Non-random coextinctions in phylogenetically structured mutualistic networks

The interactions between plants and their animal pollinators and seed dispersers have moulded much of Earth's biodiversity. Recently, it has been shown that these mutually beneficial interactions form complex networks with a well-defined architecture that may contribute to biodiversity persistence. Little is known, however, about which ecological and evolutionary processes generate these network patterns. Here we use phylogenetic methods to show that the phylogenetic relationships of species predict the number of interactions they exhibit in more than one-third of the networks, and the identity of the species with which they interact in about half of the networks. As a consequence of the phylogenetic effects on interaction patterns, simulated extinction events tend to trigger coextinction cascades of related species. This results in a non-random pruning of the evolutionary tree and a more pronounced loss of taxonomic diversity than expected in the absence of a phylogenetic signal. Our results emphasize how the simultaneous consideration of phylogenetic information and network architecture can contribute to our understanding of the structure and fate of species-rich communities.     

The challenge of emerging and re-emerging infectious diseases

Infectious diseases have for centuries ranked with wars and famine as major challenges to human progress and survival. They remain among the leading causes of death and disability worldwide. Against a constant background of established infections, epidemics of new and old infectious diseases periodically emerge, greatly magnifying the global burden of infections. Studies of these emerging infections reveal the evolutionary properties of pathogenic microorganisms and the dynamic relationships between microorganisms, their hosts and the environment.     

健康城市与完善的城市生态规划策略探析

 随着人类城市化进程的加剧，引起了一系列的生态环境问题，导致人与自然的矛盾加剧，特别是疫灾的出现，极大地危害人体健康、破坏城市秩序、危及社会的稳定和可持续性、造成社会经济的重大损失。结合史上重大疫灾的分析，从生态规划的视角，寻找疫灾产生的根本原因及生态规划工作中存在的问题，重点研究人与生物（动物、植物、微生物）之间的相互关系，并提出完善健康城市建设及生态规划的理念及策略。建议在今后的生态规划中，建立、完善人与生物和谐共生的人居环境，加强生物规划，从以人为本，打造人与自然的生命健康共同体。     

General patterns of taxonomic and biomass partitioning in extant and fossil plant communities

A central goal of evolutionary ecology is to identify the general features maintaining the diversity of species assemblages. Understanding the taxonomic and ecological characteristics of ecological communities provides a means to develop and test theories about the processes that regulate species coexistence and diversity. Here, using data from woody plant communities from different biogeographic regions, continents and geologic time periods, we show that the number of higher taxa is a general power-function of species richness that is significantly different from randomized assemblages. In general, we find that local communities are characterized by fewer higher taxa than would be expected by chance. The degree of taxonomic diversity is influenced by modes of dispersal and potential biotic interactions. Further, changes in local diversity are accompanied by regular changes in the partitioning of community biomass between taxa that are also described by a power function. Our results indicate that local and regional processes have consistently regulated community diversity and biomass partitioning for millions of years.     

Pleistocene Homo sapiens from Middle Awash,Ethiopia

The origin of anatomically modern Homo sapiens and the fate of Neanderthals have been fundamental questions in human evolutionary studies for over a century. A key barrier to the resolution of these questions has been the lack of substantial and accurately dated African hominid fossils from between 100,000 and 300,000 years ago. Here we describe fossilized hominid crania from Herto, Middle Awash, Ethiopia, that fill this gap and provide crucial evidence on the location, timing and contextual circumstances of the emergence of Homo sapiens. Radioisotopically dated to between 160,000 and 154,000 years ago, these new fossils predate classic Neanderthals and lack their derived features. The Herto hominids are morphologically and chronologically intermediate between archaic African fossils and later anatomically modern Late Pleistocene humans. They therefore represent the probable immediate ancestors of anatomically modern humans. Their anatomy and antiquity constitute strong evidence of modern-human emergence in Africa.     

