关键词： Tree-grass   Nutrients   Trophic cascade   Grazing   Allometric scaling theory  

摘要： The scale of resource heterogeneity may influence how resources are locally partitioned between co-existing large and small organisms such as trees and grasses in savannas. Scale-related plant responses may, in turn, influence herbivore use of the vegetation. To examine these scale-dependent bi-trophic interactions, we varied fertilizer [(nitrogen (N)/phosphorus (P)/potassium (K)] applications to patches to create different scales of nutrient patchiness (patch size 2 x 2 m, 10 x 10 m, or whole-plot 50 x 50 m) in a large field experiment in intact African savanna. Within-patch fertilizer concentration and the total fertilizer load per plot were independently varied. We found that fertilization increased the leaf N and P concentrations of trees and grasses, resulting in elevated utilization by browsers and grazers. Herbivory off-take was particularly considerable at higher nutrient concentrations. Scale-dependent effects were weak. The net effect of fertilization and herbivory was that plants in fertilized areas tended to grow less and develop smaller rather than larger standing biomass compared to plants growing in areas that remained unfertilized. When all of these effects were considered together at the community (plot) level, herbivory completely eliminated the positive effects of fertilization on the plant community. While this was true for all scales of fertilization, grasses tended to profit more from coarse-grained fertilization and trees from fine-grained fertilization. We conclude that in herbivore-dominated communities, such as the African savanna, nutrient patchiness results in the herbivore community profiting rather more than the plant community, irrespective of the scale of patchiness. At the community level, the allometric scaling theory's prediction of plant-and probably also animal-production does not hold or may even be reversed as a result of complex bi-trophic interactions.

关键词： brushtail possums   defoliation   dieback   foliage cover   introduced herbivore   New Zealand   pest control   tree crown recovery  

摘要： Defoliation of forest tree canopies by herbivores and other agents, leading to tree mortality and reduced productivity, threatens the ecological stability of forests globally. This study shows that long-term control of a mammalian arboreal folivore (brushtail possums;Trichosurus vulpecula Phalangeridae) reduces crown dieback and increases foliage cover in browsing-damaged canopy trees. We monitored indices of possum density, possum browsing, tree foliage cover and crown dieback for 20years following initiation of possum control in 1994 that repeatedly reduced possum densities to near zero every 5-6years and kept the population below 35% of pre-control levels over the entire period. Observable possum browsing was recorded on 20-49% of individuals of three palatable tree species at the time of first control. Those percentages fell to zero after control and never exceeded 2-10% for individual species over the next 19years. We recorded significant increases in foliage cover attributable to recovery from defoliation by possums for all three species during the first 10years. Large increases in foliage cover occurred on individuals that were heavily browsed in 1994 (mean increases: 36-89%), but mean population increases were modest (3-19%) because only 10-19% of trees were initially heavily browsed. Twenty-year mortality rates were similar for plants with, or without, initial possum browsing, indicating no residual impact of pre-control browsing on tree mortality. Times for full recovery of crown foliage cover varied from 10years for the youngest trees and faster growing species to more than 20years for mature individuals of the slowest growing species.

关键词： amphibians   bacteria   birds   fish   metagenomics   reptiles  

摘要： Vertebrates harbour microbes both internally and externally, and collectively, these microorganisms (the 'microbiome') contain genes that outnumber the host's genetic information 10-fold. The majority of the microorganisms associated with vertebrates are found within the gut, where they influence host physiology, immunity and development. The development of next-generation sequencing has led to a surge in effort to characterize the microbiomes of various vertebrate hosts, a necessary first step to determine the functional role these communities play in host evolution or ecology. This shift away from a culture-based microbiological approach, limited in taxonomic breadth, has resulted in the emergence of patterns suggesting a core vertebrate microbiome dominated by members of the bacterial phyla Bacteroidetes, Proteobacteria and Firmicutes. Still, there is a substantial variation in the methodology used to characterize the microbiome, from differences in sample type to issues of sampling captive or wild hosts, and the majority (>90%) of studies have characterized the microbiome of mammals, which represent just 8% of described vertebrate species. Here, we review the state of microbiome studies of nonmammalian vertebrates and provide a synthesis of emerging patterns in the microbiome of those organisms. We highlight the importance of collection methods, and the need for greater taxonomic sampling of natural rather than captive hosts, a shift in approach that is needed to draw ecologically and evolutionarily relevant inferences. Finally, we recommend future directions for vertebrate microbiome research, so that attempts can be made to determine the role that microbial communities play in vertebrate biology and evolution.

