沅江常德段蚬属贝类的谱系、倍性与性别特征

研究以沅江常德段蚬Corbicula为例, 采用线粒体COⅠ分子标记对其进行谱系构建, 梳理谱系与形态、倍性、性别和遗传多样性之间的关系, 以期为蚬属的系统分类和生殖特征研究提供理论参考。结果显示, 99条COⅠ序列(526 bp)中存在12个单倍型, 共有17个变异位点, 单倍型多样性、核苷酸多样性和平均核苷酸差异数分别为0.599、0.01236和6.503。12个单倍型在系统进化树中被聚为独立的两支(谱系RA和RlcB), 但谱系间壳长、壳高和壳宽没有显著差异(P>0.05)。99个样品中有二倍体50个、三倍体49个、 雌雄同体71个、 雌性21个、 雄性7个。卡方检验发现, 谱系与性别及倍性与性别之间均存在显著的相关性(P<0.05)。谱系RlcB的单倍型数、变异位点数、单倍型多样性、核苷酸多样和平均核苷酸变异数均高于谱系RA。结果表明, 虽然形态、倍性、性别和遗传多样性在谱系RA和RlcB蚬之间存在一定的差异, 但均不足以作为区分两个谱系的生物学特征, 而不同谱系是否为不同的种还有待于进一步的证实。     

山西芦芽山针叶林草本层群落谱系结构与多样性的海拔格局

物种多样性格局及其成因是生态学的经典问题之一。谱系方法将演化信息(即物种亲缘关系)整合到群落学研究中,给群落学研究带来了全新视角。该研究以山西芦芽山针叶林冠层下草本群落为研究对象,将群落物种组成数据、厘定有进化时间的谱系树与地形、土壤等生境数据相结合,运用一般线性回归、基于距离矩阵的多元回归和谱系结构主坐标分析(PCPS)等统计方法,探究了草本群落谱系结构与谱系多样性的海拔格局及其与生境因子的关系。结果表明:所有样地的谱系结构指标均落在随机置信带之内,说明中性因素对草本群落构建的影响较为强烈。同时,谱系结构与海拔梯度之间存在显著的正线性关系,暗示确定性过程的作用也不可忽略,种间竞争排斥可能促进了低海拔地区谱系结构呈发散趋势,而高海拔的生境过滤引发了谱系聚集趋势。基于最近谱系距离的beta多样性与海拔差异之间呈极显著正相关关系,同样反映了草本层物种集聚受到了生境过滤的显著影响。PCPS模型前两轴代表了55.9%的谱系-物种组成变异,海拔是引起该变异的关键因子;PCPS二维排序图显示,高海拔地区群落的谱系聚集可能由菊科、禾本科等大科所主导,低海拔则显示出较高的演化分支多样性,从而表现出谱系发散。综上所述,该研究揭示了山西芦芽山山地针叶林冠层下草本群落谱系多样性格局,并初步明晰了主要生态过程对物种集聚的影响规律。     

基于线粒体基因的东方蜜蜂群体亚分化研究

【目的】进一步了解我国境内东方蜜蜂Apis cerana(Fabricius)群体的亚分化状况,为保护和合理利用这一宝贵的蜂种资源提供理论依据。【方法】采用公开的两对引物对中国境内19个地区的东方蜜蜂线粒体tRNAIle~ND2与16S rRNA基因的部分序列进行了扩增、测序,并与其他地区东方蜜蜂的相应序列进行了比对分析。【结果】扩增获得的tRNAIle~ND2基因的部分序列长度为471~474 bp,序列中共13个变异位点;16S rRNA基因的部分序列长度为581~585 bp,序列中共6个变异位点。ND2基因部分蛋白比对结果显示,仅山西沁源东方蜜蜂有一个位点发生变异。【结论】基于两基因部分序列所构建的系统发育树表明,海南东方蜜蜂明显区别于其他地区的东方蜜蜂;阿坝地区的东方蜜蜂可能属于高海拔地区的一种生态型,未支持其单独作为一个亚种的结论;吉林3个地区的东方蜜蜂之间亲缘关系较近,可能属于一个生态型;云南东方蜜蜂的变异比较丰富。     

