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1.
The elephant calf, a defended follower is completely dependent on adults till the age of 3 months. It begins to explore and attempts to feed at 3 to 6 months, and then becomes partially independent with some feeding on its own. The characteristics of behavior in adults are examined and the development of this pattern in the calf is traced by analyis of duration, transition and clustering of the behavioural elements. Essential activities like suckling, locomotion and lying down for rest appear soon after birth whereas elements of feeding, grooming and play appear only at a later stage. The calf takes the initiative in suckling and its termination, drinking directly by mouth till the age of 6 months. The first element of feeding appears at about a week in attempts to pick up and hold objects in the trunk. Co-ordination of limb, trunk and mouth movement is achieved by about 1 month. The calf is strong enough to pull out plants by 6 months when independent feeding begins. In about a year feeding, drinking and dusting patterns are well developed.  相似文献   

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Occurrence of the Asiatic cyprinid Pseudorasbora parva in England   总被引:3,自引:1,他引:2  
Pseudorasbora parva has demonstrated, in less than four decades, its invasive potential by colonizing much of continental Europe. Established populations of P. parva have now been found in the wild, in large numbers, at several locations across England. At present, only one deliberate introduction is known to have taken place during the mid-1980s at Crampmoor Fisheries, Hampshire.  相似文献   

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Pollen grains of five species and two interspecific hybrids ofTrillium from eastern Asia have been examined with scanning electron and transmission electron microscopy. All species from eastern Asia, excludingT. govanianum, are characterized by inaperturate pollen and an unstratified and granulated exine structure. Pollen of the Himalayan species,T. govanianum, is, however, monocolpate and intectate. The palynological evidence suggests that the Asiatic species, excludingT. govanianum, are closely related to each other and toT. erectum in North America, andT. govanianum is independent of the other species in the genus.  相似文献   

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The genus Pilgnmella , known from the medial Eocene of Pakistan and northwest India, is a primitive perissodactyl, not an artiodactyl as previously identified. Upper cheek teeth of Pilgrimella , when compared with those of primitive representatives of the Equoidea, Brontotherioidea, Chalicotherioidea, Tapirioidea and Rhinocerotoidea, suggest, however, that Pilgnmella cannot on present evidence be referred to any of the five accepted perissodactyl superfamilies. Pilgrimella may represent a short-lived and hitherto unknown perissodactyl lineage.  相似文献   

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Pseudorasbora parva is recorded for the first time in the Iberian Peninsula. Its presence in the River Ebro delta is probably due to involuntary introduction.  相似文献   

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This study focuses on the effect of chemicals on acrosome reaction in elephant spermatozoa. Semen was collected at the Washington Park Zoo in Portland, Oregon, from an 11-yr-old Asian elephant by artificial vagina (7 ejaculates) and transported to Mahidol University in Bangkok in extender at 4 to 5 degrees C within 24 to 28 h. A total of 500 x 10(6) sperm/mL was used for the control and for each of the 4 treatment groups: 1) cAMP (0.1 mM); 2) caffeine (0.1 mM); 3) Penicillamine hypotaurine and epinephine, PHE (penicillamine 2 mM, hypotaurine 1 mM, epinephine 1 mM); and 4) heparin (10 microg/mL) at 39 degrees C for 2 h. Aliquots were removed and the sperm viability, abnormal morphology, and acrosome status were evaluated by triple stain technique. Transmission electron microscopy (TEM) was used to observe changes of the sperm head membrane in all treatment groups. Trypan blue reliably stained dead spermatozoa, while rose Bengal stained only the spermatozoa with intact acrosomes. The concentration of dead sperm cells was similar in the 4 groups. The percentages of live acrosome-reacted spermatozoa in the control and in groups treated with caffeine, PHE, cAMP and heparin were 19.5 +/- 4.3, 38.1 +/- 4.0, 34.8 +/- 3.7, 29.8 +/- 0.8 and 28.0 +/- 4.2, respectively. The acrosome reaction rate was higher in the treatment groups than in the control (P<0.05). Caffeine and PHE caused significantly higher acrosome reaction of the sperm head than cAMP or heparin (P<0.05). The electron micrographs showed that the acrosome reaction occurred by the presence of apical vesiculation. The results indicated that 1) the triple stain technique allowed for evaluation of both viability and acrosome reaction simultaneously in elephant spermatozoa,2) acrosome reaction occurred at a high rate in all 3 treatment groups. 3) the effects of caffeine and PHE were significantly higher (P<0.05) than of cAMP and heparin, and 4) the data obtained from the triple stain technique corresponded to those from TEM.  相似文献   

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Criteria for assessing the radioresistance of the Central Asiatic turtle   总被引:1,自引:0,他引:1  
A study was made of a phenomenal radioresistance of Testudo horsfieldi. The authors described the features of the postirradiation death at different seasons. A threshold number of the affected systems in the turtles was one order lower than that of mammals. A positive correlation was found between specific affection of the systems and the degree of their radioresistance.  相似文献   

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The population of the Asiatic wild dog or dhole (Cuon alpinus) in the wild has been estimated to be less than 2500 mature individuals. This has led to the IUCN assessing the Asiatic wild dog as Endangered. The killing of Asiatic wild dogs in retaliation for livestock depredation is one of the major threat for the species across its geographic range. Understanding the prey preference of endangered large carnivores is imperative for making informed conservation decisions and devising management strategies. We studied the prey preference of the Asiatic wild dog by reviewing studies that have been conducted on the diet and prey abundance of the species across its distributional range. Nine available studies conducted in eight protected areas of three countries, in which 5265 scats were studied, were reviewed. Across studies, we tested whether prey consumption was based on prey availability or prey body mass. The value of Jacobs’ index was determined for each prey species and tested against the proportion of available prey and body mass. Sambar (Rusa unicolor) and chital (Axis axis) were found to be significantly preferred by the Asiatic wild dog, and the preferred prey body mass range was between 40 and 60 kg. The prey preference of the Asiatic wild dog was mainly influenced by the availability of prey.  相似文献   