水生生态调控及水污染治理中微生物的应用

微生物是地球生态系统中最重要的分解者,也是开发潜力最大、人类最宝贵的资源库,在污染物的降解转化、资源的再生利用、无公害产品的生产开发、生态环境的建设保护等方面都能发挥重要作用．当今人类所面临的诸如环境污染、资源短缺、生态破坏、健康受害等许多重大问题,都有可能从微生物资源的开发研究中寻找到解决的办法,生物技术对人类社会的持续发展将产生重要影响．本文论述影响水生生态的主要因素及其相互作用,重点分析微生物在生态调控中的功能、演变及应用前景．结合国情探讨生物技术在环境保护中的研究、技术开发及产业化发展方向,分析微生物高级技术如基因工程技术、克隆技术等在环境领域中应用和产业化的可行性．文中着重介绍维持生态平衡、环境资源化和环境无害化不同层次微生物技术的作用,从微生物的多样性和功能性特点发展各种专门技术,实现废水资源化和无害化的综合协调与优化,实现其环境领域中的广泛应用．     

Low host specificity of herbivorous insects in a tropical forest

Two decades of research have not established whether tropical insect herbivores are dominated by specialists or generalists. This impedes our understanding of species coexistence in diverse rainforest communities. Host specificity and species richness of tropical insects are also key parameters in mapping global patterns of biodiversity. Here we analyse data for over 900 herbivorous species feeding on 51 plant species in New Guinea and show that most herbivorous species feed on several closely related plant species. Because species-rich genera are dominant in tropical floras, monophagous herbivores are probably rare in tropical forests. Furthermore, even between phylogenetically distant hosts, herbivore communities typically shared a third of their species. These results do not support the classical view that the coexistence of herbivorous species in the tropics is a consequence of finely divided plant resources; non-equilibrium models of tropical diversity should instead be considered. Low host specificity of tropical herbivores reduces global estimates of arthropod diversity from 31 million (ref. 1) to 4 6 million species. This finding agrees with estimates based on taxonomic collections, reconciling an order of magnitude discrepancy between extrapolations of global diversity based on ecological samples of tropical communities with those based on sampling regional faunas.     

Host specificity of Lepidoptera in tropical and temperate forests

For numerous taxa, species richness is much higher in tropical than in temperate zone habitats. A major challenge in community ecology and evolutionary biogeography is to reveal the mechanisms underlying these differences. For herbivorous insects, one such mechanism leading to an increased number of species in a given locale could be increased ecological specialization, resulting in a greater proportion of insect species occupying narrow niches within a community. We tested this hypothesis by comparing host specialization in larval Lepidoptera (moths and butterflies) at eight different New World forest sites ranging in latitude from 15 degrees S to 55 degrees N. Here we show that larval diets of tropical Lepidoptera are more specialized than those of their temperate forest counterparts: tropical species on average feed on fewer plant species, genera and families than do temperate caterpillars. This result holds true whether calculated per lepidopteran family or for a caterpillar assemblage as a whole. As a result, there is greater turnover in caterpillar species composition (greater beta diversity) between tree species in tropical faunas than in temperate faunas. We suggest that greater specialization in tropical faunas is the result of differences in trophic interactions; for example, there are more distinct plant secondary chemical profiles from one tree species to the next in tropical forests than in temperate forests as well as more diverse and chronic pressures from natural enemy communities.     

Functional metagenomic profiling of nine biomes

Microbial activities shape the biogeochemistry of the planet and macroorganism health. Determining the metabolic processes performed by microbes is important both for understanding and for manipulating ecosystems (for example, disruption of key processes that lead to disease, conservation of environmental services, and so on). Describing microbial function is hampered by the inability to culture most microbes and by high levels of genomic plasticity. Metagenomic approaches analyse microbial communities to determine the metabolic processes that are important for growth and survival in any given environment. Here we conduct a metagenomic comparison of almost 15 million sequences from 45 distinct microbiomes and, for the first time, 42 distinct viromes and show that there are strongly discriminatory metabolic profiles across environments. Most of the functional diversity was maintained in all of the communities, but the relative occurrence of metabolisms varied, and the differences between metagenomes predicted the biogeochemical conditions of each environment. The magnitude of the microbial metabolic capabilities encoded by the viromes was extensive, suggesting that they serve as a repository for storing and sharing genes among their microbial hosts and influence global evolutionary and metabolic processes.     