南京直立人的鼻骨形态及其与欧洲化石人类基因交流的可能性

根据南京直立人1号头骨有高耸的鼻梁,有人认为南京直立人有西方血统。但学术界对欧洲人类的基因流进入中国境内的时间似有不同的理解。本文对非洲、欧洲和亚洲的远古人类的鼻骨作了观察。结果表明,在距今约20万年至180万年前期间,非洲尚未有高耸鼻梁的远古人类的化石证据;距今20万年前的欧洲也无高耸鼻梁的远古人类的化石证据。南京直立人生存的年代无论是距今58—62万年或是距今33—50万年,当时的欧洲、非洲和西亚都未出现高耸鼻梁的远古人类;南京直立人的高耸鼻梁未必意味着“西方血统”。高耸的鼻梁,从其形成历史来看,有可能类似于同功特征。具有这一形态特征的东方人群与西方人群可以是血缘上并不一定相近但在各自谱系上都有过对某种气候的适应历史。     

不同尺度上环境因子对常绿阔叶林群落的谱系结构的影响

群落的谱系结构是反映作用于群落组成的各种生态过程的综合指标。通过研究群落的谱系结构, 能够有效地推断形成群落谱系结构的生态过程。该文从环境因子(海拔、地形、pH、土壤湿度和土壤元素等)对群落谱系结构的影响这一视角出发, 采用圆形随机取样, 在半径为5、25、50、75和100 m 5个尺度上, 深入研究了古田山24 hm²永久样地群落的谱系结构。研究发现: 古田山样地在所有研究尺度上(半径 > 5 m)都表现为谱系聚集, 随着尺度的增加, 群落的聚集程度呈现出先增加后下降的格局。采用多元线性回归模型分析环境因子对群落谱系结构的影响时发现: 随着尺度的增加, 环境因子对群落谱系结构的影响逐渐增强; 在小尺度上, 环境因子对谱系结构没有显著影响, 这可能是由于小尺度上近缘种之间较强的竞争排斥作用所致。当尺度达到100 m半径时, 高海拔区域表现出谱系发散格局, 而低海拔区域保持谱系聚集, 这可能是由于古田山样地海拔较高的地带生境异质性较强和较大的干扰所致。该研究在所有的尺度上都表现出显著的谱系聚集, 与中性理论所预测的群落是物种的随机组合、无谱系结构相反, 因而为生态位理论提供了证据。     

基于线粒体Cyt b基因部分序列的中国东方蜜蜂不同地理种群的系统发育

从线粒体DNA水平上对中国境内东方蜜蜂不同地理种群的系统发育进行研究,为保护和合理利用这一宝贵的蜂种资源提供理论基础。对我国10个省市的21群东方蜜蜂mtDNA Cyt b基因片段进行了扩增、测序,并以意大利蜂、卡尼鄂拉蜂、印尼蜂作为外群进行序列分析。采用Minimum-Spanning Network方法构建系统进化树。结果显示：扩增片段长度429bp;在得到的21条同源序列中,共检测出13个变异位点,其中转换数为9,颠换数为4,并且变异位点大都发生在密码子的第三位,无碱基插入或缺失;聚类分析结果显示西方蜜蜂、印尼蜂和东方蜜蜂各为独立的蜂种;在中国东方蜜蜂群体中,吉林、海南和云南的东方蜜蜂各为一个独立的类群,其它地区的东方蜜蜂为一个类群[动物学报54（6）：1005-1013,2008]。     

