关键词： 寨卡病毒   云南省   发生风险   树鼩   动物模型  

摘要： 寨卡病毒（Zika Virus）是一种虫媒传播的病毒,现已在全球80多个国家和地区传播与流行。鉴于寨卡病毒传播媒介的广泛分布及感染导致小头症等严重神经系统疾病的发生,世界卫生组织宣布寨卡疫情为“国际关注的突发公共卫生事件”。云南省作为国家“一带一路”发展战略的重要枢纽地区,与缅甸、越南、老挝三国接壤,有众多的边境口岸及边民互市点,人员跨境交流频繁。同时,云南省也是多种传染性疾病传播、流行的高危地区,多种传染病呈现跨境传入、境内高发和病原多样性的典型特征。因此,云南省面临着ZIKV境外输入、本地流行的巨大风险,但目前尚无云南省ZIKV流行及传播影响因素的调查。与云南毗邻的南亚、东南亚地区一直是寨卡主要疫区,而在2016年1月我国在广州发现首例寨卡输入性病例之前,云南是否存在ZIKV病毒的输入性病例尚不清楚。本研究对2014年8月-2016年2月云南省各口岸不明原因发热的608份样本进行了ZIKV流行病学的回顾性分析。通过针对ZIKV核酸的定性定量检测发现了1例ZIKV输入性病例,在该病例是2014年从孟加拉国由昆明机场入境,并且患者发热明显。通过对该病患血液病毒核酸提取及PCR扩增获得了毒株的全基因组序列并命名为ZK-YN001。对此毒株的起源进化分析发现,ZK-YN001属亚洲株,起源时间约为2006年,进化速率为6.819（5.929-7.709）×10-4substitutions/site/year。与亚洲主要流行毒株的序列比对发现,ZK-YN001处于亚洲寨卡低流行阶段和高流行阶段的中间过渡态。ZK-YN001的发现修正了中国寨卡的流行病史。提示云南省面临着邻国输入ZIKV传染源的潜在风险。ZIKV的传播媒介-伊蚊在云南省分布广泛,而云南省全年平均温度18.8℃,平均相对湿度79.2%,月累计平均降水量104.3毫米,气候条件特别适宜伊蚊孳生繁殖,另结合蚊媒的分布密度及活跃程度,云南省每年的6-9月份是寨卡疫情的高危月份,应提前做好应对及防控措施。人感染ZIKV临床症状比较复杂,其发病机制尚不清楚,也无有效的疫苗和治疗药物。动物模型是研究病毒感染与发病机制,进行药物、疫苗研发的必要技术平台。自寨卡疫情爆发以来,世界各国研究人员应用小鼠、猴子等动物建立了各种寨卡热疾病实验模型,为阐明寨卡病毒致小头症/神经损伤的发病机制及候选疫苗药物临床前评价奠定了重要基础。然而,感染小鼠虽然出现神经疾病甚至死亡等症状,但与人感染症状差异过大;非人灵长类感染后未能重现人类感染后的主要临床症状,且研究成本高、周期长。因此,急需寻找一种可以模拟人类自然感染及感染后相关临床症状的理想动物模型。树鼩主要分布在以云南省为主的我国西南部地区,是一种易繁殖、易饲养的小型灵长类的哺乳动物。近年来,研究人员在人类疾病发生发展及人类病毒性感染的研究中广泛使用树鼩作为模型动物,并取得了一系列令人瞩目的研究成果,但目前尚无寨卡病毒感染树鼩的研究报道。为建立ZIKV感染树鼩动物模型,本研究模拟蚊虫叮咬进行皮下注射感染子一代成年树鼩,出现了与人感染类似临床症状:有典型的皮肤疾病皮疹发生,ZIKV的感染可造成皮肤的病理损伤及炎症细胞浸润,皮下有病毒颗粒存在及出血现象;出现病毒血症及唾液有规律的排毒;可建立涉及多个组织脏器的全身性感染,其中睾丸组织敏感最高且出现明显的病理损伤。进而,用ZIKV体外感染来源于树鼩不同组织的各种原代细胞,以确定病毒对不同原代细胞的嗜性及感染特征。经病毒核酸与抗原检测发现,血管及皮肤原代细胞对ZIKV最为敏感,病毒核酸及蛋白高效复制和表达,释放大量有感染活性的子代病毒;病毒感染造成细胞死亡等严重的细胞病变,从体外细胞水平支持了树鼩可以作为ZIKV的感染动物模型。最后,为探讨ZIKV感染树鼩后引发的免疫反应,对感染后树鼩的PBMC转录组测序发现,ZIKV的感染可刺激机体的多种抗病毒相关及炎症因子基因表达,呈不同程度的升高,其中表征皮肤疾病严重程度的S100A12基因在感染期间上调明显;ZIKV感染还激发了树鼩较强的体液免疫反应,感染后20dpi树鼩体内中和抗体滴度可达534.8,中和抗体对乳鼠具有保护作用并有效防止继发性感染。综上所述,本研究通过对云南省ZIKV的流行病学与环境因素分析,揭示云南面临着ZIKV输入及流行的潜在风险,为ZIKV的科学防控提供了研究依据。ZIKV体内感染树鼩疾病模型的建立及体外对原代细胞感染性与不同嗜性的确定,弥补了现有动物模型的不足。ZIKV感染树鼩刺激机体发生强烈的免疫反应,产生的中和抗体具有较强的保护作用,为研究ZIKV的抗原靶点及药物治疗提供新思路。

