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1.
Conifer encroachment in sagebrush ecosystems reduces habitat heterogeneity, niche space, and resource availability, all of which negatively affect many wildlife populations. Sagebrush restoration is recommended as a management action to mitigate conifer encroachment and restore wildlife across millions of hectares in the Great Basin. Despite this recommendation, the effects of conifer encroachment and sagebrush restoration are unknown for most wildlife species. Small nonvolant mammal communities include keystone species, consumers and prey; facilitate energy flow and ecological function; and provide important ecological goods and services. We assessed causal relationships between conifer encroachment and sagebrush restoration (conifer removal and seeding native plants) on small mammal communities over 11 yr using a Before-After-Control–Impact design. Sagebrush habitat supported an additional small mammal species, twice the biomass, and nearly three times higher densities than conifer-encroached habitat. Sagebrush restoration increased shrub cover, decreased tree cover, and density but failed to increase native herbaceous plant density. Restoration caused a large increase in the non-native, invasive annual cheatgrass (Bromus tectorum L.). Counter to prediction, small mammal diversity did not increase in response to sagebrush restoration, but restoration maintained small mammal density in the face of ongoing conifer encroachment. Piñon mice (Peromyscus truei), woodland specialists with highest densities in conifer-encroached habitat, were negatively affected by sagebrush restoration. Increasing cheatgrass due to sagebrush restoration may not negatively impact small mammal diversity, provided cheatgrass density and cover do not progress to a monoculture and native vegetation is maintained. The consequences of conifer encroachment, a long-term, slow-acting impact, far outweigh the impacts of sagebrush restoration, a short-term, high-intensity impact, on small mammal diversity. Given the ecological importance of small mammals, maintenance of small mammal density is a desirable outcome for sagebrush restoration.  相似文献   

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3.
Chalkbrood (Ascosphaera apis) and stonebrood (Aspergillus flavus) are well known fungal brood diseases of honeybees (Apis mellifera), but they have hardly been systematically studied because the difficulty of rearing larvae in vitro has precluded controlled experimentation. Chalkbrood is a chronic honeybee-specific disease that can persist in colonies for years, reducing both brood and honey production, whereas stonebrood is a rare facultative pathogen that also affects hosts other than honeybees and can likely survive outside insect hosts. Hive infection trials have indicated that accidental drops in comb temperature increase the prevalence of chalkbrood, but it has remained unclear whether virulence is directly temperature-dependent. We used a newly established in vitro rearing technique for honeybee larvae to test whether there are systematic temperature effects on mortality induced by controlled infections, and whether such effects differed between the two fungal pathogens. We found that increasing spore dosage at infection had a more dramatic effect on mortality from stonebrood compared to chalkbrood. In addition, a 24h cooling period after inoculation increased larval mortality from chalkbrood infection, whereas such a cooling period decreased mortality after stonebrood infection. These results raise interesting questions about honeybee defenses against obligate and facultative pathogens and about the extent to which stress factors in the host (dis)favor pathogens with lesser degrees of specialization.  相似文献   

4.
Geophagy, the ingestion of earth varying in particle size from stones to soils rich in clay, is a relatively widespread behaviour across avian taxa. We reviewed its occurrence in birds and its hypothesised adaptive functions in birds. Of the ~30 avian orders, 23 exhibit geophagy. However, it has only been documented in ~260 species (~2% of birds) and therefor is relatively uncommon. Ingestion of stones and other large particles (grit) is recorded in 54 extant families across the avian phylogeny and appears to be ancient in birds and has evolved several times. Clay ingestion is recorded in 14 phylogenetically scattered families and might have evolved repeatedly. Furthermore, at least nine families exhibit both clay and grit ingestion. Six hypothesised functions of avian geophagy involve digestion and nutrition. Ingested grit might provide (1) essential minerals, particularly sodium or calcium, but it appears to primarily (2) improve mechanical digestion of food in the gizzard, where ingested stones and sand particles are known as gastroliths. Consistent with this gastrolith hypothesis, ~86% of species ingesting grit consume “hard” food: seeds, leaves, insects or other animals. In contrast, ingested clay appears to be for sodium or other nutrient intake and/or protecting birds from ingested plant secondary compounds, by (3) protecting the digestive tract and (4) adsorbing these compounds. Consistent with this, ~88% of species ingesting clay eat fruit that is often rich in secondary compounds and low in sodium, and clay ingestion is associated with frugivory in a representative sample of genera of which many have been shown to source sodium. The other two hypotheses are buffering gastric pH (5) and acquiring antidiarrheal agents (6), but no documentation of this in birds was found. We suggest additional tests of these hypotheses and additional investigation of these proposed benefits of geophagy in birds.  相似文献   

