A salmon id phylogeny inferred from mitochondrial cytochrome b gene sequences

Partial mitochondrial cytochrome b gene sequences of eight salmonid species were used in a PAUP analysis to generate a phylogeny of the group. The four genera represented are Salmo, Salvelinus, Oncorhynchus and Thymallus . The inferred phylogenetic tree coincides well with the classically derived one for these genera. The recent reclassification of the rainbow trout as a member of the genus Oncorhynchus is supported. The assignment of grayling as the outgroup is vindicated. The utility of gene sequence data to infer the phylogenetic relationships of the Salmonidae is discussed.     

Evolutionary implications of analyses of complete mitochondrial genomes across order Zoantharia (Cnidaria: Hexacorallia)

Cnidarians are early-diverging metazoans, but evolutionary aspects of some taxa are still poorly understood, as in the order Zoantharia (Anthozoa: Hexacorallia). Zoantharians have been divided into two suborders based on the arrangement of the fifth septae as complete (Macrocnemina) or incomplete (Brachycnemina). Previous molecular phylogenetic analyses have indicated the need for re-evaluation as Macrocnemina has been found to be paraphyletic. Despite many phylogenetic studies, the recovery of complete mitochondrial genomes (mt-genomes) for systematic and evolutionary studies of zoantharians has been limited. The present study represents the first to sequence the complete mt-genomes of members of eight of nine zoantharian families. Although all examined mt-genomes had the same gene order arrangement, there were variations among mt-genomes' sizes, nucleotide substitution rates, and introns. Only two species did not have the cox1 intron, which harbors a gene coding a homing endonuclease of the LAGLIDADG type. Our mitogenomic analyses also showed relatively high nucleotide diversity in mt-DNA regions other than the standard regions traditionally considered for DNA barcoding of this group. Phylogenetic analyses using 13 mt-genome protein-coding genes recovered a fully resolved tree with clear separation between macrocnemic representatives. Ancestral state reconstruction analyses revealed three main transitions in arrangement of the marginal musculature through the evolutionary history of the order. An “early” transition from reticulate mesogleal to a cteniform endodermal arrangement was followed by transitions that occurred in the common ancestor of the Brachycnemina and family Hydrozoanthidae. Our results indicate the need for clarification of higher-level phylogeny and taxonomy of Zoantharia.     

Geographical Variation of Allele Frequencies at the LDH-A* Locus in the Arctic Grayling Thymallus arcticus Pall. and in the European Grayling Thymallus thymallus L.

The allele frequencies of LDH-A* locus were studied in the populations of Siberian grayling from the Kozhym River (Pechora basin) and in the population of European grayling from Pechora, Mezen', and Vym' rivers (Northern Dvina basin). In samples of both species (n = 134), three LDH-A phenotypes have been identified in total, which proved to be under the control of two alleles: LDH-A*100 and LDH-A*50. The alternative alleles of LDH-A* locus were identified in the populations of Siberian grayling from Kozhym River and in the population of European grayling from the same river and other Pechora tributaries, namely, LDH-A*100 and LDH-A*50 in the Siberian and the European grayling, respectively. However, in the European grayling populations from the Mezen' and Vym' rivers, both alleles occur at the frequencies of the rare LDH-A*100 allele of 0.143 and 0.222, respectively. According to the published data, the frequency of LDH-A*100 allele increases in the European grayling populations of northwestern (Finland) and southern Europe (France) rivers, reaching 0.872 and 1.000 in Rhone and Loire, respectively, i.e., the values characteristic of the Siberian grayling populations.     

访花昆虫野蚜蝇线粒体基因组结构分析

野蚜蝇Syrphus torvus(Osten-Sacken)成虫具访花习性,是重要的传粉昆虫;幼虫捕食蚜虫,是蚜虫重要天敌之一.本研究通过高通量测序、组装拼接获得了完整的野蚜蝇线粒体基因组全序列(GenBank登录号:MW074962),其序列全长为16 444 bp,包含13个蛋白编码基因(PCGs)、22个tRN...     

