Male killing in three species of the tripunctata radiation of Drosophila (Diptera: Drosophilidae)

An excess of females in progenies is commonly referred to as sex-ratio (SR). In this report, we describe three new occurrences of SR in species of the tripunctata radiation, Drosophila neocardini , Drosophila ornatifrons and Drosophila paraguayensis. Repeated backcrosses with males from normal strains were used to maintain the SR strains in the laboratory, always with all-female broods. The egg–larva viability of the SR strains was approximately half that of a normal strain, and antibiotic treatment restored the production of males in SR strains. PCR screening with Spiroplasma -specific primers showed that only SR strains tested positive for Spiroplasma . The results showed that in the three species, SR was maternally inherited and involved early male-killing bacteria, most likely spiroplasmas. These new occurrences increase the number of cytoplasmic male killers described in Drosophila from 11 to 14. In this particular collection of flies, one quarter (3 out of 12) of the species from the tripunctata radiation of Drosophila was infected with a male killer, suggesting that this group may be a hot spot for the presence of male-killing organisms.     

A principle of maximum topological similarity in molecular systematics

The paper deals with the problem of phylogenetic reconstruction on the basis of comparative analysis of features. Main attention is paid to comparison and classification of the biopolymer sequences. Different approaches to this task are critically reviewed. The novel principle of construction of tree-like classification schemes permitting subsequent evolutionary analysis is proposed. It concentrates on reconstruction of the tree with a topologic structure that is most close to topologic features, imprinted in the source distance matrix. Realization of this approach was made possible by development of the special formalism, enabling evaluation and comparison of topologic features of distance matrices and trees.     

Morphology and angiosperm systematics in the molecular era

Several ways in which morphology is used in systematic and evolutionary research in angiosperms are shown and illustrated with examples: 1) searches for special structural similarities, which can be used to find hints for hitherto unrecognized relationships in groups with unresolved phylogenetic position; 2) cladistic studies based on morphology and combined morphological and molecular analyses; 3) comparative morphological studies in new, morphologically puzzling clades derived from molecular studies; 4) studies of morphological character evolution, unusual evolutionary directions, and evolutionary lability based on molecular studies; and 5) studies of organ evolution. Conclusions: Goals of comparative morphology have shifted in the present molecular era. Morphology no longer plays the primary role in phylogenetic studies. However, new opportunities for morphology are opening up that were not present in the premolecular era: 1) phylogenetic studies with combined molecular and morphological analyses; 2) reconstruction of the evolution of morphological features based on molecularly derived cladograms; 3) refined analysis of morphological features induced by inconsistencies of previous molecular and molecular phylogenetic analyses; 4) better understanding of morphological features by judgment in a wider biological context; 5) increased potential for including fossils in morphological analyses; and 6) exploration of the evolution of morphological traits by integration of comparative structural and molecular developmental genetic aspects (Evo-Devo); this field is still in its infancy in botany; its advancement is one of the major goals of evolutionary botany.     

蓝藻的分子系统学研究

藻类分子系统学是一门新兴的学科。介绍了蓝藻分子系统学的发展、定义和蓝藻分子系统学的研究方法,并举例说明了各种方法的应用。同时,对蓝藻分子系统学发展前景作出了展望。     

Anatomical and molecular systematics of Asteliaceae and Hypoxidaceae

The astelioid group of asparagoid lilies (Lilianae - Asparagales) comprises Hypoxidaceae, Asteliaceae, Blandfordia and Lanaria. New information is presented on astelioid anatomy, together with a review of other systematic characters. These data are analysed in the context of recent evidence from rbc L nucleotide sequences that astelioids are related to orchids, and that astelioids and orchids (plus Alania and Borya ) form a clade that is sister to all other asparagoid taxa. Hypoxidaceae and Asteliaceae differ from each other in several respects, but there are certain characters linking the two families, notably branched hairs and mucilage canals, unusual characters in Lilianae. Family diagnoses are upheld, but the precise relationships of Blandfordia and Lanaria are still poorly supported within the astelioid clade.     

