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11.
The development of Axiothella mucosa,Andrews   总被引:1,自引:0,他引:1  
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The genus Copidosoma (Hymenoptera: Chalcidoidea: Encyrtidae) is a diverse group of polyembryonic parasitoids of Lepidoptera, including species that have the potential to control agricultural and forestry pests. Moreover, some species of Copidosoma display polyembryony. Despite their economic and scientific importance, little is known about the phylogeny of Copidosoma and its relations to other groups of Encyrtidae. Here we infer the phylogenetic relationships of this genus from nucleotide sequences of two nuclear (18S and 28S) and one mitochondrial (COI) genes. Forty‐four species of Copidosoma and three species of Copidosomopsis plus two outgroup species are included in Maximum Parsimony and Bayesian analyses. Copidosomopsis syn. n . is proposed as a junior synonym of Copidosoma based on phylogenetic analysis results. Each of nine identical clades, resulting from both analyses, is proposed as informal species group: cervius group (cervius, chalconotum and serricorne), recovered as the basal lineage of Copidosoma; nacoleiae group (nacoleaie, meridionalis and an undescribed species, formerly belonging to the genus Copidosomopsis); boucheanum group (boucheanum, terebrator, peticus, phaloniae, ancharus, tibiale and sosares); noyesi group (noyesi and probably undescribed related species); albipes group (albipes and coimbatorense); varicorne group (including varicorne and subalbicorne in one subclade, and aretas and fuscisquama in the other); thebe group (thebe and probably undescribed related species); exiguum group (exiguum and probably undescribed related species); floridanum group (floridanum, primulum, transversum, truncatellum and agrotis). Host associations of the genus and host specificity of recognized groups are discussed. The current work offers a foundation for a comprehensive phylogeny of Copidosoma and the possibility to reconstruct cophylogeny between Copidosoma and their lepidopteran hosts.  相似文献   
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Robust quantile estimators for skewed populations   总被引:2,自引:0,他引:2  
HORN  PAUL S. 《Biometrika》1990,77(3):631-636
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1. Long‐term data on the meteorology, hydrology, physicochemistry and plankton of a reservoir and its tributaries in SE Germany run from 1976 until now. This dimictic reservoir changed from mesotrophic to eutrophic in the 1970s, remained eutrophic in the 1980s and returned to the mesotrophic state after a sharp reduction in P loading in 1990. 2. Phytoplankton biomass reaches an annual maximum in spring and consists almost entirely of diatoms. While Asterionella formosa was dominant until 1990, Aulacoseira subarctica became more frequent at the end of the 1990s and was particularly abundant in years with short winters. 3. Statistical analyses suggested that these changes were triggered primarily by the mild winters that were frequent after 1988. Climate‐related hydrophysical variables and the initial biomass of the diatoms at the beginning of the year, considered as an ‘inoculum’, were identified as most important. These variables explained 39% of the total variance of the relative abundance, whereas the change in trophic conditions was responsible for about 20%. 4. The absolute and relative abundance of A. subarctica was positively related to short ice cover, early ice‐out and a long‐lasting spring circulation. Owing to its physiological traits, and particularly its ability to survive under low‐light conditions, A. subarctica benefitted from short, mild winters. Under such conditions, it could sustain or establish a high initial biomass, whereas the concentrations of the other diatoms decreased over winter. However, this advantage may be lost if further warming causes an early onset of summer stratification. Because of its low population growth rate and requirement for high turbulence, A. subarctica needs long, cold springs to exploit the improved starting conditions and to become abundant. 5. In contrast to A. subarctica, A. formosa required a substantial soluble reactive phosphorus supply to compete successfully. The eutrophic conditions until 1990 were the prerequisite for its mass growth under low‐light and low‐temperature conditions during the spring. After reduction in P concentration from 1990, A. formosa declined and other diatom species became more abundant. 6. These other diatoms may be viewed as ‘stopgaps’ when conditions were not favourable for A. subarctica or A. formosa. Diatoma elongatum exploited brief circulation periods in years with low P loading. Synedra acus and Fragilaria crotonensis, because of their poor competitive ability at low light intensity, reached high density in the upper water column in the transitional period between spring circulation and summer stratification. 7. Our study suggests that climate‐related variables have crucial impacts on the spring phytoplankton dynamics of deep stratified waterbodies. They can mask the consequences of changes in the trophic conditions and, corresponding to the functional traits of the different phytoplankton species, also decisively control their relative abundances. In this reservoir, the warmer winters and prolonged spring circulations did not only lead to high phytoplankton biomass (despite considerably reduced nutrient loads) but also cause a marked shift in the diatom assemblage during the spring bloom.  相似文献   
