基于核糖体DNA内转录间隔区ITS序列的广义蓼属及近缘属分子系统学研究

通过对广义蓼属及近缘属共32个代表种内转录间隔区ITS序列的分子系统学分析,尝试研究备受争议的广义蓼属及近缘属的物种族、属、组级的划分问题,结果显示,广义蓼属在系统发育树上并不能形成一个单系类群,这些物种共聚为3大支,分别对应春蓼族、蓼族及荞麦族,其中荞麦属与翅果蓼属形成了一支独立于春蓼族及蓼族之外的类群。在春蓼族中,冰岛蓼属与分叉蓼组形成一个单系类群。     

ITS-2 and 18S rRNA Gene Phylogeny of Aplysinidae (Verongida, Demospongiae)

18S ribosomal DNA and internal transcribed spacer 2 (ITS-2) full-length sequences, each of which was sequenced three times, were used to construct phylogenetic trees with alignments based on secondary structures, in order to elucidate genealogical relationships within the Aplysinidae (Verongida). The first poriferan ITS-2 secondary structures are reported. Altogether 11 Aplysina sponges and 3 additional sponges (Verongula gigantea, Aiolochroia crassa, Smenospongia aurea) from tropical and subtropical oceans were analyzed. Based on these molecular studies, S. aurea, which is currently affiliated with the Dictyoceratida, should be reclassified to the Verongida. Aplysina appears as monophyletic. A soft form of Aplysina lacunosa was separated from other Aplysina and stands at a basal position in both 18S and ITS-2 trees. Based on ITS-2 sequence information, the Aplysina sponges could be distinguished into a single Caribbean–Eastern Pacific cluster and a Mediterranean cluster. The species concept for Aplysina sponges as well as a phylogenetic history with a possibly Tethyan origin is discussed.Reviewing Editor: Dr. Martin Kreitman     

Seed size and the regeneration niches of one rare (Melaleuca deanei) and three common (Melaleuca styphelioides,Melaleuca thymifolia and Melaleuca nodosa) Melaleuca (Myrtaceae) species of the Sydney region

Melaleuca species occupy varied habitats across Australia with 16 members of the genus occurring in the Sydney district including the rare species Melaleuca deanei F. Muell. Little is known of their germination and recruitment requirements. This paper reports on experiments assessing the effects of temperature, water potential, fire cues, light and shade levels on germination in four species of Melaleuca native to the Sydney region. For the shade experiment, seedling survival at 12 months is also reported. The experiments tested the hypothesis that M. deanei, which exhibits few seedlings in the field, has limited seedling recruitment because of its particular requirements for germination and establishment. Further, that it differs in these requirements from three common congenerics: M. nodosa (Sol ex Gaertn.) Sm., M. thymifolia Sm. and M. styphelioides Sm. Results indicate that M. deanei has a substantially similar temperature and water potential range for germination to the common congeners from 15 to 35°C, and 0 to ?0.65 ψ. Melaleuca nodosa displayed the broadest regeneration niche on all factors assessed. Germination of M. styphelioides was significantly reduced in the dark and M. styphelioides and M. deanei were most sensitive to shade in the seedling establishment/post‐germination phase. Melaleuca deanei had significantly larger seed that was slower to germinate in all experiments. Germination of the four species was unaffected by the application of heat and smoke. The substantially similar germination parameters exhibited by the four species, despite differences in habitat, may reflect their close phylogenetic affinities. The effects of fire on stimulating seed release from the canopy, the high‐light environment post‐fire together with adequate follow‐up rainfall may all be critical in seedling establishment for M. deanei.     

Ribosomal DNA ITS-1 Intergenic Spacer Polymorphism in Triatomines (Triatominae, Heteroptera)

The length polymorphism of ribosomal DNA ITS-1 intergenic spacer was analyzed in eight species of triatomines belonging to Triatoma, Rhodnius, and Panstrongylus genera. The analyzed species were Rhodnius domesticus, R. neivai, R. robustus, Triatoma brasiliensis, T. infestans, T. vitticeps, Panstrongylus megistus, and P. herreri. These insects are vectors of Chagas' disease, one of the most prominent public health problems among South American countries. This work allowed the differentiation between species of the Triatomini and Rhodniini tribes through the analysis of ITS-1 length polymorphism by PCR and RFLP techniques. The species of the Triatoma and Panstrongylus genera presented an amplified ITS-1 fragment between 600 and 1000 bp, whereas Rhodnius presented a less variable ITS-1 length fragment, around 300 bp, which could reflect the monophyletic origin of the Rhodniini tribe. Species belonging to this genus were further differentiated by RFLP with HaeIII and AluI endonucleases. Our results corroborate the hypothesis of polyphyletic origin in this group of insects and contribute to knowledge about evolutionary relationships in triatomines.     

