青藏高原垂穗披碱草遗传变异的地理因素分析

采用等位酶标记对我国青藏高原地区垂穗披碱草的9个种群进行遗传变异和系统关系分析.结果表明,不同种群间遗传距离范围在0.010 6-0.377 8,种群间遗传距离和地理环境关系密切.采用聚类分析和二维、三维Mantel检验,对青藏高原垂穗披碱草(Elymusnutans Griseb.)不同种群间遗传距离与环境条件的关系(纬度、经度和海拔)进一步分析发现,海拔和地理位置(纬度和经度)均明显影响垂穗披碱草种群遗传差异.种群间遗传距离和海拔(R=0.476 8)、地理位置(R=0.447 1)均呈现显著正相关,种群间遗传距离随着海拔、地理位置差距的增大而增加,但海拔是影响其遗传结构的最重要因素,其次是经纬度.     

同域分布垂穗披碱草和达乌力披碱草遗传多样性和遗传结构分析

披碱草属(Elymus L.)是禾本科(Poaceae)小麦族(Triticeae)中的一个多年生属,该属在青藏高原地区有广泛分布,多数物种是草原和草甸的组成成分,许多种类为品质优良的牧草。垂穗披碱草(E.nutans)和达乌力披碱草(E.dahuricus)同为禾本科小麦族披碱草属异源六倍体物种,染色体组组成皆为StYH。为探究垂穗披碱草遗传多样性形成的内在机制,该研究利用微卫星(SSR)分子标记,对采自青藏高原地区同域分布的垂穗披碱草和达乌力披碱草两个居群共58个个体进行遗传多样性和遗传结构分析。结果表明:8对引物在垂穗披碱草和达乌力披碱草扩增条带分别为163条和124条,多态性位点百分率(PPB)分别为89.71%和76.07%,多态性信息含量(PIC)分别介于0.583~0.929和0.524~0.830之间。垂穗披碱草遗传多样性(H_e=0.69,I=1.34,P_p=100%)高于达乌力披碱草(H_e=0.53,I=0.80,P_p=93.75%);同域分布的垂穗披碱草和达乌力披碱草居群,垂穗披碱草呈现出更高的遗传多样性。AMOVA分子变异显示,两个物种居群内遗传变异分别80.92%和63.62%,但居群间遗传分化水平较低。遗传结构分析揭示两个物种间有基因流存在。综合分析结果认为,该地区种间杂交基因渗透引起的种内遗传分化,在这两个物种多样性形成中可能起着重要作用。     

青藏高原东部矮生嵩草遗传多样性的RAPD研究

基于随机扩增多态DNA（RAPD）方法分析了青藏高原东部矮生嵩草（Kobresia humilis）8个居群的遗传多样性及分化程度。14条随机引物共扩增出194个位点数,其中多态性片段168个。研究表明,矮生嵩草无论是在物种水平（多态条带比率PPB（％）为86．60％,Nei’s基因多样性（h）为0．2622,Shannon’s信息指数（I）为0．3983）,还是在居群水平（PPB=62．65％,h=0．2126．I=0．3185）,都具有较高的遗传多样性,居群的遗传多样性大小与生境有相关性。而且,用SPSS分析得出,8个居群的遗传多样性大小与海拔没有明显相关性。用AMOVA数据表明矮生嵩草的遗传变异主要分布在居群内（83．04％）,居群间变异较小（16．96％）。遗传分化指数Gst也显示了相似的结果（0．1891）。从矮生嵩草8个居群的遗传距离和聚类分析发现,以及用NTSYS对矮生嵩草8个居群的的遗传距离矩阵与地理距离矩阵间的关系进行Mantel检测,其结果表明各居群间的遗传距离与地理距离之间没有明显相关性（r=0．37779,P=0．9718〉0．05）。     