5.
Samples from the gingival margins of 14 cats considered normal on clinical examination were cultured for facultative and obligate anaerobic bacteria. All mouths were free from any gingival marginal inflammation and tartar build-up; all cats were between 6 and 12 months of age. A mixed growth was obtained from all samples. The mean number of bacterial species per sample was 10.7 with a range of 7-16 isolates. Of the 150 isolates processed, 109 (72.66%) were obligate anaerobes. Of the facultatively anaerobic species, Actinomyces (including A. viscosus, A. hordeovulneris and A. denticolens) comprised 12%, Pasteurella multocida 9.33% of isolates and Propionibacterium species 6% of all isolates. Gram-negative bacilli belonging to the genera Bacteroides and Fusobacterium were isolated from 12 of the 14 samples, and comprised 77% of the obligate anaerobes isolated. Clostridium villosum comprised 10.1% of obligately anaerobic isolates, Wolinella species made up 6.42%, while 4.58% were Peptostreptococcus anaerobius. The most commonly isolated obligately anaerobic species was C. villosum and the most commonly isolated facultatively anaerobic species was P. multocida. These findings show a bacterial flora of the normal feline mouth which is very similar in composition to that of cat fight abscesses and feline pyothorax.  相似文献   

6.
The genus Ochotona (pikas) is a clade of cold‐tolerant lagomorphs that includes many high‐elevation species. Pikas offer a unique opportunity to study adaptations and potential limitations of an ecologically important mammal to high‐elevation hypoxia. We analyzed the evolution of 3 mitochondrial genes encoding the catalytic core of cytochrome c oxidase (COX) in 10 pika species occupying elevations from sea level to 5000 m. COX is an enzyme highly reliant on oxygen and essential for cell function. One amino acid property, the equilibrium constant (ionization of COOH), was found to be under selection in the overall protein complex. We observed a strong relationship between the net value change in this property and the elevation each species occupies, with higher‐elevation species having potentially more efficient proteins. We also found evidence of selection in low‐elevation species for potentially less efficient COX, perhaps trading efficiency for heat production in the absence of hypoxia. Our results suggest that different pika species may have evolved elevation‐specific COX proteins, specialization that may indicate limitations in their ability to shift their elevational ranges in response to future climate change.  相似文献   

7.
Evidence-based medicine in small exotic mammals is often considered challenging because of a lack of information related to reference data, validated diagnostic tests, treatment outcome, side effects, long-term prognosis, and financial constraints of the owner. However, despite this lack of information, it is still possible to provide good medical care to small exotic mammals and confirm a disease diagnosis that can be properly treated. With many small exotic mammal cases, the condition of the animal and, ultimately, the disease diagnosis, may not be familiar to the attending veterinarian, and in some cases the disease itself may not have ever been described in that species in the scientific literature. This article describes the process of diagnosing hyperthyroidism in a guinea pig using a recommended patient assessment, diagnostic, and treatment protocol.  相似文献   

8.
Two different groups of bacteria carrying genes encoding for resistance to antibiotics may be transmitted from animals to humans via food products: a.) obligate infectious agents (enteric pathogens, e.g. Salmonella enterica spp., Campylobacter spp., EHEC) and b) facultative pathogenic species (e.g. E. coli, enterococci). Thus far, it is unknown whether genes encoding for resistance to antibiotics from these bacteria may be transferred to bacteria in normal flora of the host. The transfers of genes encoding for resistance to vancomycin from animal sources to the mucosa of humans has been suggested. Thus, there is a threat that these plasmid-encoded resistance genes may also be transferred to other gram-positive organisms present in the human flora. Vancomycin is the antibiotic in reserve for treatment of infections caused by oxacillin (methicillin) resistant strains of S. aureus and by strains of pneumococcus resistant to penicillin.  相似文献   