河南灵井许昌人遗址古人类化石及相关研究进展

 2007年和2014年，河南灵井遗址出土的距今10万年左右的许昌人头骨化石引起古人类学界的广泛关注，研究显示晚更新世早期中国境内可能并存多种古人类成员，不同群体之间有杂交或者基因交流产生。许昌人为中国古人类演化的地区连续性以及与欧洲古人类之间的交流提供了一定程度的支持。本文回顾了许昌人化石的发现历史、复原和研究过程，介绍了许昌人伴生的哺乳动物化石、石制品、骨质工具的最新研究进展；讨论了灵井遗址未来工作前景。许昌人化石及伴生的文化遗物为探讨当时人类的体质特征、行为方式及中国古人类的演化模式提供了重要的参考资料。     

Extensive surface diversity of a commensal microorganism by multiple DNA inversions.

The dynamic interactions between a host and its intestinal microflora that lead to commensalism are unclear. Bacteria that colonize the intestinal tract do so despite the development of a specific immune response by the host. The mechanisms used by commensal organisms to circumvent this immune response have yet to be established. Here we demonstrate that the human colonic microorganism, Bacteroides fragilis, is able to modulate its surface antigenicity by producing at least eight distinct capsular polysaccharides-a number greater than any previously reported for a bacterium-and is able to regulate their expression in an on-off manner by the reversible inversion of DNA segments containing the promoters for their expression. This means of generating surface diversity allows the organism to exhibit a wide array of distinct surface polysaccharide combinations, and may have broad implications for how the predominant human colonic microorganisms, the Bacteroides species, maintain an ecological niche in the intestinal tract.     

Frontal and stealth attack strategies in microbial pathogenesis

Interactions between microbes and human hosts can range from a benign, even symbiotic collaboration to a competition that may turn fatal--resulting in death of the host, the microbe or both. Despite advances that have been made over the past decades in understanding microbial pathogens, more people worldwide still die every year from infectious disease than from any other cause. This highlights the relevance of continuing to probe the mechanisms used by microorganisms to cause disease, and emphasizes the need for new model systems to advance our understanding of host-pathogen interactions.     

Interactions between marine microorganisms and their phages

Viruses are the most abundant biological entities in marine ecosystems. Most of them are phages that infect bacteria and archaea. Phages play important roles in causing the mortality of prokaryotic cells, structuring microbial communities, mediating horizontal gene transfer between different microbes, influencing the microbial food web process, and promoting biogeochemical cycles (such as C, N, etc.) in the ocean. Here we provided an overview of recent advances in research on the interactions between marine microorganisms and their phages, and suggest future research directions based on our understanding of the literature and our own work.     

溴代阻燃剂微生物降解的研究进展

溴代阻燃剂带来广泛应用的同时引入了对生态和人类健康有害的污染物质,这是我们不想看到。因此,我们放眼到寻找可以降解这些有害物质的微生物上。这种思路是对的,我们找到了一些微生物可以降解这些污染,包括厌氧降解、好氧降解以及基团化降解。每种污染降解方式都不同,这是今后研究的重点,对BFRs的处理具有指导意义。     

高温胁迫对植食性昆虫影响研究进展

昆虫作为变温动物类群,极易遭受高温胁迫的影响。研究高温胁迫对植食性昆虫的影响,可为气候变暖背景下农林害虫的种群动态监测及地理适生区预测提供重要理论依据。笔者从植食性昆虫个体、种间互作关系、种群及群落3个层面,综述了高温胁迫对植食性昆虫影响的国内外进展。研究发现,高温胁迫会对植食性昆虫个体的生长发育、繁殖及生理生化带来负面效应,但昆虫自身也会进化出一系列基于形态、行为及基因表达的热胁迫响应机制。高温胁迫对寄主植物、天敌、共生微生物的影响也能够通过种间互作传递给植食性昆虫,并导致寄主植物-植食性昆虫-天敌3级营养关系发生变化。同时,高温胁迫还能通过影响昆虫个体及种间关系,间接影响昆虫的种群动态、种群多样性及其生态功能,并可能导致植食性昆虫的种群大爆发或衰退。最后,笔者认为此领域未来研究方向为:在个体层面上,应优化高温胁迫处理方式并综合考虑干旱和降水等环境因子,开展农林害虫种群的长期野外监测,应注重高温胁迫对昆虫参与生长发育繁殖功能基因的影响;在种间关系层面上,应关注高温胁迫对昆虫关联的复杂多样的食物网及互作体系的影响;此外,应结合高温胁迫对不同昆虫种类自身生理特性和行为模式的影响,阐明温度升高对昆虫群落的影响。     