索科线虫分子系统学研究进展

昆虫病原索科线虫是一类宝贵的昆虫天敌资源,对农、林及卫生害虫的综合治理、环境保护以及实现农田生物多样性,都具有重要的学术和实用价值。其分子系统学研究涉及RAPD技术、SAFLP技术和基因分子标记技术对索科线虫种属间的亲缘关系探究,以及其线粒体全基因组分析等。     

叶蝉科昆虫分子系统发育的研究进展

从基因组DNA的提取、研究的基因片段、PCR引物选用、扩增条件以及叶蝉科不同阶元的分子系统发育分析等方面,综述叶蝉科(半翅目:叶蝉科)昆虫分子系统发育的研究进展。目前角顶叶蝉类的研究成果相对较多,大叶蝉亚科次之,其余类群的研究较少或无。线粒体基因与核基因序列联合分析以及线粒体全序列分析以及基因序列与形态数据相结合分析,分子鉴定叶蝉与共生菌之间的协同进化的研究,将是叶蝉分子系统学未来发展的主要研究手段。     

A multilocus microsatellite phylogeny of the Drosophila virilis group

We used a set of 48 polymorphic microsatellites derived from Drosophila virilis to infer phylogenetic relationships in the D. virilis clade. Consistent with previous studies, D. virilis and D. lummei were the most basal species of the group. Within the D. montana phylad, the phylogenetic relationship could not be resolved. Special attention was given to the differentiation between D. americana texana, D. americana americana and D. novamexicana. Significant differences between these three groups were detected by F(ST) analyses. Similarly, a model-based clustering method for multilocus genotype data also provided strong support for the presence of three differentiated groups. This genome-wide differentiation between D. americana texana and D. americana americana contrasts with previous analyses based on DNA sequence data.     

Contributions of plant molecular systematics to studies of molecular evolution

Dobzhansky stated that nothing in biology makes sense except in the light of evolution. A close corollary, and the central theme of this paper, is that everything makes a lot more sense in the light of phylogeny. Systematics is in the midst of a renaissance, heralded by the widespread application of new analytical approaches and the introduction of molecular techniques. Molecular phylogenetic analyses are now commonplace, and they have provided unparalleled insights into relationships at all levels of plant phylogeny. At deep levels, molecular studies have revealed that charophyte green algae are the closest relatives of the land plants and suggested that liverworts are sister to all other extant land plants. Other studies have suggested that lycopods are sister to all other vascular plants and clarified relationships among the ferns. The impact of molecular phylogenetics on the angiosperms has been particularly dramatic – some of the largest phylogenetic analyses yet conducted have involved the angiosperms. Inferences from three genes (rbcL, atpB, 18S rDNA) agree in the major features of angiosperm phylogeny and have resulted in a reclassification of the angiosperms. This ordinal-level reclassification is perhaps the most dramatic and important change in higher-level angiosperm taxonomy in the past 200 years. At lower taxonomic levels, phylogenetic analyses have revealed the closest relatives of many crops and model organisms for studies of molecular genetics, concomitantly pointing to possible relatives for use in comparative studies and plant breeding. Furthermore, phylogenetic information has contributed to new perspectives on the evolution of polyploid genomes. The phylogenetic trees now available at all levels of the taxonomic hierarchy for angiosperms and other green plants should play a pivotal role in comparative studies in diverse fields from ecology to molecular evolution and comparative genetics.     

Biochemical systematics and evolutionary genetics of the common shiner species group

Electrophoretic analyses were performed on blood proteins of the five members of the Notropiscornutus species group. The protein systems included two plasma esterases, transferrin, a pre-albumin and hemoglobin. Plasma protein polymorphism within and between taxa was common. Hemoglobin appeared to be a more consistent and conservative character for assessing phylogenetic relationships. As deduced by both biochemical and morphological evidence, N. cerasinus is the most primitive member of the species group. Uniqueness for several biochemical characters suggests that the striped shiner should be afforded full species recognition as N. isolepis but additional study is needed concerning its relationship with N. cornutus chrysocephalus. The closest biochemical similarity was between the forms interpreted here as subspecies N. cornutus cornutus and N. c. chrysocephalus. N. albeolus clearly evolved from N. c. cornutus but early hybridization with N. cerasinus resulted in limited introgression from that species.     