关键词： Gypsy moth   Lymantria dispar   mechanical thinning   oak savanna   Peromyscus leucopus   pupal predation   restoration   white-footed mouse  

摘要： 1 The United States Forest Service conducted an oak savanna restoration using thinning and prescribed burning in the Manistee National Forest in Michigan to provide additional habitat for species dependent on this rare community type, including the Karner blue butterfly (Lycaeides melissa samuelis). Because the Karner blue butterfly is a federally endangered species, managers cannot spray Bt-k (Bacillus thurigiensis var kurstaki) in areas undergoing restoration to control exotic invasive defoliators, such as European gypsy moths (Lymantria dispar). 2 Although gypsy moths are invasive in North America, several native predators, such as white-footed mice (Peromyscus leucopus), other small mammals and invertebrates, help keep gypsy moth populations at nondestructive levels. 3 The present study investigated whether the small mammal community and gypsy moth predation rates were affected by the type of mechanical forest thinning method (bulldozer, masticator, shear cutter) used during an oak savanna restoration at two sites in Michigan within the suppression zone in 2010 and 2011. 4 Predation rates on gypsy moth pupae were higher in bulldozer and shear cutter thinned compared with control plots at both sites in 2010. White-footed mice relative abundance was significantly higher in thinned compared with control plots at one site in 2010 and 2011. 5 Thinning maintained or promoted white-footed mice abundance, which will maintain or enhance predation on gypsy moth pupae during oak savanna restoration.

关键词： Araucaria angustifolia   Exotic species   Invasion ecology   Invasive species   Keystone species   Life stages   Seed predation  

摘要： Despite of the widespread co-occurrence of multiple invaders, little is known on their combined ecological impacts and on their effects on different life stages of native species. We assessed the joint impacts of four non-native mammals (cattle, horse, European hare Lepus europaeus, and wild boar Sus scrofa) on seed surplus and seedling abundance of the Parana pine (Araucaria angustifolia), a critically-endangered species of the Atlantic Forest. We found that its seeds constitute an autumn food resource for a native community richer than previously thought, with 70 bird and mammal species as confirmed or potential seed consumers, of which 40 were not previously recognized as such. We also recorded the number of uneaten seeds and seedlings at the middle-end of autumn under 520 female Parana pine trees across the species' distribution and identified signs of the species consuming seeds from each tree through direct observations combined with camera trapping. Most of the sampled trees (98%) were visited by at least one seed consumer species, and over 60% were visited by at least one non-native mammal. Seed surplus strongly declined in the presence of cattle, horses and wild boars, their impacts being additive, whereas the number of seedlings declined in the presence of European hares. Our results emphasize the importance of Parana pine seeds for native fauna and the additive impact of invaders in a species-rich ecosystem. Seed predation by non-native species reduces the potential regeneration of Parana pine forests, and may severely reduce food supply for its native consumers.

关键词： Afrotropical rivers   hippopotamus   livestock defecation   savanna rivers   trophic structure  

摘要： 1. Knowledge of trophic structure is important to understand sources and pathways of energy resources in community ecology and to identify determinants of ecosystem changes. Yet, little is known from rivers of African savanna receiving large inputs of terrestrial organic matter and nutrients by large mammalian herbivores. 2. We used Stable Isotope (delta C-13 and delta N-15) Bayesian Ellipses in R (SIBER) and Layman's community-wide metrics to describe seasonal variation in trophic niches and trophic structures in midorder river reaches in the Mara River (Kenya) that differed in environmental conditions (agricultural vs. forested) and amounts of organic matter and nutrients (low vs. high inputs by livestock and hippopotami, Hippopotamus amphibius). These analyses were supplemented with data on the trophic diversity of macroinvertebrate functional feeding groups (FFGs) and fish trophic guilds. 3. The delta C-13 and delta N-15 of basal resources and consumers differed between sites and changed with seasons. Sites in agricultural areas that were utilised by livestock and a site with hippopotami had higher delta C-13 than the forested site due to the presence of C4 carbon from egestion and excretion by the grazers. 4. The forested site recorded the most taxon-rich and trophic-diverse invertebrate community, suggesting both autochthonous and allochthonous sources of energy were available. Agricultural sites and the site with hippopotami recorded high abundances of collector taxa in response to large inputs of organic matter. Fish trophic guilds were less diverse and were dominated by insectivores. 5. The food web at the forested site had the widest trophic niche size and highest isotopic trophic diversity compared to sites in areas with large mammalian herbivores. Invertebrate and fish trophic niche sizes changed according to food resources varying with space and time. Invertebrates had higher delta C-13 values during the dry season. In contrast, fish showed higher delta

