大石鸡边缘种群的遗传结构

大石鸡（Alectoris magna）分布于青海西部、东部,甘肃中部和宁夏西部的干部和半干旱区,由于环境变化,其种群向甘肃南部森林被砍伐的地区扩散,形成涟缘种群。本研究采用聚合酶链式反应（PCR）和直接测序的方法获得了采自甘肃的大石鸡一个边缘种群和两个中心地理种群共39个个体的线粒体DNA（mtDNA）控制区基因（D－loop）456－457个核苷酸的基因序列,16个变异位点（占整个序列的3.5%）有15个单倍型。边缘扩散种群有3种单倍型,M6与另两个种群共有,单倍型频率为0.108,而M4和M5为其特有,单倍型频率分别为0.081和0.027。边缘种群的单倍型比率和遗传多样性分别为37.5%和0.549。中心地理种群1和种群2各有7个单倍型,除M6炳种群共有,其余为自所特有,单倍型比率分别为46.7%和50.0%,遗传多样性分别是0.729和0.786。边缘种群的单倍型比率和遗传多样性均低于中心地理种群。     

中国橘小实蝇不同地理种群遗传多样性分析

【目的】为推测中国橘小实蝇Bactrocera dorsalis向北方扩散的路径和北方地区的传播来源。【方法】本研究对橘小实蝇15个地理种群的144个样本的mtDNA COⅠ序列进行测定;依据mtDNA COⅠ序列利用相关软件对橘小实蝇不同地理种群的遗传多样性、遗传分化等进行分析。【结果】在橘小实蝇144个样本的mtDNA COⅠ序列中获得了75个单倍型,其中单倍型H＿7为7个地理种群所共享,北方地理种群与原发生地区种群间存在共享单倍型,绝大部分为种群独享单倍型。15个橘小实蝇地理种群总体表现出高水平的核苷酸多样性(Pi=0.02076)和单倍型多样性(Hd=0.99413),不同橘小实蝇地理种群间遗传分化较大。系统进化树显示,橘小实蝇各地理种群中的单倍型分布格局较为混杂,未形成明显的系统地理结构;系统进化树分为2支,湖北武汉、重庆北碚、福建福州、湖南衡阳、江苏南京、海南海口、河北保定、河南郑州、广东广州的地理种群聚为一支,海南三亚、广西南宁、云南丽江、湖南邵阳、山东泰安、山东临沂的地理种群聚为一支,北方新发生地理种群在两个分支中均有分布。橘小实蝇整体错配分析结果显示为单峰,表明橘小实...     

内蒙古布氏田鼠地理种群遗传多样性

以MHCⅡ类基因第二外显子为分子标记,利用限制性内切酶分析法和序列分析法对8个布氏田鼠Lasiopodomys brandtii地理种群进行遗传多样性分析。结果显示,8个布氏田鼠地理种群的MHCⅡ类基因第二外显子酶切共检测到6个等位基因,定义21种单倍型,其中有3个单倍型为不同区域种群共享,经卡方检验,6个酶切多态性位点上基因型频率不符合Hardy-Weinberg平衡;序列分析显示,在261 bp的核苷酸序列中,有57个变异位点,单倍型多样性为0.746 5~0.873 3、核苷酸多样性为0.006 06~0.016 55。谱系分析得到3个稳定的分支:锡林浩特、二连浩特、东乌珠穆沁旗和西乌珠穆沁旗4个种群形成一个单元分歧的进化分支(A区域),新巴尔虎左旗、陈巴尔虎旗和新巴尔虎右旗3个种群成一个单元分歧的进化分支(B区域),而位于浑善达克沙漠南部的正镶白旗种群形成一个独立单元分歧的进化分支(C区域),分别与采集的地理种群相吻合。AMOVA分析结果表明,区域类群间的遗传变异占总变异比率的64.08%,区域内种群间占7.78%,种群内占28.14%。除正镶白旗种群外,布氏田鼠种群具有较丰富的遗传多样性,遗传变异主要发生在区域类群之间和种群内。     

