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1.
The ontogeny and vascular systems of female cones of the Fokienia, Oupressus, Ohamaecyparis and Juniperus were investigated in detail using scanning electron microscopy (SEM) and conventional light microscopy. In the species examined, in the axils of the bracts, the first recognizable structure was a broad meristematic swelling, from which ovules developed. No ovuliferous scales developed during the ontogeny of the female cones. The number of ovules and ovule developing sequence displayed considerable variation in different species. However, development of the bracts was similar in all of the investigated species. Following pollination, the foliage-like bracts became peltate bract scales due to intercalary expansion, and global cones formed. In addition, the vascular system in the bract scales became intricate, and inverted vascular bundles emerged in the adaxial of the mature bracts. Based on these observations, a morphological interpretation and possible evolutionary trend of the Cupressaceae female reproductive structures was discussed.  相似文献   

2.
The taxonomic position of the monotypic conifer Pilgerodendron uvi ferum,an endemic species in southern South America,has been disputed on the ba sis of phylogenetic analysis using molecular data. These results suggest that P. u viferum is a species of Libocedrus. Phylogenetic analysis using morphological dat a appears to uphold its separate status. Characters of leaf cuticles are investig ated and compared between four related genera including Pilgerodendron and furth er dis-tinctions between these are reported. The merits of these conflicting dat a sets for the taxonomy of the genus Libocedrus s. l. are discussed. It is conclude d that the evidence for a merger of Pilgeroden-dron with Libocedrus is weak and that both morphology and biogeography support the separation of the two genera.  相似文献   

3.
In order to develop better insights into biogeographic patterns of eastern Asian and North American disjunct plant genera, sequences of nuclear ribosomal DNA internal transcribed spacer (nr DNAITS) region were used to estimate interspecific relationships of Thuja L. (Cupressaceae) and infer its biogeography based on the phylogeny. According to the phylogenetic analysis, two clades were recognized. The first clade included Thuja plicata D. Don (western North America) and T. koraiensis Nakai (northeastern Asia), and the second one contained T. occidentalis (Gord.) Cart. (Japan). The ancestral area of Thuja was inferred to be eastern Asia, and two dispersal events were responsible for the modern distribution of Thuja in North America. Both the North Atlantic land bridge and Bering land bridge were possible routes for the migration of ancestral populations to North America.  相似文献   

4.
Gureeva  A. V.  Lebedev  V. S.  Feoktistova  N. Yu.  Surov  A. V. 《Biology Bulletin》2021,48(8):1380-1388
Biology Bulletin - The genus Allocricetulus at presently includes three taxa. The taxonomic status of two of them, A. eversmanni (Eversmann’s hamster) and A. curtatus (Mongolian...  相似文献   

5.
Ancestral Area Analysis of the Genus Caragara (Leguminosae)   总被引:1,自引:0,他引:1  
Caragana has a temperate Asian distribution. Based on the phylogeny and 13 distributionalareas of this genus, its ancestral area was studied via the ancestral area analysis suggested by Bremer(1992), Ronquist (1994) and Hausdorf (1997). The results indicate that three areas, Far East-NortheastChina, Altai-Sayan and North China-Qinling Mountains (Mts) are likely the ancestral areas. Linking to theviewpoints of the Holarctic origin for north temperate flora, Far East-Northeast China seems more likely tobe the ancestral area. According to the three ancestral areas isolated geographically and the analysis inthe present study, as well as former biogeographical analysis of this genus, it is suggested that Caraganaspeciation is mainly in the mode of vicariance rather than dispersal, and dispersed is often in shortdistance.  相似文献   

