研究者データベース
| 倉田 正観(クラタ セイカン) |
| 北方生物圏フィールド科学センター 森林圏ステーション 苫小牧研究林 |
| 助教 |
Last Updated :2024/05/09
基本情報
所属
職名
学位
科研費研究者番号
- 40899324
J-Global ID
研究キーワード
研究分野
職歴
- 2023年04月 - 現在 北海道大学 北方生物圏フィールド科学センター 森林圏ステーション 助教
- 2022年04月 - 2023年03月 秋田県立大学 生物資源科学部 助教
- 2020年04月 - 2022年03月 日本大学文理学部 非常勤講師
- 2020年04月 - 2022年03月 東京大学 大学院総合文化研究科 特任研究員
- 2015年04月 - 2017年03月 福岡市役所水道局
学歴
研究活動情報
論文
- Seikan Kurata, Shota Sakaguchi, Shun K. Hirota, Osamu Kurashima, Yoshihisa Suyama, Motomi ItoEcological Research 2024年03月07日Abstract Plant species with overlapping distributions are expected to experience the same historical events. In contrast, species with different preferred habitat types may exhibit incongruent phylogeographic patterns because of their habitat‐dependent demographic changes in spite of their overlapping distributions. On the western side of the Japanese Archipelago, boreal forest and non‐forest vegetation were dominant during the last glacial period; subsequently, temperate forests expanded, and open vegetation (e.g., grasslands) decreased. Such vegetation shifts can result in incongruent phylogeographic patterns among temperate forest and grassland species; however, few phylogeographic studies have investigated this hypothesis. Here, we evaluated the phylogeographic structure of two related Geranium species that occur in grassland (Geranium krameri) and temperate forest (Geranium shikokianum) habitats using chloroplast genome sequencing and nuclear genome‐wide single‐nucleotide polymorphisms genotyping. The phylogeographic structure was stronger for the temperate forest species than the grassland species, despite its currently scattered distribution for grassland species. The observed patterns indicate that the phylogeographic histories of these species were influenced by their habitat configurations since the last glacial period. During the ice age, grasslands in Japan were much more widespread than today; this would have enabled the grassland species to form a continuous distribution, leading to low divergence among regional populations. In contrast, the significant genetic divergence within the forest species can be attributed to the glacial isolation of regional populations. Our genetic results suggest that vegetation transitions have variously controlled the population dynamics of two species with overlapping distributions.
- Seikan Kurata, Shota Sakaguchi, Osamu Kurashima, Risa Ogawa, Yoshihisa Suyama, Sachiko Nishida, Motomi ItoBiological Journal of the Linnean Society 2024年01月02日Abstract Recent phylogeographical studies have revealed that refugia sometimes retain high levels of genetic heterogeneity due to multiple colonization events, a phenomenon defined as ‘refugia within refugium’. In previous research, we reported a complex genetic structure within the Geranium yesoense complex, an alpine plant found in an interglacial refugium at high elevation in Central Japan, probably resulting from multiple colonization and hybridization events. However, we were unable to evaluate instances of introgression due to limited sample size. In the present study, we performed additional chloroplast genome sequencing, along with Sanger sequencing of selected chloroplast DNA regions, to elucidate the phylogenetic relationships among the refugial populations. The chloroplast genome sequence of a sample from Mt. Asama (an important refugium) was nested within the northern lineage (i.e. var. yesoense and var. pseudopratense), and haplotypes from Mt. Asama and Mt. Ibuki were also grouped with those of the northern lineage. Although our previous study suggested hybridization events between northern and southern lineages (i.e. var. nipponicum) at Mt. Asama, haplotypes from the southern lineage were not detected at range margins. This suggests that directional introgression occurred in these regions. Overall, our results further support that genetic heterogeneity within these refugia was amplified by recolonization and hybridization during past climate oscillations.