中国亚洲象现状及研究进展

综述了中国亚洲象的分布、种群大小、行为和系统地理学研究现状。野生亚洲象目前在我国仅分布于云南省南部3个地区,种群大小在200～250头之间。面临着栖息地高度破碎化、较为猖獗的盗猎活动和日益严重的农业开发干扰等问题。种群遗传学研究进一步表明,我国中国亚洲象分为两大地理单元,西双版纳地理单元及南滚河地理单元。西双版纳地理单元内4个地理种群间遗传变异很低,南滚河种群与其他4个地理种群具有显著性差异和明显的遗传分化。与国外其他种群相比,中国亚洲象种群遗传多样性极端缺乏。建议野生动物管理部门将分布于西双版纳地区与南滚河地区的亚洲象种群分别对待,以保证两分枝内亚洲象种群遗传的稳定性和独特性。另外,在西双版纳地区将几个孤立的地理种群通过建立亚洲象可利用的生态走廊带是十分必要的。     

广东地区宽鳍(鱼巤)种群遗传变异和亲缘地理

通过分析88尾采自广东境内9条水系的宽鳍(鱼巤)(Zaccop,platypus)线粒体DNA(mtDNA)细胞色素b(Cyt b)基因全序列,初步研究其种群遗传变异和地理格局,所测定的Cyt b基因全序列长1140 bp,其中变异位点98个,简约信息位点75个.共检测到33个单倍型,除鉴江种群只有1个单倍型外,其余8条水系均有多个单倍型.北江、流溪河、鉴江、北流河和罗定江等5个种群有共亭单倍型Hap11,罗定江和北流河之间共享了单倍型Hap4,东江与流溪河共享Hap6,而韩江和榕江共享单倍型Hap29.种群单倍型多样性的平均值(h)为0.908,核苷酸多样性的平均值(π)为0.01961,表现出较高的遗传多样性.系统发育分析(NJ树)显示,宽鳍(鱼巤)种群33个单倍型可分为2个分支,其中来自珠江水系(北江、东江、流溪河、罗定江和北流河)和广东西部独立人海水系(鉴江和漠阳江)的宽鳍(鱼巤)种群聚为一支(分支A),广东东部独立入海水系(韩江和榕江)种群聚为另外一支(分支B).2分支间的遗传距离和碱基差异率均较高(0.0517-0.0549,5.35%-_6.49%),明显大于分支A内(O.0012-0.0099,0.26%-2.11%)和分支B内的值(0.0027,1.58%),但远小于宽鳍(鱼巤)与外类群间的遗传距离和碱基差异率(0.0945-0.1912,8.77%-17.11%).这表明分支A与B之间已有明显的遗传分化,但分化程度来达到物种级水平,韩江和榕汀的种群相对独立,推测可能与莲花山脉的阻隔有关.根据单倍型网络图推测,流溪河可能是广东中西部地区宽鳍(鱼巤)的扩散中心,分别向珠江水系的西江、北江和东江扩散,再向鉴江和漠阳江扩散:另外由扩散中心经东江到榕汀再向韩江扩散.分子变异分析(AMOVA)表明,种群间的遗传变异占38.50%,种群内的遗传变异占66.24%.中性检验和歧点分布分析皆表明广东境内9条水系的宽鳍(鱼巤)在整个种群上保持相对稳定,没有发生明显的种群扩张.     

泛希姬蝽不同地理种群的遗传多样性和遗传分化

泛希姬蝽Himacerus apterus(Fabricius)是半翅目姬蝽科中重要的天敌种类,本文旨在分析泛希姬蝽不同地理种群的遗传多样性和遗传分化情况。利用COI作为标记基因,使用DnaSP、Arlequin、MEGA等软件分析了中国4个省12个种群33个体的单倍型多样性、遗传结构分化、系统发育等。共发现19个单倍型,所有单倍型中仅H1为共享单倍型,为宁夏和陕西共有,且出现频率最高。总体单倍型多样性指数Hd=0.913,核苷酸多样性指数π=0.006,平均核苷酸差异数k=4.083。Tajima's D=-0.853,P>0.100,表明泛希姬蝽未经过种群扩张。AMOVA分析表明种群内的分子变异大于种群间分子变异,变异比例分别为45.393%和36.594%,遗传分化指数均大于0.250,差异水平极显著。泛希姬蝽不同地理种群遗传多样性较高,宁夏与内蒙古、山西、陕西省分组间存在极度的遗传分化。种群间遗传距离和地理距离无相关性,表明地理距离不是影响种群间遗传距离的重要因素。通过比较4个省采集点的环境特点,认为地区间基因流受限和气温、猎物的差异可能是影响遗传分化的重要因素。     

