两种邻域分布石鸡间的线粒体DNA渗透

采用聚合酶链式反应(PCR)和mtDNA细胞色素b基因314 bp核苷酸序列测定等方法,证明在大石鸡与山石鸡的异域种群之间存在广泛的差异.然而采自六盘山地区与山石鸡相邻分布的大石鸡种群的样本中却存在山石鸡的mtDNA基因型,这种基因型与其它大石鸡个体的基因型有4.4%核苷酸差异.在与山石鸡相邻分布的大石鸡种群中有25%的个体具有山石鸡的mtDNA基因型,而采自六盘山接触地带以西约200 km处兰州市郊的大石鸡标本中则没有发现这种基因型.此发现支持山石鸡和大石鸡之间存在或曾经有过杂交的假设.作者还提出了一种限制性内切酶分析方法,可以快速地检测这种mtDNA基因型.在此之前还没有过关于山石鸡和大石鸡之间基因流动的报道.     

扬子鳄饲养种群线粒体DNA控制区的序列多态性

扬子鳄(Alligator sinensis)是中国特有的珍稀爬行动物,至2000年,野生扬子鳄的个体数已不足150条,作为保护这一物种的措施之一,先后于80年代初建起了2个养殖场,现人工繁殖的扬子鳄总数已达9000余条。为揭示扬子鳄种群遗传多样性,从两个饲养种群中采集了42个个体的样品,其中宣州样品33个(xZSP),长兴样品9个(CxSP),用PCR方法扩增mtDNA控制区,扩增产物纯化后直接用ABI310全自动遗传分析仪荧光标记测序,得到其中39个个体的血DNA控制区5’端462bP的序列。经比对发现,39个个体间的5’端mtDNA控制区没有任何变异位点,共享一种单元型,提示扬子鳄饲养种群的遗传多样性非常贫乏,造成这一结果的主要原因是近50年来,扬子鳄种群衰退和数量迅速减少导致的遗传多样性丢失,其次是人工繁殖的群体同时受到始创者数量较少产生的瓶颈效应影响。针对扬子鳄遗传多样性的现状,作者最后就这一濒危动物遗传多样性的保护对策提出3点建议。     

白鱼线粒体DNA控制区结构和种群遗传多样性分析

用特异性引物对白鱼(Anabarilius grahami)DNA进行PCR扩增,获得了白鱼线粒体DNA控制区基因全序列(930bp)。控制区T、C、A和G碱基组成为29.8%、22.5%、33.0%和14.7%。对照其他已报道的鱼类控制区结构,对白鱼控制区结构进行了分析,识别了其终止序列区、中央保守区和保守序列区,找到了终止相关的序列TAS以及保守序列(CSB-F、CSB-D、CSB-1、CSB-2、CSB-3)。同时运用DNA分析软件对白鱼一个驯养种群(中国科学院昆明动物研究所珍稀鱼类繁育中心)及两个自然地理种群(江川县明星鱼洞、江川县牛摩村)进行了遗传多样性分析。结果显示:两个自然种群存在较强基因交流,未出现遗传分化;人工驯养种群遗传多样性最高,种群复壮程度较好。     

白鱼线粒体DNA控制区结构和种群遗传多样性分析

用特异性引物对白鱼（Anabarilius grahami）DNA进行PCR扩增,获得了白鱼线粒体DNA控制区基因全序列（930 bp）。控制区T、C、A和G碱基组成为29.8%、22.5%、33.0%和14.7%。对照其他已报道的鱼类控制区结构,对白鱼控制区结构进行了分析,识别了其终止序列区、中央保守区和保守序列区,找到了终止相关的序列TAS以及保守序列（CSB-F、CSB-D、CSB-1、CSB-2、CSB-3）。同时运用DNA分析软件对白鱼一个驯养种群（中国科学院昆明动物研究所珍稀鱼类繁育中心）及两个自然地理种群（江川县明星鱼洞、江川县牛摩村）进行了遗传多样性分析。结果显示：两个自然种群存在较强基因交流,未出现遗传分化;人工驯养种群遗传多样性最高,种群复壮程度较好。     