Abundance and polymorphism of microsatellite markers in the tea tree (Melaleuca alternifolia, Myrtaceae)

 The sequencing of 831 clones from an enriched microsatellite library of Melaleuca alternifolia (Myrtaceae) yielded 715 inserts containing repeat motifs. The majority of these (98%) were dinucleotide repeats or trinucleotide repeats averaging 22 and 8 repeat motifs respectively. The AG/GA motif was the most common, accounting for 43% of all microsatellites. From a total of 139 primer pairs designed, 102 produced markers within the expected size range. The majority of these (93) were polymorphic. Primer pairs were tested on five selected M. alternifolia genotypes. Loci based on dinucleotide repeats detected on average a greater number of alleles (4.2) than those based on trinucleotide repeats (2.9). The loci described will provide a large pool of polymorphisms useful for population studies, genetic mapping, and possibly application in other Myrtaceae. Received: 28 July 1998 / Accepted: 8 October 1998     

Phylogeny and Phytogeography of Eupatorium (Eupatorieae, Asteraceae): Insights from Sequence Data of the nrDNA ITS Regions and cpDNA RFLP

Eupatorium were examined by sequencing the internal transcribed spacers (ITS) of nuclear ribosomal DNA and restriction site analysis of chloroplast DNA. Molecular data provided strong evidence that (1) this genus originated in North America, (2) the genus diverged into three morphological species groups, Eutrochium, Traganthes and Uncasia in North America, and (3) one of the North American Uncasia lineages migrated into temperate Europe and eastern Asia over the Bering land bridge. The estimated divergence times support a late Miocene to early Pliocene migration from North America to Eurasia via the Bering land bridge. A European species was sister to all of the eastern Asian species examined. The disjunct distribution pattern of the genus Eupatorium is incongruent with the classical Arcto-Tertiary geoflora concept. Received 13 September 1999/ Accepted in revised form 4 January 2000     

丛赤壳科部分属之间的系统学关系

对nrDNA大亚基部分序列进行序列分析,探讨丛赤壳科11个属的属间关系。研究结果表明,Cosmospora不是单起源,它的成员分别与Nectria,Haematonectria以及Neocosmospora3个不同的属聚类在一起;Haematonectria和Neocosmospora的亲缘关系最接近;Lanatonectria为一个独立的属;以Neonectriadiscophoravar.discophora为代表的Neonectria是一个可靠的属。     

Natural variation in the essential oil content of Melaleuca alternifolia Cheel (Myrtaceae)

The composition and yield of oil in 615 trees representing the natural populations of Melaleuca alternifolia, or tea tree, was investigated. A sixth distinct oil chemotype was identified. Of the six chemotypes, one chemotype is dominated by terpinen-4-ol, one by 1,8-cineole, one by terpinolene and the remaining three chemotypes are all dominated by 1,8-cineole and differ in either terpinen-4-ol or terpinolene content. Whilst most chemotypes are present throughout the distribution range, a definite correspondence of oil types with geographic location was found. Terpinen-4-ol types predominate in and around the Bungawalbin basin in the Casino area of northern New South Wales (NSW), high 1,8-cineole types predominate toward the southern end of the distribution around Grafton and terpinolene types predominate in southern Queensland. Preliminary formulae have been developed to allow comparisons of oil data obtained by steam distillation with a static headspace gas chromatography method.     

番荔枝科研究35.Guatteria类群和有关属的系统发育

Guatteria类群由4个新热带的属组成,即Guatteria,Guatteriopsis,Guatteriella和Heteropetalum。不同的作者基于不同的证据得出的它在番荔枝中的地位各不相同。基于宏观和微观的形态特征,对该类群进行了表型和分支分析。分支分析表明,所研究属的系统发育分支方式仅由极少数共同衍征支持,同型现象非常明显,所获得的唯一的最简约分支图可分为两个基本部分,即一个(假)合生心皮分支和一个离生心皮grade。在表征聚类图和主成分分析的三维构象图中同样可以区分出离生心皮和(假)合生心皮两个表征群,表征分析表明Guatteria类群处在其它离生心皮类和(假)合生心皮类的中间位置。然而分支分析表明Guatteria类群与番荔枝科中最进化的(假)合生心皮类有姊妹群关系。Guatteria类群是离生心皮类中最进化的一类。番荔枝科中离生心皮类和(假)合生心皮类在漫长的进化过程中经历了强烈的形态分化而显示出极大的形态差异,然而在系统发育上它们可以通过Guatteria类群作为纽带而联系起来。     