高原鼢鼠线粒体谱系地理学和遗传多样性

高原鼢鼠是一类地下独居啮齿动物,为青藏高原特有种之一。为研究该物种的谱系地理学和遗传多样性,本文测定了采自青藏高原东部3个地理种群8个小种群共37个个体的线粒体D-loop区序列变异。在长度为627bp的序列中,共发现50个变异位点,定义了26种单倍型。该物种的单倍型多样性（Haplotype diversity,H）较高和核苷酸多样性（Nucleotide diversity,πn）较低。谱系分析得到3个稳定的分支,分别与采集的地理种群相吻合：同一地理种群内单倍型之间遗传差异小,而不同地理来源的单倍型之间存在较大区别。距离隔离分析表明高原鼢鼠的遗传分化与地理距离呈正相关。AMOVA分析同样表明地理种群之间存在显著差异：地理种群间变异占遗传变异的80.45%。高原鼢鼠的这种遗传结构特点可能主要是由于第四纪气候变迁、该物种稳定的地下生活环境和有限的迁移能力造成的。     

物种谱系不确定性对群落谱系格局指标的影响

物种谱系关系常被用于衡量群落谱系格局及推断格局背后的生态过程,但多数研究往往忽视谱系关系的不确定性及其可能对群落谱系格局造成的影响.为此,本文以浙江天童20 hm^2样地内150个树种为研究对象,采用这些物种叶绿体DNA的rbcL和matK碱基序列构建1棵一致系统发育树和反映谱系不确定性的999棵系统发育树,然后结合样地物种分布数据计算标准化净亲缘指数(NRI)和最近亲缘指数(NTI),最后运用独立置换零模型衡量样地群落谱系格局.结果表明:物种系统发育树在拓扑结构和物种谱系分支节点年龄上均存在较大的不确定性,谱系不确定性随着谱系分支节点年龄的减小而增大,也随物种间平均谱系距离的增加而增加;在样方尺度上,物种谱系的不确定性增加了标准化NRI和NTI指数的变异,但对两个指数的影响几乎独立;其对两指数的空间分布影响不同,且程度不一,其中标准化NRI受到的影响相对更大;在群落尺度上,物种谱系的不确定性增加了标准化NRI和NTI的变异,平均变异系数分别为0.37和0.077,表明群落水平的标准化NRI更易受到谱系不确定性的影响.这说明物种谱系不确定性会传递到常用的群落谱系格局指标中,且不同指标受影响的程度不同,进而影响对群落谱系格局的衡量及相关生态过程的推断.该结论也暗示以往不考虑谱系不确定性的研究中,非随机的群落谱系格局比例可能被高估.     

中国古代人骨眶上孔和舌下神经管二分发生率的调查与日本人起源问题的讨论

通过对两千余中国古代人骨眶上孔和舌下神经管二分形态小变异发生率的调查 ,探讨中国古代人群与日本古代人群之间的关系 ,支持日本渡来系弥生人与中国大陆古代人群之间有着密切联系的观点。     

地理距离及环境差异对云南元江干热河谷植物群落beta多样性的影响

beta多样性反映了群落间物种组成的差异, 是生物多样性研究的热点之一。本研究通过对云南元江干热河谷41个植物群落样方进行调查, 用Jaccard相异系数表征物种beta多样性, 用样方之间的最近谱系距离(mean nearest taxon distance, MNTD)及平均谱系距离(mean pairwise distance, MPD)表征谱系beta多样性, 采用基于距离矩阵的多元回归和方差分解方法, 探讨了该区域干热河谷典型植物群落的物种beta多样性和谱系beta多样性与样方间环境差异(主要是气候)及地理距离之间的关系。结果表明: (1)群落间的地理距离和年平均温度差异对干热河谷植物群落的物种beta多样性和谱系beta多样性有显著影响; (2)地理距离对物种beta多样性和MNTD的影响最大; 地理距离和年平均温度差异对MPD的影响均较大; (3)样方间年平均温度与年平均降水量的差异和地理距离能够解释群落间beta多样性及谱系beta多样性11-13%的变异。以上结果表明, 生态位分化和扩散限制对该地区植物群落的beta多样性均有显著影响, 其中扩散限制的影响可能更大。此外, 人类活动等其他因素也很可能对元江干热河谷的群落组成具有非常重要的影响。     

