中国近海重要生态建群红藻真江蓠的群体遗传多样性

真江蓠(Gracilaria vermiculophylla)是中国近海潮间带生态系统结构组成和功能维持的重要支撑物种, 但有关其群体遗传结构和多样性分布模式的研究目前仍较缺乏。本研究利用线粒体cox1序列对我国近海19个真江蓠地理群体进行了系统发育和群体遗传分析。461个长度为641 bp的cox1序列片段共含有21个多态位点, 产生15个单倍型。基于cox1序列的系统进化分析、单倍型分析和主成分分析显示, 19个真江蓠群体分化为南北两个类群, 其中浙江嵊泗以北的13个群体形成北方类群, 福建厦门以南的6个群体形成南方类群。遗传距离和分子方差分析显示真江蓠南北各类群内的遗传分化较小, 南北类群间的遗传分化达到亚种水平。南北类群间的差异是我国近海真江蓠群体遗传变异的主要来源。     

福建南北泥蚶种内分化的RAPD分析

采用随机扩增多态性DNA(RAPD)技术,对泥蚶在福建以南(广东汕头和湛江)和福建以北(浙江温岭和韩国)种群(分别合称南方类群和北方类群)做了遗传分化研究。由筛选出的20个随机引物共获得103个清晰可辨的RAPD标记,扩增片段长度在250—2500bp。汕头种群与湛江种群,韩国种群与温岭种群之间的最小遗传距离分别为0．0612和0．0692,而南、北类群间的遗传距离却在0．3261-0．4511。类群间近交系数也大于类群内。NJ和UPGMA法构建的系统树均显示汕头种群、湛江种群首先聚在一起,再与温岭种群和韩国种群聚合,说明两个类群发生了较明显的遗传分化,估计与地理隔离有关。     

短柄枹种群遗传多样性的ISSR分析

利用ISSR分子标记方法对分布在浙江省境内的7个短柄枹种群的遗传多样性和遗传分化进行了分析。从100个引物中筛选出12个用于正式扩增的ISSR引物,在7个种群140个个体中共检测到132个位点,其中多态位点118个,多态位点百分率(P)为89.39%,各种群P平均为58.87%。短柄枹总的Shannon信息指数(I)为0.493 3、Nei指数(h)为0.334 7,各种群I平均为0.336 2、h平均为0.229 1。P、I、h均显示云峰种群最高,天台山种群最低。AMOVA分子差异分析表明,67.97%的变异存在于种群内,32.03%的变异存在于种群间,种群间的基因分化系数(G_ST)为0.315 4。短柄枹种群间的基因流为(N_m)为1.085 3。7个种群的平均遗传距离为0.173 9。利用UPGMA法对7个种群进行聚类,结果显示天台山和雪窦山种群聚成一类,其它5个种群聚成另一类。     

大壁虎不同地理居群的遗传变异与分化

以线粒体细胞色素b (Cyt b) 基因作为分子标记，对中国广西12个地区，以及越南和老挝大壁虎(Gekko gecko) 进行序列测定，获得Cyt b基因424 bp的序列片段，共有7个单倍型。以白脊壁虎和沙虎为外群，用邻接法和最大简约法构建了大壁虎不同地理种群的系统发育关系，其结果显示中国广西4个不同单倍型黑大壁虎之间的平均遗传距离为0.20%—1.20%，越南红大壁虎与老挝红大壁虎之间的平均遗传距离为0.50%，广西宁明红大壁虎与越南红大壁虎和老挝红大壁虎之间平均遗传距离分别为1.70%和2.20%。广西黑大壁虎种群与红大壁虎种群之间的平均遗传距离为8.60%—9.50%，达到了亚种或种分化的差异。     