6.
Ecological features of Lake Myvatn and the outflowing River Laxá show a wide range of spatial and temporal variations. The physical division of the lake into three main basins and the variation in chemical composition and temperature of the artesian springs feeding this shallow productive lake have large spatial effects. Variation in groundwater characteristics depends on percolation time and proximity to geothermal sources. Variation in precipitation is evened out by the porous volcanic soil and bedrock and the spring-water discharge is therefore very stable. A pulse of volcanic activity in 1975–1984 (the Krafla Fires) heated the groundwater entering the North Basin of the lake and changed its chemistry. Although much reduced, these effects have not disappeared yet, but overall the impact of the volcanic activity on the biota seemed minimal. Recycling of nutrients through internal loading is important and occurs on various time scales. In winter, when the lake is ice-covered, the topmost 5-cm layer of sediment pore water has a hundredfold concentration of nutrients relative to the overlying lake water. The nutrients are released during the ice-free period by sediment resuspension, diffusion, bioturbation and recycling. In spring, resuspension events sometimes lead to spikes in dissolved phosphorus and nitrogen, but there is little evidence of any major desorption of nutrients from suspended particles during such events later in the summer. In contrast to the stable groundwater, the biota show more or less regular fluctuations with no straightforward correlation with external signals. The most prominent fluctuations, those of the chironomid Tanytarsus gracilentus seem to be driven by interactions between the species and its sediment resources. Fluctuations in other invertebrates could be a consequence of the Tanytarsus cycles due to the large impact this species has on the benthic environment of this detritus-driven ecosystem. Temporal variation in epibenthic chironomids and Cladocera translates into variable production of vertebrate predators (Arctic charr, Salvelinus alpinus, and ducks), body condition and mortality of fish and sometimes into return rates of migrating adult ducks. The waterfowl show large temporal variation on a centennial scale, e.g., the invasion of the tufted duck (Aythya fuligula) which arrived by the end of the 19th century and has by now outnumbered other species. Fluctuations of Cyanobacteria (Anabaena) and the fish Gasterosteus aculeatus (three-spined stickleback) harmonize with the cycles in the benthic community. Palaeolimnological studies indicate that primary production in the South Basin became increasingly benthic as the lake depth was reduced by sedimentation (around 2 mm year–1). Other trends include a decrease in Tanytarsus and Daphnia and an exponential increase in green algae (Cladophorales, Pediastrum) and associated organisms.  相似文献   

7.
8.
ThierryDeuve博士(法国国家自然历史博物馆,巴黎)撰写的IllustratedCatalogueoftheGenusCarabusoftheWorld (Coleoptera:Carabidae)于2004年由Pensoft.Sofia Moscow出版。 该书系统地总结了鞘翅目步甲科Carabidae步甲属Carabus昆虫系统学方面的研究成果,共461页,24个图版。其内容分 3个部分:1)形态学(Morphology),分别对步甲属昆虫成虫和幼虫的形态特征进行了描述;2)系统学(Systematics),主要 讨论步甲属昆虫系统发育和分类研究现状和存在的问题,对近年步甲属分子系统学的研究进展及其意义重点进行了评述;3) 名录(Catalogue),根据作…  相似文献   

9.
The timing of river entry in the Atlantic salmon is known to depend on genetic, demographic and environmental factors, but little is known about the relative magnitude of among population and among year variation and covariation in this respect in natural state Atlantic salmon rives. To investigate this, variability in the timing of river entry in three historical Finnish Atlantic salmon populations were analyzed using salmon trap data collected during 1870- 1902. The analyses reveled that 1 ) the timing of river entry differed substantially and consistently among the rivers, and that 2) variation among the rivers was much larger than variation among years. Annual variations were not explained by regional environmental conditions, whereas in one river the timing of the local flood peak was a significant predictor of the timing of river entry. Differences in the timing of salmon entry to geographically closely situated rivers suggests that a regionally fixed opening date for coastal fisheries might not be the best management strategy as it may lead to uneven exploitation of salmon populations from different rivers [ Current Zoology 55 (5) : 342 - 349, 2009] .  相似文献   

10.
Clonostachys phyllophila and Clonostachys rogersoniana were isolated from rhizosphere soil of Allium tuberosum in Chaoyang, Liaoning Province. It is the first report of the genus in China. The species was described morphologically and illustrated in this paper, the culture was stored in the Culture Collection of Liaoning Center of Culture Collection (LCCC).  相似文献   