川西北高原不同海拔高度披碱草与垂穗披碱草核型分析

目的：为研究不同海拔居群染色体核型变异及进化程度,为披碱草的分类及进化研究提供细胞学资料。方法：以川西北高原6个海拔梯度的披碱草居群和5个海拔梯度的垂穗披碱草居群为材料,采用滴片法制片对染色体进行核型分析。结果：披碱草居群D3057（海拔3 057 m）、D2682（海拔2 682 m）的核型公式为2n=6x=42=42m,为1B型;D2384（海拔2 384 m）核型公式为2n=6x=42=42m(4sat),为1A型;D2143（海拔2 143 m）、D1747（海拔1 747 m）的核型公式为2n=6x=42=40m+2sm,为1B型;D1589（海拔1 589 m）的核型公式为2n=6x=42=36m+6sm,为2B型。垂穗披碱草Y2126（海拔4 050 m）、Y2117（海拔3 800 m）、Y2291a(4 150 m)居群的核型公式为2n=6x=42m,ZY3034（海拔3 200 m）的居群核型公式为2n=6x=40m+2M,Y2122（海拔4 800 m）核型公式为2n=6x=40m+2sm,5个居群的核型类型均为1B型。基于核型对称性与进化指数,披碱草居群D158...     

珍稀濒危植物硬叶兜兰的遗传多样性及遗传结构研究

由于人为采集、走私贩卖以及生境的破坏,分布于中国西南石灰岩地区的野生硬叶兜兰居群受到严重的干扰与威胁。为有效地保护这种珍稀野生植物,本研究采用ISSR和SRAP两种分子标记对15个硬叶兜兰野生居群进行遗传多样性及遗传结构的研究。结果表明,硬叶兜兰在物种水平上具有较高的遗传多样性（ISSR：PPB=91．66％,He=0．3839;SRAP：PPB=99．29％,Hc=0．2806）。硬叶兜兰居群间存在一定程度的遗传分化（ISSR：Gs1： 0．2577;SRAP：Gst=0．2383）,可能由于较低的基因流（ISSR：Nm=0．7201;SRAP：Nm=0．7991）所致。UPGMA聚类分析以及主成分分析均把15个居群分成2个主要分支。居群间的地理距离和海拔差距是引起居群遗传分化的自然因素。     

披碱草属野生居群表型多样性及其与环境关系研究

以来自8省区38个披碱草属野生居群的22个表型性状为调查对象,利用变异系数及多样性指数法对性状内和性状间及种间的表型变异进行分析,并对表型性状与地理气象因子间的关系进行相关性分析,用平均聚类法对38个居群进行分类,以揭示不同来源披碱草属种质资源表型多样性。结果显示:(1)营养器官性状中旗叶至穗基部长变异系数最高(44.695%),穗部性状中的每穗小穗数变异系数最高(77.005%)。(2)披碱草、麦宾草、圆柱披碱草与老芒麦这4个种间总体平均多样性指数为0.920～1.560,披碱草最高,麦宾草次之,圆柱披碱草最低。(3)表型性状变异受海拔、经度及年均温的影响较大。(4)UPGMA聚类结果将所有材料分成4组,披碱草属植物性状的表型特征没有严格按地理距离而聚类。研究表明,披碱草属植物野生种质材料具有丰富的表型多样性,表型性状与环境之间关系密切,采集过程中应尽量保持居群的完整性,最大程度地保护中国披碱草属牧草的遗传多样性。     

扁蓿豆24个居群遗传多样性的SSR研究

利用SSR技术研究分布于蒙古高原和大兴安岭地区24个扁蓿豆居群的遗传多样性,以明确扁蓿豆种群等位基因分布状况及在居群内和居群间的分异规律,揭示居群分布与环境的相关关系。结果显示:(1)利用紫花苜蓿的10个引物进行扩增,5个引物表现出多态性,共检测出15个等位基因变异,平均多态信息含量(PIC)为0.342 3。(2)24个扁蓿豆居群间基因分化系数(Fst)为0.17,表明扁蓿豆82.8%的变异来自居群内,基因流(Nm)为1.2。(3)聚类分析表明,24个扁蓿豆居群可聚成三大类,其中:大青山北部的扁蓿豆居群(hs)单独聚为一类,内蒙古高原东部、东南部和东北部的居群(kh、hb1、hb2、hb3、lq、lx、bl、zs、lh)聚为一类,蒙古高原东北部向大兴安岭的过渡区和大兴安岭地区的居群(dm、db、xs、eg、xb、eh、al、kj、aq1、dw、hb4、ys、aq2、xl)聚为一类。(4)遗传距离和环境条件关系的Mantel检验表明,地理位置(经度和纬度)的影响大于海拔,且大于单一的经度或者纬度(r=0.402 7,P<0.01);水平距离上,经度对遗传距离的影响大于纬度。     

