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1.
A crossing programme including 30 species and 40 cytotypes within the genusHordeum was undertaken. Viable hybrids were obtained in 302 combinations, 15 of which were intraspecific. Differences in seed set and in germination were observed in crosses between different groups of species. Obtaining crosses between different taxonomic groups was generally more difficult when diploid material was used. Some species, e.g.,H. lechleri, H. jubatum, andH. brachyantherum showed a higher crossability than others. The chromosome numbers of the hybrids were usually those expected from the parental numbers but aneuploid series around the expected numbers were rather frequent. Three cases of unreduced gametes were found. Selective chromosome elimination was restricted to combinations including eitherH. vulgare orH. bulbosum.—Despite a very diverse morphology, all South American diploid species together with the two North American diploidsH. intercedens andH. pusillum appear to be closely related. The hexaploid American speciesH. procerum, H. lechleri, andH. arizonicum are also related. The two North American tetraploid speciesH. jubatum andH. brachyantherum sometimes form semifertile hybrids. The Asiatic speciesH. roshevitzii appears to be related to both North and South American taxa.  相似文献   

2.
李玉  陈双林  李惠中 《菌物学报》1992,11(Z1):171-174
贫丝菌属Oligonema是由Rostafinski在1875年建立的,至今仅承认4个种,中国前此尚无记载。作者在长白山采到的这份标本,孢丝极少且短小,中部膨肿,有不甚清晰的螺纹带,具贫丝菌的特征,与已知的种明显不同,因此确认为本属的新成员,定名为膨丝贫丝菌O. oedonema,主模式保存在中国科学院微生物研究所真菌标本室。  相似文献   

3.
Sclerorhachis rechingeri Iranshahr, sp. n., from N. Khorasan is closely related to the Afghanistan speciesS. caulescens (Aitch. & Hemsl.)Rech. f. andS. polysphaera Rech. f. It differs from both in the thicker and woolly collar and the much larger capitulum.Vorarbeiten zuK. H. Rechinger, Flora Iranica, Nr. 21.  相似文献   

4.
郭林 《菌物学报》1995,14(Z1):163-168
本文报道炭黑粉菌一新种,即细叶蒿草炭黑粉菌(Anthracoidea filifoliae L. Guo sp.nov.)和4个我国新记录种:1)角孢炭黑粉菌(A. angulata(H. Sydow) Boidol & Poclt), 2)黍状苔炭黑粉菌(A. paniceae Kukkenen), 3)狼尾草团黑粉菌(Sorosporium penniseti Mundkur)和4)米勒粘孢黑粉菌(Tolyposporium muellerianum (Thuemen) McAlpine)。  相似文献   

5.
There are seven known species of Azolla, two of which have been used in cultivated systems, the tropical speciesA. pinnata, and the temperate speciesA. filiculoides. OnlyA. pinnata is indigenous in Thailand. In this study the two exotic species,A. caroliniana andA. microphylla, were evaluated under the various tropical field conditions in Thailand. When compared with seven selected strains ofA. pinnata under three field conditions,A. caroliniana andA. microphylla were similar to the indigenous species, in terms of growth performance, N2 fixation, and yield. This study suggests thatA. caroliniana andA. microphylla can be successfully cultivated as a nitrogen fixing green manure for rice production in the tropics.  相似文献   

6.
A new species ofEmericella isolated from forest soil in the Oman,E. omanensis, is described and illustrated. It differs from the other known species of the genus in having bivalvate ascospores with a tuberculate or verruculose convex wall. The new species is compared with the closely related speciesE. desertorum andE. echinulata.  相似文献   

7.
Mature seeds of diploid and tetraploidHibiscus species were analyzed for enzyme activity (alcohol dehydrogenase, malate dehydrogenase, leucine aminopeptidase), total protein content, DNA amount and dry weight. The recently formed tetraploid,H. radiatus, generally had enzyme and protein levels very similar to the sum of its progenitors, while the more ancient speciesH. acetosella had several lower levels. This difference may reflect the greater amount of timeH. acetosella has had to evolve dosage compensations.Michigan Agricultural Experiment Station Journal Article 9665.A part of this research was used to satisfy the requirements ofA. Hoisington for a M.S. degree at the University of South Carolina.  相似文献   

8.
New osteological material of the endemic deer from Lunel-Viel and l’Igue des Rameaux (France) reveals its evolutionary specialization, and gives reason for establishing a new genus,Haploidoceros, with a single speciesH. mediterraneus (Bonifay, 1967). The cranial proportions and morphology suggest thatH. mediterraneus is close to the Late Villafranchian speciesMetacervocerus rhenanus, which may be a possible forerunner of the deer under study. The evolutionary origin ofH. mediterraneus took place in the Iberian glacial refugia during the “Mindel glaciation” of the early Middle Pleistocene. The North-East distribution ofH. mediterraneus was limited by unfavorable climate influence of the Arctic and Alpine Ice Shields.   相似文献   

