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本文系统地综述了不同遗传标记在杨属植物遗传进化、分类系统、基因流、杂种鉴定及遗传多样性等方面的研究进展。同工酶的研究主要用于杨属植物遗传变异及无性系的特征和分化等方面的研究,DNA分子标记的研究很多,根据研究的目的选择RFLP、RAPD、AFLP、SSR(SSLP)和SNP等不同的方法进行分析,综合国内外的研究现状提出今后工作的展望。 相似文献
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生物多样性的研究和保护是当今世界普遍关注的问题,遗传多样性是生物多样性的重要组成部分。在被子植物中木兰科植物受到严重威胁的种类最多,且部分是中国濒危稀有植物,研究其遗传多样性具有重要意义。文章综述了木兰科重要属、种的遗传多样性研究进展,并根据国内的研究现状,对今后木兰科植物的保护工作提出建议。 相似文献
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表型性状遗传多样性是植物遗传多样性的重要组成部分,研究植物表型性状遗传多样性对于开展植物遗传资源的保护与利用具有重要意义.本文对红山茶组12个物种的6个质量性状、5个数量性状以及茶果3个品质性状进行分析,结果显示各质量性状重要程度是果实质量性状>叶片质量性状;各数量性状变异程度较大,具有较高的遗传多样性,多样性指数1.43~1.91,其中3个果实经济性状(仁含油率、油酸含量、亚油酸含量)的多样性值占数量性状多样性总值的37.12%.聚类分析结果表明物种聚类与原种地理分布存在关联. 相似文献
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应用SSR标记技术,对新疆齐斯河流域河谷分布的白杨派树种银白杨、银灰杨和欧洲山杨天然居群的克隆结构、克隆多样性和遗传多样性进行研究。结果表明:欧洲山杨、银白杨和银灰杨均有很强的克隆繁殖特性。欧洲山杨、银白杨居群的克隆多样性均比较高,Simpson指数分别为0.987和0.983。与欧洲山杨相比较,银白杨居群具有较低的遗传多样性,Shannon信息指数分别为1.068 9和0.324 9,Nei多样性指数平均为0.505 6和0.211 2。欧洲山杨和银白杨居群间的遗传一致度均较高,变幅分别为0.778 1 0.954 4和0.975 1 0.994 6,反映出其超长距离的基因流特性,超强的基因流阻止了银白杨和欧洲山杨居群的遗传分化。研究发现,银白杨和欧洲山杨分别有95%和89.98%的遗传变异存在于居群内。 相似文献
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利用SSR分子标记技术,对采自新疆额尔齐斯河流域阿尔泰市哈巴河及北屯地区的白杨派3个树种银白杨、银灰杨、欧洲山杨的半同胞家系子代进行遗传多样性分析.结果表明:筛选12对SSR引物在90个样本中共检测到58个等位基因(A)、112种基因型,多态位点百分率是100%,Nei遗传多样性指数(h)平均为0.648 5,Shannon多样性指数平均为1.234.基因分化系数(Fst)为0.337 l,即在总的遗传变异中有33.71%的变异来自于不同树种之间,绝大部分存在于子代个体间.白杨派内种间分化程度较高,种间遗传距离为0.3863~1.869;银灰杨的遗传变异最大,而银白杨的遗传变异最小. 相似文献
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Han Y.H. Chen Stan Vasiliauskas Gordon J. Kayahara Triin Ilisson 《Forest Ecology and Management》2009
Postfire tree species compositions are predicted to be the same prior to fire according to the direct regeneration hypothesis (DRH). We studied 94 upland boreal forest stands between 5 and 18 years after fire in Ontario, Canada. Postfire species-specific regeneration density was positively related to prefire stand basal area for Pinus banksiana, Populus spp., Betula papyrifera and Picea mariana, but not for Picea glauca and Abies balsamea. In addition, seedling density of Populus spp., B. papyrifera, P. mariana, P. glauca and A. balsamea were positively affected by build up index and, except Populus spp., their density increased with age of burn. To facilitate testing the DRH, we introduced a term called compositional difference (CD) that is the difference in a species relative percentage between the postfire and prefire stand. The testable null hypothesis is CD = 0 for a given species. CD was not different from 0 for P. banksiana, was 19.8% for Populus spp., 10.4% for B. papyrifera, −17.9% for P. mariana, −14.6% for P. glauca, and −14.9% for A. balsamea, indicating fire increases broadleaves at the expenses of mid- and late-successional coniferous species. Compositional increases of Populus spp. and B. papyrifera in postfire stands occurred mostly where these species were a minor component prior to fire. In conclusion, the DRH was supported by the specific positive relationships between postfire regeneration densities and prefire basal area for P. banksiana, Populus spp., B. papyrifera and P. mariana. However, if the DRH is used for predicting postfire composition, P. banksiana is the only species that had the same composition between postfire and prefire stands. Nevertheless, CD for P. banksiana was negatively related to its prefire composition. Similarly, CD for other species was negatively related to their prefire compositions with varying effects of build up index and age of burn. Our results suggest, if fire occurrences increase with global change, the boreal landscape will be more dominated by hardwoods and mixtures of conifers and hardwoods. 相似文献