9.
布鲁菌属革兰氏阴性兼性胞内寄生菌,能感染多种宿主动物和人。该属可分为6个典型种,包括羊种、牛种、猪种、沙林鼠种、绵羊附睾种以及犬种布鲁菌等。此分类是基于其致病性以及宿主偏好性的差异划分。尽管6个种通过传统表型试验能区分,但布鲁菌种内采用DNA-DNA杂交证明DNA同源性高度一致(相似性大于90%)。因此有人提议布鲁菌由单一种组成,即布鲁菌属中只有羊种布鲁菌,其他种都是羊种菌的生物亚型之一。然而基于其他分子技术的基因分型表明其DNA多态性表现明显,说明目前对这个种的分型还是比较准确。而最近分离的海洋种布鲁氏菌分离株(鳍型和鲸型)采用传统分型标准和一些特异的分子标记也证明这种分型比较正确。本文对目前布鲁菌种属进化和分类学进行综述,希望对研究其进化和分类有所帮助。  相似文献   

10.
Pinnipeds have evolved enlarged ocular bulbs to catch fish in the dark. However, their large protruding eyes are easily damaged, which increases the risk of blindness and death in these animals. In captivity, ophthalmic disorders, manifested as keratitis and cataracts, are common among pinnipeds. In this study, we investigated symptoms of ophthalmic disorders in pinniped species using a questionnaire distributed to 32 zoos and aquariums throughout Japan. We conducted this study in cooperation with the Japanese Association of Zoos and Aquariums. The survey included 295 pinnipeds from four otariid species, five phocid species, and one odobenid species. Of these, 43.1% of the pinnipeds had diseases affecting the lens, cornea, and/or other eye parts. Age was positively associated with lens disorders in California sea lions, South American sea lions, and spotted seals. Conflicts and public appearances were also associated with corneal and/or lens disorders in California sea lions. Treatments were evaluated as effective for corneal disorders and conjunctivitis. The results of this study indicate that ophthalmic disorders in pinnipeds are related to the conditions of their captive environment. Aquariums and zoos should be encouraged to share information regarding optimal maintenance practices to improve the living conditions of pinnipeds.  相似文献   

11.
Grazing by large mammals alters vegetation physiognomy, consequently changing habitat suitability for small mammal communities. We investigated the response of terrestrial small mammals to grazing by wild and domesticated ungulates at the boundary of a protected area (Telperion Nature Reserve) and surrounding cattle ranches in Mpumalanga, South Africa over two seasons. Fifteen paired grids were set on either side of the boundary fence at which small mammals were trapped in Sherman live traps placed flat on the ground. A total of 11 760 trap nights resulted in the capture of 187 animals belonging to 14 species (11 rodents, two shrews and one elephant shrew). The small mammal communities in grasslands grazed by domesticated or wild ungulates were similar in abundance, species richness, diversity and demographic parameters, likely due to the fact that vegetation structure of the two grazing systems was also similar. We used generalised linear models to show that rock and grass cover were plausible predictors of small mammal abundance in this system. Rock cover showed a positive relationship with small mammal abundance whilst grass cover showed a negative relationship. Our observations suggest that at the scale of our study and with the current stocking densities, wild and domesticated ungulates have similar impacts on the small mammal community.  相似文献   

12.
ABSTRACT: Numerous mammal species, including domestic and wild animals such as ruminants, dogs, cats and rodents, as well as humans, serve as reservoir hosts for various Bartonella species. Some of those species that exploit non-human mammals as reservoir hosts have zoonotic potential. Our understanding of interactions between bartonellae and reservoir hosts has been greatly improved by the development of animal models for infection and the use of molecular tools allowing large scale mutagenesis of Bartonella species. By reviewing and combining the results of these and other approaches we can obtain a comprehensive insight into the molecular interactions that underlie the exploitation of reservoir hosts by Bartonella species, particularly the well-studied interactions with vascular endothelial cells and erythrocytes.  相似文献   