红腹锦鸡线粒体DNA控制区结构和遗传变异研究

红腹锦鸡(Chrysolophus pictus)是中国特有珍稀鸟类,仅见于中国中部和西部的山地,为国家二级重点保护动物.采用聚合酶链式反应和直接测序的方法测定了采自湖南新宁县和龙山县的28只红腹锦鸡线粒体DNA控制区序列.在获得的1 123 bp的碱基序列中,碱基含量为T 32.79%、C 26.07%、A 26.62%和G14.52%,共检测出20个多态性核苷酸变异位点,其中简约信息位点11个.对比其它已报导的雉类控制区结构,对红腹锦鸡控制区结构进行了分析,识别了其高变Ⅰ区、中间保守Ⅱ区和保守Ⅲ区,找到了与终止相关的序列TAS以及保守序列(F、E、D、C).28个样本共发现11种单倍型,其中单倍型hap1和hap2的比例很高.新宁种群的遗传多样性比龙山种群的高,两个种群存在基因流较频繁,未出现明显遗传分化.     

基于线粒体DNA控制区的斑翅草螽不同地理种群遗传分化研究

采用PCR扩增结合DNA克隆测序技术,分析了斑翅草螽Conocephalus maculates 9个地理种群mtDNA控制区序列的变异及遗传多样性。切除侧翼RNA基因序列后,最终获得的斑翅草螽mtDNA控制区比对后全长为676 bp,平均碱基组成T(37.8%),C(11.7%),A(41.3%)和G(9.1%)。共检测到98个可变位点,占总位点数的14.5%,其中,9处碱基插入/缺失,74处转换(40个T/C,34个A/G),50处颠换(18个A/T,11个T/G,15个A/C,6个C/G)。共定义46个单倍型,其中,4个为种群间共享单倍型(H02、H05、H08和H10),其余42个为各种群独有单倍型,包括6个种群内共享单倍型(H09、H11、H15、H18、H26和H38)。单倍型总数占实验个体总数的69.7%,除四川峨眉山外,其余种群单倍型百分比均﹥50%。通过两两地理种群间的FST值差异显著性检验,将这些群体分为4组,分别为SC+CQ,GX+FLB+HN+YN,XZ和HB。以长瓣草螽C.gladiatus、峨眉草螽C.emeiensis、悦鸣草螽C.melaenus、竹草螽C.bambusanus为外群,构建的斑翅草螽mtDNA控制区单倍型NJ法系统树形成3个自举支持度较高的分支,其中,分支A由28种单倍体组成,包括本研究中除四川峨眉山(SC)和重庆万州(CQ)以外的7个种群;分支B由12种单倍体组成,包含除菲律宾拉乌尼翁(FLB)和江西南昌(JX)以外的7个种群;分支C由6种单倍型组成,全部来自西藏林芝(XZ)的单倍型。聚类结果表明,斑翅草螽不同地理种群间的遗传分化并不明显,即使是两两群体间FST值差异显著的群体,也未能形成完全独立的分支。     

基于线粒体DNA的中国亚洲象种群遗传多样性及种群遗传结构

亚洲象是我国国家一级保护动物.本文利用非损伤性取样法,以亚洲象粪便中脱落的肠道上皮细胞为DNA来源,选用线粒体DNA作为分子标记,对分布于我国境内的亚洲象种群的遗传结构和种群遗传多样性进行研究.本研究得到mtDNA序列片段长度为556 bp,经对178个个体进行扩增结果分析,共得到24个单倍型.在5个地理种群中,除南滚河种群外,其他4个种群中的114个个体共享同一单倍型,南滚河种群与其他种群间未观察到共享单倍型.系统发生分析,观察到中国境内现有亚洲象种群在进化上分为两大分支,α和β.其中分支α中包含除南滚河种群外的4个地理种群,分支β仅含有南滚河种群,表明南滚河种群与其他4个地理种群间存在明显分化.遗传多样性分析结果表明,中国境内的亚洲象种群的遗传多样性水平较低,分析原因认为是栖息地破碎化阻断了种群间有效的基因交流.     