关键词： 肾虚血瘀   树鼩   动物模型  

摘要： 目的:探索肾虚血瘀证树鼩动物模型的制做方法。方法:将树鼩随机分为对照组、模型1组(腹腔注射氢化可的松结合肾上腺素)和模型2组(腹腔注射氢化可的松结合角叉菜胶),5只/组,通过观察树鼩表征、脏器指数、血液流变学、下丘脑-垂体-靶腺轴(甲状腺轴、性腺轴)激素水平的变化情况评判肾虚血瘀证模型是否建立。结果:造模后动物均出现"耗竭"现象,肾、前列腺、脾、睾丸不同程度肿大,模型2组甲状腺萎缩;模型1组血清中雌二醇(E2)和睾酮(T)水平及模型2组中甲状腺激素(FT3、FT4)、E2水平显著下降;血液流变学结果显示模型2组血液黏度和红细胞压积增高,而模型1组无显著变化。结论:腹腔注射氢化可的松与肾上腺素的方法能够较好地模拟肾虚血瘀证树鼩动物模型。

关键词： 知识技能树   动物传染病   总论   教学   应用  

摘要： 动物传染病是高职畜牧兽医类相关专业一门重要的专业课,作为本课程的总论部分,内容繁杂、深奥抽象,学生常难以驾驭。总论教学成功与否,将对本门课程的后续教学影响深远。笔者从教学内容和学情入手,就高职动物传染病总论部分进行问题架构式的"知识技能树"教学方法和过程进行了探讨。教学结果表明:将"知识技能树"应用于教学,效果良好,突出了在教学中学生主体的地位,有利于学生形成自己的知识体系,提升了学生的综合能力。

关键词： Asexual reproduction   Chichibu forest   Genotype pair   Microsatellite marker   Pieris japonica  

摘要： Pieris japonica is a poisonous tree species that is rarely eaten by herbivorous animals, a fact that could enable the expansion of its distribution range and influence ecosystems into which it encroaches. In a regional-scale study, 300 P. japonica trees from 13 populations were sampled at the University of Tokyo Chichibu Forest, Japan, and were analyzed using 11 microsatellite markers. Genetic differentiation among the populations was low (F (ST) = 0.022 and G' (ST) = 0.024). A plot (30 x 30 m) was established for a fine-scale study, in which all P. japonica trees and saplings were measured and genetically analyzed using the microsatellite markers. Using this approach, we detected 84 genotypes among the 121 P. japonica trees in the plot. A few genotypes had expanded by more than 5 m, indicating that the ability to reproduce asexually could facilitate P. japonica trees to remain in a given location. Autocorrelation analysis showed that the extent of nonrandom spatial genetic structure was approximately 7.0 m, suggesting that seed dispersal was limited. KINGROUP analyses showed that 44 genotype pairs were full siblings, 23 were half-siblings, and 40 were parent-offspring. Only 32 seedlings were observed, of which 15 had reproduced asexually. The number of P. japonica trees has been increasing gradually for more than half a century in our study areas.

关键词： Canopy   habitat disturbance   hunting   threatened species   survey methods  

摘要： Traditionally, arboreal rainforest mammals have been inventoried using ground-based survey techniques. However, given the success of camera traps in detecting secretive terrestrial rainforest mammals, camera trapping could also be a valuable tool for inventorying arboreal species. Here we assess, for the first time, the effectiveness of arboreal camera traps for inventorying arboreal rainforest mammals and compare the results with those from other methodologies. We do so in one of the world's most biodiverse conservation areas, the Manu Biosphere Reserve, Peru. We accumulated 1201 records of 24 arboreal mammal species. Eighteen species were detected by arboreal cameras, seven by diurnal line transects, six by nocturnal transects and eighteen through incidental observations. Six species were only detected using arboreal camera traps. Comparing arboreal camera traps with traditional ground-based techniques suggests camera traps are an effective tool for inventorying arboreal rainforest mammal communities. They also detected more cryptic species compared with other methodologies. Daily detection frequency patterns were found to differ between ground-based techniques and arboreal cameras. A cost-effort analysis indicated that despite greater upfront costs in equipment and training for arboreal camera trapping, when accounting for the additional survey hours required to provide similar numbers of records using ground-based methods, overall costs were similar. Our work demonstrates that arboreal camera trapping is likely to be a powerful technique for inventorying canopy mammals. The method has considerable potential for the study of charismatic and threatened arboreal mammal species that may otherwise remain largely unknown and could quietly disappear from the world's tropical forests.