四川地区猕猴线粒体DNA 控制区遗传多样性及其种群遗传结构

猕猴是最理想的医学实验灵长类动物,并且是国家二级保护动物。四川地区的猕猴数量多、分布广,全面了解其遗传背景对于该地区猕猴资源的保护与合理利用具有重要的意义。本研究对来自四川8 个地理种群的231个不同猕猴个体的线粒体DNA 控制区部分序列进行了测定和群体分析,发现了110 个变异位点(22. 49% ),定义了56 种单倍型,其单倍型多样性(h)平均值为0. 686、核苷酸多样性(π)平均值为0. 01483,种群总体遗传多样性较高;进一步分析表明,8 个地理种群间存在着明显的遗传分化(F_st = 0. 70412,P < 0. 05),种群间基因交流较低(N_m < 1);系统发育树显示,四川猕猴8 个地理种群的单倍型基本上成簇分布在系统树上,与地理位置呈现一定的对应关系,说明四川猕猴具有明显的系统地理分布格局。地理隔离和人类活动可能是促使四川猕猴种群分化的主要因素。     

基于mtDNA Cytb基因序列的我国北方地区甜菜夜蛾遗传多样性与种群历史分析

为了明确我国北方不同地理种群甜菜夜蛾Spodoptera exigua遗传多样性与种群遗传结构,阐明该种害虫的种群历史动态,首次对采自我国北方8省17县(市)304头甜菜夜蛾样品进行mt DNA Cytb基因序列测定与分析,利用Dna SP 5.0和Arlequin 3.0软件分析种群遗传多样性、遗传结构、遗传分化与分子变异,基于MP、ML与贝叶斯法构建单倍型系统发育树,与此同时,基于Median-joining法对所有个体构建单倍型网络关系图。结果表明,在所分析的304个序列样本中,共检测出19个单倍型,其中,包括9个共享单倍型,单倍型Hap6为所有种群所共享。总群体具有较低的遗传多样性(Hd=0.422±0.035,π=0.00119±0.00011)与较小的遗传分化(F_(ST)=0.108,P0.001)。单倍型系统发育分析与网络关系图结果表明,虽然19个单倍型被分为2个分支,但各单倍型相互散布在不同种群中,未形成明显谱系地理格局。AMOVA分析表明,甜菜夜蛾遗传变异主要来自种群内(89.18%),种群间变异水平较低(10.82%)。中性检验(Tajima's D=-1.897,P0.05;Fu's FS=-4.424,P0.05)与错配分布分析表明,我国北方地区甜菜夜蛾种群曾经历过种群的近期扩张。     