Application of molecular systematics to study of bacterial cultures consuming volatile organic compounds

A range of species of four mixed bacterial cultures was studied by molecular systematics methods with the use of 16S rRNA genes. The cultures had been developed for application in minireactors, to degrade volatile organic compounds (VOCs): ethyl benzene, m-xylene, styrene, and o-xylene. A sample of 30 plasmid rDNA clones was obtained for each of the mixed cultures. The clones were analyzed by RFLP according to two restriction sites. Major variants of the 16S-rDNA sequences, corresponding to the most abundant species, were determined for each association. Sequencing of four clones of predominant 16S-rDNAs showed that the culture consuming ethyl benzene was dominated by Pseudomonas fluorescens; o-xylene, by Achromobacter xylosoxydans; styrene, by Pseudomonas veronii; and m-xylene, by Delftia acidovorans. Minor components of all four cultures were generally similar. They included species of the genera Sphingobacter, Rhizobium, Mesorhizobium, Pedobacter, and Paenibacillus. Sampling sequencing of genes for 16S rRNA cloned from total genomic DNA allowed quantitative determination of the composition of actual bacterial associations consuming VOCs in minireactors.     

Application of molecular systematics to study of bacterial cultures consuming volatile organic compounds

A range of species of four mixed bacterial cultures was studied by molecular systematics methods with the use of 16S rRNA genes. The cultures had been developed for application in minireactors, to degrade volatile organic compounds (VOCs): ethyl benzene, m-xylene, styrene, and o-xylene. A sample of 30 plasmid rDNA clones was obtained for each of the mixed cultures. The clones were analyzed by RFLP according to two restriction sites. Major variants of the 16S-rDNA sequences, corresponding to the most abundant species, were determined for each association. Sequencing of four clones of predominant 16S-rDNAs showed that the culture consuming ethyl benzene was dominated by Pseudomonas fluorescens; o-xylene, by Achromobacter xylosoxydans; styrene, by Pseudomonas veronii; and m-xylene, by Delftia acidovorans. Minor components of all four cultures were generally similar. They included species of the genera Sphingobacter, Rhizobium, Mesorhizobium, Pedobacter, and Paenibacillus. Sampling sequencing of genes for 16S rRNA cloned from total genomic DNA allowed quantitative determination of the composition of actual bacterial associations consuming VOCs in minireactors.Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 2, 2005, pp. 176–184.Original Russian Text Copyright © 2005 by Khomenkov, Shevelev, Zhukov, Kurlovich, Zagustina, Popov.     

Advances in molecular systematics of the vetigastropod superfamily Trochoidea

Williams, S.T. (2012). Advances in molecular systematics of the vetigastropod superfamily Trochoidea. —Zoologica Scripta, 41, 571–595. The gastropod superfamily Trochoidea Rafinesque, 1815 is comprised of a diverse range of species, including large and charismatic species of commercial value as well as many small or enigmatic taxa that are only recently being represented in molecular studies. This study includes the first sequences for rarely collected species from the genera Gaza Watson, 1879, Callogaza Dall, 1881, Antimargarita Powell, 1951 and Kaiparathina Laws, 1941. There is also greater taxon sampling of genera that have proved difficult to place in previous phylogenetic analyses, like Tectus Montfort, 1810, Tegula Lesson, 1832, Margarites Gray, 1847, Margarella Thiele, 1893 and trochoid skeneimorphs. There is also greater sampling of poorly represented families Solariellidae and Liotiidae. Bayesian analysis of combined gene data sets based on four (28S, 12S, 16S and COI) or five genes (plus 18S) suggests that there are eight, possibly nine families in Trochoidea including the families Margaritidae and Tegulidae, which are recognized for the first time at familial rank. Other trochoidean families confirmed are Calliostomatidae, Liotiidae, Skeneidae, Solariellidae, Trochidae and Turbinidae. A clade including Cittarium and the commercially important genera Rochia and Tectus may represent a possible ninth family, but this is not formally recognized or described here and awaits confirmation from further studies. Relationships among families were not generally well supported except in the 5‐gene tree. In the 5‐gene tree, Turbinidae, Liotiidae, Tegulidae, Cittarium, Rochia and Tectus form a well‐supported clade consistent with the previous molecular and morphological studies linking these groups. This clade forms another well‐supported clade with Margaritidae and Solariellidae. Trochidae is sister to Calliostomatidae with strong support. Subfamilial relationships within Trochidae are consistent with recent molecular studies, with the addition of one new subfamily, Kaiparathininae Marshall 1993 (previously a tribe). Only two subfamilies are recognized within Turbinidae, both with calcareous opercula: Prisogasterinae and Turbininae. Calliostomatidae includes a new subfamily Margarellinae. Its assignment to Calliostomatidae, although well supported by molecular evidence, is surprising considering morphological evidence.