异质性生境对半红树植物海漆(Excoecaria agallocha)居群遗传结构的影响

选取半红树植物——海漆（Excoecaria agallocha）作为研究对象,采用简单重复序列（ISSR）分子标记技术,对不同地理位置、不同生境（潮间带和陆生）海漆居群的遗传多样性及遗传结构进行研究。结果表明,在同一地点,潮间带居群的遗传变异水平均高于其陆生居群。潮间带居群间的遗传分化水平（GST=0．191）略低于其陆生居群间的遗传分化（GST=0．218）．表明潮间带居群间通过漂浮的种子进行的基因交流较陆生居群间频繁。AMOVA分析显示,由异质性生境造成的分子变异为15．13％,而采样不同地区间（相距181～759km）造成的分子变异却只有11．63％．暗示环境胁迫造成的选择压力导致海漆居群适应性进化。同时地理隔离、南海北部的西南季风漂流及中国沿岸流和遗传漂变对海漆居群的遗传分化均有着重要影响。     

地理因素对箭竹复合体遗传多样性与遗传分化的影响

地理因素对植物天然居群的物种分布和种内分化具有重要影响。该研究通过对箭竹复合体内39个居群的14对SSR数据进行深入分析,旨在揭示重要地理因素(如海拔、纬度、地理距离)对该复合体内遗传多样性和遗传分化式样的影响。结果表明:(1)糙花箭竹亚支系遗传多样性最高(H_e=0.50),而团竹亚支系的遗传多样性最低(H_e=0.33)。(2)遗传多样性与纬度、海拔在A、B两个支系水平呈显著正相关关系,但在亚支系水平,遗传多样性的变化趋势呈现出更为复杂的局面,部分支系表现为负相关关系,推测纬度和海拔对箭竹复合体内遗传多样性水平具有一定影响,但也需重视其他进化因素的作用。(3)Mantel检验显示,仅在团竹亚支系中检测出较弱的正相关关系,表明地理距离不是影响箭竹复合体内遗传分化的主导因素,后续需结合基因流检测推断杂交事件对其遗传分化的影响。     

用EST-SSR标记分析中国北部和中部地区天蓝苜蓿的遗传多样性和遗传结构

天蓝苜蓿（Medicago lupulina）隶属于苜蓿属,是一年生或越年生、广布的草本植物。通常认为它是自交种,但也有些研究报道它具有异交或者混合交配的繁育系统。为了了解它的居群遗传变异、基因流、繁育方式及其遗传背景,我们用9个EST—SSR标记分析了中国新疆、内蒙古、甘肃、北京、山西、陕西、湖北7个省区的17个天蓝苜蓿野生居群。结果表明：（1）EST—SSR的多态位点百分率（PPL）为71．9％;每个SSR位点的等位基因数似）为4-11（平均为7．333）;遗传多样性（HE）最高的居群是新疆那拉提（0．388）,最低的为陕西西安（0．042）。自交率达93．8％。（2）居群间的遗传分化水平高（FST=0．528;RST=0．499）,AMOVA分析结果显示遗传变异主要存在于居群问,占总变异的59．02％。（3）Mantel检验发现遗传距离和地理距离有显著的相关性（r=0．4141,P≤0．0003）。根据Nei’s遗传距离（Da）得出的Neighbor-joining树显示,地理距离近的居群聚在一起,这进一步验证了Mantel检验的结果。由此推测,天蓝苜蓿中等水平的遗传多样性和高度的居群间遗传分化主要受它的自交特性和分布方式影响。上述结果有助于初步了解天蓝苜蓿的种群动态和遗传结构,同时对苜蓿属种质资源的保护和遗传育种有重要意义。     

Genetic diversity pattern of Stipa purpurea populations in the hinterland of Qinghai–Tibet Plateau

