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。     

Molecular systematics of the Philippine malaria vector Anopheles flavirostris

Allozyme and molecular sequence data from the malaria vector Anopheles flavirostris (Ludlow) (Diptera: Culicidae) were analysed from 34 sites throughout the Philippines, including the type locality, to test the hypothesis that this taxon is a single panmictic species. A finer-scaled allozyme study, of mainly Luzon samples, revealed no fixed genetic differences in sympatric sites and only low levels of variation. We obtained data from partial sequences for the internal transcribed spacer 2 (ITS2) (483 bp), the third domain (D3) (330 bp) of the 28S ribosomal DNA subunit and cytochrome c oxidase subunit I (COI) of mitochondrial DNA (261 bp). No sequence variation was observed for ITS2, only a one base pair difference was observed between Philippine and Indonesian D3 sequences and An. flavirostris sequences were unique, confirming their diagnostic value for this taxon. Sixteen COI haplotypes were identified, giving 25 parsimony informative sites. Neighbour-Joining, Maximum Parsimony, Maximum Likelihood and Bayesian phylogenetic analysis of COI sequences for An. flavirostris and outgroup taxa revealed strong branch support for the monophyly of An. flavirostris, thus confirming that Philippine populations of this taxon comprise a single separate species within the Minimus Subgroup of the Funestus Group. Variation in the behaviour of An. flavirostris is likely to be intraspecific rather than interspecific in origin.     

Taxonomic status of two South American sympatric squat lobsters, Munida gregaria and Munida subrugosa (Crustacea: Decapoda: Galatheidae), challenged by DNA sequence information

We investigated the taxonomic status of two sympatric morphospecies of squat lobsters from southern South America (Beagle Channel, Strait of Magellan, and Burdwood Bank), Munida gregaria and Munida subrugosa , by DNA sequence analysis of three mitochondrial (mt)DNA gene fragments [416 bp of 16S rDNA(165), 566 bp of cytochrome c oxidase subunit I(COI) and 418 bp of NADH dehydrogenase subunit 1 (ND1)]; and the nuclear rDNA internal transcribed spacer (ITS) 1 (883–952 bp). We obtained a total of 79 sequences from 32 individuals. The 16S sequences of all M. gregaria and M. subrugosa were invariant and identical, whereas COI and ND1 showed 12 and 15 variable sites, respectively. These polymorphisms were shared between morphospecies. Interspecific Tamura–Nei distances for COI and ND1 sequences were 0.0024 and 0.0032, respectively, and were not significantly different from intraspecific distances (Kruskal–Wallis tests: P  = 0.58 and P  = 0.69, for COI and ND1, respectively). Similar to the results obtained from the mtDNA sequences, no relationship was found between the ITS1 maximum parsimony tree topology and the morphologic classification of specimens in M. gregaria and M. subrugosa . We conclude that M. gregaria and M. subrugosa from southern South America may either represent a case of a dimorphic species, or a case of incomplete lineage sorting. The fact that these two morphospecies did not show fixed differences over a total of 1947 bp analysed reinforces the hypothesis of a single dimorphic species.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 421–434.     

DNA barcoding identifies Eimeria species and contributes to the phylogenetics of coccidian parasites (Eimeriorina, Apicomplexa, Alveolata)

Partial (～ 780 bp) mitochondrial cytochrome c oxidase subunit I (COI) and near complete nuclear 18S rDNA (～ 1,780 bp) sequences were directly compared to assess their relative usefulness as markers for species identification and phylogenetic analysis of coccidian parasites (phylum Apicomplexa). Fifteen new COI partial sequences were obtained using two pairs of new primers from rigorously characterised (sensu Reid and Long, 1979) laboratory strains of seven Eimeria spp. infecting chickens as well as three additional sequences from cloned laboratory strains of Toxoplasma gondii (ME49 and GT1) and Neospora caninum (NC1) that were used as outgroup taxa for phylogenetic analyses. Phylogenetic analyses based on COI sequences yielded robust support for the monophyly of individual Eimeria spp. infecting poultry except for the Eimeria mitis/mivati clade; however, the lack of a phenotypically characterised strain of E. mivati precludes drawing any firm conclusions regarding this observation. Unlike in the 18S rDNA-based phylogenetic reconstructions, Eimerianecatrix and Eimeria tenella formed monophyletic clades based on partial COI sequences. A species delimitation test was performed to determine the probability of making a correct identification of an unknown specimen (sequence) based on either complete 18S rDNA or partial COI sequences; in almost all cases, the partial COI sequences were more reliable as species-specific markers than complete 18S rDNA sequences. These observations demonstrate that partial COI sequences provide more synapomorphic characters at the species level than complete 18S rDNA sequences from the same taxa. We conclude that COI performs well as a marker for the identification of coccidian taxa (Eimeriorina) and will make an excellent DNA 'barcode' target for coccidia. The COI locus, in combination with an 18S rDNA sequence as an 'anchor', has sufficient phylogenetic signal to assist in the resolution of apparent paraphylies within the coccidia and likely more broadly within the Apicomplexa.     