DNA barcoding of genus Toxoptera Koch (Hemiptera: Aphididae): Identification and molecular phylogeny inferred from mitochondrial COI sequences

Abstract Identification of aphid species is always difficult due to the shortage of easily distinguishable morphological characters. Aphid genus Toxoptera consists of species with similar morphology and similar to Aphis in most morphological characters except the stridulatory apparatus. DNA barcodes with 1 145 bp sequences of partial mitochondrial cytochrome‐coxidase I (COI) genes were used for accurate identification of Toxoptera. Results indicated mean intraspecific sequence divergences were 1.33%, whereas mean interspecific divergences were greater at 8.29% (0.13% and 7.79% if T. aurantii 3 and T. aurantii 4 are cryptic species). Sixteen samples were distinguished to four species correctly by COI barcodes, which implied that DNA barcoding was successful in discrimination of aphid species with similar morphology. Phylogenetic relationships among species of this genus were tested based on this portion of COI sequences. Four species of Toxoptera assembled a clade with low support in maximum‐parsimony (MP) analysis, maximum‐likelihood (ML) analysis and Bayesian phylogenetic trees, the genus Toxoptera was not monophyletic, and there were two sister groups, such as T. citricidus and T. victoriae, and two clades of T. aurantii which probably presented cryptic species in the genus.     

Zoogeographical implications of variation in mitochondrial DNA of Arctic grayling (Thymallus arcticus)

Most of the northern half of North America's freshwater fish survived the last glacial period in unfrozen refugia peripheral to the ice sheets. In our study, the question of which refugia Arctic grayling ( Thymallus arcticus ) inhabited during the Wisconsinan Ice Age, and how they subsequently dispersed to their present geographical range, was examined using mitochondrial DNA (mtDNA) analysis. mtDNA from 12 T. arcticus populations was analysed by direct sequencing and restriction fragment length polymorphism analysis (RFLP). Our data support the hypotheses that T. arcticus had a large refugial population in the Bering Refuge (shown by high mtDNA diversity in extant Alaskan populations) and that British Columbia was colonized from the Bering Refuge (shown by mtDNA haplotype similarities). Our data also show that a disjunct southern set of populations in Montana is significantly different from the northern grayling, in terms of restriction haplotype frequency and distinguishing sequence characteristics. Sequence results yielded an estimated divergence time of 370 000 years between the northern and Montana grayling haplotypes. We conclude that T. arcticus survived the Wisconsinan glaciation in at least two refugia: (i) the Bering Refuge north of the ice sheets; and (ii) either the Upper Missouri or the southwest Alberta Refuge, south of the ice sheet.     

Molecular phylogeny of gobioid fishes (Perciformes: Gobioidei) based on mitochondrial 12S rRNA sequences

The molecular phylogeny of the gobioid fishes, comprising 33 genera and 43 valid species, was examined by use of complete mitochondrial 12S rRNA and tRNA(VAL)genes. Both parsimony and neighbor-joining analyses revealed comparable results and are generally congruent with those of morphological studies. The Odontobutis, which was always placed at the base of the phylogenetic trees, can be treated as a sister group of all other nonrhyacichthyid gobioids. Within eleotrid fishes, the monophyly of the Eleotrinae is strongly supported by molecular data. The Butinae is closer to fishes with five branchiostegal rays and should be treated as a sister group of the latter. The group with five branchiostegal rays, except for sicydiines, can be divided into two groups according to their epural counts. Fish with one epural, the Gobiinae of Pezold plus Microdesmidae, form a monophyletic group which is sister to those with two epurals, the Oxudercinae and Gobionellinae of Pezold. However, Sicydiinae, which have one epural, are closer to the Oxudercinae and Gobionellinae rather than to the Gobiinae. Since progressive reduction in epural number has been observed along this lineage, the sicydiines should be treated as a derived group within the groups with two epurals.     

Distribution and Biological Features of Grayling Thymallus thymallus (Thymallidae) in the European North-East of Russia

Journal of Ichthyology - The distribution and some ecological features of the European grayling Thymallus thymallus are studied in the extreme European Northeast of Russia. In many water systems of...     

The first complete mitochondrial genome of the Indian Tent Turtle,Pangshura tentoria (Testudines: Geoemydidae): Characterization and comparative analysis