日本岛屿山茶种群遗传结构的ISSR分析

为查明日本岛屿山茶种群的生存状况及了解岛屿隔离对山茶种群遗传结构的影响,采用ISSR分子标记,利用筛选的20条引物对日本5个山茶（Camellia japonica）种群的遗传结构进行分析。结果表明：山茶种群的多态位点百分比（PPB）为70.29％,Nei’s基因多样性指数（H_E）为0.281 9,Shannon信息多态性指数（H）为0.409 5,与其它岛屿种群相比遗传多样性水平较高,表明山茶种群的生存状况较好。基因分化系数G_st=0.205 7,种群间具有较高的遗传分化;地理距离与遗传距离具有显著相关性（r=0.821 7,p<0.05）,UPGMA也将同岛种群聚在一起,表明岛屿隔离对山茶种群的遗传分化具有重要影响。借鉴日本岛屿山茶种群的保护经验,建议加强我国岛屿山茶种群的就地保护力度,同时建立山茶种质资源库,促进基因交流。     

珍稀濒危植物长叶红砂种群遗传多样性的ISSR分析

采用ISSR分子标记技术,对濒危小灌木长叶红砂(Reaumuria trigyna) 集中分布的5个种群的遗传多样性水平和遗传结构进行了研究。14条引物共检测到114个位点,其中99个为多态位点,多态位点比率为86.84％,长叶红砂种群具有较高的遗传多样性。物种水平上Shannon多样性指数(I)为0.468 8,Nei基因多样性指数(H)为0.308 4;种群水平上,多态位点比率P为77.89%,I为0.410 6,H为0.260 9,基因分化系数Gst为0.106 9,揭示了长叶红砂种群遗传变异多存在于种群内,种群间的遗传分化较小,占10.69%。 基因流(Nm)为4.178 7＞1,说明种群间的基因交流,防止了由于遗传漂变导致的遗传分化。聚类分析表明长叶红砂种群遗传距离与地理距离之间无显著的相关性。研究结果说明遗传多样性水平与物种本身特性和所处不同群落有关,濒危植物并不一定表现为遗传变异水平的降低。     

5个泥蚶群体遗传多样性的RAPD分析

采用随机扩增多态性DNA(RAPD)技术 ,对 5个泥蚶群体的遗传多样性进行了研究。在选择的 2 0个随机引物中共检测到 15 4个扩增片段 ,长度在 30 0bp～ 2 30 0bp之间 ,每个个体扩增条带在 1～ 11条不等。利用Popgen3.2和PHILIP统计软件 ,获得实验数据 ,确立了 5个群体间的亲缘关系。结果表明 :( 1)泥蚶的 5个地理群体分化不明显 ,没有形成不同的地理种群 ;( 2 )聚类分析显示 ,韩国群体与浙江群体亲缘关系最近 ,然后依次为山东群体和福建群体 ;( 3) 5个群体无论是在多态位点比例还是在平均遗传杂合度上都处于较高水平 ,说明泥蚶当前种质资源状况良好 ,遗传多样性水平较高 ,泥蚶养殖有很好的发展前景 ;( 4)与韩国野生群体相比 ,其他 4个泥蚶群体在多态位点比例和遗传平均杂合度上都有不同程度的降低 ,表明人为等因素已经开始影响到泥蚶的种质资源状况。因此 ,为持续发展泥蚶养殖业 ,必须加强保护泥蚶现有的种质资源并制定相应的渔业管理措施。     