六种灵猫科动物的分子系统关系研究

对六种灵猫科物种线粒体12 S rRNA基因及其中四种的Cytb基因部分序列进行了测定,并从Gen-Bank获得斑林狸(Prionodon pardicolor)、熊狸(Arctictis binturong)的Cytb基因同源序列。两基因整合序列比对后长755 bp,12 S rRNA基因序列中有70个变异位点,31个简约信息位点,在Cytb基因序列中,共有120个位点呈现变异,60个简约信息位点,Cytb基因的碱基变异百分比高于12 S rRNA基因的碱基变异百分比。使用邻接法(NJ)、最大似然法(ML)重建的分子系统树显示:斑林狸从灵猫亚科中分离出来,支持灵猫亚科的多系起源,而且斑林狸可能是中国起源最早且最特化的灵猫科动物。另外,同属于灵猫亚科的大灵猫(Viverra zibe-tha)、小灵猫(Viverricula indica)聚为一支,同属于棕榈狸亚科的果子狸(Viverricula indica)、熊狸聚为姐妹群,这些与传统形态学分类观点一致。     

Genetic structure of the endangered species <Emphasis Type="Italic">Pinna nobilis</Emphasis> (Mollusca: Bivalvia) inferred from mtDNA sequences

This study examines the population genetic structure of the endangered bivalve Pinna nobilis (Mollusca: Bivalvia), based on novel mtDNA sequences (partial COI and 16S rDNA mtDNA genes). The analyzed nucleotide sequences of COI were 729 bp in size, coding for a 243 amino acid peptide, while the analyzed nucleotide sequences of 16S rDNA were 489 bp in size. These sequences of P. nobilis were the first DNA sequences of the species submitted to any Genetic Data Base. Population samples from four geographic regions from Greece, as well as a population sample of Atrina fragilis (as an outgroup) were used. High values of haplotypic diversity were found in the population samples of P. nobilis, based on the COI sequences. A single base in the analyzed 16S rDNA sequences was different in all analyzed individuals from a single population sample (Chios island) differentiating it from the other ones. These mtDNA sequences could be informative for further genetic analyses of the endangered species, contributing in conservation plans for its protection and/or aquaculture investigations.     

Analysis of genetic diversity among different geographical populations and determination of biotypes of Bemisia tabaci in China

Abstract:  Analysis of the genetic diversity among 27 different geographical populations of Bemisia tabaci and determination of biotypes of B. tabaci in China based on amplified fragment-length polymorphism (AFLP) and the mitochondrial cytochrome oxidase I (mtDNA COI) gene sequences were conducted. In AFLP assay, the use of five primer combinations selected from 64 primer combinations allowed the identification of 229 polymorphic bands (97.03%) from 60 to 500 bp, suggesting abundant genetic diversity among different geographical populations of B. tabaci. To further identify biotypes of B. tabaci in China, the mtDNA COI gene sequences of nine representative populations from China, Israel and Spain were obtained. Molecular phylogenetic tree based on AFLP and mtDNA COI gene analyses revealed the presence, in China, of at least four different genetic groups of B. tabaci. B biotype, Q biotype and two non-B/Q biotype. B biotype was distributed nationwide. Q biotype was present only in the local region of China including the YunNan province and BeiJing city. This was also the first report about the invasion of Q biotype into China. Of the other two non-B/Q biotype groups, one was found in ShanDong and HeBei provinces, and another in ZheJiang province. The non-B/Q biotype ZheJiang population showed very high similarity with another Asian population India-IW ( AF110704 ) in mtDNA COI sequences and was possibly a Chinese indigenous population. The close monitoring of the Q biotype in locales of China where commercial plants were exported or imported, is now essential to avoid the further accidental distribution of the Q biotype.     