The characterization of a complete mitogenome is widely used in genomics studies for systematics and evolutionary research. However, the sequences and structural motifs contained within the mitogenome of Testudines taxa have rarely been examined. The present study decodes the first complete mitochondrial genome of the Indian Tent Turtle, Pangshura tentoria (16,657 bp) by using next‐generation sequencing. This denovo assembly encodes 37 genes: 13 protein‐coding genes (PCGs), 22 transfer RNA (tRNAs), two ribosomal RNA, and one control region (CR). Most of the genes were encoded on majority strand, except for one PCG (NADH dehydrogenase subunit 6) and eight tRNAs. Most of the PCGs were started with an ATG initiation codon, except for Cytochrome oxidase subunit 1 with “GTG” and NADH dehydrogenase subunit 5 with “ATA.” The termination codons, “TAA” and “AGA” were observed in two subunits of NADH dehydrogenase gene. The relative synonymous codon usage analysis revealed the maximum abundance of alanine, isoleucine, leucine, and threonine. The nonsynonymous/synonymous ratios were <1 in all PCGs, which indicates strong negative selection among all Geoemydid species. The study also found the typical cloverleaf secondary structure in most of the tRNA genes, except for serine with the lack of the conventional DHU arm. The comparative study of Geoemydid mitogenomes revealed the occurrence of tandem repeats was frequent in the 3′ end of CR. Further, two copies of a unique tandem repeat “TTCTCTTT” were identified in P. tentoria. The Bayesian and maximum‐likelihood phylogenetic trees using concatenation of 13 PCGs revealed the close relationships of P. tentoria with Batagur trivittata in the studied dataset. All the Geoemydid species showed distinct clustering with high bootstrap support congruent with previous evolutionary hypotheses. We suggest that the generations of more mitogenomes of Geoemydid species are required, to improve our understanding of their in‐depth phylogenetic and evolutionary relationships.     

Molecular characterization of the complete mitochondrial genome sequence of Indian wild pig (Sus scrofa cristatus)

The Indian wild pig is a sub-species (Sus scrofa cristatus) which is different from the other pig breeds and is protected under Schedule-III of the Indian Wildlife (Protection) Act, 1972. In this study, complete mitogenome of two Indian wild pigs was sequenced and characterized by shotgun sequencing and de novo assembly, which revealed sequence size of 16,738 and 16,251?bp, respectively, (Accession no. MG725630 and MG725631). The mitogenome sequence in this study displayed 98% homology with previously reported mitogenome of pigs from different parts of the world. Mitogenome analysis by MITOS Web server revealed similarity of gene organization with the other vertebrates (13 protein-coding, 22 tRNAs, 2 rRNAs genes, and a control region). The mitogenomic sequences of Indian wild pig maintained a separate clade in the phylogenetic tree constructed by using 62 whole mitogenome sequences across the world. The phylogeny derived from mitogenomic sequences revealed distinct separate European–American and Asiatic pig clades. It was concluded that whole mitogenome sequencing using NGS without designing mitogenome-specific primer for amplification, is possible thereby reducing the cost and labor. This study is the first report of complete sequence of mitogenome of Indian wild pig.     

Molecular phylogeny of Chinese Rubia (Rubiaceae: Rubieae) inferred from nuclear and plastid DNA sequences

Rubia L. is the type genus of the coffee family Rubiaceae and the third largest genus in the tribe Rubieae, comprising ca. 80 species restricted to the Old World. China is an important diversity center for Rubia, where approximately half of its species occur. However, its internal phylogenetic relationships are still poorly understood. The objective of the present study is to contribute to the phylogenetic relationships within Rubia, using the nuclear internal transcribed spacer and six plastid markers and focusing on species from China. Twenty-seven species of Rubia were sampled to infer their phylogeny using Maximum parsimony, Maximum likelihood, and Bayesian analyses. The monophyly of Rubia is supported, provided that R. rezniczenkoana Litv. is excluded from Rubia and transferred to Galium as a new combination: G. rezniczenkoanum (Litv.) L. E Yang & Z. L. Nie. Within Rubia, two clades are clearly supported. They correspond to the traditional sect. Rubias.l. (A) and sect. Oligoneura Pojark. (B), and are morphologically mainly separable by their pinnate (A) versus palmate (B) leaf venation. Plesiomorphic features are the pinnate leaf veining in sect. Rubia s.l. and the occurrence of some species with opposite leaves and true stipules in sect. Oligoneura. In sect. Oligoneura one can assume an evolution from species with opposite leaves and true stipules (as in the R. siamensis Craib group) to those with whorls of two leaves and two leaf-like stipules (as in ser. Chinenses and the R. mandersii Collett & Hemsl. group) and finally with whorls of 6 or even more elements (as in ser. Cordifoliae). The correlation between clades recognized by DNA analyses and available differential morphological features is partly only loose, particularly in the group of R. cordifolia with 2×, 4×, and 6× cytotypes. This may be due to rapid evolutionary divergence and/or hybridization and allopolyploidy.     