基于线粒体COI基因的桔小实蝇种群遗传分化研究

【目的】推测桔小实蝇Bactrocera dorsalis在中国的扩散路径和新发生地区的入侵来源。【方法】本研究测序获得来自中国、泰国、日本、老挝、孟加拉国和美国等地31个种群的192头桔小实蝇个体的COI序列（1 496 bp,占COI基因全长97.3%）,并以软件DnaSP 5.0, MEGA 6.0和Arlequin 3.5等完成各种群的遗传多样性、种群间的遗传分化以及单倍型分析。【结果】所测31个桔小实蝇种群总体表现出较高水平的核苷酸多样性（0.00663）和高水平的单倍型多样性（0.98069）。以F-统计法度量种群间遗传分化程度, 结果显示中国桔小实蝇地理种群间遗传分化较弱, 中国种群与泰国、日本、老挝、孟加拉国、美国种群间的遗传分化程度不同, 中国种群与美国种群及日本种群的遗传分化最大。而Mantel检验发现,中国、泰国、日本、老挝、孟加拉国和美国种群间的遗传分化与空间距离有关（R=0.670, P<0.0001）, 中国种群间的遗传分化不是地理隔离所造成的（R=0.038, P=0.534）。中国种群与泰国、日本、老挝、孟加拉国和美国种群间不存在共享单倍型。根据种群系统发育树,可将中国原发生地区种群划分为西南、东南两大分支。中性检验和错配分析结果均表明桔小实蝇曾存在大规模的扩张。【结论】桔小实蝇以东南地区和西南地区为源头向中国内陆扩散,其中广东、福建、广西和贵州种群为中国内陆种群较为有影响力的源头。根据遗传多样性、遗传分化、单倍型分析,推测新发生地区桔小实蝇的来源, 例如安徽合肥桔小实蝇种群主要来源于福建长乐、广东珠海和上海。     

基于线粒体COI基因序列的大豆食心虫中国东北地理种群遗传多样性分析

【目的】大豆食心虫Leguminivora glycinivorella (Matsumura)是一种危害大豆的主要害虫,在中国北方地区危害较重。本研究旨在探讨大豆食心虫在中国东北不同地理种群间的遗传变异。【方法】测定了10个不同地理种群153个个体的线粒体细胞色素氧化酶亚基Ⅰ (mtCOI)基因的657 bp序列,利用DnaSP 5. 0和Arlequin 3. 5. 1. 2等软件对大豆食心虫种群间的遗传多样性、基因流水平和分子变异进行分析。【结果】结果表明：10个地理种群间的COI基因共有36个变异位点和17个单倍型,其中1个单倍型为10个种群所共享。总种群的单倍型多样性指数Hd为0.456,各地理种群单倍型多样度范围在0~0.634之间。总群体的固定系数Fst为0.12545,遗传分化系数Gst为0.06326,总基因流Nm为3.49,且各种群间的基因流均大于1,种群间基因交流的水平较高。【结论】大豆食心虫种群内遗传多样性水平处于中低等水平。总群体和各种群的Tajima’s D检验结果皆不显著,说明中国东北地区大豆食心虫在较近的历史时期内没有出现种群扩张现象。AMOVA分子变异分析结果表明,大豆食心虫的遗传分化主要来自种群内部,而种群间未发生明显的遗传分化。各地理种群的单倍型在系统发育树上和中介网络图上散布在不同的分布群中,缺乏明显的地理分布格局。各种群的遗传距离与地理距离之间没有显著线性相关性,种群间的基因交流并未受到地理距离的影响。     

Asian Elephants in China: Estimating Population Size and Evaluating Habitat Suitability

We monitored the last remaining Asian elephant populations in China over the past decade. Using DNA tools and repeat genotyping, we estimated the population sizes from 654 dung samples collected from various areas. Combined with morphological individual identifications from over 6,300 elephant photographs taken in the wild, we estimated that the total Asian elephant population size in China is between 221 and 245. Population genetic structure and diversity were examined using a 556-bp fragment of mitochondrial DNA, and 24 unique haplotypes were detected from DNA analysis of 178 individuals. A phylogenetic analysis revealed two highly divergent clades of Asian elephants, α and β, present in Chinese populations. Four populations (Mengla, Shangyong, Mengyang, and Pu’Er) carried mtDNA from the α clade, and only one population (Nangunhe) carried mtDNA belonging to the β clade. Moreover, high genetic divergence was observed between the Nangunhe population and the other four populations; however, genetic diversity among the five populations was low, possibly due to limited gene flow because of habitat fragmentation. The expansion of rubber plantations, crop cultivation, and villages along rivers and roads had caused extensive degradation of natural forest in these areas. This had resulted in the loss and fragmentation of elephant habitats and had formed artificial barriers that inhibited elephant migration. Using Geographic Information System, Global Positioning System, and Remote Sensing technology, we found that the area occupied by rubber plantations, tea farms, and urban settlements had dramatically increased over the past 40 years, resulting in the loss and fragmentation of elephant habitats and forming artificial barriers that inhibit elephant migration. The restoration of ecological corridors to facilitate gene exchange among isolated elephant populations and the establishment of cross-boundary protected areas between China and Laos to secure their natural habitats are critical for the survival of Asian elephants in this region.     