9.
The solitary parasitoids Aphidius erviHaliday (Hymenoptera: Aphidiidae) and Aphelinus asychisWalker (Hymenoptera: Aphelinidae) attacked but generally did not oviposit in pea aphids parasitized by the other species. Wasps selectively oviposited in unparasitized hosts when given a choice. Host discrimination depended on the recognition of internal cues. Females of A. asychiseither could not recognize or ignored A. ervi'sexternal host marking pheromone. Under most conditions, A. ervisurvived in superparasitized hosts, killing competing A. asychislarvae by physical attack and possibly physiological suppression. The outcome of larval competition was not affected by oviposition sequence or age difference between larvae; A. asychissurvived only when it had substantially completed larval development before the host was superparasitized by A. ervi.It is suggested that competition for host resources incurs a cost, for the winner in terms of reduced size or increased development time and for the loser in terms of lost progeny and searching time. Consequently, heterospecific host discrimination can be functional. Internal, and probably general, cues enable wasps to recognize and avoid oviposition in hosts already parasitized by an unrelated species.  相似文献   

10.
Pothos crassipedunculatus Sivadasan & Mohanan (Araceae), a new species closely related to the SW. Indian endemic and little known speciesP. thomsonianus Schott is described. It is characterized by the the non-ligulate, shortly vaginate petiole, thickly peduncled inflorescence, broadly ovate spathe and a sessile spadix. It is included in ser.Brevivaginati Engler of sect.Allopothos Schott.  相似文献   

11.
A new fossil priacanthid fish,Cookeolus spinolacrymatus, is described on the basis of a single specimen from the Late Pliocene Shinzato Formation, Shimajiri Group, Miyagi-shima, Okinawa, Japan. This species is distinguished from the Recent speciesC. japonicus (Cuvier, 1828) by having a strong spine on the anterior portion of the lacrymal. The specimen was identified as a small benthic adult, or large juvenile, based on comparison with pelvic fin length development in the Recent species.  相似文献   

12.
A study was made of the genetic variability of 101 barley populations belonging to the four, wild, Spanish species of the genusHordeum (the autogamousH. marinum subspp.marinum andgussoneanum, andH. murinum subspp.murinum andleporinum, plus the allogamous speciesH. bulbosum andH. secalinum). Electrophoresis of endosperm proteins was performed using a large number of individuals from each population sampled, in order to determine intra- and interpopulational variation. The distribution of variability observed by population and taxonomic unit, is closely related to the breeding system.Hordeum bulbosum showed the greatest intrapopulational variability andH. marinum subsp.gussoneanum the least. In contrast to the autogamous species, the allogamous species showed low levels of interpopulational variation.  相似文献   

13.
A comparative investigation was carried out on the ovule and seed development of three mountain species ofGentianaceae, the perennial speciesGentiana pyrenaica, and the two short-lived monocarpic speciesGentianella caucasea andG. germanica. In all three species most embryological characters conform to those generally found in the family of theGentianaceae. In some features, however,G. pyrenaica and the twoGentianella species differ from each other. InG. pyrenaica the ovule is anatropous, the integument 8–10 layered and the three reduced antipodals degenerate soon after fertilization. In contrast,G. caucasea andG. germanica form a hemitropous ovule, a 4–5 layered integument and up to 16 antipodal cells by secondary multiplication. All three species exhibit differences in synchronization between embryogenesis and endosperm development. Functional relations between the antipodal structure and the dynamics of seed development of the investigated species are postulated.  相似文献   

14.
The natural reservoir ofHistoplasma capsulatum var.duboisii, the etiological agent of histoplasmosis duboisii (African histoplasmosis) is not yet known. We report the isolation ofH. capsulatum var.duboisii from soil admixed with bat guano and from the intestinal contents of a bat in a sandstone cave in a rural area, Ogbunike in Anambra State of Nigeria. Eight of 45 samples of soil admixed with bat guano yieldedH. capsulatum var.duboisii. Of the 35 bats belonging to the speciesNycteris hispida andTadirida pumila examined, only one (N. hispida) yielded this fungus from its intestinal contents. Identification of the isolates asHistoplasma was confirmed by exoantigen tests and by mating with tester strains ofH. capsulatum. In vitro conversion to large yeast from suggestive ofH. capsulatum var.duboisii was obtained on brain heart infusion agar supplemented with sheep blood and glutamine or cysteine. Pathogenicity tests with mice for all the isolates confirmed their identity by the demonstration of large yeast forms (8–15 µm in diameter) within giant cells in the infected tissues. Investigations on the possible occurrence of human infections in the area are in progress.A poster based on this work was presented at the 11th ISHAM Congress in Montreal, Canada (22–28 June 1991), La-Hoffman Roche, Basel, Switzerland kindly financed the trip of one of us (H.C.G) for the Congress.  相似文献   