基于线粒体DNA控制区基因讨论雉鸡阿拉善亚种分类地位

雉鸡阿拉善亚种的分类地位存在争议.采用聚合酶链式反应(PCR)和直接测序方法讨论雉鸡阿拉善亚种是否确立.共测定了雉鸡12个种群132个样本的线粒体DNA(mtDNA)控制区(control-region)1 078个碱基长度的基因序列,61个变异位点产生68个单倍型.系统发育树和单倍型网络图结果显示,雉鸡阿拉善亚种是单系枝.雉鸡阿拉善亚种与甘肃亚种的分歧时间(0.15 ～0.23百万年)发生在晚更新世,中国西部干旱化、腾格里沙漠的形成以及贺兰山的存在导致分歧形成.结合系统发生树、单倍型网络图、Fst值(P＜0.001)以及基因流(Msohokhotensis to strauchi=0.006,Mstrauchi to sohokhotensis=0.014),雉鸡阿拉善亚种在其分布区内独立进化.     

三种小型猪线粒体DNA控制区的比较研究

目的分析五指山小型猪、巴马小型猪和贵州香猪线粒体DNA控制区碱基序列,比较研究不同猪种的遗传标志。方法应用PCR技术分别对这三种小型猪的血液总DNA样品中线粒体DNA D-loop区进行扩增,测序比对。结果猪的线粒体DNA D-loop区分3个区域。Ⅰ区（靠近5′端区域）704 bp,五指山小型猪在此区共有6个变异位点,通过6个变异位点中归纳出3个单倍体,而巴马小型猪在此区有9个变异位点,通过9个变异位点归纳出4个单倍体,贵州香猪在此区共有6个变异位点,通过6个变异位点归纳出3个单倍体。     

陇东黄土高原石鸡的遗传多样性与保护

石鸡 (Alectorischukar)是我国北方重要的猎鸟 ,由于栖息地片断化和人类狩猎 ,陇东黄土高原上的石鸡数量正日益减少。本文用PCR直接测序的方法 ,测定了陇东黄土高原 8个石鸡种群mtDNA控制区I区和部分II区的4 91个碱基 ,探讨其遗传多样性。 78个样本共发现 2 4个变异位点 (占所测序列的 4 .89% )和 2 5种单倍型 (占所测样本的 32 .0 5 % )。 8个种群中 ,铜川种群的序列变异率、单倍型多样性和核苷酸多样性都最高 ,分别是 0 .4 7、0 .82和 0 .0 0 2 9;而红回种群的最低 ,仅分别为 0 .10、0 .2 8和 0 .0 0 0 8,这与红回种群受奠基者效应、遗传隔离和自然选择的作用有关。 8个种群共享 1种单倍型C1,说明它们来自共同祖先 ,是 1个单系群 ,属于 1个进化显著单元 ,但它们聚成两个集群。两集群间单倍型相似性指数仅 0 .15 ,遗传距离达 0 .4 3% ,单因素方差分析显示遗传变异差异显著 (F =5 .0 2 >F0 .0 5(14 ,1) =4 .0 6 ) ,分别有 13种和 10种单倍型为两个集群所特有。基于遗传差异性 ,陇东黄土高原的石鸡应分为两个管理单元进行保护 ,尤其对遗传变异和遗传多样性最高的铜川种群应进行重点保护。     

Genetic Evidence of Postglacial Population Expansion in Puget Sound Rockfish (Sebastes emphaeus)

Several rockfish species (genus Sebastes) along the northeastern Pacific Ocean have rapidly declined in abundance owing in part to overfishing. A striking exception is the dwarf-like Puget Sound rockfish Sebastes emphaeus, whose densities have increased by several orders of magnitude over the last several decades. To describe their genetic structure, we sequenced 395 bp from the mitochondrial control region of 128 S. emphaeus adults from 5 locations spanning approximately 120 km of the Northwest Straits of Washington state. We detected no significant genetic differentiation among these populations and substantial genetic variation within populations, a pattern that may indicate high levels of ongoing gene flow. Preliminary data from 2 microsatellite loci are also consistent with panmixia. The mtDNA sequences also suggest that Puget Sound rockfish populations have expanded substantially since the retreat of Pleistocene glaciers made habitat in Puget Sound region available approximately 12,000 years ago.     