PHYLOGEOGRAPHY OF THE ASIAN ELEPHANT (ELEPHAS MAXIMUS) BASED ON MITOCHONDRIAL DNA

Abstract Populations of the Asian elephant (Elephas maximus) have been reduced in size and become highly fragmented during the past 3000 to 4000 years. Historical records reveal elephant dispersal by humans via trade and war. How have these anthropogenic impacts affected genetic variation and structure of Asian elephant populations? We sequenced mitochondrial DNA (mtDNA) to assay genetic variation and phylogeography across much of the Asian elephant's range. Initially we compare cytochrome b sequences (cyt b) between nine Asian and five African elephants and use the fossil‐based age of their separation (～5 million years ago) to obtain a rate of about 0.013 (95% CI = 0.011–0.018) corrected sequence divergence per million years. We also assess variation in part of the mtDNA control region (CR) and adjacent tRNA genes in 57 Asian elephants from seven countries (Sri Lanka, India, Nepal, Myanmar, Thailand, Malaysia, and Indonesia). Asian elephants have typical levels of mtDNA variation, and coalescence analyses suggest their populations were growing in the late Pleistocene. Reconstructed phylogenies reveal two major clades (A and B) differing on average by HKY85/Γ‐corrected distances of 0.020 for cyt b and 0.050 for the CR segment (corresponding to a coalescence time based on our cyt b rate of ～1.2 million years). Individuals of both major clades exist in all locations but Indonesia and Malaysia. Most elephants from Malaysia and all from Indonesia are in well‐supported, basal clades within clade A, thus supporting their status as evolutionarily significant units (ESUs). The proportion of clade A individuals decreases to the north, which could result from retention and subsequent loss of ancient lineages in long‐term stable populations or, perhaps more likely, via recent mixing of two expanding populations that were isolated in the mid‐Pleistocene. The distribution of clade A individuals appears to have been impacted by human trade in elephants among Myanmar, Sri Lanka, and India, and the subspecies and ESU statuses of Sri Lankan elephants are not supported by molecular data.     

Reconciling apparent conflicts between mitochondrial and nuclear phylogenies in African elephants

Conservation strategies for African elephants would be advanced by resolution of conflicting claims that they comprise one, two, three or four taxonomic groups, and by development of genetic markers that establish more incisively the provenance of confiscated ivory. We addressed these related issues by genotyping 555 elephants from across Africa with microsatellite markers, developing a method to identify those loci most effective at geographic assignment of elephants (or their ivory), and conducting novel analyses of continent-wide datasets of mitochondrial DNA. Results showed that nuclear genetic diversity was partitioned into two clusters, corresponding to African forest elephants (99.5% Cluster-1) and African savanna elephants (99.4% Cluster-2). Hybrid individuals were rare. In a comparison of basal forest "F" and savanna "S" mtDNA clade distributions to nuclear DNA partitions, forest elephant nuclear genotypes occurred only in populations in which S clade mtDNA was absent, suggesting that nuclear partitioning corresponds to the presence or absence of S clade mtDNA. We reanalyzed African elephant mtDNA sequences from 81 locales spanning the continent and discovered that S clade mtDNA was completely absent among elephants at all 30 sampled tropical forest locales. The distribution of savanna nuclear DNA and S clade mtDNA corresponded closely to range boundaries traditionally ascribed to the savanna elephant species based on habitat and morphology. Further, a reanalysis of nuclear genetic assignment results suggested that West African elephants do not comprise a distinct third species. Finally, we show that some DNA markers will be more useful than others for determining the geographic origins of illegal ivory. These findings resolve the apparent incongruence between mtDNA and nuclear genetic patterns that has confounded the taxonomy of African elephants, affirm the limitations of using mtDNA patterns to infer elephant systematics or population structure, and strongly support the existence of two elephant species in Africa.     