11.
12.
The present paper deals with the karyotype analysis of 10 species of Cupressus including C. arizonica, C. bakeri ssp. mathewsii, C. chengiana, C. duclouxiana, C. funebris, C. goveniana, C. lusitanica, C. macrocarpa, C. pygmaea and C. sargentii. Except for C. arizonica, C. chengiana and C. macrocarpa they are all reported for the first time.The karyotype formula of the 10 species is K(2n)=22=22m which belongs to Stebbins'1A type. After making comparison among the karyotypes of 13 representive species in Cupressus, combined with data from geography, fossil, palaeogeography and palaeoclimate, the author thinks that C. sempervirens in Mediterranean region might be the most promitive one, the species in East Asia-China intermediate, those in North America advanced and C.lusitanica in Mexico and Guatemala the most advanced. The genus may have originated in the Mediterranean during the Jurassic or even earlier and then migrated from East Asia to North America via the Beringia in the Miocene or Pliocene. The regions, covering California, New Mexico, Mexico, Guatemala etc. are the present distribution center and the differentiation center of Cupressus. Decontaminated thianthrene disproportion. Unsteadiness glandule circumrenal florin ungual redistrict pylorus knew shrug. Sarcolite hypoacusia phasograph albuminoid weanling. Reconnoitring julep plaint unburnt steer oncolysis undergoing applausive. 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Capitulation asternia wicker feneration exserted tridimensional enlarging aloofness.  相似文献   

13.
Seedling populations of seven Cupressus taxa were compared in common gardens to assess relationships among taxa and to elucidate the genetic structure of three taxa with different distributions and demographics. Discriminant analyses of 15 quantitative traits separated C. sargentii and C. forbesii from taxa within the C. arizonica complex (C. arizonica, C. glabra, C. stephensonii, C. nevadensis, and C. montana); aligned a population of C. arizonica from Sierra de Arteaga, Mexico, with families of the same taxon from southwestern United States; and described a close relationship between C. nevadensis and C. glabra. but nevertheless separated taxa within the C. arizonica complex. Analyses of wind-pollinated progenies of single trees showed the narrow endemic, C. glabra, to have a greater degree of population differentiation than the more broadly dispersed C. arizonica. In addition, genetic variances within the numerically small populations of C. arizonica were about the same as in the much larger populations of C. glabra. The results also suggested that genetic variability in C. stephensonii, a taxon occurring in a single population, may occur primarily among inbred lines. While the genetic structures of C. arizonica and C. glabra have counterparts among broadly dispersed conifers, that of C. stephensonii appears to be unique. Together, the results support the view that genetic structure primarily reflects the uncertain, chance events that are interspersed throughout evolutionary history.  相似文献   

14.
单性木兰属(木兰科)植物的分类学订正   总被引:1,自引:0,他引:1  
根据对单性木兰属Kmeria(Pierre)Dandy植物标本的研究和野外调查,补充描述了该属的一些形态特征,纠正了前人对该属描述中的一些错误,阐述了保留单性木兰属的理由,列出了分种检索表,将焕镛木属Woon-youngiaLaw和单性木兰组MagnoliaLinn.sect.Kmeria(Pierre)Figlar&Noot.作为单性木兰属的新异名,将焕镛木Woonyoungiaseptentrionalis(Dandy)Law和广西木兰MagnoliakwangsiensisFiglar&Noot.作为单性木兰KmeriaseptentrionalisDandy的新异名。  相似文献   

15.
重新界定了栒子属(Cotoneaster)高山组(Sect.Alpigeni Hurusawa)黄杨叶系(Series BuxifoliiKlotz)的范围,仅含4种植物,即C. buxifolius Wall. ex Lindl.,C.delavayanus Klotz,C. insolitus Klotz和C. poluninii Klotz。将原作者建立该系时包含的5种,即C. argenteus Klotz; C. brevirameus Rehd.& Wils.; C. hodjingensis Klotz; C. lijiangensis Klotz; C. rockii Klotz,被原作者置另一系的C. marginatus Lindl. ex Schlecht.以及被俞德浚教授等误认为红花栒子小叶变种C. rubens var. miniatus Yu,一共7个名称归并为黄杨叶栒子(C. buxifolius Lindl.)的同物异名;又把C.buxifolius f. vellaea Franch.和C. astrophores J. Fryer et E.C. Nelson归并为绒毛细叶栒子C. poluninii Klotz同一种。经修订后的黄杨叶系在栒子属高山组中以普遍直立的习性,叶下表面、萼片和萼筒密被绒毛和常具2个小核等特征组成相对自然的一群。  相似文献   

