五个罗氏沼虾群体遗传多样性的微卫星分析

利用16对微卫星标记对来自泰国(CP)、缅甸(MN)、孟加拉(BD)和中国(MP和DP)的共5个罗氏沼虾群体进行了遗传多样性和遗传结构的分析。结果显示, 16个微卫星位点均具有较高的多态性, 平均等位基因数(N_a)、期望杂合度(H_e)、Shannon信息指数(I)和多态信息含量(PIC)分别为17.563、0.8316、2.1662和0.7328。5个群体的期望杂合度(H_e)介于0.7025—0.8594, 多态信息含量(PIC)介于0.6538—0.8048, 表明所有群体均具有高度遗传多样性, 遗传多样性水平CP>MP>BD>MN>DP。遗传分化指数(F_st)值介于0.03430—0.17333, 表明所有群体间均有不同程度的遗传分化。16个微卫星位点的F_st值均大于0.05, 均值为0.0977, 与群体间有遗传分化相符。AMOVA分析显示群体间变异占总变异的6.22%, 群体内个体间的变异占总变异的40.72%, 个体内部的遗传变异占总变异的53.07%。基于Nei氏遗传距离构建的UPGMA系统进化树显示, MN群体首先与MP群体聚为一类, 再与DP群体聚为一类, 之后再与BD群体聚为一类, 最后与CP群体聚为一类, 表明中国群体与泰国群体亲缘关系较远。遗传结构分析显示, 参试样本被划分为5个理论群体, 除MP群体中个体遗传结构混杂外, 其余群体中个体遗传结构相对独立。研究为罗氏沼虾种质资源的开发利用和优良品种的选育提供了参考数据。     

广东高州普通野生稻(Oryza rufipogon Griff)的遗传多样性和居群遗传分化研究

利用30对SSR引物对广东高州普通野生稻3个群体进行了遗传多样性分析和居群遗传分化研究.结果表明,30对引物中只有20对表现出多态,多态位点比率P为66.7%;在20个多态位点中共检测出81个等位变异,平均等位变异数(Ap)为4.05 个;3个群体总的遗传多样性(Ht)为0.61,其中,居群内的遗传多样性为居群间的遗传多样性的3倍多,说明总的遗传多样性主要来自居群内;虽然居群间的遗传分化系数(G ST)较低,仅为0.2427,但当遗传相似系数临界值增加时,3个群体在聚类图上相对独立 ,说明3个群体既存在着高度的遗传相似性,又具有一定程度的遗传分化,可以作为3个居群进行原生境保护.     

河北省华北落叶松河北群体遗传多样性分析

以来自河北8个群体共312个华北落叶松天然个体为材料,利用10对SSR引物对群体进行扩增,所得数据用于其遗传多样性和遗传结构的研究。结果表明:10对SSR位点共检测到42个位点,平均每个位点有4.2个等位基因,位点的等位基因数(Na)为2~6个。群体平均等位基因数为3.36,Shannon指数(I)平均为0.749,观察杂合度Ho为0.405、期望杂合度He为0.423,来自河北北部的围场台子水和吉字以及兴隆雾灵山的多样性水平最高,南部的阜平群体多样性水平最低。AMOVA分子差异分析显示3%的遗传变异存在于群体间,97%的遗传变异则存在于群体内,基因分化系数Gst仅为0.028,表明华北落叶松在河北的群体分化很低。聚类结果表明河北围场两个群体为一类,蔚县、隆化和涿鹿为一类,阜平和赤城为一类,兴隆雾灵山群体距离其他较远。多样性北部群体较高,南部较低,表明华北落叶松可能的衍化方向是从北向南,印证了北部可能是起源中心的结论。     

栲树天然群体遗传结构的RAPD分析

利用RAPD分子标记对5个栲树(Castanopsis fargesii Franch.) 天然群体共计188个个体的遗传多样性和群体遗传结构进行了分析.41个随机寡核苷酸引物共检测到385个位点,其中多态位点157个,占40.78%.物种水平的Shannon多样性指数I=0.459 7,Nei基因多样度h=0.296.遗传变异分析表明,栲树群体的遗传变异主要存在于群体内,利用Shannon多样性指数估算的分化(Hsp-Hpop)/Hsp=0.047 6,遗传分化系数Gst =0.042 9,分子方差分析(AMOVA)也证实了这一结论,群体内的变异组分占了94.97%,群体间变异只占5.03%.AMOVA分析结果的显著性检验也表明,群体间及群体内个体间均呈现出显著分化(P<0.001).     

