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1.
Electrophoretic data for 15 enzymes encoded by 18 loci were analysed in samples of larval lampreys from two southern hemisphere species (Geotria australis and Mordacia mordax). Low values for Nei genetic distance coefficients for all loci in populations of G. australis from Western Australia, Tasmania and New Zealand (0.0013 to 0.0058) suggest that adults may intermix over distances greater than 4000 km. The average heterozygosity for four populations of G. australis (0.086) was much greater than for two populations of the far less widely distributed M. mordax (0.021).  相似文献   

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Perl's Prussian blue and bathophenanthroline have been used to investigate the sites where iron-containing granules are found within representatives of each of the three extant families of lampreys. Amongst the larvae, granules were present in the columnar cells of the posterior intestine in small amounts in some but not all northern hemisphere species (Petromyzonidae), and in moderate and very large amounts in the southern hemisphere families Geotriidae and Mordaciidae respectively. Granules were only found in large numbers elsewhere in the body of larvae of the Geotriidae, in which they were predominant in the adipose tissue of the nephric fold and fat column. It is suggested that these large iron deposits reflect the intake of an unusually large amount of iron, a feature which in turn could be related to the relatively high plasma iron levels and haemotocrit found in larvae of the Geotriidae. During metamorphosis, iron deposits accumulate in the liver of all species as haemoglobin is broken down.  相似文献   

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A revision of the Iranian Bolboschoenus was made based on studies of herbarium material and cultivated plants. Fruit features (fruit shape and pericarp anatomy) were used as the main distinguishing characters; style branching, inflorescence structure and the colour of floral scales were considered as accompanying distinguishing characters. The following taxa were recognized: Bolboschoenus glaucus (Lam.) S. G. Sm., B. affinis (Roth) Drobov, B. schmidii (Raymond) Holub, B. planiculmis (F. Schmidt) T. V. Egorova and B. maritimus (L.) Palla. Taxonomical difficulties, especially in the B. affinis group and B. maritimus are discussed. Bolboschoenus glaucus was found in all of the phytogeographical regions of Iran, and it is more frequent than any other Bolboschoenus species. Bolboschoenus planiculmis is very rare in the Irano–Turanian and Hyrcanian regions and grows only in human‐influenced habitats; it might be introduced as a weed in rice fields. Bolboschoenus maritimus, B. affinis and B. schmidii occur in the Irano–Turanian region only rarely. Bolboschoenus maritimus reaches the southeastern border of its distribution area in this region. All these species typically grow at higher altitudes. Great morphological variability in inflorescence structure was found in some species (especially in B. glaucus), which may be partly explained as a response to habitat conditions and partly by genotypic diversity.  相似文献   

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The taxonomy and distribution of Azolla species in southern Africa   总被引:2,自引:0,他引:2  
The three Azolla species which occur in southern Africa, A. pinnata var. pinnata, A. nilotica and A. filiculoides are identified and their distributions illustrated. The endosymbiotic cyanobacterium Anabaena azollae occurred in dorsal leaf lobe cavities of all three species. The first two species are indigenous to southern Africa, whilst the third, A. filiculoides , is an introduced species from North America. Possible means whereby this species could have been introduced are discussed.  相似文献   

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The way in which the huge Australian parasite fauna is described (discovery and naming) is the subject of this address. The approach to the task has never been well-organised so that a few groups of parasites are now relatively well-known because of the efforts of small groups of workers who have made sustained efforts in these groups, but equally some host-parasite systems have been almost completely ignored in that no worker has ever given them sustained attention. A high proportion of Australian parasites have been described by international workers. The sustaining of interest in a group of parasites over a long period is the key to real progress being made. The nature of the organisation of Australian science presently means that few positions are available for parasite taxonomists and funding for taxonomic research is scarce. Thus, parasite taxonomy (like the taxonomy of many groups of Australian plants and animals) can only be considered to be in crisis.  相似文献   

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The frond-like fimbriae surrounding the oral disc of the lamprey, Geotria australis , have been examined in living specimens, and by using histological, histochemical and ultra-structural techniques. Approximately 57 fimbriae are present in this species, with those at the posterior end of the disc being significantly larger than those in the anterior and lateral regions. The terminal finger-like projections of the fimbriae possess a stratified epithelium composed solely of a series of rows of mucous-producing cells. Tests have shown that the mucus of the epithelial cells contains large amounts of N-acetyl neuraminic acid. Since the adjacent fimbriae are closely apposed when the lamprey is using its oral disc for suction, it is suggested that their flexible shape, mucous secretions and production of an increased surface area for attachment, help to provide a more efficient seal. Since fimbriae are present in all lampreys except those species belonging to the Mordaciidae, it is postulated that their absence in this latter family can be related to known differences in the behaviour of their adult stages.  相似文献   

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The taxonomic position ofEuchresta trifoliolata is discussed, and it is concluded that it is identical withE. japonica. Consequently,E. japonica can be considered to be discontinuously distributed between SW. Japan and S. China and represents a unique pattern of distribution, which has not been known for the flora of Japan and China.E. japonica is also considered to represent a relic distribution pattern.  相似文献   