关键词： aphid   leafhopper   mealybug   predator   pequi  

摘要： The Cerrado occupies about 23% of the Brazilian territory and is characterized by great diversity of plants and insects and a great degree of endemism, and Caryocar brasiliense A. St.-Hil. (Malpighiales: Caryocaraceae) is widely distributed in this region. The diversity and abundance of hemipterans and their natural enemies were studied on trees of C. brasiliense in the Cerrado, pasture, and anthropic area in Montes Claros, Minas Gerais State, Brazil. We observed 1 rare, 8 common, and 1 frequent species of sucking insects;and 2 rare, 7 common, and 6 frequent species of natural enemies. Sucking insects and their natural enemies were most abundant in the pasture and least abundant in the Cerrado. Increasing diversity indices and numbers of species and individuals of sucking insects were followed by similar trends in the populations of natural enemies. Increasing populations of sucking insects led to greater numbers of individuals of ants, green lacewings, predator thrips, and ladybeetles. Aluminum level positively affected the number of species and individuals, and the pH of the soil reduced those of sucking insects. Leafhoppers had greater numbers on plants on soils with low pH values and high aluminum levels, but the opposite was noted for the aphids.

关键词： exclosure experiments   grasshoppers   insect herbivory   Kruger National Park   Macrotermes   nutrients  

摘要： African savannas are highly seasonal with a diverse array of both mammalian and invertebrate herbivores, yet herbivory studies have focused almost exclusively on mammals. We conducted a 2-yr exclosure experiment in South Africa's Kruger National Park to measure the relative impact of these two groups of herbivores on grass removal at both highly productive patches (termite mounds) and in the less productive savanna matrix. Invertebrate and mammalian herbivory was greater on termite mounds, but the relative importance of each group changed over time. Mammalian offtake was higher than invertebrates in the dry season, but can be eclipsed by invertebrates during the wet season when this group is more active. Our results demonstrate that invertebrates play a substantial role in savanna herbivory and should not be disregarded in attempts to understand the impacts of herbivory on ecosystems.

关键词： Small mammals   Thinning   Oak savanna   Quercus spp.   Habitat restoration   Michigan  

摘要： Oak (Quercus spp.) savannas have declined drastically in the midwestern United States since European settlement. Oak savanna restoration projects are primarily driven by species closely linked to this habitat type, such as the federally endangered Karner blue butterfly (Lycaeides melissa samuelis). However, it is essential that other species are monitored during restoration. Small mammals, due to their importance in ecosystem function, are particularly useful to study. The United States Forest Service is currently conducting an oak savanna restoration in the Manistee National Forest in Lower Michigan using forest thinning and prescribed burning. To understand management impacts on small mammal communities, we live trapped small mammals in each of the mechanically thinned plots (i.e., bulldozer, masticator, and shear cutter) and control plots in five blocks over six years (2008-2013), as well as measured vegetation variables each year. Initially, we used a permutation multivariate analysis of variance (perMANOVA) to determine if there were treatment and year interactions for both small mammal community assemblages and vegetation variables. We then compared changes in small mammal diversity, relative abundance, and vegetation variables among treatments using exploratory randomized block design analysis of variances (ANOVAs). Canopy cover was significantly lower in bulldozer and shear cutter thinned plots than control plots five years following thinning. We observed significant treatment by year interactions in how the small mammal community responded. A large increase in relative abundance of white-footed mice occurred one year post-thinning in all treatments. Within 1-2 years of treatment, thirteen-lined ground squirrels and meadow jumping mice, both open-canopy grassland species became established on thinned plots. The retention of brush piles in bulldozer and shear cutter plots provided important refuge habitat for small mammals following thinning, Restoration effo