{"created":"2021-03-01T06:13:34.760964+00:00","id":6946,"links":{},"metadata":{"_buckets":{"deposit":"d8969925-57d0-4f06-b562-73ff2869fec4"},"_deposit":{"id":"6946","owners":[],"pid":{"revision_id":0,"type":"depid","value":"6946"},"status":"published"},"_oai":{"id":"oai:nagoya.repo.nii.ac.jp:00006946","sets":["643:835:836:845"]},"author_link":["18533","18534"],"item_1615768549627":{"attribute_name":"出版タイプ","attribute_value_mlt":[{"subitem_version_resource":"http://purl.org/coar/version/c_970fb48d4fbd8a85","subitem_version_type":"VoR"}]},"item_9_alternative_title_19":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"Clonal diversity and genetic variation in Ilex leucoclada, a clone-forming dioecious shrub","subitem_alternative_title_language":"en"}]},"item_9_biblio_info_6":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2005-12","bibliographicIssueDateType":"Issued"},"bibliographicPageEnd":"84","bibliographicPageStart":"45","bibliographicVolumeNumber":"24","bibliographic_titles":[{"bibliographic_title":"名古屋大学森林科学研究","bibliographic_titleLang":"ja"}]}]},"item_9_description_4":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"In clone-forming plants, individuals can be identified on the basis of either physiological or genetic identity (as `ramets' or `genets'), respectively.  The population biology of clonal plants has been studied at both of these module levels.  Determinations of population characteristics such as population size, recruitment, mortality, levels of polymorphism and conformance to Hardy- Weinberg equilibrium are all contingent on genets being identified. Moreover, the potential for evolutionary change within a population is governed by the available genetic variation among   genets. Therefore, discrimination of genets, determination of genet numbers, visualization of the spatial patterns of genets and detection of genetic variation among genets are essential for elucidating the dynamics and evolution of clone-forming plant populations. Ilex leucoclada (Aqulifoliaceae,Ilex L.) is an evergreen dioecious shrub that is distributed in mountainous regions where there is heavy snowfall in Honshu and the southern part of Hokkaido, Japan. This species is a common shrub of the deciduous broad- leaved forests in the cool temperate zone along the Sea of Japan, which are dominated by Japanese beech, Fagus crenata. Avian Seed dispersal and insect-mediated pollination are typical of the Aquifoliaceae, including I . leucoclada. Field observations of I. leucoclada indicate that the species grows clonally by layering, forming distinct patches as well as reproducing by seeds. Therefore, the spatial (patch formation) and reproductive (dioecy) characteristics of I.  leucoclada make the species an attractive subject for studying the dynamics and evolution of clone-forming plant populations. In this study, the clonal diversity and genetic variation of I. leucocolada growing in beech forests in the Forest Reserve on Mt. Daisen in Tottori Prefecture were investigated by distinguishing genets using random amplified polymorphic DNAs (RAPDs) and microsatellite genetic markers. The implications of the findings for the mechanisms involved in the creation and maintenance of I. leucoclada populations are discussed. In the first stage of the investigation, clonal diversity within patches and genetic variation within and among patches were investigated,using 31 RAPD markers, in a 1-ha plot (50×200m) within an old-growth beech forest. Thirty-eight patches that exhibited a clumped distribution in