不同种源马尾松ISSR遗传结构及影响因素分析

应用ISSR分子标记技术,对来自广西、贵州3个种源的马尾松开展遗传多样性、遗传结构及遗传距离等研究。结果表明：从100条引物中筛选出12条引物,共扩增出92个条带,86条具有多态性。 POPGENE分析显示：马尾松群体水平上的Nei’ s基因多样性指数的变化范围为0.1824~0.2065,Shannon遗传多样性指数的变化范围为0.2818~0.3178,3个群体的多态性水平差异不大;物种水平上的多态性百分率为93.48％, Nei’ s基因多样性指数为0.2842,Shannon信息指数为0.4381;表明马尾松在物种水平上具有较高水平的遗传多样性。遗传结构分析显示：马尾松的基因分化系数( Gst)为0.3153,表明遗传变异主要来源于群体内;基因流Nm为1.0853,表明不同群体间存在一定的基因流动。 AMOVA分析显示：马尾松的遗传分化指数( Fst)为0.246( P＝0.001),表明群体间已出现明显的遗传分化。 UPGMA聚类和Mantel检测结果显示：每个群体内的个体均能很好地首先聚集为一个分支,群体间的遗传距离与地理距离之间存在显著相关性( r＝0.972, P＝0.001)。这说明马尾松在裸子植物界中具有较高水平的遗传多样性,遗传变异主要分布于群体内,群体间已出现了明显的遗传分化,这种分化并非由遗传漂变引起,可能与地理生境的差异有关。     

澜沧江中上游光唇裂腹鱼四个地理群体遗传多样性分析

利用简化基因组测序对澜沧江中上游的苗尾-功果桥库区、黄登-大华桥库区、里底江段和乌弄龙江段4个地理群体60个光唇裂腹鱼(Schizothorax lissolabiatus Tsao)样本进行了简化基因组测序, 平均测序深度255.26X, Q30为94.96%, 平均GC含量为39.80%; 测序获得多态性SLAF标签252623个, SNP标记1151083个, 其中, SNP平均完整度为36.66%, SNP平均杂合率为9.5%; 通过测序结果进行遗传多样性分析, 结果表明, 观测等位基因数均为2, 平均期望等位基因数为1.4211—1.5029, 平均观测杂合度为0.2381—0.3131, 平均期望杂合度为0.2690—0.3115, 平均多样性指数为0.2868—03248, 平均香浓指数为0.4269—0.481, 平均次要基因频率(MAF)为0.1854—0.2216, 平均多态信息含量(PIC)为0.2237—0.2553; AMOVA分析结果显示, 在总的变异中, 89.73%的遗传变异来自群体内部, 10.27%的遗传变异来自于群体间, 群体间遗传分化指数在–0.0150—0.1299(P<0.05), 表明群体间存在不同程度的分化。4个群体间遗传距离为0.05—0.15, UPGMA聚类表明, 苗尾-功果桥库区、黄登-大华桥库区和里底3个地理群体相互交叉聚类, 乌弄龙地理群体单独聚为一类。综上, 4个群体的遗传多样性处于中等水平, 遗传距离及聚类结果与试验群体地理距离基本相符, 研究结果将为光唇裂腹鱼种质资源评价与保护提供参考依据。     

