, Fagus crenata, at its northernmost distribution limit on an island in Japan Sea: Okushiri Island, Hokkaido.pdf

Siebold’s beech, Fagus crenata, is widely distributed across the Japanese Archipelago and islands in Japan Sea. Similar to the northern limit of the geographical distribution of F. crenata on the mainland of Hokkaido, the northern limit of the distribution of F. crenata on islands in the Japan Sea is observed on Okushiri Island (ca 42°N). To understand the genetic relationships of F. crenata on Okushiri Island, we examined chloroplast (cp) DNA haplotypes and 11 nuclear microsatellite (SSR) loci among 1,838 individuals from 44 populations from Okushiri Island, mainland Hokkaido, and the northern part of the Tohoku region on Honshu Island. We identified 2 cpDNA haplotypes, which represent not only populations on the Japan Sea coast but also those on the Pacific coast and this suggested the Okushiri Island populations might not be formed by single colonization. Genetic diversity of the Okushiri Island populations of nuclear SSR was not lower than the mainland and the STRUCTURE analysis revealed the Okushiri Island individuals were admixed between Hokkaido and Tohoku clusters. Approximate Bayesian computation inferred that divergence between Tohoku and Hokkaido, and admixture between two populations which generated Okushiri populations occurred before the last glacial maximum (LGM), that is, 7,890 (95% hyper probability density (HPD): 3,420 – 9,910) and 3,870 (95% HPD: 431– 8,540) generations ago, respectively. These inferences were well supported by a geological history which suggested an isolation of Okushiri Island from Hokkaido started prior to the Middle Pleistocene. We discuss the possible persistence of F. crenata during the last glacial maximum on northern islands in the Japan Sea such as Okushiri Island.</p

Image_3_Possible northern persistence of Siebold’s beech, Fagus crenata, at its northernmost distribution limit on an island in Japan Sea: Okushiri Island, Hokkaido.tiff

Siebold’s beech, Fagus crenata, is widely distributed across the Japanese Archipelago and islands in Japan Sea. Similar to the northern limit of the geographical distribution of F. crenata on the mainland of Hokkaido, the northern limit of the distribution of F. crenata on islands in the Japan Sea is observed on Okushiri Island (ca 42°N). To understand the genetic relationships of F. crenata on Okushiri Island, we examined chloroplast (cp) DNA haplotypes and 11 nuclear microsatellite (SSR) loci among 1,838 individuals from 44 populations from Okushiri Island, mainland Hokkaido, and the northern part of the Tohoku region on Honshu Island. We identified 2 cpDNA haplotypes, which represent not only populations on the Japan Sea coast but also those on the Pacific coast and this suggested the Okushiri Island populations might not be formed by single colonization. Genetic diversity of the Okushiri Island populations of nuclear SSR was not lower than the mainland and the STRUCTURE analysis revealed the Okushiri Island individuals were admixed between Hokkaido and Tohoku clusters. Approximate Bayesian computation inferred that divergence between Tohoku and Hokkaido, and admixture between two populations which generated Okushiri populations occurred before the last glacial maximum (LGM), that is, 7,890 (95% hyper probability density (HPD): 3,420 – 9,910) and 3,870 (95% HPD: 431– 8,540) generations ago, respectively. These inferences were well supported by a geological history which suggested an isolation of Okushiri Island from Hokkaido started prior to the Middle Pleistocene. We discuss the possible persistence of F. crenata during the last glacial maximum on northern islands in the Japan Sea such as Okushiri Island.</p