线蛱蝶亚科蝶类部分类群线粒体COI基因的分子系统发生分析

以线粒体细胞色素氧化酶I（COI）基因作分子标记,对线蛱蝶亚科蝴蝶进行序列测定．序列分析的结果表明．经比对和处理后的序列总长度是645bp,其中有199个变异位点,147个简约信息位点;所编码的氨基酸序列中有18个变异位点,7个信息位点．A＋T平均含量为69．6％,G＋C平均含量为30．4％,碱基组成出现AT偏斜．以蛱蝶亚科及秀蛱蝶亚科物种为外类群,用NJ、MP及贝叶斯法重建了该亚科的系统发生树,探讨了它们主要类群间的系统发生关系．分子系统树显示,线蛱蝶亚科由以下3大支系：环蛱蝶族＋翠蛱蝶族、线蛱蝶族、丽蛱蝶族构成;其中,环蛱蝶族为单系群（NJ树也支持线蛱蝶族的单系性）;翠蛱蝶族与环蛱蝶族亲缘关系较近：丽蛱蝶族可能是该亚科较早分化出的一支．     

Global phylogeography of a cryptic copepod species complex and reproductive isolation between genetically proximate "populations"

The copepod Eurytemora affinis has a broad geographic range within the Northern Hemisphere, inhabiting coastal regions of North America, Asia, and Europe. A phylogenetic approach was used to determine levels of genetic differentiation among populations of this species, and interpopulation crosses were performed to determine reproductive compatibility. DNA sequences from two mitochondrial genes, large subunit (16S) rRNA (450 bp) and cytochrome oxidase I (COI, 652 bp), were obtained from 38 populations spanning most of the species range and from two congeneric species, E. americana and E. herdmani. Phylogenetic analysis revealed a polytomy of highly divergent clades with maximum sequence divergences of 10% in 16S rRNA and 19% in COI. A power test (difference of a proportion) revealed that amount of sequence data collected was sufficient for resolving speciation events occurring at intervals greater than 300,000 years, but insufficient for determining whether speciation events were approximately simultaneous. Geographic and genetic distances were not correlated (Mantel's test; r = 0.023, P = 0.25), suggesting that populations had not differentiated through gradual isolation by distance. At finer spatial scales, there was almost no sharing of mtDNA haplotypes among proximate populations, indicating little genetic exchange even between nearby sites. Interpopulation crosses demonstrated reproductive incompatibility among genetically distinct populations, including those that were sympatric. Most notably, two geographically distant (4000 km) but genetically proximate (0.96% 16S, 0.15% COI) populations exhibited asymmetric reproductive isolation at the F2 generation. Large genetic divergences and reproductive isolation indicate that the morphologically conservative E. affinis constitutes a sibling species complex. Reproductive isolation between genetically proximate populations underscores the importance of using multiple measures to examine patterns of speciation.     

Molecular phylogeny of the nasuta subgroup of Drosophila based on 12S rRNA, 16S rRNA and CoI mitochondrial genes, RAPD and ISSR polymorphisms

The nasuta subgroup is a cluster of morphologically almost similar forms with a wide range of geographic distribution. During the last three decades nature of inter-relationship among the members has been investigated at different levels of organization. The phylogenetic relationships of the members of the nasuta subgroup of the immigrans species group of Drosophila was made by employing Random Amplified Polymorphic DNA (RAPD), Inter Simple Sequence Repeats-PCR (ISSR-PCR) polymorphisms, mitochondrial 12S rRNA, 16S rRNA and Cytochrome C Oxidase subunit I (CoI) gene sequences. The phylogenetic tree generated by RAPD analysis is in nearly complete congruence with the classification based on morphophenotypic characters. The 12S and 16S rRNA genes were highly conserved across the nasuta subgroup and revealed only 3 and 4 variable sites respectively, of which only one site was informative. The CoI gene, on the other hand, revealed 57 variable sites of which 25 sites were informative. All the three species of orbital sheen complex were included in a major cluster in the phylogenetic trees derived from mitochondrial gene sequence data consistent with the morphophenotypic classification. The CoI analysis placed two species of frontal sheen complex, D. n. nasuta and D. n. albomicans in two different clades and this is inconsistent with morphological classification. The molecular clock suggested that divergence between the kohkoa complex and the albomicans complex occurred approximately 2.2 MYA, indicating recent evolution of the nasuta subgroup. The higher transition bias in the mitochondrial genes reported in the present study also suggested recent evolution of the nasuta subgroup.