the middle of the plot were found. A total of 166 RAPD phenotypes were identified among the 215 stems sampled from 27 patches that were completely within the plot. The population showed high clonal diversity within patches (mean number of genets relative to number of stems= 0.79 ; mean Simpson's D =0,89). Variation in RAPD phenotypes among patches was highly significant (ΦST in the molecular variance analysis = 0.316, P < 0.001), indicating genetic differentiation among patches. Pairwise genetic distances, Φst, between the patches did not correlate with the geographic distances between them. Cluster analysis based on the genetic distances detected few clear clusters of patches, indicating that there was no spatial genetic structure among them. High levels of clonal diversity both within patches and within the population may be explained by multiple founders, seedling recruitment during patch-formation, and somatic mutation. The significant genetic differentiation observed among patches have been due to separate founding events and/or kin structuring within patches. Secondly, an investigation was undertaken of fine-scale clonal structure (the number of genets per patch, the number of stems per genet, and the spatial distribution of each genet) and diversity within patches. Six patches in the 1-ha plot described above were selected for this purpose. Two of the selected patches were composed predominantly of stems with male flowers (male patches), two contained stems with predominantly female flowers (female patches), and the other two contained stems with male flowers and stems with female flowers in more or less equal proportions (mixed patches). Different genets were distinguished using 6-8 RAPD markers for each patch. One hundred and fifty-six genets with different RAPD phenotypes were identified among 1928  stem form the six patches. Among the six patches, the male patches had the lowest clonal diversity, and the mixed patches the highest. Distribution maps of the genets showed that they extended downhill, reflecting natural layering that occurred when stems were pressed to the ground by heavy snow. In every patch, there were a few large genets with many stems and many small genets with a few stems. The differences in clonal diversity among patches may be due to differences in seedling recruitment frequencies. The skewed distribution of genet size (defined as the number of stems per genet) within patches may be due to differences in the timing of germination, or age (with early-establishing genets having clear advantages for acquiring resources) and/or intraspecific competition. Microsatellite markets have been considered to be the most effective tools for studying the parentage analysis, pollen and seed dispersal, mating system, and genetic structure in plant populations. Therefore, I also developed microsatellite markers for I. leucoclada. One hundred and eighty-nine out of 432 clones were found to contain microsatellite repeats. Primer pairs were designed for 92 of these clones according to their sequence data. Thirteen of these primer pairs yielded polymorphic, single-locus polymerase chain reaction amplification products. Using these primer pairs, three individuals from each of twelve population (36 individuals in total) of I.leucoclada scattered throughout its entire distribution were genotyped and the levels of polymorphism were estimated. Three to twenty-seven alleles per locus were detected, and the expected heterozygosity ranged from 0.133 to 0.971. Since these thirteen microsatellite