栲树天然群体遗传结构的RAPD分析

利用RAPD分子标记对 5个栲树 (CastanopsisfargesiiFranch .)天然群体共计 188个个体的遗传多样性和群体遗传结构进行了分析。 4 1个随机寡核苷酸引物共检测到 385个位点 ,其中多态位点 15 7个 ,占 4 0 .78%。物种水平的Shannon多样性指数I=0 .4 5 97,Nei基因多样度h =0 .2 96。遗传变异分析表明 ,栲树群体的遗传变异主要存在于群体内 ,利用Shannon多样性指数估算的分化 (Hsp_Hpop) /Hsp=0 .0 4 76 ,遗传分化系数Gst =0 .0 4 2 9,分子方差分析 (AMOVA)也证实了这一结论 ,群体内的变异组分占了 94 .97% ,群体间变异只占 5 .0 3%。AMOVA分析结果的显著性检验也表明 ,群体间及群体内个体间均呈现出显著分化 (P <0 .0 0 1)。     

中国和国际豌豆核心种质群体结构与遗传多样性差异分析

通过对中国和国际栽培豌豆(Pisum sativum L.)核心种质群间SSR等位变异数(NA)、有效等位变异数(NE)、有效等位变异所占比重(NE/NA)、等位基因丰度(AR)、基因多样性指数(GD)、Shannon′s信息指数(I)的比较,发现中国核心种质的遗传多样性指标均高于国际核心种质.中国和国际核心种质群在11个位点间存在等位变异种类的差异,属于两个明显不同的基因库,其遗传多样性差异达到显著水平.群体结构分析将核心种质划分成3个组群,组群1代表典型的中国核心种质,组群2与组群3代表不同类型的国际核心种质;组群1内种质间的平均遗传距离远高于组群2和组群3,表明中国核心种质基因型间亲缘关系明显远于国际核心种质间的亲缘关系.     

草鱼野生群体遗传变异的微卫星分析

利用12个微卫星标记, 对来自长江水系(邗江、吴江、九江、石首、木洞和万州)、珠江水系(肇庆)和黑龙江水系(嫩江)的8个草鱼野生地理群体进行了遗传多样性及遗传结构等分析。遗传多样性分析显示, 12个微卫星位点均为高度多态位点(PIC=0.755~0.930), 8个草鱼野生群体显示出较高的遗传多样性水平(Ho=0.839~0.893), 其中长江水系的6个群体和肇庆群体的多样性水平高于嫩江群体。瓶颈效应分析显示, 嫩江、肇庆群体及2个长江上游群体(木洞、万州)近期出现了瓶颈效应, 群体数量发生下降。群体间遗传分化指数F^ST及AMOVA分析显示, 群体间出现极显著遗传分化(P<0.01), 整体分化水平较低(F^ST<0.05)。遗传距离分析结果显示, 长江水系的6个群体与肇庆群体遗传距离较近, 与嫩江群体较远; 基于此的UPGMA聚类树显示, 长江水系下游、中游和上游的群体依次聚类, 然后与肇庆群体聚类, 最后与嫩江群体聚类, 遗传距离与地理距离呈现出较强的正相关性。遗传结构分析显示, 所有样本被划分为5个理论群, 肇庆和嫩江群体中个体的遗传结构相对独立, 而长江上游、中游和下游群体中个体的遗传结构则存在一定程度的混杂。综上所述, 中国草鱼野生资源具有较高的遗传多样性, 地理群体间存在遗传分化, 具有进一步遗传改良的潜力; 但部分群体出现的瓶颈效应也需要引起重视。     

采用微卫星标记分析10个双峰驼群体的遗传变异和群体间的遗传关系

为从分子水平上对我国双峰驼(Camelus bactrianus)群体的遗传多样性、群体间遗传关系、群体遗传分化及近交情况进行全面、系统地研究,为双峰驼种质资源保护和新品种培育提供基础数据,本文利用18对微卫星引物,分析了我国9个双峰驼群体和1个蒙古双峰驼群体的遗传多样性和遗传关系。结果显示:10个群体均具有较高的遗传多样性,共检测到242个等位基因,平均等位基因数为13.44,平均有效等位基因数为4.18,平均观察杂合度(Ho)为0.5528。10个群体间存在显著的遗传分化,有9.6%的遗传变异来自群体间,90.4%的遗传变异来自群体内部的个体间。聚类分析、主成分分析和群体遗传结构分析结果都表明10个群体被分成2个明显的分支,新疆4个群体单独聚为一类,剩下的6个群体聚为一类。这一结果可能与它们的地理分布和群体间的地理屏障有关。     