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Pinheiro F.L., Horn B.L.D., Schultz C.L., de Andrade J.A.F.G. and Sucerquia P.A., 2012: Fossilized bacteria in a Cretaceous pterosaur headcrest. Lethaia, Vol. 45, pp. 495–499. We report herein the first evidence of bacterial autolithification in the Crato Formation of Araripe Basin, Brazil. The fossilized bacteria are associated with a tapejarid pterosaur skull, replacing the soft‐tissue extension of the headcrest. EDS analyses indicate that the bacteria were replaced by phosphate minerals, probably apatite. The bacterial biofilm was likely part of the prokaryotic mat that decomposed the pterosaur carcass at the bottom of the Araripe lagoon. This work suggests that bacterial autolithification could have played a key‐role on soft‐tissue preservation of Crato Formation Lagerstätte. □Bacterial autolithification, Crato Formation, phosphatization, pterosaur, soft‐tissue preservation.  相似文献   
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Within the insect order Lepidoptera (moths and butterflies), the so‐called nonditrysian superfamilies are mostly species‐poor but highly divergent, offering numerous synapomorphies and strong morphological evidence for deep divergences. Uncertainties remain, however, and tests of the widely accepted morphological framework using other evidence are desirable. The goal of this paper is to test previous hypotheses of nonditrysian phylogeny against a data set consisting of 61 nonditrysian species plus 20 representative Ditrysia and eight outgroups (Trichoptera), nearly all sequenced for 19 nuclear genes (up to 14 700 bp total). We compare our results in detail with those from previous studies of nonditrysians, and review the morphological evidence for and against each grouping The major conclusions are as follows. (i) There is very strong support for Lepidoptera minus Micropterigidae and Agathiphagidae, here termed Angiospermivora, but no definitive resolution of the position of Agathiphagidae, although support is strongest for alliance with Micropterigidae, consistent with another recent molecular study. (ii) There is very strong support for Glossata, which excludes Heterobathmiidae, but weak support for relationships among major homoneurous clades. Eriocraniidae diverge first, corroborating the morphological clade Coelolepida, but the morphological clades Myoglossata and Neolepidoptera are never monophyletic in the molecular trees; both are contradicted by strong support for Lophocoronoidea + Hepialoidea, the latter here including Mnesarchaeoidea syn.n. (iii) The surprising grouping of Acanthopteroctetidae + Neopseustidae, although weakly supported here, is consistent with another recent molecular study. (iv) Heteroneura is very strongly supported, as is a basal split of this clade into Nepticuloidea + Eulepidoptera. Relationships within Nepticuloidea accord closely with recent studies based on fewer genes but many more taxa. (v) Eulepidoptera are split into a very strongly supported clade consisting of Tischeriidae + Palaephatidae + Ditrysia, here termed Euheteroneura, and a moderately supported clade uniting Andesianidae with Adeloidea. (vi) Relationships within Adeloidea are strongly resolved and Tridentaformidae fam.n. is described for the heretofore problematic genus Tridentaforma Davis, which is strongly supported in an isolated position within the clade. (vii) Within Euheteroneura, the molecular evidence is conflicting with respect to the sister group to Ditrysia, but strongly supports paraphyly of Palaephatidae. We decline to change the classification, however, because of strong morphological evidence supporting palaephatid monophyly. (viii) We review the life histories and larval feeding habits of all nonditrysian families and assess the implications of our results for hypotheses about early lepidopteran phytophagy. The first host record for Neopseustidae, which needs confirmation, suggests that larvae of this family may be parasitoids. This published work has been registered in ZooBank: http://zoobank.org/urn:lsid:zoobank.org:pub:C17BB79B‐EF8F‐4925‐AFA0‐2FEF8AC32876 .  相似文献   
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