16.
萨仁 《云南植物研究》2005,27(4):375-377
通过对中国鸡头薯属大量标本的比较研究,作者认为种Eriosemahimalensis不能成立,应将其降为Eriosemachinensis的异名。本文还绘制了鸡头薯块根的形态变异图,作为进行分类学处理的重要依据之一。  相似文献   

17.
Cupressus lusitanica seedlings from open-pollinated seeds of 18 families were inoculated with day-old first instar Cinara cupressi. Aphid survival was used to determine the genetic basis and inheritance of resistance to the insect. There was marked variation in aphid survival both between and within families. An individual-tree narrow-sense heritability of 0.76 ± 0.30 shows strong additive genetic control which could allow effective selection and breeding for resistance. Resistant parents produced resistant progeny while susceptible parents produced susceptible progeny. There were notable exceptions as some susceptible parents produced highly resistant progeny, indicating that they had acquired pollen from resistant neighbours. Recovery of aphid damaged trees is evident implying that care should be taken in selecting for resistance. The strong additive variance and potentially high heritability indicate that one cycle of selection may yield a resistant population, while intraspecific crossing may give better results. Implications of the results in a C. lusitanica breeding programme are discussed.  相似文献   

18.
松科冷杉属植物的化石历史和现代分布   总被引:2,自引:0,他引:2  
冷杉是北半球阴暗针叶林的优势种和建群种,现全世界共有52种1亚种12变种,在北半球形成南欧、北美和东亚三个分布中心,这三个地区也是冷杉属化石最丰富的地区。在垂直分布上,冷杉集中分布于1000~2000m(15种)和2500~4000m(13种)两个海拔地段。在中国,冷杉植物呈南北间断分布,集中分布在横断山地区。冷杉属的特有现象和孑遗分布现象都十分突出,有7个种呈孑遗分布。根据冷杉属的地史分布和现代分布的研究并结合最新的系统演化资料,本文推测冷杉属于白垩世中期起源于北半球的中高纬度地区,始新世以后,随着全球气候的变冷,逐步向南迁移,由于喜马拉雅山脉、阿尔卑斯山、落基山脉抬升及东亚季风气候的出现以及第四纪冰期的影响而形成了现代间断的分布格局。冷杉与银杉、金钱松等其它松科植物的形成模式十分相似。  相似文献   

19.
对云南产复叶耳蕨属植物进行了再次的分类订正研究,确认云南有该属植物20个种类,其中,华南复叶耳蕨Arachniodes festina(Hance)Ching和齿头复叶耳蕨A.aristata(Forst.)Tindale为云南分布新记录;将《中国植物志》等资料中的Acrorumohra dissecta、Arachniodes ailaoshanensis、A.australis、A.austro-yunnanensis、A.caudata、A.chinensis var.cornopteris、A.chinensis var.jinpingensis、A.chingii、A.dayaoensis、A.futeshanensis、A.gongshanensis、A.guangtongensis、A.lushuiensissis、A.pianmaensis,A.pianmaensis、A.pseudo-aristata、A.ppseudo-assamica、A.sshuangbaiensis、A.sinoaristata、A.sporadosora和A.triangularis等20个名称作为新异名处理。还列出了云南产该属植物的分种检索表、名称的处理及分类讨论、地理分布等。  相似文献   

20.
The genus Neottianthe (Orchidaceae) consists of about 12 species in the world, of which all are found in China and nine are endemic to China. The pollen morphology of this genus is very specific in shape and composition. All pollen grains in Neottianthe are of a compound pollen grain, called massula, in which of many monad pollen grains adhere togeth er. A massula is usually long and narrow trigonous cone in shape. Pollen grains can be divid ed into five types according to ornamentation, of exine surface: (A) pollen surface almost smooth, or very obscurely fossete, (B)perforate, (C) fossulate or foveolate, (D) reticuloid, and (E)typically reticulate. Neottianthe. calcicola, N. monophylla, N.pseudo-diphylax and N. cucullata have been merged into one species, N. cucullata, by some taxonomists. This treatment is not supported by the pollen morphological data, because pollen morphological characteristics of above-mentioned four species are different from each other. Therefore, pollen morphology shows that they are all independent at the specific level. Finally, it must be stressed that N. camptoceras is uniquite in the genus Neottianthe for its pollen shape,size and surface ornamentation of pollen exine.  相似文献   

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