- Naoyuki Nakahama, Seikan Kurata, Atushi UshimaruPlant Species Biology 2023年05月31日
- Seikan Kurata, Shota Sakaguchi, Hajime Ikeda, Shun K. Hirota, Osamu Kurashima, Yoshihisa Suyama, Motomi ItoPlant Systematics and Evolution 308 4 2022年08月 [査読有り]
- Seikan Kurata, Diego Tavares Vasques, Shota Sakaguchi, Shun K. Hirota, Osamu Kurashima, Yoshihisa Suyama, Sachiko Nishida, Motomi ItoPLANT SYSTEMATICS AND EVOLUTION 307 6 2021年12月 [査読有り]
Eleven native Geranium species have been reported in Japan, several of which include infraspecific taxa. Although phylogenetic analyses have been conducted using conventional methods (i.e., chloroplast fragment and ribosomal DNA sequencing), relationships at the infraspecific level have not been elucidated due to a lack of genetic polymorphisms. We collected specimens of 22 Geranium taxa from Japan and peripheral areas (e.g., mainland China, South Korea, Russia, and Taiwan), and performed detailed phylogenetic analyses using chloroplast genome sequencing and genome-wide single-nucleotide polymorphisms. Some discrepancies were observed between the current taxonomy and the phylogenetic relationships elucidated in our analyses. The Geranium tripartitum complex was found to be paraphyletic, and Geranium onoei f. yezoense, which is synonym of Geranium reinii, was found to be more closely related to Geranium erianthum than to G. reinii. In particular, G. tripartitum var. hastatum located at intermediate position between Geranium thunbergii and Geranium wilfordii in the network analysis. Therefore, we suggest that G. tripartitum var. hastatum should be treated as an independent species, and that G. onoei f. yezoense should be transferred to G. erianthum. - Seikan Kurata, Naoko Ishikawa, Diego Vasques, Masayuki Saito, Osamu Kurashima, Motomi ItoBiodiversity Data Journal 9 2021年09月27日 [査読有り]
Recent studies revealed that green spaces in urban areas are critical for conservation of native biodiversity and that assessment of the present flora of green spaces in urban areas is critical for protection of the native biodiversity. The Komaba Campus of the University of Tokyo embraces a relevant green area, located in a highly urbanised area in Tokyo Metropolis (35.66 N 139.68 E, Japan). The total area of this Campus is 25.4 ha, from which, 4.5 ha are covered by vegetation. Although intense urbanisation can be observed around the Campus, new insect species had been reported for the Campus area, suggesting that the biodiversity on the Campus still demands some attention. Differently from fauna surveys, no flora survey has been done for more than 30 years on the Campus. In this study, we have extensively surveyed the plants diversity on the Komaba Campus of the University of Tokyo, aiming for an update of the plants list on this green urban area in Tokyo. The survey covered all herbaceous and arboreous plants growing wild on the Campus. Garden plants were excluded in this survey because these plants were supposed to be cultivated. The final dataset contained, in total, 324 taxa, from which 234 were herbaceous plants and 90 were arboreous plants. The top three taxa are as follows: Poaceae (38 taxa), Asteraceae (34 taxa) and Rosaceae (14 taxa), respectively. This is the first update to the Flora of the Komaba Campus of the University of Tokyo in 30 years and represent an important contribution to conservation of native species in the Tokyo metropolis. - Seikan Kurata, Shota Sakaguchi, Hitomi Mishima, Takashi Tsuchimatsu, Motomi ItoGENES & GENETIC SYSTEMS 96 2 99 - 104 2021年04月 [査読有り]
Nuclear microsatellite markers were developed for Geranium thunbergii, an herbaceous plant characterized by petal color polymorphism. Utilizing RNA sequencing data obtained by next-generation sequencing techniques, we developed and characterized 19 polymorphic microsatellite markers with two to 12 alleles in the nuclear genome. These markers will be used to reveal the genetic structure and demographic history of G. thunbergii in the Japanese archipelago, which will elucidate the genetic background of flower color polymorphism among populations. - Seikan Kurata, Shota Sakaguchi, Shun K. Hirota, Osamu Kurashima, Yoshihisa Suyama, Sachiko Nishida, Motomi ItoBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY 132 3 552 - 572 2021年03月 [査読有り]
Recent studies have found that geographical fragmentation and recurrent colonization result in complex genetic structures in refugial areas. This phenomenon, known as 'refugia within refugium', has been identified from many geographical locations. In Japan, the high-elevation mountains of central Honshu provided an interglacial refugium for alpine plants. Here we focused on the Geranium yesoense complex, which exhibits increased morphological variation in the refugial area, to determine whether this variation was shaped by recurrent colonization, range fragmentation or phenotypic changes independent of population history. We analysed single nucleotide polymorphism data and chloroplast genome sequences. Diversification in the G. yesoense species complex occurred in the midPleistocene. The varieties are distinct entities and suggest the presence of a genetic cluster with highly disjunct distributions, occurring both in northern Japan and in southern refugial areas in central Honshu. Demographic analysis suggests that a single ancestral variety (var. nipponicum) evolved in the alpine region of central Honshu, and that subsequent migration from one of the two diverged northern varieties (var.pseudopratense)led to secondary contact with var. nipponicum during the last glacial period. Recolonization into refugial populations in central Honshu and hybridization between diverged populations have resulted in complex genetic structures among refugial populations. - Seikan Kurata, Shota Sakaguchi, Motomi ItoCONSERVATION GENETICS 20 3 431 - 445 2019年06月 [査読有り]