Population differentiation within and among Asian elephant (Elephas maximus) populations in southern India

Southern India, one of the last strongholds of the endangered Asian elephant (Elephas maximus), harbours about one-fifth of the global population. We present here the first population genetic study of free-ranging Asian elephants, examining within- and among-population differentiation by analysing mitochondrial DNA (mtDNA) and nuclear microsatellite DNA differentiation across the Nilgiris-Eastern Ghats, Anamalai, and Periyar elephant reserves of southern India. Low mtDNA diversity and 'normal' microsatellite diversity were observed. Surprisingly, the Nilgiri population, which is the world's single largest Asian elephant population, had only one mtDNA haplotype and lower microsatellite diversity than the two other smaller populations examined. There was almost no mtDNA or microsatellite differentiation among localities within the Nilgiris, an area of about 15,000 km2. This suggests extensive gene flow in the past, which is compatible with the home ranges of several hundred square kilometres of elephants in southern India. Conversely, the Nilgiri population is genetically distinct at both mitochondrial and microsatellite markers from the two more southerly populations, Anamalai and Periyar, which in turn are not genetically differentiated from each other. The more southerly populations are separated from the Nilgiris by only a 40-km-wide stretch across a gap in the Western Ghats mountain range. These results variably indicate the importance of population bottlenecks, social organization, and biogeographic barriers in shaping the distribution of genetic variation among Asian elephant populations in southern India.     

Conserving small and fragmented populations of large mammals: Non-invasive genetic sampling in an isolated population of Asian elephants in Nepal

The Terai is one of the world's most spectacular landscapes, encompassing parts of Nepal and northern India. This area used to harbour large and continuous populations of charismatic species like elephants, tigers and rhinoceros. However, recent habitat fragmentation reduced these populations into small, partially or completely isolated remnants. The largest of these fragments in Nepal is the Bardia National Park. Here, the elephant population was functionally extinct in the early 1970s and -80s, but was rescued by a considerable number of immigrants in 1994. In order to assess population size, sex ratio, age structure, and levels of genetic variation, we carried out non-invasive genetic sampling, using elephant dung as the source of DNA. A capture-mark-recapture estimate of population size suggested that there were 57 individuals in the study area, which agrees well with field observations. Notably, a strongly male-biased sex ratio was evident among sub-adult individuals. This observation suggests the presence of sub-adult immigrants in the population, which was supported by formal migrant detection analysis. Genetic variation was quite high and the evidence for male immigrants suggests that there are good prospects for maintenance of genetic diversity. A decade ago a large-scale project was initiated in the Terai region to link remaining populations of large mammals through dispersal corridors. The program is basically founded on the assumption that habitat fragments are isolated with little or no migration between them. Our results indicate that this may not be the case, at least not for the Asian elephant in western Nepal, which therefore reduces the alleged extinction risk from genetic erosion and stochastic demographic events.     

云南南滚河国家级自然保护区亚洲象种群旱季生境选择及保护策略

以云南南滚河国家级自然保护区内的亚洲象种群为研究对象,利用村寨调查、样线调查和3S (GIS、GPS、RS)技术对该地区野生亚洲象的栖息地状况和亚洲象在旱季对栖息地选择利用进行了初步研究。研究结果表明该地区的亚洲象偏好海拔1 000 m 以下的低海拔,坡度小于20°,坡位为平坦的沟谷和山坡的下部,坡向为东南、南、北方向的区域。偏好的植被类型是竹阔混交林和灌丛。本研究还分析了该地区自1988 ～ 2007 年20年间亚洲象栖息地的变化情况,针对目前南滚河种群及其栖息地现状提出了保护策略。     

Liriomyza huidobrensis in Yunnan, China: current distribution and genetic structure of a recently established population

Liriomyza huidobrensis Blanchard (Diptera: Agromyzidae) is a very serious and economically important pest around the world. Liriomyza huidobrensis in China was first reported from Kunming of Yunnan province in 1993. We report here that this pest has recently expanded its distribution, along with a host plant range extension and population explosion. The mitochondrial cytochrome oxidase II gene was sequenced for eight populations from Yunnan. All individuals were identical: no genetic variation was observed between populations either from different geographical localities or from different host plants. The phylogenetic analysis shows that the Yunnan population is grouped into the South American clade, which also includes other recently introduced Asian populations. Together with ecological data and colonization history of this pest, our results suggest that Yunnan population might have an ultimate, albeit not immediate, origin from South American populations.     