markers showed high degrees of genetic variation, they should be useful tools for studying population and ecological genetics of I.leucoclada. Finally, I examined the patterns of within-population genetic architecture in two plots with different types of I.leucoclada populations (one immature and one secondary) by estimating their clonal diversity, genetic variation, and deviation from Hardy-Weinberg equilibrium using the eight of the 13 microsatellite markers mentioned above. I identified 78 and 85 genets among 145 and 510 stems analyzed in the immature and secondary plots, respectively. The number of genets with multiple stems and the number of stems per genet were approximately two and three times larger in the immature plot than in the secondary plot, respectively, indicating that the clonal structure was more developed in the secondary plot than in the immature plot. The clonal diversity was significantly higher in the immature plot than in the secondary plot. However, there was no significant difference in expected heterozygosity between the plot, and significant departures from Hardy-Weinberg genotypic proportions for both plots. The correlogram of coancestry for genets in both plots exhibited significant positive values in the shortest distance class, indicating the presence of genetic structure. Moreover, the correlogram of the secondary plot exhibited significant negative values in long distance classes, indicating genetic differentiation among distant genets. The results of these studies show that there was hierarchical structure at three levels (ramets, genets, and patches) within the populations of I.leucoclada. The hierarchical structure may have been generated by the effects of clonal growth and seed dispersal at relatively small spatial scales and environmental heterogeneity at larger spatial scales. Moreover, the extent of clonal diversity within patches in I.leucoclada populations may be affected by variations in the amount of seeds dispersed by birds caused by variations in bird abundance and behavior. Altough the extent of clonal diversity decreased with development of the populations, there were seeding recruitments in the populations so that the loss of the clonal diversity may be retarded. The genetic structure may be generated by the group dispersal of full-sib seeds within fruits and promoted by frequent seed dispersal around the mother trees. Determining genets of plants such as I.leucoclada may not be easy in the field, but can be done using genetic markers. This study demonstrated that genetic markers are useful tools for distinguishing genets in clonal plant populations. Furthermore, using microsatellite markers with very high levels of polymorphism, it was found that the level of allelic variation was not necessarily consistnt with that of genotypic (genet) variation in the studied populations. The mechanisms involving in the creation and maintenance of I.leucoclada populations could be investigated and elucidated at three different levels (ramets, genets, and alleles). However, a number of aspects of the population biology of I.leucocolada remain to be elucidated. For instance, further studies of population dynamics in the plots are required to clarify aspects such as the relatives frequencies of mortality, recruitment and net changes in genet numbers during population development, and thus enhance our understanding of the mechanisms that maintain clonal diversity in the species. In addition, the degree to which pollen flow influences the genetic structure is not clear, so patterns of pollen flow need to be quantified through paternity analysis with microsatellite markers.","subitem_description_language":"en","subitem_description_type":"Abstract"},{"subitem_description":"クローン植物の個体の定義には,生理的独立性を重視した ｢ラメート｣と遺伝的に同一性を重視した｢ジェネット｣という二種類がある｡