13.
The mountains of northern Mozambique have remained poorly studied biologically until recent years with surveys covering a variety of taxonomic groups highlighting their biological and conservation value. Even so, the medium and large mammal fauna remains poorly known and to date no systematic mammal surveys have been published from any of Mozambique’s mountains. We present results of a medium and large mammal survey of Serra Jeci’s Mt Chitagal, Mt Sanga and the Njesi Plateau in Niassa, northern Mozambique; the first mammal diversity data collected from these isolated mountains. We recorded 27 mammal species, of which six represent range expansions; Sykes’s monkey (Cercophitecus mitis), Mozambique dwarf galago (Paragalago granti), Smith’s red rock hare (Pronolagus rupestris), lesser cane rat (Thryonomys gregorianus), rock hyrax (Procavia capensis) and African buffalo (Syncerus caffer). We also reviewed and collated records of medium and large mammals from previously published fieldwork on northern Mozambique’s mountains, amounting to a total of 34 large mammal species from seven montane areas, highlighting the lack of mammalian knowledge in Mozambique’s Afromontane habitats.  相似文献   

14.
When animals are offered a choice of feeds that are nutritionally complementary, they are able to select a consistent combination of these feeds over long periods of time. Analysis of how such consistent diet choice is achieved, in terms of short-term feeding behavior, may further our knowledge of how animals regulate nutrient intake. Previous work, on meal pattern analysis and on nutrient synchronization, led us to hypothesize that animals may select a consistent diet within a meal. In three experiments cows were offered a choice between high- (H) and low- (L) protein feeds and short-term feeding behavior data were collected using computerized feeders. Feeding behavior was first analyzed in terms of visit characteristics. A greater average daily intake of H, relative to L, was more closely related to the ratio of H visits to L visits than to differences in the intake per visit to feeders supplying H or L. Individual meal criteria were estimated using a mixed-distribution model, and visits were clustered into meals. Cows typically had approximately six meals per day. The observed frequency distribution of meal composition, in terms of the proportion of visits to H feeders, was determined. Subsequently, the observed visits were randomly reclustered into bouts consisting of the same number of visits as were observed in meals, and the frequency distribution of random bout composition was calculated. If frequency distributions of meals and random bouts coincide, then this is evidence that cows do not regulate diet choice within a meal. Comparison of the frequency distributions of meals and random bouts provided no evidence that cows attempted to achieve their long-term average diet composition within a meal. We also investigated whether cows tried to achieve a consistent diet choice within a meal by adjusting their intake per visit, depending on the feed type visited and the proportion of visits to H feeders in a meal. There was no evidence that this occurred. In conclusion, our analyses have shown that cows did not attempt to select within a meal a consistent diet in terms of protein to energy ratio. Indeed, our data and the literature suggest that the timeframe over which the intake of energy and protein is regulated must be greater than a meal in a number of animal species.  相似文献   

15.
Interest in wild boar hunting has been growing, so the importance of wild boar preserves has also increased. Different opinions exist regarding the optimal size of these preserves, notably regarding the optimal number of artificial feeding sites and the distance between them because those strongly affect the behavior of the animals. In this study, wild boars' feeding habits were examined in a preserve of 300 ha. We wondered how the animals would use 4 feeders. More specifically, we assessed whether wild boars would share or divide the feeders among themselves and how the distances between the feeders would influence their feeding habits. We marked the forage (corn) of each feeder with glitter of 4 different colors. After a first observation, we repeated this intervention 4 days later, again with 4 different colors. The glitter was evaluated to ascertain the optimal characteristics of the material: digestibility, ease of identification in the feces, and color fading or change. Feces were collected from selected routes, localized using global positioning system, and the colors were identified. In total, 210 samples were collected and glitter was found in 165 of them. Our results show that wild boars' movements can be estimated through the use of glitter. We could show that 1 animal used several feeders, and the feeders have a remarkable effect on habitat use. The development of this method could significantly help game managers in establishing an optimal feeder configuration.  相似文献   

16.
为了深入了解黑龙江穆棱东北红豆杉国家级自然保护区兽类组成及东北虎(Panthera tigris altaica)猎物资源现状,于2016—2018年在保护区内布设40个红外相机监测点和7个大样方调查兽类多样性和分析东北虎主要猎物资源。相机监测累计照相日12250个,共获得有效独立照片1139张,从中鉴定出野生兽类4目8科17种,其中国家一级重点保护动物有东北虎和东北豹(Panthera pardus orientalis)。样方调查记录到兽类足迹261条,足迹识别出兽类4目7科10种,其中包括国家一级重点保护动物东北豹1种,东北虎主要猎物野猪(Sus scrofa)、马鹿(Cervus elaphus)、西伯利亚狍(Capreolus pygargus)和梅花鹿(Cervus nippon)4种。兽类物种相对丰富度分析表明,相对丰富度最高的是西伯利亚狍和狗獾(Meles leucurus),赤狐(Vulpes vulpes)和东北豹最低。猎物资源分析表明,保护区内分布有西伯利亚狍681只,野猪510只,马鹿35只,梅花鹿27只,4种动物的生物量分别为西伯利亚狍生物量为20210.94 kg,野猪生物量为64735.00 kg,马鹿生物量为6023.25 kg,梅花鹿生物量为1635.00 kg,保护区东北虎可捕食的主要猎物生物量为92604.19 kg。研究表明,保护区内兽类种类虽然较多,但东北虎、东北豹、梅花鹿和马鹿数据仍然较少,需要重点加强保护。  相似文献   

