园蛛总科网型不同的蜘蛛间分子系统发生关系的初步探讨

为初步探讨园蛛总科内网型不同的蜘蛛间分子系统发生关系,测定了9种蜘蛛核18S rRNA基因的部分序列。联合GenBank中的2种蜘蛛18S rRNA基因序列数据,用NJ法、MP法和ML法重建分子系统树,结果表明：（1）织圆网的园蛛科和肖蛸科蜘蛛在园蛛总科中不是姊妹群;（2）不织圆网的球蛛科和皿蛛科也不是单系发生,证实了皿蛛片网和球蛛网独立起源的观点;（3）皿蛛科蜘蛛的分子系统发生地位与肖蛸科较近、而与园蛛科较远,这表明皿蛛科和园蛛科问雄性触肢结构的相似性很可能是类似而不是同源相似。     

Market Perceptions and Opportunities for Native Plant Production on the Southern Colorado Plateau

Increases in revegetation activities have created a large demand for locally adapted native plant materials (NPM) in the southwestern United States. Currently, there is a minimal supply of local genotypes to meet this demand. We investigated the potential for the initiation of a native plant market in the southern Colorado Plateau. Through a literature search, interviews, and site visits, we identified existing native plant markets outside of the region as useful models to help initiate a regional market. We used web‐based surveys to identify and analyze current and future NPM needs and concerns. Survey results indicate that management policy strongly drives decisions regarding the use and purchase of NPM. From a demand perspective , lack of availability and cost of NPM has kept purchasing minimal, despite policy changes favoring the use of natives. For suppliers, further development of NPM is limited by inconsistent and unreliable demand and lack of production knowledge. The knowledge and tools necessary to initiate an NPM market are available, but inadequate funding sources and insufficient information sharing hinder its development. Communication among producers, land managers, buyers, and researchers, as well as partnerships with local growers, appear to be vital to initiating a functional market.     

Sentinel systems on the razor's edge: effects of warming on Arctic geothermal stream ecosystems

The Earth is experiencing historically unprecedented rates of warming, with surface temperatures projected to increase by 3–5 °C globally, and up to 7.5 °C in high latitudes, within the next century. Knowledge of how this will affect biological systems is still largely restricted to the lower levels of organization (e.g. species range shifts), rather than at the community, food web or ecosystem level, where responses cannot be predicted from studying single species in isolation. Further, many correlational studies are confounded with time and/or space, whereas experiments have been mostly confined to laboratory microcosms that cannot capture the true complexity of natural ecosystems. We used a ‘natural experiment’ in an attempt to circumvent these shortcomings, by characterizing community structure and trophic interactions in 15 geothermal Icelandic streams ranging in temperature from 5 °C to 45 °C. Even modest temperature increases had dramatic effects across multiple levels of organization, from changes in the mean body size of the top predators, to unimodal responses of species populations, turnover in community composition, and lengthening of food chains. Our results reveal that the rates of warming predicted for the next century have serious implications for the structure and functioning of these fragile ‘sentinel’ ecosystems across multiple levels of organization.     

Environmental factors determining invasibility of urban waters for exotic macroinvertebrates

Aim Urbanization usually leads to biotic homogenization with a decrease in native species and increase in exotic species. We investigated whether local environmental factors in urban water bodies, such as water quality, habitat structure and biotic interactions, influenced the invasion of these systems by exotic macroinvertebrate species. Location Urban surface water systems in lowlands of the Rhine‐Meuse delta. Methods Presence and abundance of native and exotic macroinvertebrate species were compared between different urban water types and related to environmental variables with multivariate analysis and spearman’s correlations. Moreover, co‐existence of related native and exotic species was studied. Results In total nine exotic species were found in the following taxa: Tricladida (1), Crustacea (5), Bivalvia (1) and Gastropoda (2). Taxonomically related native and exotic crustacean species did not seem to be influenced by competition in nutrient‐rich urban waters; most species showed high abundances. Nevertheless, two exotic crustacean species were much more abundant in waters where other crustacean species were absent, possibly filling empty niches. Native species richness and abundance was positively related to environmental heterogeneity in the form of submerged vegetation. The occurrence and abundance of most exotic species were positively related to several eutrophication indicators, such as nitrate, sludge layer and lemnid vegetation. Main conclusions Exotic species in urban waters were mostly detritivorous or omnivorous and therefore dependent on leaf breakdown. In nutrient‐rich water systems, where food availability was high, exotic crustacean species co‐existed with native crustacean species, while in nutrient‐poor, richly vegetated systems, native Asellidae dominated exotic Asellidae. In the turbid water bodies with very little vegetation, native species richness was low and two exotic crustacean species were relatively abundant in these water systems. Invasibility of urban water systems could be reduced by stimulating the development of submerged and nymphaeid vegetation and decreasing nutrient levels.     

Influence of an invasive ant on grazing and detrital communities and nutrient fluxes in a tropical forest

Aim  Pathways linking grazing and detrital subsystems of terrestrial ecosystems are important for ecosystem processes and function, but remain poorly understood. The invasion of a generalist predator creates a unique opportunity to study the effects of predation across these subsystems. We examine here, the effects of a non-native generalist predator, the little red fire ant ( Wasmannia auropunctata, Roger) on both grazing and detrital invertebrate communities and ecosystem processes in a rain forest understorey.
Location  Gamba Protected Area Complex, south-western Gabon, Africa.
Methods  We measured abundances and diversities of understorey grazing and detrital invertebrate communities, soil nutrients, herbivory, litter fragmentation rates and leaf chemistry of a dominant understorey shrub inside and outside of 19 separate invasion fronts. We then explored possible trophic cascades and pathways of interaction using path analysis.
Results  Results suggest that invasive ants may alter herbivory regimes, grazing and detrital communities, and may indirectly alter litter decomposition and nutrient cycling in the soil by suppressing important microbivore and detritivore populations with consequences for leaf chemistry.
Main conclusions  These results demonstrate that generalist predators may be major drivers of both grazing and detrital subsystems by inducing strong shifts in adjacent communities that ultimately affect ecosystem processes.     