关键词： Birds   Bats   Community composition   Functional traits   Terrestrial small mammals   African elephant  

摘要： Savannas are increasingly threatened by anthropogenic forces that are causing broad-scale directional shifts in woody vegetation that homogenizes their structure. Yet, whether animal communities respond consistently to changes in woody vegetation in savannas, particularly in terms of the effects of spatial scale, remains poorly understood. We addressed this gap by testing for changes in birds, bats and terrestrial small mammals across a gradient of woody cover in the savannas of southeastern Africa for two years at multiple spatial scales. We found that homogenization of vegetation structure corresponded with decreases in animal richness, diversity and functional diversity. Additionally, metrics of animal diversity declined at opposing ends of a canopy cover gradient (< 10% and > 65%), where we found distinctly different animal assemblages. These patterns were consistently more pronounced on a broader grid scale (30.25 ha) when compared with the plot scale (0.25 ha). The broad-scale reductions in the diversity and functions of animals observed may be indicative of reductions in the resilience, stability and ecosystem function of tropical savannas. Our results suggest that conservation and management aimed at promoting heterogeneity at broad scales may be critical for maintaining diversity and functionality in savannas.

关键词： Productive landscape   Tree plantations   Species richness   Species composition   Human access   Forest fragments  

摘要： Forest plantations of fast-growing exotic species constitute an important economic activity in tropical and temperate regions of developing countries. Large areas of native forests and grasslands are being turned into tree plantations without assessing their impacts on natural communities. We evaluated the effects of replacing native forests by non-native pine (Pinus taeda) plantations on the diversity and composition of assemblages of terrestrial mammals and ground-dwelling and understory birds, in a forest productive landscape of the Upper Parana Atlantic Forest of Misiones, Argentina. Camera-trap stations were deployed in three different "environments": 53 in a continuous forest, 69 in forest fragments, and 62 in tree plantations. The evaluation focused on the effect of the environment, the structural complexity of the vegetation, the cost-distance (distance weighted by connectivity) to the continuous forest, the percentage of native forest within different radii, and the cost of human access (as a proxy for hunting pressure) on both mean species richness per station and species composition. Alpha diversity of the assemblages of each environment was estimated using Hill numbers (effective number of species): (q(0) = richness, q(1) = number of common species and q(2) = number of dominant species. Changes in community composition were evaluated by comparing the assemblages of the three environments using three similarity indices: Sorensen (q(0) = similarity in species identity), Horn (q(1) = similarity in common species), and Morisita-Horn (q(2) = similarity in dominant species). For mammals and birds, richness was significantly higher in forest stations (both continuous and fragmented) than in those located in plantations. For both taxa, it also decreased with the distance to the continuous forest (but with a negative quadratic term in birds). Tree plantation stands contained biased and impoverished subsets of the original assemblages. Mammal composition was affec

关键词： Predator-proof fence   Reptile   Feral cat   Invasive species   Predation  

摘要： Feral cats have been responsible, in part, for the extinction of many species of mammal, bird and reptile globally, especially on islands. Whilst there is extensive evidence of the predatory impacts of cats on mammals and birds, far less is known about their ecological impacts on reptiles, especially in continental situations. We conducted a field experiment to evaluate the impact of feral cats on terrestrial vertebrates in tropical savanna environments of northern Australia. Three experimental treatments were applied to six 64 ha plots to compare and contrast responses of reptile abundance and species richness to predator exclusion and the additive effects of frequent fire. Replicated pitfall-trapping was undertaken in each plot on seven sampling occasions between November 2013 and November 2015. We analysed relative abundance and species richness data using generalized linear mixed models. There was a significant increase in the abundance of reptiles over a two year period in cat excluded plots with reptile abundance increasing at twice the rate in cat-exclusion plots compared with cat accessible plots and there was an additive effect of time-since-fire. Cat exclusion had a positive effect on reptile species richness over time, however the evidence for this pattern was weak when seasonal variation was taken into account. Predation by cats, in synergy with other disturbance processes, could adversely impact reptile species and communities elsewhere in the world where feral cats have been established and warrants further investigation.