Molecular phylogeography of the red deer (Cervus elaphus) populations in Xinjiang of China: comparison with other Asian,European, and North American populations

To illustrate phylogeography of red deer (Cervus elaphus) populations of Xinjiang, we determined their mitochondrial DNA (mtDNA) control region sequences, and then investigated geographic variations and phylogenetic relationships between Xinjiang populations and other populations from Asia, Europe, and North America. The C. elaphus mtDNA control region shared different copy numbers of tandem repeats of 38 to 43-bp motifs which clearly distinguished the Western lineage from the Eastern lineage of this species in Eurasia. The western lineage comprised the Tarim populations from southern Xinjiang and the European populations, all of which had four copies of the motifs. By contrast, the Eastern lineage consisted of populations from northern Xinjiang (Tianshan and Altai Mountains), other Asian areas (Alashan, Gansu, Tibet, Mongolia, and northeastern China), and North America, all of which shared six copies of the motifs. MtDNA phylogenetic trees showed that there are two major clusters of haplotypes which referred to the Western and Eastern lineages, and that subgroupings of haplotypes in each cluster were congruent with their geographic distributions. The present study revealed that a boundary separating the Western lineage from the Eastern lineage occurs between Tarim Basin and Tianshan Mountains in Xinjiang. Meanwhile, North American populations were genetically closer to those of northern Xinjiang, northeastern China, and Mongolia, supporting that C. elaphus immigrated from northeastern Eurasia to North America through the glacier-induced land-bridge (Beringia) which had formed between the two continents after Late Pleistocene.     

Appropriate Body Mass Index and Waist Circumference Cutoffs for Categorization of Overweight and Central Adiposity among Uighur Adults in Xinjiang

Objective

The current overweight and central adiposity guidelines based on Western populations were not consistent with many studied based on the Asian populations. Uighur people live in Xinjiang Uighur Autonomous Region which is located in the center of Asia. Their overweight and central cutoffs were largely unknown. We aimed to identify cutoffs for body mass index (BMI; in kg/m²) and waist circumference (WC; in cm) for categorization of overweight and central adiposity among Uighur adults in Xinjiang.

Methods

4767 Uighur participants were selected from the Cardiovascular Risk Survey (CRS) which was carried out from October 2007 to March 2010. The age of the participants were from 35 to 101 years old with the mean age of 50.09 years. Anthropometric data, blood pressure, serum concentration of serum total cholesterol, triglyceride, low density lipoprotein (LDL), high density lipoprotein (HDL) and fasting glucose were documented. The prevalence, sensitivity, specificity and distance on the receiver operating characteristic (ROC) curve of each BMI and waist circumference values were calculated.

Results

The prevalence of hypertension, hypercholesterolemia and hypertriglyceridemia were higher with higher BMI for both men and women. The prevalence of hypertension and hypercholesterolemia were higher with higher waist circumference for both men and women. In women, the prevalence of hypertriglyceridemia was noticed to increase as the waist circumference increased. The shortest distance in the receiver operating characteristic curves for hypertension, dyslipidemia, diabetes, or ≥ 2 of these risk factors suggested a BMI cutoff of 26 and a waist circumference cutoff of 90 cm for both men and women.

Conclusions

Higher cutoffs for BMI and waist circumference are needed in the identification of Uighur patients at high risk of cardiovascular disease.     

Gene admixture in ethnic populations in upper part of Silk Road revealed by mtDNA polymorphism

To evaluate the gene admixture on the current genetic landscape in Gansu Corridor (GC) in China, the upper part of the ancient Silk Road which connects the Eastern and Central Asia, we examined mitochondrial DNA (mtDNA) polymorphisms of five ethnic populations in this study. Using PCR-RFLP and sequencing, we analyzed mtDNA haplotypes in 242 unrelated samples in three ethnic populations from the GC region and two ethnic populations from the adjacent Xinjiang Uygur Autonomous Region of China. We analyzed the data in comparison with the previously reported data from Eastern, Central and Western Asia and Europe. We found that both European-specific haplogroups and Eastern Asian-specific haplogroups exist in the Gansu Corridor populations, while a modest matrilineal gene flow from Europeans to this region was revealed. The Gansu Corridor populations are genetically located between Eastern Asians and Central Asians, both of who contributed significantly to the maternal lineages of the GC populations. This study made the landscape of the gene flow and admixture along the Silk Road from Europe, through Central Asia, to the upper part of the Silk Road more complete.     