17.
In this review, we assess the current state of knowledge on domestication of the major livestock species. We present first some historical background on location and dates of domestication of livestock. The characteristics that favoured domestication are described, especially gregariousness, precocity of young and diet. We then describe the genetic processes involved during domestication, i.e. uncontrolled processes such as inbreeding and genetic drift, partially controlled processes such as relaxation of natural selection and natural selection in captivity and controlled processes such as active selection. Details are also given on how the resource allocation theory explains changes occurring during domestication. The methods used to assess the extent to which domestication has changed animals (comparisons of wild and domestic stocks, longitudinal analysis and molecular genetics) are also listed. Finally, major behavioural modifications observed during domestication are described, including relationships with humans and predators, and social, feeding, reproductive and maternal behaviours as well as morphological changes.  相似文献   

18.
Venomous reptiles are common in zoo, research, and private collections. These animals will require veterinary care at some time during their captivity, and treating venomous reptiles can be both challenging and rewarding. Extensive training and experience in handling venomous reptiles, particularly snakes, is required before making the important decision on whether to add these patients to one’s practice. Veterinarians who have a desire to treat venomous reptiles should be familiar with proper equipment, handling techniques, and special considerations required for these species. Veterinarians should also be prepared in the event of an emergency and aware of specific medical conditions affecting these species.  相似文献   

19.
The Cracidae family of neotropical birds is regarded as one of the most severely threatened in the world. They traditionally have been extensively hunted, and, thus, ex situ efforts for their conservation are recommended and involve the optimization of their care in captivity. Nutrition is a fundamental aspect of husbandry, which influences survival and reproduction in captivity. In this study, a total of 29 animals, including 3 species (Penelope obscura, Penelope superciliaris, and Aburria jacutinga), were subjected to monthly physical examination and blood sampling before and after dietary conversion from the traditional diet of broiler feed, fruits, and vegetables to a nutritionally balanced commercial diet specifically designed for wild Galliformes. The diet change produced differences in several parameters tested, including an increase (P < 0.05) in hemoglobin concentration for all species. Increases (P < 0.05) in erythrocyte count, packed cell volume, and body weight were observed in P. obscura, with a concomitant decrease in the standard deviation for such parameters that show improved uniformity. Globulins and lipase also were reduced (P < 0.05) in P. obscura. Although leukocyte count was lowered and eosinophils were increased in all 3 species after dietary conversion, only these 2 changes were significant (P < 0.05) in P. superciliaris. A. jacutinga had higher (P < 0.05) blood glucose concentrations than the other species, but diet had no effect on this parameter. Blood uric acid concentrations were higher (P < 0.05) after conversion to the commercial diet in P superciliaris. The provision of a commercial extruded diet as a single food source was beneficial, which led to a general improvement in clinical aspects and group uniformity in these 3 species of Cracidae.  相似文献   

20.
From the 62 swine abscesses examined, 56 yielded positive cultures, of which 38 cases were mixtures of facultative aerobes and obligate anaerobic bacteria (OAB). Only 6 species appeared to be sterile. In all specimens, which yielded OAB, VFA (C4-C6) could be detected by gas-liquid chromatography (GLC). False negatives were not recorded, and only one false positive was found, which might have been due to faulty culture technique, or to the fact that the metabolic markers may persist longer than the OAB themselves. Because current methods to isolate non-sporulating OAB are laborious and not available in most veterinary clinical situations and because there is a need to evaluate the importance of non-sporulating OAB in veterinary medicine, GLC seems to be a useful alternative to culture techniques for detecting the presence of OAB in infectious processes in animals.  相似文献   

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