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Plant invasions of natural communities are commonly associated with reduced species diversity and altered ecosystem structure and function. This study investigated the effects of invasion and management of the woody shrub Lantana camara (lantana) in wet sclerophyll forest on the south-east coast of Australia. The effects of L. camara invasion and management on resident vegetation diversity and recruitment were determined as well as if invader management initiated community recovery. Vascular plant species richness, abundance and composition were surveyed and compared across L. camara invaded, non-invaded and managed sites following L. camara removal during a previous control event by land managers. Native tree juvenile and adult densities were compared between sites to investigate the potential effects of L. camara on species recruitment. Invasion of L. camara led to a reduction in species richness and compositions that diverged from non-invaded vegetation. Species richness was lower for fern, herb, tree and vine species, highlighting the pervasive threat of L. camara. For many common tree species, juvenile densities were lower within invaded sites than non-invaded sites, yet adult densities were similar across all invasion categories. This indicates that reduced species diversity is driven in part by recruitment limitation mechanisms, which may include allelopathy and resource competition, rather than displacement of adult vegetation. Management of L. camara initiated community recovery by increasing species richness, abundance and recruitment. While community composition following L. camara management diverged from non-invaded vegetation, vigorous tree and shrub recruitment signals that long-term community reinstatement will occur. However, secondary weed invasion occurred following L. camara control. Follow-up weed control may be necessary to prevent secondary plant invasion following invader management and facilitate long-term community recovery. 相似文献
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以云南省境内金沙江、元江、红河和怒江流域自然分布的构树为试材,采用AFLP分子标记技术对90份构树种质资源进行了遗传多样性分析研究.结果表明:筛选出的7对引物组合共扩增获得786条清晰可辩的条带,其中,多态性带632条,多态性条带百分率达80.4%,平均每对引物组合检测出90.3个多态位点.分布于4条水系流域的构树居群间,金沙江流域构树居群的遗传多样性水平最高,Nei's基因多样性指数为0.145 5,而元江流域构树居群的遗传多样性水平最低,Nei's基因多样性指数为0.1129.4个构树居群间的遗传分化系数为0.038 6,表明构树的遗传变异主要存在于居群内不同个体之间.在遗传距离为0.003时,4个构树居群可分为2组,第1组由金沙江流域的构树居群构成,第2组包含分布于红河、怒江和元江流域的3个构树居群. 相似文献
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The impact of selective logging on genetic diversity of two tropical tree species with contrasting breeding systems was examined using direct comparison and simulation methods. Shorea leprosula is a diploid and predominantly outcrossed species, whereas Shorea ovalis ssp. sericea is an autotetraploid species with apomictic mode of reproduction. Direct comparison of adjacent natural and logged-over stands showed reduction of genetic diversity of S. leprosula, but not of S. ovalis ssp. sericea. These results clearly demonstrated that a single logging event would cause the genetic erosion of S. leprosula. However, the apomictic mechanisms and the effects of tetrasomic inheritance of S. ovalis ssp. sericea might be a way of maintaining the level of genetic diversity. These results clearly implied that outcrossing species might be more susceptible to the negative impact of logging on genetic diversity than apomictic species. Simulation studies were conducted using three approaches: (1) simulated-removal of individuals based on diameter size classes; (2) simulated-removal of individuals at random; and (3) simulated-removal of individuals in clump. The simulation study based on the first approach showed that the loss of genetic diversity was higher for the Malayan Uniform System (MUS) compared with the Selective Management System (SMS). This might suggest that SMS is more orientated towards the conservation of genetic diversity. In addition, the simulation study showed that to conserve 100% of the total number of alleles, the tolerable cutting limits of S. leprosula in the 50-ha plot of Pasoh FR should be >85 cm diameter at breast height (dbh). Comparison of simulation studies based on the second and third approaches showed that the loss of genetic diversity was more rigorous if logging activities were anticipated through extraction of trees in clump rather than to extract trees at random. Implications of the studies for conserving and managing the tropical forests are discussed. 相似文献