Genetic consequences of Pleistocene glaciations for the tundra vole (Microtus oeconomus) in Beringia

Repeated glacial events during the Pleistocene fragmented and displaced populations throughout the northern continents. Different models of the effects of these climate-driven events predict distinct phylogeographic and population genetic outcomes for high-latitude faunas. The role of glaciations in (i) promoting intraspecific genetic differentiation and (ii) influencing genetic diversity was tested within a phylogeographic framework using the rodent Microtus oeconomus. The spatial focus for the study was Beringia, which spans eastern Siberia and northwestern North America, and was a continental crossroads and potential high arctic refugium during glaciations. Variation in mitochondrial DNA (cytochrome b and control region; 214 individuals) and nuclear DNA (ALDH1 intron; 63 individuals) was investigated across the Beringian region. Close genetic relationships among populations on either side of the Bering Strait are consistent with a history of periodic land connections between North America and Asia. A genetic discontinuity observed in western Beringia between members of a Central Asian clade and a Beringian clade is geographically congruent with glacial advances and with phylogeographic discontinuities identified in other organisms. Divergent island populations in southern Alaska were probably initially isolated by glacial vicariance, but subsequent differentiation has resulted from insularity. Tests of the genetic effects of postglacial colonization were largely consistent with expansion accompanied by founder effect bottlenecking, which yields reduced diversity in populations from recently deglaciated areas. Evidence that populations in the Beringian clade share a history of expansion from a low-diversity ancestral population suggests that Beringia was colonized by a small founder population from central Asia, which subsequently expanded in isolation.     

基于微卫星标记的中国东北地区灰飞虱遗传变异及种群遗传结构分析

【目的】本研究旨在明确我国东北地区灰飞虱Laodelphax striatellus种群遗传变异及种群遗传结构,阐明种群间遗传分化与基因流。【方法】利用9对微卫星引物对采自我国东北地区15个地理种群的375头灰飞虱样品进行测序与分析;利用GeneAlex6.51,GENEPOP4.0.9和STRUCTURE 2.3.4等软件分析灰飞虱地理种群间的遗传多样性、遗传分化、基因流及种群遗传结构。【结果】在所分析的375头灰飞虱个体中,各位点平均有效等位基因数Na=6.898;总体上,灰飞虱不同地理种群遗传多样性较高(平均观测杂合度Ho=0.548;平均期望杂合度He=0.582),各种群间基因流较低(Nm=0.660)。UPGMA聚类树、PCoA及STRCTURE分析结果表明,东北地区灰飞虱种群分为两分支:吉林(JL)和沈阳(SY2012,SY2013和SY2014)种群聚为一支;其余种群聚为一支。AMOVA分析结果表明,灰飞虱遗传变异主要来自种群内(87%),种群间变异水平较低(13%)。【结论】中国东北地区灰飞虱遗传多样性较高,不同地理种群存在一定程度的遗传分化,且基因交流较低,存在一定的种群遗传结构。     

Patterns of molecular genetic variation among African elephant populations

The highly threatened African elephants have recently been subdivided into two species, Loxodonta africana (savannah or bush elephant) and L. cyclotis (forest elephant) based on morphological and molecular studies. A molecular genetic assessment of 16 microsatellite loci across 20 populations (189 individuals) affirms species level genetic differentiation and provides robust genotypic assessment of species affiliation. Savannah elephant populations show modest levels of phylogeographic subdivision based on composite microsatellite genotype, an indication of recent population isolation and restricted gene flow between locales. The savannah elephants show significantly lower genetic diversity than forest elephants, probably reflecting a founder effect in the recent history of the savannah species.