Genetic Variation Analysis of Mugil cephalus in China Sea Based on Mitochondrial COI Gene Sequences

In this study, genetic diversity and population genetic structure of flathead grey mullet, Mugil cephalus, among four China Sea populations were investigated by COI sequences. All the populations studied had high values of haplotype and nucleotide diversity, except for the Yellow Sea population. In the phylogenetic tree, these haplotypes clustered in two groups, one for the populations from the Bohai and East China seas, and the other from the Yellow and South China seas. Analysis of molecular variance indicated that the northern populations (Bohai and East China) had lower genetic divergence (0.0725, P > 0.05) than that of the southern population (South China) (0.4530-0.6827, P < 0.001), suggesting that two distinct genetic groups exist in Chinese waters. Tests of neutral evolution and mismatch distribution indicated that no historical demographic expansion occurred in these populations. The results provide new information for genetic assessment, fishery management, and conservation of this species.     

Randomly Amplified Polymorphic DNA Variation in Populations of Eastern Australian Koalas, Phascolarctos cinereus

Randomly amplified polymorphic DNA (RAPD) variation in populations of the koala, Phascolarctos cinereus, was investigated, revealing significant differences in the level of diversity between southern and northern regions of eastern Australia. Of the 20 polymorphic RAPD markers identified in koalas, 4-7 were polymorphic in southern populations, while 12-17 were polymorphic in northern populations. Analysis of molecular variance revealed a significant difference in the estimated variance between koalas from northern and those from southern regions (P < 0.001), where populations from the north were greater than twice as variable as their southern cousins. The total genetic diversity observed was attributed to regional differences (30.91%), population differences within a region (11.77%), and differences among individuals within a population (57.32%). For the within-region analyses, a large proportion of the genetic diversity was attributable to individual differences within a population, 80.34% for the north and 91.23% for the south. These results demonstrate that RAPD markers are useful for determining population structure among koalas.     

Patterns of genetic and phenotypic variation in Iris haynei and I. atrofusca (Iris sect. Oncocyclus = the royal irises) along an ecogeographical gradient in Israel and the West Bank

Iris haynei and I. atrofusca are two closely related narrow endemics distributed vicariously along an ecogeographical north-south gradient in Israel and the West Bank. To obtain baseline information of the taxonomic status, conservation and population history of these taxa, we investigated patterns of phenotypic variation and the partitioning of genetic variation within and among populations using dominant random amplified polymorphic DNA (RAPD) markers. Multivariate (principal components analysis) and taxonomic distance analyses based on morphometric traits from eight populations revealed no unambiguous separation into two distinct groups. Results of genetic analyses for nine populations differed only slightly when either allele- or marker-based approaches were employed. Mean within-population diversity was high (0.258 for Nei's expected heterozygosity), but there was no significant relationship between genetic diversity and either population size or latitude. Although the range-wide estimate of GST ( approximately 0.20) revealed relatively high differentiation among populations this value was inflated because of a small, but significant, component of molecular variance among regions viz. taxa ( approximately 5%). Limited long-distance dispersal capabilities in conjunction with a linearized habitat distribution are proposed to contribute to the approximate isolation by distance pattern observed. It also appears that extant populations are currently deviating from equilibrium conditions because of primary divergence of a formerly more widespread ancestral population. Given the absence of deep genetic and phenotypic subdivision among northern (I. haynei) vs. central/southern (I. atrofusca) populations, we argue for a revision of their species status. Nonetheless, we recommend conservation attention to these geographically differentiated segments as separate management units, which can be seen as an instructive example of incipient species formation.     