Stipa purpurea is among constructive endemic species in alpine meadow and steppe on the Qinghai–Tibet Plateau. To reveal the genetic diversity of this species and its relationship with geographic distribution pattern, we sampled eight populations across a northward transect with an increasing aridity gradient in the hinterland of Qinghai–Tibet Plateau. Their genetic diversity was quantified using eight intersimple sequence repeat (ISSR) primers. We found that S. purpurea had relatively low genetic diversity ( H _e = 0.135) but significant genetic differentiation among populations ( G _st = 0.391), indicating relatively more genetic diversity retained within populations. A Mantel test revealed a significant relationship between genetic and geographic distance in the S. purpurea populations. The genetic diversity tended to decrease with increasing latitude and longitude, while no significant relationship was found between genetic diversity and altitude, suggesting the possible influences of humidity and temperature on genetic diversity of alpine plant. We propose conservation measures for this plant on the plateau.     

华北地区小丛红景天种群的AFLP遗传多样性

利用扩增片段长度多态性(AFLP)标记, 对分布于华北地区5个山脉的25个小丛红景天(Rhodiola dumulosa)自然种群的776个样品进行了遗传多样性和遗传结构的研究。结果表明: 华北地区小丛红景天种群具有较高的遗传多样性, 4对选择扩增引物共扩增出398条清晰的条带, 其中多态带312条, 种群的平均多态位点百分率为78.46%, 种群总的Nei’s基因多样性为0.364 9, 总Shannon多态性信息指数为0.542 2。华北地区小丛红景天种群间的遗传分化系数G_st = 0.150 7, 基因流Nm = 2.817 9, 表明种群间遗传分化较低, 有一定的基因交流。AMOVA分析结果也表明: 华北地区小丛红景天的遗传变异主要存在于种群内, 地理单元间有一定的遗传分化, 而种群间的遗传分化较低。STRUCTURE的分析和UPGMA聚类分析结果一致, 结果显示地理分布距离相近的种群优先聚在一起。Mantel检验也进一步证实, 华北地区小丛红景天种群的遗传距离与地理距离间呈显著的正相关关系(r = 0.512 9, p < 0.001)。种群的遗传多样性与海拔呈显著的负相关关系(p < 0.05), 而与坡向没有显著相关性。用Dfdist软件分析海拔对遗传多样性的影响, 结果表明没有显著的受选择位点。     

不同地理分布区紫椴种群的遗传多样性变化

该文运用ISSR分子标记技术,研究不同纬度、不同海拔紫椴(Tilia amurensis)天然种群的遗传多样性变化规律,探讨紫椴种群的濒危机制,为紫椴遗传资源的有效保护和合理利用提供理论依据。14个ISSR引物扩增结果显示:紫椴种群多态位点百分率(P)为93.85%,基因多样性指数(H)和Shannon多样性指数(I)分别为0.243 3和0.380 3。不同纬度紫椴种群的遗传多样性由高到低依次为:CBS种群>BL种群>NA种群>LS种群>FHS种群>DYS种群;不同海拔紫椴种群的遗传多样性由高到低依次为:H1种群>H2种群>H3种群>H4种群>H6种群>H5种群。紫椴种群的遗传多样性没有随纬度的升高而呈现规律性的变化,但随海拔的升高呈现遗传多样性逐渐降低的趋势。用AMOVA进行分子方差分析表明,紫椴种群间遗传分化较大,遗传变异主要来自种群内部。紫椴种群间遗传距离与地理距离没有相关性,但随着海拔的逐渐增高种群间遗传距离增大。该研究结果揭示,紫椴种群具有较高的遗传多样性,遗传多样性不是导致其种群濒危的主要原因,导致其濒危的主要原因可能与人为采伐、生境破坏和生境退化及其自身生物学特性所导致的自然更新不良有密切关系。因此,应加强对紫椴生境的保护,防止人为因素对紫椴天然种群的进一步破坏。     

Genetic Variability of Hymenoscyphus pseudoalbidus on Ash Leaf Rachises in Leaf Litter of Forest Stands in Poland