关键词： Agriculture   Cattle ranching   Cropland   Fire   Shrub/woody encroachment  

摘要： Grasslands and savannas are among the most degraded biomes in the world. These biomes face a diverse number of anthropogenic threats, and despite this scenario, little attention is given to their conservation and sustainable use. This meta-analysis aims to analyze the effect of anthropogenic activities on the abundance of native mammals in these grassy ecosystems. A systematic research in the literature was carried out in order to find studies that analyzed variations in abundance of mammals in response to an anthropogenic activity in any grassland, savanna or shrubland environment around the world. After filtering, 24 studies were analyzed, generating 202 effect sizes for five anthropogenic factors: cropland activities (32 effect sizes - ES);cattle ranching (58 ES);fire (30 ES);shrub/woody encroachment (56 ES) and urbanization (26 ES). Analyzed papers included field data from all continents. In general, mammalian abundance is decreasing under anthropogenic disturbance, as shown by the general effect size. This result highlights the need for more intense conservation programs in grasslands and savannas, since its species are under threat. When comparing the different anthropogenic threats, only cropland activities affected mammals significantly, reducing their abundance. The estimate of the mean effect of cattle ranching, fire, shrub/woody encroachment and urbanization on abundance of mammals did not differ from zero. However, for cattle ranching, fire and shrub/woody encroachment the mean effects measured had large confidence intervals, indicating that these mean effects could not be estimated accurately. Cattle ranching, fire and shrub/woody encroachment effects on mammalian abundance probably depend on their intensity and on the environmental characteristics of each ecosystem, and therefore each case must be analyzed in an ecosystem-specific perspective. Urbanization did not affect mammals, although this anthropogenic activity was analyzed only in two ecosystems

关键词： Aging   Comparative biology   Complexity   Disposable soma   Diversity   Model organism  

摘要： Use of model organisms in aging research is problematic because our ability to extrapolate across the tree of life is not clear. On one hand, there are conserved pathways that regulate lifespan in organisms including yeast, nematodes, fruit flies, and mice. On the other, many intermediate taxa across the tree of life appear not to age at all, and there is substantial variation in aging mechanisms and patterns, sometimes even between closely related species. There are good evolutionary and mechanistic reasons to expect this complexity, but it means that model organisms must be used with caution and that results must always be interpreted through a broader comparative framework. Additionally, it is essential to include research on non-traditional and unusual species, and to integrate mechanistic and demographic research. There will be no simple answers regarding the biology of aging, and research approaches should reflect this. This article is part of a Special Issue entitled: Animal models of aging - edited by Houtkooper Riekelt.

关键词： extinction risk   fire management   Melville Island   native mammal diversity   northern Australia   pyrodiversity   threatened species   tropical savanna  

摘要： 1. The increasing awareness that a fire regime that promotes biodiversity in one system can threaten biodiversity in another has resulted in a shift away from fire management based on vague notions of maximising pyrodiversity, towards determining the optimal fire regime based on the demonstrated requirements of target species. 2. We utilised a long-running, replicated fire experiment on Melville Island, the largest island off the northern Australian coast, to test the importance of pyrodiversity for native mammals in a northern Australian savanna landscape. We first developed statistical models to determine how native mammal abundance has responded to nine years of experimentally-manipulated fire frequency. Next, given each species' modelled response to fire frequency, we identified the level of pyrodiversity and optimal mix of fire frequencies that would be expected to maximise mammal diversity and abundance, and minimise extinction risk. This was done for both the entire mammal assemblage and for the mammal species currently declining on Melville Island. 3. Fire frequency was a significant predictor of abundance of the northern brown bandicoot Isoodon macrourus, black-footed tree-rat Mesembriomys gouldii, brush-tailed rabbit-rat Conilurus penicillatus, grassland melomys Melomys burtoni, pale field-rat Rattus tunneyi, and mice/dunnarts but not for the common brushtail possum Trichosurus vulpecula. 4. The geometric mean abundance (GMA) of the entire mammal assemblage was positively associated with pyrodiversity, but peaked at an intermediate value. Hence, maximising pyrodiversity would reduce native mammal assemblage GMA below its potential maximum. The fire history for an area that maximised the entire native mammal assemblage GMA consisted of 57% long-unburnt, 43% triennially burnt and <1% annually burnt. Pyrodiversity did not reduce the extinction risk, nor increase the GMA of declining mammals above that predicted in areas entirely annually or triennially burnt.