Influence of glaciation on divergence patterns of the endemic minnow, Zacco pachycephalus, in Taiwan

The genetic subdivision of the endemic minnow, Zacco pachycephalus, in 12 rivers of Taiwan was studied by allozyme electrophoresis. Among 26 loci surveyed, six were significantly differentiated among sites. Allozyme genotype frequencies within samples accord with Hardy-Weinberg expectations. A highly divergent genetic structure among sites (FST = 0.497) with low genetic variability within samples (H = 0.006-0.062, mean = 0.03) suggests that local populations originated from a small number of founders. UPGMA and Fitch trees derived from Nei's genetic distance and hierarchical analysis of FST values reveal that samples of Z. pachycephalus can be divided into northern, middle, and southern subgroups and that most genetic variation (87%) is distributed among rather than within groups. It is proposed that there were two isolated refugia during the most recent glacial period, and that populations of the southern group (Group I) originated from a southern refugium in Taiwan below the boundary of the Kaoping River, and other groups (Group II), including northern and middle subgroups, originated from a refugium located on the extinct land-bridge between Taiwan and mainland China. The postglacial division between northern and middle subgroups may be due to hydrological differences between these two regions.     

小菜蛾不同地理种群遗传多样性的ISSR标记研究

为阐明小菜蛾Plutella xylostella不同地理种群的遗传多样性, 应用ISSR技术对我国小菜蛾8个地理种群的遗传多样性进行了研究分析。15条引物扩增出395条ISSR条带, 其中多态性条带占89.11%, 全部个体显示了各自独特的ISSR图谱。ISSR标记的遗传多样性分析结果表明： 小菜蛾无论在物种水平上（P=89.11%, H=0.2706, I=0.4286）, 还是在种群水平上（P=88.80%, H=0.2759, I=0.4349）都表现出较高的遗传多样性。其中, 北京南口种群内遗传变异最大, 海南海口和甘肃兰州种群内遗传变异最小, 南方地区（云南、 湖北）小菜蛾种群遗传多样性明显高于北方地区（北京、 天津、 山东、 黑龙江、 甘肃）种群。据种群变异来源分析, 有5.66%的遗传变异来自种群间, 94.34%的变异来源于种群内（N_m=8.3399）, 不同地理种群间没有明显的遗传分化。本文有关小菜蛾不同地理种群基因流动和遗传变异的研究为小菜蛾抗药性的控制及田间种群的综合防治提供了有价值的分子生物学依据。     

Genetic Structure and Demographic History Reveal Migration of the Diamondback Moth Plutella xylostella (Lepidoptera: Plutellidae) from the Southern to Northern Regions of China

The diamondback moth Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) is one of the most destructive insect pests of cruciferous plants worldwide. Biological, ecological and genetic studies have indicated that this moth is migratory in many regions around the world. Although outbreaks of this pest occur annually in China and cause heavy damage, little is known concerning its migration. To better understand its migration pattern, we investigated the population genetic structure and demographic history of the diamondback moth by analyzing 27 geographical populations across China using four mitochondrial genes and nine microsatellite loci. The results showed that high haplotype diversity and low nucleotide diversity occurred in the diamondback moth populations, a finding that is typical for migratory species. No genetic differentiation among all populations and no correlation between genetic and geographical distance were found. However, pairwise analysis of the mitochondrial genes has indicated that populations from the southern region were more differentiated than those from the northern region. Gene flow analysis revealed that the effective number of migrants per generation into populations of the northern region is very high, whereas that into populations of the southern region is quite low. Neutrality testing, mismatch distribution and Bayesian Skyline Plot analyses based on mitochondrial genes all revealed that deviation from Hardy-Weinberg equilibrium and sudden expansion of the effective population size were present in populations from the northern region but not in those from the southern region. In conclusion, all our analyses strongly demonstrated that the diamondback moth migrates within China from the southern to northern regions with rare effective migration in the reverse direction. Our research provides a successful example of using population genetic approaches to resolve the seasonal migration of insects.     