Genetic structure of natural populations of Castanea sativa in Turkey: evidence of a hybrid zone

This study points out the evidence of a hybrid zone between two groups of genetically differentiated populations of chestnut (Castanea sativa Mill.) in Turkey. Genetic structure, gene flow and introgression levels, based on 16 allozyme loci, were investigated on 34 population samples spanning the entire C. sativa distribution area in this country. The occurrence of the hybrid zone, located in the Bithynian region, was inferred in a group of populations showing the following genetic characteristics: (i) enhanced genetic variability and intermediate allelic frequencies between those of the Western and Eastern groups of populations; (ii) sharp and concordant changes in allele frequencies; (iii) decreased gene flow with the Western and Eastern populations. Starting from the cline width estimated to be 324 km, strength of selection was evaluated from the gene flow distance, as indicated from the degree of genetic structuring outside the hybrid zone. Evolutionary processes shaping the observed genetic differentiation and introgression are discussed on the basis of palynological data, palaeoclimatic events and evidence of hybridization found in other plant and animal species in the same region.     

Gene admixture in ethnic populations in upper part of Silk Road revealed by mtDNA polymorphism

To evaluate the gene admixture on the current genetic landscape in Gansu Corridor (GC) in China, the upper part of the ancient Silk Road which connects the Eastern and Central Asia, we examined mitochondrial DNA (mtDNA) polymorphisms of five ethnic populations in this study. Using PCR-RFLP and sequencing, we analyzed mtDNA haplotypes in 242 unrelated samples in three ethnic populations from the GC region and two ethnic populations from the adjacent Xinjiang Uygur Autonomous Region of China. We analyzed the data in comparison with the previously reported data from Eastern, Central and Western Asia and Europe. We found that both European-specific haplogroups and Eastern Asian-specific haplogroups exist in the Gansu Corridor populations, while a modest matrilineal gene flow from Europeans to this region was revealed. The Gansu Corridor populations are genetically located between Eastern Asians and Central Asians, both of who contributed significantly to the maternal lineages of the GC populations. This study made the landscape of the gene flow and admixture along the Silk Road from Europe, through Central Asia, to the upper part of the Silk Road more complete.     

Political mobilization of a regional minority: Han Chinese settlers in Xinjiang

The tumultuous events of summer 2009 have brought Uighur protests and minority mobilization in the Xinjiang Uighur Autonomous Region (XUAR) to the forefront. But this focus overlooks similar protests organized by various groups of Han Chinese settlers over the years. This paper contributes to the body of literature on minority mobilization and ethnic relations in Xinjiang by illustrating how the political mobilization of a group that is simultaneously a national majority and a regional minority differs substantially from ‘traditional’ minority mobilization. Reviewing the main instances of Han Chinese political mobilization since the XUAR was created in 1955, I argue that two factors are particularly important in enabling their mobilization: the Han Chinese's subjective perception of discrimination and their close ethnic ties to the state. This paper concludes with a discussion on the presence of a cycle of protests between Han settlers and the Uighurs in Xinjiang.     