Two hundred and thirty cultures of Hymenoscyphus pseudoalbidus were obtained from ascospores created in apothecia on the previous years' ash leaf rachises in the stand floor. Fruiting bodies of the pathogen were collected in four regions of Poland differing by geographical location, the altitude above sea level and climatic conditions. Isolates were identified based on the sequences of ribosomal DNA (ITS1‐5.8S‐ITS2) and the calmodulin gene. Only the presence of H. pseudoalbidus was identified in the decaying ash stands in Poland; morphologically similar, saprotrophic species of H. albidus was absent. Intrapopulation and interpopulation genetic variability of isolates was determined based on 84 RAMS markers obtained using four primers. Genetic variability of the fungus populations, measured by the Dice coefficient of genetic similarity and the Shannon coefficient of genetic diversity, decreased along with a decrease in the location of isolate collection area above sea level. A significant dependency was shown between intrapopulation genetic variability of isolates and altitude of regions above sea level. The Mantel test excluded existence of dependence between geographical and genetic distance among populations (r = ?0.038, P = 0.55). A significant correlation was found between the genetic distances of individuals within populations and locations above sea level. Based on PCA and geographical location of populations, it was shown that populations create four distinct groups. amova showed that a majority of total genetic variability (65.80%) constitutes intrapopulation variability. Variability between populations was high (28.7%), and individual regions had a smallest influence (5.5%) on the level of total variability.     

Genetic and morphometric diversity in Wallacea: geographical patterning in the horse shoe bat, Rhinolophus affinis

Genetic and morphometric variation was examined in eleven island populations of the horse‐shoe bat, Rhinolophus affinis, at the easterly end of this widespread species’ range and encompassing the Australian–Oriental biogeographic interface. Allozyme variation revealed mean heterozygosity levels within islands of 0.047, which is near the mammalian average. However, heterozygosity tended to decline from west to east as populations approached the periphery of the species’ distribution, and was lowest in those islands that were separated by the greatest sea‐crossing from source populations. There is extensive between‐island genetic differentiation (mean F_ST = 0.40) and relationships between islands are associated with their arrangement in geographical space; genetic distance is correlated with geographical distance and the genetic arrangement of islands is associated with longitude. The arrangement of islands as indicated by variation in body and skull metrics is also associated with their geographical positions, and the metric and genetic measures are themselves associated. While other taxa in the region have shown genetic‐geographical concordances, R. affinis is the only one that displays concordant patterns in metrical features. These patterns in biological diversity are interpreted as arising from the sequential island population structure and clines in key biogeographic gradients.     

Large-scale spatial patterns in the distribution of Collembola (Hexapoda) species in Antarctic terrestrial ecosystems

Aim  We tested whether the distribution of three common springtail species ( Gressittacantha terranova , Gomphiocephalus hodgsoni and Friesea grisea ) in Victoria Land (Antarctica) could be modelled as a function of latitude, longitude, altitude and distance from the sea.
Location  Victoria Land, Ross Dependency, Antarctica.
Methods  Generalized linear models were constructed using species presence/absence data relative to geographical features (latitude, longitude, altitude, distance from sea) across the species' entire ranges. Model results were then integrated with the known phylogeography of each species and hypotheses were generated on the role of climate as a major driver of Antarctic springtail distribution.
Results  Based on model selection using Akaike's information criterion, the species' distributions were: hump-shaped relative to longitude and monotonic with altitude for Gressittacantha terranova ; hump-shaped relative to latitude and monotonic with altitude for Gomphiocephalus hodgsoni ; and hump-shaped relative to longitude and monotonic with latitude, altitude and distance from the sea for Friesea grisea .
Main conclusions  No single distributional pattern was shared by the three species. While distributions were partially a response to climatic spatial clines, the patterns observed strongly suggest that past geological events have influenced the observed distributions. Accordingly, present-day spatial patterns are likely to have arisen from the interaction of historical and environmental drivers. Future studies will need to integrate a range of spatial and temporal scales to further quantify their respective roles.     