クローン植物に関する集団生物学は,このラメートとジェネットという異なるモジュールレベルで研究されてきた｡集団の大きさ,新規加入,枯死,遺伝的変異,ハーデイ･ワインバーグ平衡からの遺伝子型頻度の偏りの程度などの集団の特性は全てジェネット次第で決まってくる｡さらに,集団内の進化的変化における潜在的な可能性はジェネットの保有する遺伝的変異に支配される｡したがって,ジェネットの識別やその数の決定,ジェネットの空間分布の把握、そしてジェネットの保有する遺伝的変異の定量化は,クローン植物集団の個体群動態や小進化の素過程に関する研究にとって不可欠であると考えられる｡ヒメモチはモチノキ科モチノキ属の雌雄異株の常緑低木である。北海道南西部や本州の日本海側に分布し,積雪の多い山地のブナ林の林床に生育する。一般にモチノキ属は花粉が虫媒,種子が鳥散布であるといわれている｡ヒメモチはこのような種子による繁殖とともに伏条によるクローン成長も行い,パッチを形成していることが認められている｡したがって,このような空間特性(パッチ形成)と繁殖特性(雌雄異株、クローン成長)をもつヒメモチは,クローン植物集団の個体群動態や小進化の素過程を理解する上で興味深い研究対象の一つであると考えられる｡本研究では,鳥取県大山ブナ老齢林のヒメモチ集団を研究対象とし,RAPD とマイクロサテライトを遺伝マーカーとして用いてジェネットを識別し,クローン多様性と遺伝的変異を明らかにし,その結果をもとにヒメモチ集団の形成と維持機構を検討することを目的とした｡まず,ブナ老齢林内に設置した1haプロット(50×200m)全体のヒメモチのパッチを対象として,31個のRAPDマーカ一を用いてジェネットを識別し,パッチ内のクローン多様性,パッチ内とパッチ間の遺伝的変異を調べた｡1haプロットには,38個のパッチが存在し,それらはプロットの中央付近に集中分布していた｡1haプロット内に完全に含まれる27個のパッチの合計215幹は168個のジェネットに識別された｡各パッチでは高いクローン多様性が認められた(平均のG/N=0.79,平均のSimpsonのD=0.89).また,パッチ間のRAPD表現型の変異性は有意となり(分子分散分析のΦST=0.316),パッチ間の遺伝的分化が明らかになった｡しかし,パッチ間の遺伝的距離と地理的距離には相関が認められず,遺伝距離に基づくクラスター分析によって得られた類似度関係図もパッチの分布と明瞭な関連性が認められなかった。このことは,パッチ間に階層的な遺伝的構造がないことを示す｡調査した集団とパッチにおいて認められた高いクローン多様性は,複数の創始者やパッチ形成途上での実生の加入,体細胞突然変異によって説明されると考えられる｡また,パッチ間の有意な遺伝的分化は別々の創始イベントや血縁構造化に起因すると考えられる｡次に,パッチという限られた空間内のクローン構造(パッチを構成するジェネット数,ジェネットあたりの幹数,各ジェネットの空間分布) とクローン多様性を調べた。前述の研究の1haプロット内から,雄花をもつ幹の優占するパッチ(雄パッチ),雌花をもつ幹の優占するパッチ(雌パッチ),雄花をもつ幹と雌花をもつ幹が混在しているパッチ(雌雄混在パッチ)杏それぞれ2個ずつ選定した。ジェネットの識別には6-10個のRAPDマーカーを用いた｡6パッチの合計1928個の幹は156個のジェネットに識別された｡クローン多様性は,雄パッチで衆も低く,雌雄混在パッチで最も高い傾向が認められた.空間分布図からジェネットは斜面に沿って拡大したことが認められ,これは幹が雪の重みで接地した際に起こった伏条によるクローン成長によるものと考えられる｡どのパッチでも,多数の幹をもつ大きいジェネットが少数と少数の幹をもつジェネットが多数存在していることが認められた｡パッチ間のクローン多様性の差異は,実生の加入頻度が異なることに起因すると考えられる｡また,パッチにおけるジェネットサイズ(ジェネットあたりの幹数)の歪んだ頻度分布は,発芽のタイミングや齢(早期に定着したジェネットの資源獲得における有利性),種内競争の両方または一方によって説明されると考えられる。植物集団を対象とした親子鑑定,花粉･種子の散布,交配様式,遺伝的構造などに関する研究において,マイクロサテライトマーカーは最も有効なマーカーであると考えられている｡そこで,ヒメモチのマイクロサテライトマーカーの開発を行った｡432個のクローン中,189個にマイクロサテライト部位が認められた｡これらのDNA断片の塩基配列から92組のプライマーを設計した｡これらのプライマーを用いてPCR増幅を試みた結果,13組のプライマーで明瞭なDNA断片の増幅がみられた｡ヒメモチの分布域全体に渡る12集団から各集団3サンプルずつ合計36サンプルを用いて,開発された13個のマイクロサテライトマーカーの多型性を調べた｡その結果,マーカーあたり3から27個の対立遺伝子が検出され,へテロ接合度の期待値は各マーカーあたり0.133から0.971までの値を示した｡これら13個のマイクロサテライトマーカーはヒメモチの集団遺伝や生態遺伝を研究する有効なツールであることが示された｡次に,開発した8個のマイクロサテライトマーカーを用いて異なるヒメモチ集団(未成熟プロットと二次林プロット)の遺伝的構成(genetic architecture)パターンを,クローン多様性,遺伝的変異,ハーデイ･ワインバーグ平衡からの遺伝子型頻度の偏りの程度,遺伝的構造を調べることにより明らかにした｡未成熟プロットと二次林プロットのそれぞれ145個と510個の幹の遺伝子型を決定した結果,78個と85個のジェネットに識別された｡複数の幹から構成されるジェネットの数やジェネットあたりの幹数は,二次林プロットが未成熟プロットよりもそれぞれ約2倍と約3倍多く,二次林プロットはクローン構造の発達した集団であることが明らかになった。クローン多様性は,未成熟プロットが二次林プロットよりも有意に高かった｡しかし,遺伝的変異を表す-テロ接合体の期待値は,プロット問に有意な差が認められなかった｡両プロットでは,ハーデイ･ワインバーグ平衡から期待される遺伝子型頻度からの有意な偏りが認められた｡両プロットでは,小さな距離階級において同素係数が有意な正の値を示し,遺伝的構造の存在が示唆された｡さらに,二次林プロットでは大きな距離階級において同素係数が有意な負の値を示し,遠距離のジェネット間における遺伝的分化の存在が示唆された｡以上の研究を通して,ヒメモチの集団内にはラメート,ジェネット,パッチという3つの階層からなる構造があることが明らかとなった｡小さな空間スケールではクローン成長と種子散布そしてより大きな空間スケールでは不均一な微環境による効果が作用することによって,この階層構造が形成されていると考えられる｡また,ヒメモチ集団では,鳥類の行動パターンに依存した種子散布の程度によってパッチ内のクローン多様性の程度が変化していることが考えられる｡そして,集団の発達に伴いクローン多様性は減少する傾向が認められるが,集団内には実際に実生の加入があるため,クローン多様性の減少程度は抑えられていると考えられる｡遺伝的構造は,全兄弟にある種子が一緒に散布されることによって形成され,さらに母樹の周囲に種子散布が集中されることによって促進されるものと考えられる｡ヒメモチのように野外においてジェネットの境界が識別困難である場合にも,遺伝マーカーを用いればジェネットの識別が可能である｡本研究では他の研究と同様に遺伝マーカーがクローン植物集団のジェネットの識別に有効なツールであることが示された｡