Phylogenetic relationships within the class mammalia: A study using mitochondrial 12S RNA sequences

The interrelationships of the three mammalian groups, Monotremata, Marsupialia, and Eutheria, have been studied using DNA sequences from the mitochondrial 12S ribosomal RNA gene. The results suggest that the monotremes diverged from the living therians only shortly before eutherians and marsupials separated from each other, although there is some evidence for a slowdown in rate of base change in the monotreme lineage. Whtin the Monotremata, the two extant species of tachyglossids show a very close genetic relationship and the data suggest a very recent divergence. We have also confirmed that the Patagonian Monito del Monte,Dromiciops australis, is more closely related to the australidephian marsupials than it is to other South American species.     

甜果螨全线粒体基因组测序与分析

【目的】测定和分析甜果螨Carpoglyphus lactis线粒体基因组全序列,并在线粒体基因组水平探讨其在真螨总目(Acariformes)中的系统发育地位,为真螨总目分类及果螨科线粒体基因组研究提供科学依据。【方法】挑取实验室饲养的甜果螨成螨,用传统的酚氯仿抽提法和试剂盒提取法提取甜果螨基因组DNA。然后采用节肢动物或螨类线粒体基因的通用引物PCR扩增出甜果螨线粒体基因cox1,cob,rrnS和nad4-nad5的部分序列;再设计种特异性引物进行Long-PCR扩增和步移法测序,测出甜果螨线粒体基因组全序列。应用SeqMan, SEQUIN 9.0和tRNAscan等生物信息学软件,对甜果螨线粒体基因组的基因结构等进行生物信息学分析。最后基于17种真螨总目螨类的蛋白质编码基因,采用最大似然法构建系统发育树。【结果】甜果螨线粒体全基因组总长为14 060 bp(GenBank登录号:MN073839),为典型的闭合双链DNA分子,共由37个基因组成,包括13个蛋白质编码基因(PCGs)、22个tRNA基因和2个rRNA基因;甜果螨线粒体基因组还包括1个大的非编码区(large n...     

Phylogenetic relationships and divergence dates of softshell turtles (Testudines: Trionychidae) inferred from complete mitochondrial genomes

The softshell turtles (Trionychidae) are one of the most widely distributed reptile groups in the world, and fossils have been found on all continents except Antarctica. The phylogenetic relationships among members of this group have been previously studied; however, disagreements regarding its taxonomy, its phylogeography and divergence times are still poorly understood as well. Here, we present a comprehensive mitogenomic study of softshell turtles. We sequenced the complete mitochondrial genomes of 10 softshell turtles, in addition to the GenBank sequence of Dogania subplana, Lissemys punctata, Trionyx triunguis, which cover all extant genera within Trionychidae except for Cyclanorbis and Cycloderma. These data were combined with other mitogenomes of turtles for phylogenetic analyses. Divergence time calibration and ancestral reconstruction were calculated using BEAST and RASP software, respectively. Our phylogenetic analyses indicate that Trionychidae is the sister taxon of Carettochelyidae, and support the monophyly of Trionychinae and Cyclanorbinae, which is consistent with morphological data and molecular analysis. Our phylogenetic analyses have established a sister taxon relationship between the Asian Rafetus and the Asian Palea + Pelodiscus + Dogania + Nilssonia + Amyda, whereas a previous study grouped the Asian Rafetus with the American Apalone. The results of divergence time estimates and area ancestral reconstruction show that extant Trionychidae originated in Asia at around 108 million years ago (MA), and radiations mainly occurred during two warm periods, namely Late Cretaceous–Early Eocene and Oligocene. By combining the estimated divergence time and the reconstructed ancestral area of softshell turtles, we determined that the dispersal of softshell turtles out of Asia may have taken three routes. Furthermore, the times of dispersal seem to be in agreement with the time of the India–Asia collision and opening of the Bering Strait, which provide evidence for the accuracy of our estimation of divergence time. Overall, the mitogenomes of this group were used to explore the origin and dispersal route of Trionychidae and have provided new insights on the evolution of this group.     