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This study was designed to answer questions about the patterns of understory diversity in managed forests of southern New England, and the factors that appear associated with those patterns. At the landscape-level, we used plot data to answer questions regarding the spatial distribution of forest understory plant species. Data from a combination of fixed area (understory vegetation) and variable radius (overstory trees) plot methods are combined with site variables for the analysis. Univariate and multivariate statistical methods are used to test for understory diversity relationships with overstory cover types and topography separately, and in combination. Analyses also test for relationships between specific understory species and cover types. In general the understory flora is dominated by four common clonal species that occur across the range of forest cover types: wild sarsaparilla (Aralia nudicaulis L.), Canada mayflower (Maianthemum candense Desf.), star flower (Trientalis borealis Raf.), and partridgeberry (Mitchella repens L.). Results also show that over story composition and structure can be used to assess understory species richness. Species richness follows a general trend among cover types of: hardwood ≥ regenerating forest, hardwood–pine, and pine ≥ mixed ≥ hardwood–hemlock > hemlock. Eastern hemlock (Tsuga canadensis L. Carriere) and mountain laurel (Kalmia latifolia L.) (which decreased in dominance from ridge to valley) both showed negative trends with understory species richness. Topographic position also appears associated with understory floristic patterns (particularly for the hardwood cover type), both in terms of species richness and compositional diversity which both increased from ridge, to midslope, to valley. However, overstory composition (covertype) appears to have a higher order influence on vegetation and mediates the role of topography. The results from this study provide foresters with a better understanding for maintaining floristic diversity and composition of the understory in managed forests. 相似文献
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中国是槭树种质资源丰富且分布集中的国家。为了更科学地开发和利用兼具观赏、药用、经济等多种珍贵价值的槭树种质资源,文中综述了国内分子生物学研究前期对槭树DNA和RNA提取的方法,以及RAPD、AFLP、ISSR、ITS和SRAP等分子标记技术在槭树植物研究中的应用,主要包括种质资源鉴定、种群遗传结构与遗传多样性、濒危植物保护、物种谱系地理分析等方面的研究;针对槭树类植物的分子生物学研究中存在的问题,提出了今后研究的重点和发展方向,以期为槭树植物的种质资源开发和深入研究提供参考。 相似文献
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João P.F. Carvalho 《Forest Ecology and Management》2011,262(10):1928-1937
Stand composition and structure of natural mixed-oak stands of common-oak (Quercus robur L.) and pyrenean-oak (Quercus pyrenaica Willd.) were studied. Diverse compositional and structural elements in early and late successional stand stages were analysed. The study was conducted in north and central Portugal where different natural mixed oak forests types are located. The following mixed-oak forest types involving common-oak and pyrenean-oak were studied: common-oak & other hardwoods; common-oak & cork-oak (Quercus suber L.); ash (Fraxinus angustifolia Vahl) & pyrenean-oak; and pyrenean-oak & madrone (Arbutus unedo L.). Measurements were made in early and late successional stand stages on the different mixed oak forest types. Different stand characteristics and indices were used to describe and compare stand structure and composition. The study showed changes in species diversity and stand structure. Most tree species in mature stands are present in early stages but with higher abundance. Shannon diversity index may change between 0.798 and 1.915. Significant differences on species diversity and abundance were found depending on the forest type and successional stage. Mature mixed-oak forests have high species diversity with an abundance of small to medium tree size species. Species distribution and diameter differentiation indices range from 0.30 to 0.70 and 0.52 to 0.82, respectively, revealing significant structural complexity. The average number of standing and downed dead trees was 265 and 83 trees ha−1 for early and late stage, respectively, with 6.9 and 65.4 m3 ha−1. Higher values of stand diversity index were 41 and 53 in more complex and developed forests. Later stand stages have complex structure, with a wider range of tree diameter distribution and higher degree of irregularity. 相似文献