Mitochondrial DNA variation and language replacements in the Caucasus

Sequences of the first hypervariable segment of the mitochondrial DNA (mtDNA) control region were obtained from 353 individuals representing nine groups and four major linguistic families (Indo-European, Altaic and North and South Caucasian) of the Caucasus region. The diversity within and between Caucasus populations exceeded the diversity within Europe, but was less than that in the Near East. Caucasus populations occupy an intermediate position between European and Near Eastern populations in tree and principal coordinate analyses, suggesting that they are either ancestral to European populations or derived via admixture from European and Near Eastern populations. The genetic relationships among Caucasus populations reflect geographical rather than linguistic relationships. In particular, the Indo-European-speaking Armenians and Altaic-speaking Azerbaijanians are most closely related to their nearest geographical neighbours in the Caucasus, not their linguistic neighbours (i.e. other Indo-European or Altaic populations). The mtDNA evidence thus suggests that the Armenian and Azerbaijanian languages represent instances of language replacement that had little impact on the mtDNA gene pool.     

Morphometric diagnosis of <Emphasis Type="Italic">Glossina palpalis</Emphasis> (Diptera: Glossinidae) population structure in Ghana

Objective

This study aimed to identify isolated population(s) of Glossina palpalis in Ghana using geometric morphometrics to evaluate variations in wing-shape and size between populations of the fly from three regions.

Results

Wing shape of G. palpalis tsetse flies from the Northern, Western and Eastern Regions varied significantly between each other. Populations from the Northern and Western Regions varied the most (Mahalanobis Distance = 54.20). The least variation was noticed between populations from the Western and Eastern Regions (MD = 1.99). On morphospace, the Northern population clearly separated from the Eastern and Western populations both of which overlapped. Wing centroid size also significantly varied among populations. Reclassification scores were satisfactory reaching 100% for the Northern population. The Northern population of G. palpalis is possibly isolated from the Western and Eastern Region populations. Meanwhile, a panmictic relationship could be on-going between the Western and Eastern populations. We speculate that geographical distance and subspecific difference between populations are among factors responsible for observed pattern of wing shape variations among the studied populations. The implications of results regarding choice of control strategy and limitations of the study are discussed.

     

克里雅河下游封闭人群DYS19和DYS390多态性研究

本文以居住于塔克拉玛干沙漠当中克里雅河下游地区封闭人群(51例男性)为研究对象,采用基因扫描对其DYS19和DYS390两个STR基因座进行基因扫描研究其遗传多态性。对于DYS19基因座,克里雅河下游的封闭人群等位基因分布呈现“M”形分布,以DYS19*14和DYS19*16最常见,基因频率分别为0.353和0．510;对于DYS390基因座,其人群等位基因分布也并非呈现“钟形”分布,而是以DYS390*21和DYS390“24两种基因型基因频率最高,并且DYS390*21为此人群等位基因重复次数最少的基因型,基因频率分别为0．235和0．431,这可能是提示克里雅河下游的封闭人群的来源包含两个不同的群体分支。     

Diversity among African pygmies

Although dissimilarities in cranial and post-cranial morphology among African pygmies groups have been recognized, comparative studies on skull morphology usually pull all pygmies together assuming that morphological characters are similar among them and different with respect to other populations. The main aim of this study is to compare cranial morphology between African pygmies and non-pygmies populations from Equatorial Africa derived from both the Eastern and the Western regions in order to test if the greatest morphological difference is obtained in the comparison between pygmies and non-pygmies. Thirty three-dimensional (3D) landmarks registered with Microscribe in four cranial samples (Western and Eastern pygmies and non-pygmies) were obtained. Multivariate analysis (generalized Procrustes analysis, Mahalanobis distances, multivariate regression) and complementary dimensions of size were evaluated with ANOVA and post hoc LSD. Results suggest that important cranial shape differentiation does occur between pygmies and non-pygmies but also between Eastern and Western populations and that size changes and allometries do not affect similarly Eastern and Western pygmies. Therefore, our findings raise serious doubt about the fact to consider African pygmies as a homogenous group in studies on skull morphology. Differences in cranial morphology among pygmies would suggest differentiation after divergence. Although not directly related to skull differentiation, the diversity among pygmies would probably suggest that the process responsible for reduced stature occurred after the split of the ancestors of modern Eastern and Western pygmies.