Sex ratio adjustment and kin discrimination in malaria parasites

Malaria parasites and related Apicomplexans are the causative agents of the some of the most serious infectious diseases of humans, companion animals, livestock and wildlife. These parasites must undergo sexual reproduction to transmit from vertebrate hosts to vectors, and their sex ratios are consistently female-biased. Sex allocation theory, a cornerstone of evolutionary biology, is remarkably successful at explaining female-biased sex ratios in multicellular taxa, but has proved controversial when applied to malaria parasites. Here we show that, as predicted by theory, sex ratio is an important fitness-determining trait and Plasmodium chabaudi parasites adjust their sex allocation in response to the presence of unrelated conspecifics. This suggests that P. chabaudi parasites use kin discrimination to evaluate the genetic diversity of their infections, and they adjust their behaviour in response to environmental cues. Malaria parasites provide a novel way to test evolutionary theory, and support the generality and power of a darwinian approach.     

Competition and mutualism among the gut helminths of a mammalian host

Most animal species are infected with multiple parasite species; however, the role of interspecific parasite interactions in influencing parasite dynamics and shaping parasite communities has been unclear. Although laboratory studies have found evidence of cross-immunity, immunosuppression and competition, analyses of hosts in the field have generally concluded that parasite communities are little more than random assemblages. Here we present evidence of consistent interspecific interactions in a natural mammalian system, revealed through the analysis of parasite intensity data collected from a free-ranging rabbit (Oryctolagus cuniculus) population, sampled monthly for a period of 23 yr. The wild rabbit plays host to a diverse gut helminth community that reflects the communities seen in other economically important domestic herbivores. These findings suggest that parasite interactions could have profound implications for the dynamics of parasite communities. The efficacy of parasite control programmes could be jeopardized if such interactions are not taken into account. In contrast, a clear understanding of such interactions may provide the basis for the development of more environmentally acceptable methods of parasite control.     

Strain-resolved community proteomics reveals recombining genomes of acidophilic bacteria

Microbes comprise the majority of extant organisms, yet much remains to be learned about the nature and driving forces of microbial diversification. Our understanding of how microorganisms adapt and evolve can be advanced by genome-wide documentation of the patterns of genetic exchange, particularly if analyses target coexisting members of natural communities. Here we use community genomic data sets to identify, with strain specificity, expressed proteins from the dominant member of a genomically uncharacterized, natural, acidophilic biofilm. Proteomics results reveal a genome shaped by recombination involving chromosomal regions of tens to hundreds of kilobases long that are derived from two closely related bacterial populations. Inter-population genetic exchange was confirmed by multilocus sequence typing of isolates and of uncultivated natural consortia. The findings suggest that exchange of large blocks of gene variants is crucial for the adaptation to specific ecological niches within the very acidic, metal-rich environment. Mass-spectrometry-based discrimination of expressed protein products that differ by as little as a single amino acid enables us to distinguish the behaviour of closely related coexisting organisms. This is important, given that microorganisms grouped together as a single species may have quite distinct roles in natural systems and their interactions might be key to ecosystem optimization. Because proteomic data simultaneously convey information about genome type and activity, strain-resolved community proteomics is an important complement to cultivation-independent genomic (metagenomic) analysis of microorganisms in the natural environment.     

黄河典型支流入干区底栖动物群落结构特征比较研究

基于2015年春季(4月)和秋季(10月)在黄河流域湟水、汾河、渭河和洛河等入干支流采集的底栖动物样品, 开展支流入干区底栖动物群落结构特征比较研究。监测结果表明, 春秋两季在各支流入干区采集到的底栖动物种属数量排序为洛河(28种)>湟水(26种)>汾河(23种)>渭河(17种); 支流入干区春秋两季优势功能摄食类群皆为牧食收集者(除洛河在秋季以刮食者为主外)。底栖动物群落的除趋势对应分析表明, 底质对底栖动物群落分布起重要作用, 水草等水生植物的存在利于底栖动物生存。进一步地, 底栖动物群落与环境因子的冗余分析表明, pH和电导率是影响底栖动物群落的关键因子。从物种组成、密度、生物量、功能摄食类群和群落与生境因子关系等方面研究了底栖动物的群落结构, 较为系统地揭示了黄河主要支流入干区的底栖动物分布特征, 研究结果可为黄河水生生物群落结构的系统性研究提供支撑。