Genetic analysis of scattered populations of the Indian eri silkworm, Samia cynthia ricini Donovan: Differentiation of subpopulations

Deforestation and exploitation has led to the fragmentation of habitats and scattering of populations of the economically important eri silkworm, Samia cynthia ricini, in north-east India. Genetic analysis of 15 eri populations, using ISSR markers, showed 98% inter-population, and 23% to 58% intra-population polymorphism. Nei's genetic distance between populations increased significantly with altitude (R(2) = 0.71) and geographic distance (R(2) = 0.78). On the dendrogram, the lower and upper Assam populations were clustered separately, with intermediate grouping of those from Barpathar and Chuchuyimlang, consistent with geographical distribution. The Nei's gene diversity index was 0.350 in total populations and 0.121 in subpopulations. The genetic differentiation estimate (Gst) was 0.276 among scattered populations. Neutrality tests showed deviation of 118 loci from Hardy-Weinberg equilibrium. The number of loci that deviated from neutrality increased with altitude (R(2) = 0.63). Test of linkage disequilibrium showed greater contribution of variance among eri subpopulations to total variance. D('2)IS exceeded D('2)ST, showed significant contribution of random genetic drift to the increase in variance of disequilibrium in subpopulations. In the Lakhimpur population, the peripheral part was separated from the core by a genetic distance of 0.260. Patchy habitats promoted low genetic variability, high linkage disequilibrium and colonization by new subpopulations. Increased gene flow and habitat-area expansion are required to maintain higher genetic variability and conservation of the original S. c. ricini gene pool.     

RAPD analysis of genetic diversity and population structure of Elymus sibiricus (Poaceae) native to the southeastern Qinghai-Tibet Plateau, China

Genetic diversity of Elymus sibiricus (Poaceae) was examined in eight populations from the southeast Qinghai-Tibet Plateau. We detected 291 RAPD polymorphic loci in 93 samples. The percentage of polymorphic bands (PPB) was 79%. Genetic diversity (H(E)) was 0.264, effective number of alleles (N(E)) was 1.444, Shannon's information index (H(O)) was 0.398, and expected Bayesian heterozygosity (H(B)) was 0.371. At the population level, PPB = 51%, N(E) = 1.306, H(E) = 0.176, I = 0.263, and H(B) = 0.247. A high level of genetic differentiation was detected based on Nei's genetic diversity analysis (G(ST) = 32.0%), Shannon's index analysis (33.7%), and the Bayesian method (θ(B) = 33.5%). The partitioning of molecular variance by AMOVA demonstrated significant genetic differentiation within populations (60%) and among populations (40%). The average number of individuals exchanged between populations per generation (N(m)) was 1.06. The populations were found to share high levels of genetic identity. No significant correlation was found between geographic distance and pairwise genetic distance (r = 0.7539, P = 0.9996). Correlation analysis revealed a significant correlation (r = 0.762) between RAPD H(E) found in this study and ISSR H(E) values from a previous study.     

陕西省森林群落乔灌草叶片和凋落物C、N、P生态化学计量特征

研究陕西省121个森林群落中乔叶、灌叶、草叶和凋落物4个层次的C、N、P化学计量学特征及其变异性,分析了各层次间及其与地理因子间的关系.结果表明： 乔叶C、N含量最高,草叶P含量最高,凋落物C、N、P含量均最低.乔叶、灌叶、草叶和凋落物的C∶N∶P分别为439.4∶14.2∶1、599.2∶13.5∶1、416.5∶13.3∶1、504.8∶15.5∶1,乔叶、灌叶、草叶N∶P值差异不显著,但均与凋落物N∶P值差异显著,表明不同生活型活体植物叶片的N∶P值具有一定的稳定性.与N含量相比,C和P含量在各层次间表现出更好的相关性;C、N、P含量及其比值在草叶与乔叶之间较在灌叶与乔叶之间表现出更好的相关性;凋落物与乔叶和草叶之间C、N、P含量均表现出显著正相关,与灌叶只在P含量之间存在显著正相关.灌叶N、P含量随纬度增加而增加,草叶N、P含量随经度增加而降低,海拔对叶片和凋落物C、N、P含量及其比值的影响较小,只有乔叶N∶P与海拔之间存在显著负相关.各地理因子对草叶的影响大小表现为经度>纬度>海拔,对乔叶、灌叶和凋落物的影响大小表现为纬度>经度>海拔.