Molecular phylogeny and phylogeography of the Greek populations of the genus Orthometopon (Isopoda, Oniscidea) based on mitochondrial DNA sequences

We infer phylogenetic relationships among isopod species of the genus Orthometopon distributed in the Greek area, comparing partial mitochondrial DNA sequences for cytochrome oxidase I (COI). All phylogenetic analyses produced topologically identical trees that revealed a well-resolved phylogeny. These trees support the monophyly of the genus Orthometopon , and suggest two clades that correspond to separate geographical regions (west and east of the mid-Aegean trench). However, the phylogenetic relationships among Greek populations of Orthometopon spp. are different from the presumed pattern on the basis of morphological evidence. The distinct geographical distribution of the major clades of the phylogenetic tree and its topology suggest a spatial and temporal sequence of phylogenetic separations, which coincide with some major palaeogeographical separations during the geological history of the Aegean Sea. The results stress the need for a reconsideration of the evolutionary history of Orthometopon species, which will help overcome difficulties encountered in classical taxonomy at the species level. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 707–715.     

利用叶绿体DNA trnL-F序列初步探讨菊科风毛菊属的系统发育

风毛菊属Saussurea DC.是菊科物种分化十分剧烈和分类处理十分困难的一个属。该属的单系起源性质、属下分类系统以及一些独特形态物种的系统位置尚不清楚,有待进一步验证。本文测定了代表该属5个亚属37种植物43个样品和川木香属Dolomiaea DC.的１种样品的叶绿体DNA trnL-F序列,并调取菜蓟族Cardueae Cass.与风毛菊属具有一定亲缘关系的13属的该序列,一起进行了分支分析,重点验证该属的属下形态分类系统以及形态特殊、青藏高原地区特有的雪兔子亚属subgen. Eriocoryne     

Polyphyly of Limoniastrum (Plumbaginaceae): evidence from DNA sequences of plastid rbcL, trnL intron and trnL-F intergene spacer

Phylogenetic relationships of Limoniastrum and other genera of subfamily Staticoideae (Plumb-aginaceae) were studied using parsimony analysis of the plastid gene rbc L, the intron of trn L and the intergene spacer of trnL-trn F. Our analysis showed that Limoniastrum was polyphyletic. Limoniastrum ifniense , in both rbc L and combined data analyses, is sister to Armeria and Psylliostachys , whereas in the trn L-F (intron and spacer combined) analysis it is sister to a clade composed of Acantholimon, Dictyolimon and the remaining species of Limoniastrum . In all analyses, the five remaining species of Limoniastrum (excluding Limoniatrum ifniense ) formed a clade with two groups of species: L. monopetalum+L. guyonianum and those sometimes considered as the segregate genus Bubania ( L.feei, L. weygandiorum and L. rechingeri ). Levels of sequence divergence among these three groups of Limoniatrum were greater than for other well supported genera in the family and, in combination with morphological differences and paucity of synapomorphies, led us to conclude that separate generic status for each of the three clades is warranted.     

Angiosperm phylogeny inferred from sequences of four mitochondrial genes

An angiosperm phylogeny was reconstructed in a maximum likelihood analysis of sequences of four mitochondrial genes, atpl, matR, had5, and rps3, from 380 species that represent 376 genera and 296 families of seed plants. It is largely congruent with the phylogeny of angiosperms reconstructed from chloroplast genes atpB, matK, and rbcL, and nuclear 18S rDNA. The basalmost lineage consists of Amborella and Nymphaeales (including Hydatellaceae). Austrobaileyales follow this clade and are sister to the mesangiosperms, which include Chloranthaceae, Ceratophyllum, magnoliids, monocots, and eudicots. With the exception of Chloranthaceae being sister to Ceratophyllum, relationships among these five lineages are not well supported. In eudicots, Ranunculales, Sabiales, Proteales, Trochodendrales, Buxales, Gunnerales, Saxifragales, Vitales, Berberidopsidales, and Dilleniales form a basal grade of lines that diverged before the diversification of rosids and asterids. Within rosids, the COM (Celastrales-Oxalidales-Malpighiales) clade is sister to malvids (or rosid Ⅱ), instead of to the nitrogen-fixing clade as found in all previous large-scale molecular analyses of angiosperms. Santalales and Caryophyllales are members of an expanded asterid clade. This study shows that the mitochondrial genes are informative markers for resolving relationships among genera, families, or higher rank taxa across angiosperms. The low substitution rates and low homoplasy levels of the mitochondrial genes relative to the chloroplast genes, as found in this study, make them particularly useful for reconstructing ancient phylogenetic relationships. A mitochondrial gene-based angiosperm phylogeny provides an independent and essential reference for comparison with hypotheses of angiosperm phylogeny based on chloroplast genes, nuclear genes, and non-molecular data to reconstruct the underlying organismal phylogeny.