Geranium soboliferum var. kiusianum and var. hakusanense (Geraniaceae) are believed to be relict plants that migrated southward from the Eurasian continent to the Japanese archipelago during the last glacial period. G. soboliferum var. kiusianum individuals and populations, which occur in wetlands in the Aso-Kuju region of Kyushu Island, are declining as a result of the deteriorating quality of the microhabitat, a process that is associated with the decrease in semi-natural grasslands. Using 10 polymorphic microsatellite markers, we evaluated the genetic diversity and population structure of the G. soboliferum complex, with the aim of understanding the species' genetic characteristics to facilitate efficient conservation. Genetic demographic analysis suggested that Japanese G. soboliferum populations branched off from the Eurasian continental G. soboliferum var. soboliferum during the last glacial period and that, thereafter, the Japanese populations of the plant diverged into two lineages at the beginning of the Holocene epoch. The genetic diversity of G. soboliferum var. kiusianum was significantly lower than that of var. hakusanense, which is more widely distributed in central Honshu Island (mean Ar=3.288 vs. 3.830 and H-e = 0.366 vs. 0.546). Genetic differentiation among populations was significantly higher (mean F-ST = 0.368 vs. 0.184) in var. kiusianum populations and, notably, exhibited non-significant patterns of isolation by distance, indicating that the populations underwent strong genetic drift independent of adjacent populations. Our findings suggested that the population's isolation, and its associated habitat specialization and limited inter-population gene flow, would have accelerated genetic differentiation in var. kiusianum. Overall, G. soboliferum var. kiusianum, which is genetically unique to wetland habitats in the Aso-Kuju region, merits conservation, and appropriate human intervention and management are critical to maintaining its remaining habitats in semi-natural grasslands. - Seikan Kurata, Shota Sakaguchi, Motomi ItoPLANT SPECIES BIOLOGY 32 4 466 - 470 2017年10月 [査読有り]
Nuclear microsatellite markers were developed for the threatened plant Geranium soboliferum var. kiusianum, which has decreased its population size as a result of loss of its wetland habitat in Kyushu, Japan. Utilizing RNA-seq data obtained by next-generation sequencing techniques, 10 polymorphic microsatellite markers with 3-16 alleles in a nuclear genome were developed and characterized. Two to 15 alleles were observed in G. soboliferum. These markers will be used to investigate the genetic circumstance of remnant populations of G. soboliferum var. kiusianum and their phylogenetic relationship with G. soboliferum. - Shota Sakaguchi, Guillaume Lannuzel, Bruno Fogliani, Adrien S. Wulff, Laurent L'Huillier, Seikan Kurata, Saneyoshi Ueno, Yuji Isagi, Yoshihiko Tsumura, Motomi ItoAPPLICATIONS IN PLANT SCIENCES 3 8 2015年08月 [査読有り]
Premise of the study: Microsatellite markers were developed for Callitris sulcata (Cupressaceae), an endangered conifer species in New Caledonia.Methods and Results: Using sequencing by synthesis (SBS) of an RNA-Seq library, 15 polymorphic nuclear and chloroplast microsatellite markers were developed. When evaluated with 48 individuals, these markers showed genetic variations ranging from two to 15 alleles and expected heterozygosity ranging from 0 to 0.881.Conclusions: These markers will be useful for examining the genetic diversity and structure of remaining wild populations and improving the genetic status of ex situ populations.
共同研究・競争的資金等の研究課題
- 日本学術振興会：科学研究費助成事業研究期間 : 2021年10月 -2025年03月代表者 : 上原 浩一, 梅木 清, 加藤 顕, タヴァレス・ヴァスケス ジエーゴ, 倉田 正観本研究は、国家や大陸を超えて蔓延し、生物多様性に深刻な悪影響を及ぼす侵略的外来種の侵略のメカニズムを解明する国際共同研究である。対象とするのは日本と近隣のアジア地域に自生し、19世紀以降欧米に人為的に導入され悪質な侵略的外来種として問題になっているイタドリ(Fallopiajaponica, 英名 Japanese knotweed)、オオイタドリ(Fallopia sachalinensis,英名 Giant knotweed)である。これら原産地では他の植物に埋もれた、めだたない植物が、新たな地域に導入後、どのようにして強い侵略性を 獲得し分布を拡大したか、イタドリをモデルとして侵略的外来種の侵 略的性質の形成メカニズムを解明し、今後の侵略的外来種抑制のため の基盤情報を得ることを目的としている。そのためイタドリの原産国である日本と、侵入 地域である英国・米国の研究者が共同で日本の自生地域と欧米の侵入地域の詳細な調査を 行い、それらの植物体と周囲の生物相や環境を比較解析することで侵略的外来植物の侵略 的性質獲得の法則性を見いだし、その抑制法を検討することで地球規模の生物多様性の保全に貢献したい。 本年度は英国およびアメリカの海外研究協力者と連携し海外調査のため、新型コロナ感染症の蔓延状況などの情報も含め調査計画を立てた。また英国の侵略的イタドリ・オオイタドリについて、DNAサンプル採集用の歯を送ってもらい、これまで日本各地とお逢い街で得られたイタドリと合わせ予備的解析を行なった。