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赵利琴 《广西植物》2005,25(4):327-334
选取木兰科木兰属15种植物的108种萜类化合物成分作为研究资料,根据各种萜类化合物成分的结构类型从中找出34条可能的生源合成途径,并将各种生源途径作为数量性状,用聚类分析的方法得到木兰属各分类群之间的相关系数、作出树形分支图,根据所含萜类比较复杂成分的比例对该属的演化关系作出推论,结果表明木兰亚属与玉兰亚属是属于平行演化的两支。  相似文献   

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History and taxonomy: their roles in the core-satellite hypothesis   总被引:2,自引:0,他引:2  
Metapopulation models are important in explaining the distribution and abundance of species through time and space. These models combine population dynamics with stochastic variation in extinction and immigration parameters associated with local populations. One of the predictions of metapopulation models is a bimodal distribution of species frequency of occurrence, a pattern that led to the development of the core-satellite species hypothesis. The spatial scale and taxonomic classification of past core-satellite studies has often been undefined. In our study, we have integrated metapopulation dynamics with the roles that differential dispersal ability and history play in the shaping of communities. The differences in distribution patterns between landbridge islands and oceanic islands, and among various taxa (birds, mammals, herptiles, arthropods, fish, and plants) are analyzed. The majority of landbridge islands comprised locally and regionally abundant species (core species), whereas the majority of oceanic islands had a uniform distribution (or no end-peak in their distribution). The patterns of distribution among the taxonomic groups also showed differences. Birds (good dispersers) consistently showed bimodal- and core-distribution patterns. The bimodal prediction of species distribution is best exemplified in the landbridge islands and in birds, and least in oceanic islands and in organisms other than birds. These results illustrate the importance of testing models with various taxonomic groups and at different spatial scales and defining these scales before formally testing the predictions of the models.  相似文献   

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Rogers, P. A., Glenn, A. R., Potter, I. C. 1980. The bacterial flora of the gut contents and environment of larval lampreys. (School of Environmental and Life Sciences, Murdoch University, Australia.) — Acta zool. (Stockh.) 61(1): 23–27. The microbial flora of the contents of the intestine of larval lampreys, as well as of the water and substrate in the ammocoetes' habitat, have been cultured on Trypticase Soy Agar. The bacteria have been separated into taxonomic groups, using the scheme of Cowan and Steele (1974) and the API 20E system. The microbial flora of the gut contents of larval lampreys closely parallels that found in the environment in which the ammocoetes live. Bacillus, Aeromonas and Aeromonas-like organisms were by far the most abundant bacteria identified, followed by Pseudomonas and members of the Enterobacteriaceae. The only anaerobic components of the bacterial flora in the gut contents and the environment were Clostridium and a relatively uncommon and unidentified Gram-negative organism. Estimates of abundance of the microflora indicated that the concentration of bacteria was much greater in both the gut contents and the substrate than in the water overlying the animals' burrow.  相似文献   

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Turtle remains are common in the Miocene-Holocene deposits of Greece, and are a key focus of the growing research interest in Neogene herpetofaunas from the Aegean region. Some of the most important finds include one of Europe's stratigraphically youngest pleurodiran taxa, Nostimochelone lampra, from the Early Miocene of Macedonia, together with arguably the richest record of fossil tortoises from the Eastern Mediterranean. This incorporates the presently oldest definitive representatives of the quintessential genus Testudo sensu stricto from the Late Miocene of Attica and Macedonia, and numerous specimens of the colossal (carapace ∼2 m-length) testudinid Cheirogaster from Late Miocene-Late Pliocene sediments in southern and northern Greece, as well as on the eastern Aegean islands of Samos and Lesvos. Tantalising, but as yet unconfirmed Miocene accounts of the geoemydid Mauremys in Macedonia, and indeterminate emydid-like remains from Euboea, also provide potentially significant range extensions. Although hampered by a historically sparse documentation, the fossil turtles of Greece are a significant resource that record both assemblage changes and the origin of modern lineages.  相似文献   

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The pest termites of South America: taxonomy, distribution and status   总被引:3,自引:0,他引:3  
Abstract: A total of 77 species of termites have been reported as structural or agricultural pests in South America. These records are reviewed, with indication of the damage they cause, their pest status, distribution and sources of information. Among these, 40 species are reported as structural pests, 53 species as agricultural pests and 15 species as both. However, only 18 species are considered major pests and the status of most of the others is uncertain. Uncertainty about status is much higher among agricultural pests. Specific taxonomic problems are discussed and distribution maps of the main pest genera and species are presented. The most important structural pests are the introduced Coptotermes havilandi and Cryptotermes brevis and the native Nasutitermes corniger. Reticulitermes was introduced into Uruguay and Chile, where it is the only serious pest. The main agricultural pests are Heterotermes spp., Nasutitermes spp., Cornitermes spp., Procornitermes spp. and Syntermes spp., and the most affected crops are sugarcane, upland rice and eucalyptus.  相似文献   

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All CBS strains of the ballistosporic genera Bullera and Sporobolomyces were screened for the presence of xylose by means of gas-liquid chromatographic analysis of derivatized whole-cell hydrolysates. Xylose was found in the majority of Bullera strains, whereas it was mostly absent from Sporobolomyces. The results do not suggest the necessity of any changes in the present concepts of both genera.  相似文献   

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