11.
103份亚洲棉表型多样性分析   总被引:5,自引:0,他引:5  
对103份分别来源于印度、越南、贵州、广西和云南等不同地域的亚洲棉进行了表型遗传多样性分析。结果发现亚洲棉在质量性状和数量性状上均存在不同程度的遗传多样性;质量性状遗传多样性指数在主茎、叶、花、铃等不同部位表现不同;21个质量性状的多样性指数为0.04~1.01,平均0.57,3个数量性状的多样性指数为1.65~1.96,平均1.82,表明数量性状的遗传多样性大于质量性状。研究发现不同地域的亚洲棉遗传多样性不同,并将这103份亚洲棉聚类到8个组群。  相似文献   

12.
The only known introduction of a squirrel species into South America is the case of the Asiatic red-bellied tree squirrel Callosciurus erythraeus that was introduced in the Pampas Region of Argentina in 1970. To inform management programmes, we analysed the current distribution, expansion rate, and abundance of the red-bellied squirrel in Argentina, and identified invasion pathways. Apart from the first and main focus of invasion, three other invasion foci have originated as a consequence of intentional releases between 1995 and 2000. The main invasion focus already extends over >1300 km2, where estimated density averaged 15 ind ha?1 and numbers of squirrels may reach 100,000 individuals. The area invaded in the other three invasion foci varied between <1 and 34 km2 and mean densities were around 3–5 ind ha?1. Squirrel abundance and residents’ attitude towards this introduced species in the main invasion focus make eradication unfeasible, though management actions such as control, containment and mitigation of damages should be undertaken. Eradication of the relatively small invasion foci must be immediately evaluated, with priority given to valuable conservation areas under high invasion risk.  相似文献   

13.
Mechanical Aspects of Rapid Flower Opening in Asiatic Lily   总被引:3,自引:0,他引:3  
Several processes contribute to the rapid opening of Asiaticlily flowers. Opening occurs after the tepals stop increasingin length, and have reached maximum thickness. Up to day -0.5(where day 0 is time that flowers are half-open), the sepalsentirely encase the petals, and their edges are tightly claspedin deep grooves beside the petal midribs. At day -0.5 to -0.3,the petal midrib reduces in width, opening the groove and allowingthe tepals to pull apart (bud ‘cracking’). Unlockingis not complete until about day -0.15: it is not the key eventdirecting opening, but helps to sharpen its onset. The midribscontrol subsequent opening, pulling the laminae behind them.In the first 3–4 h of opening (‘dark phase’),the main process is an increase in the angles the midribs makewhere they join the pedicels. During this time, the petals andsepals are only slightly curved. Subsequently through to day0.5 (the ‘light phase’), an increasingly markedcurvature of the midribs pulls the tepals further apart andcauses them to progressively reflex. By day 1 the flowers aremature and the laminae are no longer being pulled by the midribs.In studies of isolated tissue segments, we found that in thelater stages of opening there is greater cell expansion in theepidermis of the inner surfaces, contributing to the recurving.Petal expansion is accompanied by cell separation and osmoticchanges, and inhibitors of starch hydrolysis inhibit expansionof petal segments. Of the various processes operating duringlily opening, we believe that the most influential is the changein angle between midribs and pedicel, suggesting a pulvinus-likemechanism.Copyright 2000 Annals of Botany Company Flower opening, lily, mechanics, petal lock, osmotic changes, starch, epinasty  相似文献   

14.
A large scale inventory along the Meuse River (the Netherlands), showed that floodplain lakes function as spawning, nursery and adult habitats, while the main river channel merely serves as a dispersal corridor for adult Pseudorasbora parva , one of the most successful invasive fish species that have colonized Europe.  相似文献   

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The Mongolian Gobi is the most important stronghold of the Asiatic wild ass (Equus hemionus), housing >?75% of the remaining global population. However, even in this remote refuge, poaching and changes in land use are challenging the species’ conservation. Whereas progress has been made in monitoring population size, little data are available on population structure and dynamics. To fill this gap, we determined the age and sex of 440 skulls collected in two regions of the Mongolian Gobi. Foals and yearlings were underrepresented in our skull sample with 3 and 7.3% only, but the rest of the age pyramid was well balanced. The mean age was 7.7 years, the maximum age 29 years, and the sex ratio was not different from even. Mortality risk analysis revealed low annual mortality rates of about 15% in the most productive age classes of 5–10 years, followed by a slow increase with age until about 17 years and a likely faster increase thereafter. As the large majority of carcasses suggested a poaching-related mortality which appears random, our dataset provides the first insight into the structure of the largest remaining Asiatic wild ass population and can be used as a benchmark for future monitoring and population viability modeling.  相似文献   

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The types and amounts of pigments in fibers from variously colored Tajik, Hissar, and Caracul sheep were determined by three methods: high-performance liquid chromatography, electron spin resonance spectroscopy, and light microscopic evaluation of melanosomes. In both dominant and recessive black lambs the color is due to eumelanin pigment. Brown and red phenotypes are the result of interaction of AWt and EBl, EBr, or EY alleles, and these colors are caused by mixtures of eumelanin and pheomelanin in varying ratios. The HPLC and ESR measurements detected these differences in melanin type, while direct characterization of melanosomes generally failed to distinguish between melanin type or relative ratio of melanin type.  相似文献   

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