花楸树天然群体的遗传多样性研究

花楸树(Sorbus pohuashanensis)是我国北方一种观赏兼经济用途的树种。本研究采用水平淀粉凝胶同工酶电泳技术, 对采自山东、山西、河北、辽宁4个省的8个花楸树天然群体的种子样本进行了分析, 旨在了解花楸树天然群体的遗传多样性和遗传结构, 为该树种的保护与利用提供科学依据。4个酶系统10个位点的检测结果表明, 花楸树群体水平上的遗传多样性较高, 每位点平均等位基因数(N_a)为2.2000, 多态位点百分率(P)为100%, 期望杂合度(H_e)为0.4240。花楸树8个群体间的有效等位基因数(N_e)、H_e和Shannon信息指数差异较小,3个指标从高到低依次为: 河北驼梁山＞河北雾灵山＞山西庞泉沟＞河北白石山＞山东崂山＞河北塞罕坝＞山东泰山＞辽宁老秃顶子。群体间遗传分化系数(F_st)为0.0758, 群体间总的基因流较高(N_m = 3.0472), 群体间遗传一致度较高(I为0.8585– 0.9872), 表明群体间遗传分化程度小。在单个群体中, 通过χ2检验, 花楸树群体有73.62%的位点组合显著偏离Hardy-Weinberg平衡(P＜0.05), 总群体水平近交系数(F_it)和单个群体水平近交系数(F_is)分别为–0.3105和–0.4180, 表明无论在总体水平还是群体内个体间, 花楸树群体表现为杂合体过量的现象。UPGMA聚类结果显示, 8个群体的遗传距离与地理距离相关性不显著。     

茶园黑刺粉虱(Aleurocanthus spiniferus)种群的RAPD多样性

用RAPD技术对华东地区7个茶园的黑刺粉虱种群进行遗传结构分析。从40个随机引物中筛选出9条具特异性的引物,扩增出248条长度约为200~2000 bp的DNA条带,其中199条多态性条带,多态性为80.24 %。经Popgene软件分析,黑刺粉虱种群平均水平的多态位点百分比 (PPL) 为48.33 %, Nei’s 基因多样性 (HE) 为0.2910, Shannon’s多态性信息指数 (H) 为0.4442,表明黑刺粉虱种群遗传多样性丰富;各种群间遗传分化程度 (Gst) 较高,达0.3749,其中PPL以福建武夷山区的九龙山种群 (JLS) 最高,达77.42 %,其次为安徽九华山种群 (JHS) 的65.73 %;而且两种群的HE, H 等遗传指标均较高。以NTSYSpc软件包,基于Nei’s遗传距离对昆虫个体进行UPGMA和NJ法聚类分析,构建分子系统树,并进行多维标度分析 (MDS) 。系统树显示：同一种群的个体优先聚类,遗传相似度高的种群依次聚类。多维标度分析也显示：浙江杭州、富阳和绍兴3种群集中分布,安徽宣城种群靠近该3种群;而九华山种群则与武夷山区的九龙山种群聚拢;福建金山种群独立成簇。多维标度分析与聚类分析结果一致。认为粉虱种群间的遗传距离与地理距离之间存在相关性;两个山地种群的多样性有别于其它种群,是因为山地环境和气候引起粉虱适应性的生态地理分化。     

白沙蒿不同地理种群遗传分化的ISSR分析

运用ISSR技术,对白沙蒿的5个种群进行遗传分化的分析。12个引物在108个个体中共扩增出222个位点,其中,多态位点为218个,多态位点百分率为98.20%,Shannon多样性指数为0.315 4,具有高的多态性。种群间的遗传分化系数（G_st）为0.076 7,与AMOVA分析的结果一致（Ф_st为7.96%）,表明绝大多数的遗传变异存在于种群内部。各种群间遗传一致度高达98%以上,遗传距离很小,基因流达3.008 2,均表现出白沙蒿各种群存在着广泛的基因交流,有着很小的遗传分化。     

Phylogenetic study and barcoding of the blood cockle, Tegillarca granosa, found on the west coast of peninsular Malaysia using the COI gene

Blood cockles are among the most economically important brackish water invertebrates found in Malaysia. However, our knowledge of blood cockle phylogeny and systematics is rudimentary, especially for the species Tegillarca granosa. It is unclear, for instance, whether the cockles occurring on the west coast of peninsular Malaysia constitute a single species, or multiple, phylogenetically distinct species. We performed the first DNA molecular phylogenetic analysis of T. granosa to distinguish it from other related species found in other parts of the world and to create a DNA database for the species. An approximately 585-nucleotide fragment of the mitochondrial DNA (cytochrome oxidase I, COI) was sequenced for 150 individual cockles, representing 10 populations: three from the north, four from the central part and three from the southern part of peninsular Malaysia. Phylogenetic analyses of the resulting dataset yielded tree topologies that not only showed the relationship between T. granosa and its closest relatives but its position in the evolutionary tree. Three mitochondrial clades were evident, each containing an individual genus. Using the mutation rate of the COI gene, the divergence time between T. granosa and its closest related species was estimated to be 460 thousand years ago. This study provides a phylogenetic framework for this ecologically prominent and commercially important cockle species.     