15.
Samples of Mytilus were collected at eight sites located in and around Bergen, Norway, and analysed by starch gel electrophoresis for the two highly polymorphic loci PGM* and PGI*. The genotype distribution and allele frequencies varied significantly among samples from the different locations. The variations were most significant between localities with full strength seawater and brackish water, and this difference was so large that it indicated the presence of two populations, possibly representing two species. The brackish water mussels may represent the species Mytilus trossulus, while the species Mytilus edulis may be distributed on the outer shores where salinity is normally around 30. Differential survival, as a result of specific adaptation to different salinities, may be the mechanism that maintains the populations (or species) and prevents gene flow between them.Communicated by H.-D. Franke  相似文献   

16.
Hybrids between the Chinese endemic speciesPsathyrostachys huashanica Keng and the SW. Asian speciesP. fragilis (Boiss.)Nevski (all 2n = 14) developed normally but were completely sterile. Meiotic analyses revealed a high chiasma frequency indicating that the two species as well asP. juncea (Fisch.)Nevski share the same basic genome (called N). The hybrid nature of the plants was established through karyotype analysis and Giemsa C-banding.  相似文献   

17.
The two closely related speciesLycopsis variegata andAnchusa cretica, formerly placed inAnchusa subg.Rivinia, were compared with the type species ofLycopsis andAnchusa, on the basis of a set of macro and microcharacters. The presence of only two fertile stamens as well as other peculiar characters in flower structure, androecium, gynoecium, pollen and fruit, supports the institution of the new genusAnchusella, consisting ofA. variegata andA. cretica. Karyological and eco-chorological aspects are consistent with morphological data in pointing to the autonomy of this genus, which appears characterized by autapomorphic, advanced traits.  相似文献   

18.
DNA contents have been determined cytophotometrically in the three Central European, relatedScilla speciesS. bifolia (2n = 18, 2 x, 1 C = 6.2 pg),S. drunensis (2n = 36, 4 x, 1 C = 12.8 pg), andS. vindobonensis (2n = 18, 2 x, 1 C = 9.4 pg). The tetraploid speciesS. drunensis contains twice as much DNA as the diploidS. bifolia. However, the diploid speciesS. vindobonensis differs in DNA content fromS. bifolia by a factor of about 1.5. This difference is largely due to euchromatic DNA, although the higher DNA content inS. vindobonensis is combined with higher heterochromatin content. The data indicate thatS. bifolia andS. drunensis on the one hand, andS. vindobonensis on the other hand are phyletically well separated. Previous taxonomic conclusions from morphology as well as C-banding are thus corroborated.Evolution ofScilla and Related Genera, V.  相似文献   

19.
The responses of 3 phytoseiid mite speciesPhytoseiulus persimilis Athias-Henriot,Phytoseius finitimus Ribaga andAmblyseius gossipi Elbadry to allelochemics emitted by prey mite speciesTetranychus urticae Koch,Brevipalpus pulcher (Canestrini & Fanzago) andEriophyes dioscoridis Soliman & Abou-Awad were studied using a test of two-choice assays. The repellent effect elicited by the tenuipalpid mite,B. pulcher and the eriophyid mite,E. dioscoridis againstP. persimilis could be an evidence for the existence of allomones produced by these 2 prey species. The negative response ofP. persimilis to the different stadia ofB. pulcher and the attraction ofP. finitimus toward the same prey suggest that the volatile semiochemicals produced by this prey act as kairomones forP. finitimus and as allomones forP. persimilis. The strong attraction ofP. finitimus andA. gossipi to the different stadia ofT. urticae and the considerable attraction of either predator toB. pulcher compared to the neutral response toE. dioscoridis reveal that both predators show a hierarchy of preference for the kairomones of the 3 prey species studied.   相似文献   

20.
The cranium of a robust australopithecine, KNM WT 17000, was discovered from the Plio/Pleistocene deposits west of Lake Turkana in Kenya, and assigned to the speciesAustralopithecus boisei Leakey, 1959. A comparative morphological study shows that it does not conform with the diagnosis forA. boisei. It is characterized by having a much smaller brain, a low hyperprognathous facial skeleton, and a less developed masticatory apparatus. Its unique morphological pattern justifies its placement in a new taxon which is calledAustralopithecus walkeri n. sp.  相似文献   

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