六盘山地区石鸡和大石鸡间的渐渗杂交

在六盘山地区发现鹑类的两种鸟类石鸡和大石鸡进行杂交,本实验采用PCR和RFLP的方法,分析了六盘山西侧20个大石鸡和东侧36个石鸡的mtDNA基因,发现宁夏海原5个和甘肃庄浪8个的大石鸡具有石鸡的基因型,说明这可能是雌性石鸡与雄性大石鸡杂交的结果,在六盘山东侧石鸡种群中没有发现大石鸡的基因型,其基因是从石鸡到大石鸡的单向流动。杂交后代的形态与大石鸡相似且体型比双亲都大。这种渐渗杂交可能是杂交个体与雄性大石鸡回交的结果。根据分子钟推测,这种不对称的基因流动,可能是由于冰期隔离后次级相遇形成的。杂交种可与雄性大石鸡回交。虽然还需要加大样本量来进一步研究这种不对称基因流动,但是持续的渐渗杂交会导致大石鸡基因的灭绝     

GENETIC STRUCTURE AND MALE-MEDIATED GENE FLOW IN THE GHOST BAT (MACRODERMA GIGAS)

The Australian ghost bat is a large, opportunistic carnivorous species that has undergone a marked range contraction toward more mesic, tropical sites over the past century. Comparison of mitochondrial DNA (mtDNA) control region sequences and six nuclear microsatellite loci in 217 ghost bats from nine populations across subtropical and tropical Australia revealed strong population subdivision (mtDNA φ_ST = 0.80; microsatellites UR_ST = 0.337). Low-latitude (tropical) populations had higher heterozygosity and less marked phylogeographic structure and lower subdivision among sites within regions (within Northern Territory [NT] and within North Queensland [NQ]) than did populations at higher latitudes (subtropical sites; central Queensland [CQ]), although sampling of geographically proximal breeding sites is unavoidably restricted for the latter. Gene flow among populations within each of the northern regions appears to be male biased in that the difference in population subdivision for mtDNA and microsatellites (NT φ_ST = 0.39, UR_ST = 0.02; NQ φ_ST = 0.60, UR_ST = ?0.03) is greater than expected from differences in the effective population size of haploid versus diploid loci. The high level of population subdivision across the range of the ghost bat contrasts with evidence for high gene flow in other chiropteran species and may be due to narrow physiological tolerances and consequent limited availability of roosts for ghost bats, particularly across the subtropical and relatively arid regions. This observation is consistent with the hypothesis that the contraction of the species' range is associated with late Holocene climate change. The extreme isolation among higher-latitude populations may predispose them to additional local extinctions if the processes responsible for the range contraction continue to operate.     

Drastic post‐LGM expansion and lack of historical genetic structure of a subtropical fig‐pollinating wasp (Ceratosolen sp. 1) of Ficus septica in Taiwan

The climatic oscillations of the last glacial period have had profound influences on the demography and levels of genetic diversity of extant species. Molecular evidence of glacial effects on temperate species has been well documented, whereas little is known regarding that on subtropical species. Here we present analyses based on partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene (1052 bp) and genotypes at 15 microsatellite loci to investigate the historical demography, population structure and ongoing gene flow of an undescribed fig‐pollinating wasp (Ceratosolen sp. 1) of Ficus septica in subtropical Taiwan. Reconstructed historical demography based on the coalescent tree of COI sequences suggests that C. sp. 1 has undergone a drastic population expansion which was tightly coupled with climatic changes since the last glacial maximum (LGM). The magnitude of the population size change was approximately 500‐fold, indicating that the population of this wasp and its host was likely highly compressed during the last glacial period. The lack of significant population differentiation (F_ST < 0.02, for all pairwise F_ST values) may be due to rapid postglacial expansion facilitated by long‐distance dispersal, although a low frequency of first‐generation migrants was detected. Our results clearly demonstrate how recent climatic changes since the LGM and dispersal ability have jointly shaped the genetic composition of a subtropical fig‐pollinating wasp.