Genetic variation of Mytilus coruscus Gould (Bivalvia: Mytilidae) populations in the East China Sea inferred from mtDNA COI gene Sequence

In order to characterize the genetic relationship of six populations of Mytilus coruscus Gould in the East China Sea, a 681 bp region of mtDNA COI gene was sequenced and analyzed. Eighty four individuals in total were collected from three cultured populations and three wild populations from three localities of the coast of East China Sea. The sequences from these different populations identified 62 polymorphic sites, which included 41 singleton variable sites and 21 parsimony informative sites that defined 45 distinct haplotypes. Phylogenetic analysis showed that most haplotypes were highly interconnected with each other. Thirty seven of the 45 haplotypes were only found in their own populations, seven were found at two-four localities and only haplotype NO.2 was found in all six populations, indicating that most haplotypes were locally restricted. All haplotypes had shaped two similar branches, each including individuals from all six strains. The results of F_ST values indicated that the genetic distances between populations are not closely associated with their geographic distances.     

COI-based DNA barcoding of Arcoida species (Bivalvia: Pteriomorphia) along the coast of China

DNA barcoding is a promising tool for the rapid and unambiguous identification of species. Some arcoid species are particularly difficult to distinguish with traditional morphological identification owing to phenotypic variation and the existence of closely related taxa. Here, we apply DNA barcoding based on mitochondrial cytochrome c oxidase I gene (COI) to arcoid species collected from the coast along China. Combining morphology with molecular data indicates the 133 specimens of Arcoida could be assigned to 24 species. Because of the deep genetic divergence within Tegillarca granosa, there was an overlap between genetic variation within species and variation between species. Nevertheless, NJ and Bayesian trees showed that all species fell into reciprocally monophyletic clades with high bootstrap values. Our results evidence that the COI marker can efficiently identify species, correct mistakes caused by morphological identification and reveal genetic differentiation among populations within species. This study provides a clear example of the usefulness of barcoding for arcoid identification. Furthermore, it also lays a foundation for other biological and ecological studies of Arcoida.     

湖北省烟粉虱生物型鉴定

本研究利用mtDNA COI基因片段作标记,通过序列分析对湖北省烟粉虱Bemisa tabaci(Gennadius)生物型进行了鉴定。结果表明当阳、仙桃、天门、监利、宜昌和武汉6个地理种群烟粉虱的720bp COI基因序列的同源性高达100%,且该6个地理种群烟粉虱与USA-Q型烟粉虱、湖北Q型烟粉虱的同源性也高达100%。枣阳地区烟粉虱与Israel-B型烟粉虱、我国浙江B型烟粉虱、我国湖北B型烟粉虱的同源性为100%。由此可见当阳、仙桃、天门、监利、宜昌和武汉6个地区烟粉虱生物型属于Q型,仅枣阳地区烟粉虱属于B型。     

Genetic diversity and population connectivity of the Asian green mussel Perna viridis in South China Sea,inferred from mitochondria DNA markers

The Asian green mussel Perna viridis is ecologically and economically important in the coastal regions of China. In order to characterize the genetic diversity and population connectivity of P. viridis in South China Sea, a 664 bp region of mitochondrial COI gene and a 293 bp region of 16S rRNA gene were sequenced and analyzed for 78 and 92 individuals from four populations in South China Sea, respectively. A total of 15 haplotypes were defined by 14 variable nucleotide sites in COI gene, and 7 haplotypes by 6 variable nucleotide sites in 16S rRNA gene. High haplotype diversity and low nucleotide diversity were observed in COI gene, while moderate haplotype diversity and low nucleotide diversity were observed in 16S rRNA gene. Pairwise F_ST values of COI gene were all negative and those of 16S rRNA gene ranged from −0.01409 to 0.10289. The results showed that no significant genetic divergence (or shallow genetic structure) and high levels of population connectivity among the four populations of P. viridis in South China Sea.     