さらに,多型性の極めて高いマイクロサテライトマーカーを用いることによって,調査したヒメモチ集団ではジェネットレベルと対立遺伝子レベルの変異は必ずしも同じ傾向を示さないことがわかった｡そして,ヒメモチ集団の形成と維持機構をラメート,ジェネット,対立遺伝子レベルという異なるレベルで捉えることができた。しかし,時間経過に伴うジェネットの増加がどれぐらいの枯死と加入の程度によって決まっているのかは明らかでなく,今後,設置されたプロットで個体群動態を追跡することによってクローン多様性の維持機構についてより理解が深められると考えられる｡また,花粉流動が遺伝的構造に及ぼす程度については明らかでなく,今後,開発されたマイクロサテライトマーカーを用いて父性解析を行うことで花粉流動パターンを定量的に把握することができると考えられる。","subitem_description_language":"ja","subitem_description_type":"Abstract"}]},"item_9_description_5":{"attribute_name":"内容記述","attribute_value_mlt":[{"subitem_description":"農林水産研究情報センターで作成したPDFファイルを使用している。","subitem_description_language":"ja","subitem_description_type":"Other"}]},"item_9_identifier_60":{"attribute_name":"URI","attribute_value_mlt":[{"subitem_identifier_type":"HDL","subitem_identifier_uri":"http://hdl.handle.net/2237/8623"}]},"item_9_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.18999/nagufs.24.45","subitem_identifier_reg_type":"JaLC"}]},"item_9_publisher_32":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"名古屋大学農学部付属演習林","subitem_publisher_language":"ja"}]},"item_9_select_15":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_select_item":"publisher"}]},"item_9_source_id_7":{"attribute_name":"ISSN（print）","attribute_value_mlt":[{"subitem_source_identifier":"1344-2457","subitem_source_identifier_type":"PISSN"}]},"item_9_text_14":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_text_value":"application/pdf"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"open access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_abf2"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"鳥丸, 猛","creatorNameLang":"ja"}],"nameIdentifiers":[{"nameIdentifier":"18533","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"TORIMARU, Takeshi","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"18534","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2018-02-19"}],"displaytype":"detail","filename":"nagufs_24_45.pdf","filesize":[{"value":"4.6 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"nagufs_24_45.pdf","objectType":"fulltext","url":"https://nagoya.repo.nii.ac.jp/record/6946/files/nagufs_24_45.pdf"},"version_id":"88bdeb62-4d9b-40b3-bef1-260361331a04"}]},"item_keyword":{"attribute_name":"キーワード","attribute_value_mlt":[{"subitem_subject":"ramet","subitem_subject_scheme":"Other"},{"subitem_subject":"genet","subitem_subject_scheme":"Other"},{"subitem_subject":"genetic marker","subitem_subject_scheme":"Other"},{"subitem_subject":"clonal structure","subitem_subject_scheme":"Other"},{"subitem_subject":"clonal diversity","subitem_subject_scheme":"Other"},{"subitem_subject":"genetic variation","subitem_subject_scheme":"Other"},{"subitem_subject":"ラメート","subitem_subject_scheme":"Other"},{"subitem_subject":"ジェネット","subitem_subject_scheme":"Other"},{"subitem_subject":"遺伝マーカー","subitem_subject_scheme":"Other"},{"subitem_subject":"クローン構造","subitem_subject_scheme":"Other"},{"subitem_subject":"クローン多様性","subitem_subject_scheme":"Other"},{"subitem_subject":"遺伝的変異","subitem_subject_scheme":"Other"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_title":"クローンを形成する雌雄異株低木ヒメモチにおけるクローン多様性と遺伝的変異","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"クローンを形成する雌雄異株低木ヒメモチにおけるクローン多様性と遺伝的変異","subitem_title_language":"ja"}]},"item_type_id":"9","owner":"1","path":["845"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2007-08-03"},"publish_date":"2007-08-03","publish_status":"0","recid":"6946","relation_version_is_last":true,"title":["クローンを形成する雌雄異株低木ヒメモチにおけるクローン多様性と遺伝的変異"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-01-16T04:17:29.896722+00:00"}