陕西省异色瓢虫种群遗传结构及其多样性

异色瓢虫是一种重要的天敌昆虫,广泛应用于农业生物防治中.本研究以线粒体COII基因作为分子标记,对陕西省分布的异色瓢虫不同地理种群的遗传结构及遗传多样性进行分析,并探讨不同种群间的遗传分化程度及基因交流水平.结果表明: 在21个种群529头异色瓢虫供试样本的COII序列中,共检测到15种单倍型(Hap1～Hap15),其中Hap1和Hap2所占比例最高,分别占总群体的34.4%和37.6%.总群体单倍型多样性指数为0.732,各种群内单倍型多样性范围在0.652～0.786.种群间总基因流为10.13,总群体遗传分化指数为0.024,说明种群间整体遗传分化程度较低.陕西异色瓢虫种群在进化上呈现中性模型,群体大小保持相对稳定,种群间的遗传分化主要来自种群内部.基于Nei遗传距离构建的种群系统发育树,陕南区域种群与陕北和关中区域种群分化明显.种群间遗传分化与地理距离之间存在一定的相关性,并且区域种群的遗传结构与遗传多样性也表现出一定的地理分布模式,推测秦岭的阻隔及南北气候的差异,使陕北、关中与陕南种群间的基因交流存在阻力,导致南北种群间遗传结构和遗传多样性存在差异.     

The Genetic Structure of Natural Populations of DROSOPHILA MELANOGASTER. Xviii. Clinal and Uniform Genetic Variation over Populations

It has been reported in the previous papers of this series that in the eastern United States and Japan there is a north-to-south cline of additive genetic variance of viability and that the amount of the additive genetic variance in the northern population can be explained by mutation-selection balance. To determine whether or not the difference in the genetic variation in northern and southern populations can be explained by the differences in mutation rate and/or effective population size, numerical calculations were made using population genetic parameters. In addition, the average heterozygosities of the northern and southern populations at ten of 19 polymorphic structural loci surveyed were estimated in relation to the cline of additive genetic variance of viability, and the following findings were obtained. (1) The changes in mutation rate and population size cannot simultaneously explain the difference in additive genetic variance and inbreeding decline between the northern and southern populations. Thus, the operation of some kind of balancing selection, most likely diversifying selection, was suggested to explain the observed excess of additive genetic variance. (2) Estimates of the average heterozygosities of the southern population were not significantly different from those of the northern population. Thus, it was strongly suggested that the excess of additive genetic variance in the southern population cannot be caused by structural loci, but by factors outside the structural loci, and that protein polymorphisms are selectively neutral or nearly neutral.     

Genetic differentiation among Hemarthria compressa populations in south China and its genetic relationship with H. japonica

Within and among populations genetic variance of twelve Hemarthria compressa populations and one Hemarthria japonica population from China were analyzed using inter simple sequence repeat (ISSR). Twelve primers amplified a total of 165 genomic DNA fragments across a total of 148 individuals of which 156 were polymorphic (94.55%). 75.76% of the bands were unique to each species, while the average genetic distance (GD) between one population of H. japonica and twelve populations of H. compressa was 0.44, which suggest that there was distinct differentiation between these two species. In H. compressa, twelve primers produced 145 bands across 145 individuals. High genetic diversity was observed at species level. The percentage of polymorphic loci (P) was 86.21% and Shannon's information index of diversity (I) was 0.357. In contrast, there were relatively low levels of genetic diversity within population (P=32.93%, I=0.174). Analysis of molecular variance (AMOVA) showed that a considerable proportion of genetic variation (48.02%) resided among populations. The coefficient of gene differentiation (G(ST)=48.6%) also suggested that there was strong genetic differentiation among H. compressa populations in southern China. An indirect estimate of the number of migrants per generation (N(m)=0.264) indicated that gene flow was low among populations of this species. Relative high clonal diversity was found, and all local genotypes were found.     

缢蛏种群遗传多样性的周年变异分析

利用线粒体COI标记分析了福建省宁德市漳湾镇横屿村滩涂5个月份缢蛏群体(S3,S5,S7,S9,S11)的遗传结构,以期评估不同月份时期种群的遗传多样性差异。基于线粒体COI基因的结果表明,5个缢蛏群体的平均核苷酸差异数位于2.7836-3.6894之间,核苷酸多样性指数位于0.0050-0.0066之间,遗传多样性水平大致表现为S3和S5群体较高于S7和S9群体,明显高于S11群体。AMOVA分析结果显示,群体间遗传变异量占总变异的7.18%,而群体内变异达到了92.82%,说明遗传差异主要来自于群体内部。由此可见,从3月份到11月份,缢蛏群体的遗传多样性水平呈现出下降趋势,尤其是在11月份,差异最为明显。