利用COI基因序列分析长江与澜沧江水系日本沼虾群体的遗传结构

测定了我国长江水系和澜沧江水系的日本沼虾9个群体,共79个个体的线粒体COI基因序列片段(约450bp),结果发现有89个变异位点,共计有46个单倍型。其中云南昆明(KM)群体具有较丰富的遗传多样性(h=1.000,π=0.028),而重庆(CQ)群体的遗传多样性最小(h=0.700,π=0.008)。AMOVA分析表明,群体间的遗传变异占总遗传变异的9.66%,而90.34%的遗传变异源于群体内。采用邻接法(NJ)构建的分子系统树显示,46个单倍型明显地聚为长江中下游和长江上游与澜沧江两个族群。其结果可以为合理开发和利用日本沼虾自然野生资源,以及建立和保护日本沼虾种质资源库及基因库提供必要的参考。     

Mitochondrial DNA variation in the caramote prawn <Emphasis Type="Italic">Penaeus (Melicertus) kerathurus</Emphasis> across a transition zone in the Mediterranean Sea

In this study we analysed mitochondrial DNA variation in Penaeus kerathurus prawns collected from seven locations along a transect across the Siculo–Tunisian region in order to verify if any population structuring exists over a limited geographical scale and to delineate the putative transition zone with sufficient accuracy. Partial DNA sequences of COI and 16S genes were analysed. In contrast to the highly conservative 16S gene, the COI sequences exhibited sufficient diversity for population analysis. The COI gene revealed low levels of haplotype and nucleotide diversities. The size of the annual landings of this commercial species suggests large population sizes. Hence, the low genetic diversity detected in this study could indicate a possible reduction in effective population sizes in the past. We detected significant genetic differentiation between eastern and western populations likely due to restricted gene flow across the Siculo–Tunisian boundary. We discuss the different evolutionary forces that may have shaped the genetic variation and suggest that the genetic divide is probably maintained by present-day dispersal limitation. R. Zitari-Chatti and N. Chatti are contributed equally to the work.     

Genetic diversity of cultured populations of giant freshwater prawn (Macrobrachium rosenbergii) in China using mtDNA COI and 16S rDNA markers

Partial sequences of mitochondrial DNA 16S rDNA and COI genes (395 bp and 498 bp respectively) were sequenced from samples of ten cultured populations of Macrobrachium rosenbergii (Giant Freshwater Prawn – GFP) in Zhejiang, Guangdong and Guangxi Provinces in China and two wild populations of GFP from Mekong River and Dongnai River in Viet Nam. Five haplotypes of 16S rDNA were identified in the 360 samples. The wild populations displayed nucleotide diversity (π) of 0.0008 and 0.0003, and genetic diversity (h) of 0.3030 and 0.1310 in the Mekong River and Dongnai River respectively. The cultured populations displayed no significant genetic diversity. COI sequences identified 17 haplotypes based on 21 polymorphic sites. At this marker, the 12 populations showed a range of h from 0.1290 to 0.6940 and π from 0.0003 to 0.0073. The largest genetic distance (Da) among the 12 populations was 0.0065 (between ZJB and BT/DN populations) and the lowest Da was 0.0003 (between GDD and GDA populations). The wild populations had higher genetic diversity than the cultured populations, but three of cultured populations from Zhejiang (ZJA, ZJB and ZJC) had π higher than wild populations, because they originated from Thailand, Bangladesh and the Mekong River in Viet Nam.