樟属植物ITS序列多态性分析

对樟科樟属(Cinnamomum Schaeffer) 17个代表样本的核糖体DNA内转录间隔区(nrDNA ITS)进行克隆测序。对获得的87条不同ITS序列的长度变异、GC含量、5.8S区二级结构的稳定性、遗传距离、进化模式以及系统发育关系进行了相关分析。研究结果显示, ITS序列在樟属植物内存在明显的多态性, 87条序列中的22条序列被鉴定为假基因序列, 其余65条序列为功能基因序列; 假基因序列采用中性进化模式, 变异明显大于功能序列。ITS序列在樟属植物中出现一致性进化不完全和假基因现象也可能发生在樟科其它类群中, 这可能是导致樟科植物ITS序列直接测序方式成功率低的重要原因。     

Phylogenetic Analysis of the Genus Bifidobacterium and Related Genera Based on 16S rDNA Sequences

The 16S rRNA gene sequences were determined for type strains of 21 Bifidobacterium species. A phylogenetic tree was constructed using the determined sequences and sequences from DNA databases, which contain the sequences of 11 type strains of Bifidobacterium species and 11 strains of related genera. All species of the genus Bifidobacterium and Gardnerella vaginalis ATCC 14018 belonged to a cluster phylogenetically distinct from the other genera. The cluster was divided into two subclusters: subcluster 1 composed of most species of Bifidobacterium and G. vaginalis, and subcluster 2 consisting of two species, B. denticolens and B. inopinatum; both of which were isolated from human dental caries. In the genus Bifidobacterium, four groups of species are known to be moderately to highly related by DNA-DNA hybridization. The four groups of species exhibited more than 99% similarity among their 16S rDNA sequences within each group. These results indicated that species with around 99% or more similarity in their 16S rDNA sequences should be confirmed for species identities.     

广义青篱竹属(Arundinaria)核糖体DNA ITS序列及亲缘关系研究

利用PCR扩增产物直接测序的方法分析广义青篱竹属(Arundinaria)中有关争议类群的代表种或模式种(毛竹为外类群)等18种竹种的核糖体DNA内转录间隔区(Internal Transcribed Spacers,ITS)序列。通过最简约性分析产生的ITS系统发育树表明,供试竹种形成一个自然的单系类群,这说明广义青篱竹属中这些不同的类群归属青篱竹属是合理的。17种竹种可聚为2大分支：其中斑苦竹(A,oleosa)、仙居苦竹(A．hsienchuensis)、茶秆竹(A．amabilis)、长叶苦竹(A．chino)、苦竹(A．amara)、宜兴苦竹(A．yixingensis)、菲白竹(A．fortunei)、翠竹(A．pygmaea)为一个分支;而大明竹(A．graminea)、巴山木竹(A．fargesii)、冷箭竹(A．faberi)、凤竹(A．hupehense)、鼓节矢竹(Pseudosasa japonica cv．Tsutsumiana)、矢竹(Pseudosasa japonica)、短穗竹(Brachystachyum densiflorum)、肿节竹(A．oedogonata)、少穗竹(A．sulcata)组合在另一分支。ITS系统发育树还表明,大明竹与巴山木竹、鼓节矢竹与矢竹、少穗竹与短穗竹和肿节竹关系极为密切,均得到较高的Bootstrap(分别为99％、100％和87％)的支持;茶秆竹与仙居苦竹关系非常密切,茶秆竹可归隶到青篱竹属中;翠竹和菲白竹关系密切,且与苦竹类竹种分为两个分支。     

Geographic variation in the essential oils and morphology of natural populations of Melaleuca alternifolia (Myrtaceae)

In recent decades, Melaleuca alternifolia has been grown in plantations for the commercial production of tea tree oil extracted from harvested leaf and stem material by steam distillation. Plantations are grown from seedlings raised from seeds collected from wild populations of this endemic Australian species. Considerable variation in morphology and leaf oil composition and yield has been observed and studies have demonstrated genetic and phenotypic heterozygosity between populations.Here we examine the variation in leaf oil chemical composition (chemotypes) between geographically defined locations of wild populations of M. alternifolia and investigate the relationships between tree size, chemotype and geographic location.Forty separate populations of M. alternifolia distributed amongst three river catchments (two in a warm moist coastal region and one in cool drier highlands) were studied. Total variation in tree size was significantly greater within individual sites than between them. However, the highland catchment populations exhibited significantly smaller mean tree size and a significantly different chemotype profile than the lowland populations. Contrary to the observation of lower genetic diversity, the highland catchment populations had greater chemotypic diversity. Furthermore, highly significant differences in population chemotypes were demonstrated between catchments.The possibilities that these differences could be ascribed to either genetic divergence or to environmental differences are discussed.     

Characterization of the 23S and 5S rRNA genes and 23S-5S intergenic spacer region (ITS-2) of Photobacterium damselae

The 23S ribosomal RNA (rRNA) gene has been sequenced in strains of the fish pathogens Photobacterium damselae subsp. damselae (ATCC 33539) and subsp. piscicida (ATCC 29690), showing that 3 nucleotide positions are clearly different between subspecies. In addition, the 5S rRNA gene plus the intergenic spacer region between the 23S and 5S rRNA genes (ITS-2) were amplified, cloned and sequenced for the 2 reference strains as well as the field isolates RG91 (subsp. damselae) and DI21 (subsp. piscicida). A 100% similarity was found for the consensus 5S rRNA gene sequence in the 2 subspecies, although some microheterogeneity was detected as inter-cistronic variability within the same chromosome. Sequence analysis of the spacer region between the 23S and 5S rRNA genes revealed 2 conserved and 3 variable nucleotide sequence blocks, and 4 different modular organizations were found. The ITS-2 spacer region exhibited both inter-subspecies and intercistronic polymorphism, with a mosaic-like structure. The EMBL accession numbers for the 23S, 5S and ITS-2 sequences are: P. damselae subsp. piscicida 5S gene (AJ274379), P. damselae subsp. damselae 23S gene (Y18520), subsp. piscicida 23S gene (Y17901), P. damselae subsp. piscicida ITS-2 (AJ250695, AJ250696), P. damselae subsp. damselae ITS-2 (AJ250697, AJ250698).     

Microsatellite variation and assessment of genetic structure in tea tree (Melaleuca alternifolia– Myrtaceae)

Analysis of five microsatellite loci in 500 Melaleuca alternifolia individuals produced 98 alleles that were useful for population genetic studies. Considerable levels of observed heterozygosity were recorded (HO = 0.724), with approximately 90% of the variability being detected within populations. A low level of selfing (14%) was suggested to be the principal cause of excess homozygosity in a number of populations (overall FIS = 0.073). This study showed low levels of inbreeding in certain populations as well as a significant isolation-by-distance model. Only two groups of populations (Queensland and New South Wales) constituted different genetic provenances as a result of geographical isolation. The M. alternifolia data suggest that microsatellite loci did not always arise by a stepwise mutation process but that larger jumps in allele size may be involved in their evolution.     

Anomopterellidae Restored,with Two New Genera and Its Phylogeny in Evanioidea (Hymenoptera)

Background

Anomopterellidae was originally classified as a family within the Evanioidea, and later lowered to a subfamily, Anomopterellinae, of Praeaulacidae. Up to date, only Rasnitsyn 1975, with four species, was assigned to Anomopterellinae. Due to their special wing venation and their metasomal attachment similar to those known in Evanioidea, the systematic position of Anomopterellinae in Evanioidea has been in contention.

Principal Findings

Here we report a new fossil genus Synaphopterella gen. nov. and six species from the Middle Jurassic of China and transfer Anomopterella stenocera Rasnitsyn, 1975, from Upper Jurassic of Kazakhstan, to Choristopterella gen. nov. We place these three genera in the restored family Anomopterellidae and provide a key to known genera and species.

Conclusions/Significance

Based on new fossil specimens and phylogenetic analyses, Praeaulacidae has the most basal position in Evanioidea and it is justifiable to restore Anomopterellidae Rasnitsyn, 1975 as a full family. Comparing the size of all described anomopterellids from China, Mongolia and Kazakhstan, we conclude that the species from China have larger bodies and forewings. Diversity of the Praeaulacidae and Anomopterellidae in the late Middle Jurassic of Daohugou suggests that Evanioidea appeared at least before the late Middle Jurassic.     

Molecular Phylogeny and Evolutionary Relationships between the Ciliate Genera Peniculistoma and Mytilophilus (Peniculistomatidae,Pleuronematida)

Peniculistoma mytili and Mytilophilus pacificae are placed in the pleuronematid scuticociliate family Peniculistomatidae based on morphology and ecological preference for the mantle cavity of mytiloid bivalves. We tested this placement with sequences of the small subunit rRNA (SSUrRNA) and cytochrome c oxidase subunit 1 (cox1) genes. These species are very closely related sister taxa with no distinct genetic difference in the SSUrRNA sequence but about 21% genetic difference for cox1, supporting their placement together but separation as distinct taxa. Using infection frequencies, M. pacificae, like its sister species P. mytili, does not interact with Ancistrum spp., co‐inhabitants of the mantle cavity. On the basis of these ecological similarities, the fossil record of host mussels, and features of morphology and stomatogenesis of these two ciliates, we argue that M. pacificae derived from a Peniculistoma‐like ancestor after divergence of the two host mussels. Our phylogenetic analyses of pleuronematid ciliates includes the SSUrRNA gene sequence of Sulcigera comosa, a Histiobalantium‐like ciliate from Lake Baikal. We conclude: (i) that the pleuronematids are a monophyletic group; (ii) that the genus Pleuronema is paraphyletic; and (iii) that S. comosa is a Histiobalantium species. We transfer S. comosa to Histiobalantium and propose a new combination Histiobalantium comosa n. comb.