Identification of tetracycline‐ and erythromycin‐resistant Gram‐positive cocci within the fermenting microflora of an Italian dairy food product

Aims: Microbiological and molecular analysis of antibiotic resistance in Gram‐positive cocci derived from the Italian PDO (Protected Designation of Origin) dairy food product Mozzarella di Bufala Campana. Methods and Results: One hundred and seven coccal colonies were assigned to Enterococcus faecalis, Lactococcus lactis and Streptococcus bovis genera by ARDRA analysis (amplified ribosomal DNA restriction analysis). Among them, 16 Ent. faecalis, 26 L. lactis and 39 Strep. bovis displayed high minimum inhibitory concentration (MIC) values for tetracycline, while 17 L. lactis showed high MIC values for both tetracycline and erythromycin. Strain typing and molecular analysis of the phenotypically resistant isolates demonstrated the presence of the tet(M) gene in the tetracycline‐resistant strains and of tet(S) and erm(B) in the double‐resistant strains. Southern blot analysis revealed plasmid localization of L. lactis tet(M), as well as of the erm(B) and tet(S) genes. Genetic linkage of erm(B) and tet(S) was also demonstrated by PCR amplification. Conjugation experiments demonstrated horizontal transfer to Ent. faecalis strain JH2‐2 only for the plasmid‐borne L. lactis tet(M) gene. Conclusions: We characterized tetracycline‐and erythromycin‐resistance genes in coccal species, representing the fermenting microflora of a typical Italian dairy product. Significance and Impact of the Study: These results are of particular relevance from the food safety viewpoint, especially in the light of the potential risk of horizontal transfer of antibiotic‐resistance genes among foodborne commensal bacteria.     

Vertical Micro‐Zonation of Testate Amoebae and Ciliates in Peatland Waters in Relation to Potential Food Resources and Grazing Pressure

The aim of this study was to examine the community structure and vertical micro‐distribution of testate amoebae and ciliates in a raised bog in eastern Poland, as well as to assess the influence of potential food resources (Chl‐a, bacteria, heterotrophic flagellates) and predators (rotifers and copepods) on protozoa communities. Samples were taken from surface, bottom and interstitial waters. At each type of micro‐habitat and each sampling date water was sampled using a plexiglass corer or mini‐piezometers. Additionally, in order to evaluate grazing pressure, field enclosures were used in which metazoan abundance and composition was manipulated by size‐fractionation. Over experiments, metazoan populations shifted from dominance of rotifers to copepods. In the first experiment, with rotifers dominating, metazoa had only a modest predatory impact on the protozoa. In contrast, the second experiment, with copepods prevailing, demonstrated a clear top‐down control of the protozoa communities by metazoan. The density and biomass of protozoa significantly differed between the studied stations, with the lowest numbers in the interstitial water and the highest in the surface water. Surface sampling were dominated by mixotrophic taxa, whereas the deepest sampling level was characterized by increase in the proportion of bacterivore species. These differences between micro‐habitats may be due to differences in environmental conditions (food resources and grazing pressure). Ordination analysis revealed that bacteria can strongly regulate the abundance and taxonomic composition of protozoa in the bottom and interstitial waters. Metazoan predators could be the main regulators of protozoa communities in surface water. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Niche conservatism as an emerging principle in ecology and conservation biology

The diversity of life is ultimately generated by evolution, and much attention has focused on the rapid evolution of ecological traits. Yet, the tendency for many ecological traits to instead remain similar over time [niche conservatism (NC)] has many consequences for the fundamental patterns and processes studied in ecology and conservation biology. Here, we describe the mounting evidence for the importance of NC to major topics in ecology (e.g. species richness, ecosystem function) and conservation (e.g. climate change, invasive species). We also review other areas where it may be important but has generally been overlooked, in both ecology (e.g. food webs, disease ecology, mutualistic interactions) and conservation (e.g. habitat modification). We summarize methods for testing for NC, and suggest that a commonly used and advocated method (involving a test for phylogenetic signal) is potentially problematic, and describe alternative approaches. We suggest that considering NC: (1) focuses attention on the within‐species processes that cause traits to be conserved over time, (2) emphasizes connections between questions and research areas that are not obviously related (e.g. invasives, global warming, tropical richness), and (3) suggests new areas for research (e.g. why are some clades largely nocturnal? why do related species share diseases?).     

多巴胺对长爪沙鼠 贮食行为的影响

长爪沙鼠的贮食行为具有高低二型性。禁食诱导的贮食行为可能与中脑多巴胺系统（Dopamine,DA）有关,但尚乏证据。本文通过Fos标记相关脑区的活性,酪氨酸羟化酶（TH）标记DA神经元,以免疫组化方法观察高贮食组沙鼠腹腔注射DA拮抗剂haloperidol （1 mg/kg）和对低贮食组沙鼠腹腔注射DA激动剂apomorphine（0.3 mg/kg）的行为和神经变化,验证中枢DA对贮食行为的调节。结果显示,haloperidol抑制了禁食诱导的沙鼠的贮食行为,这种抑制刺激了伏隔核和尾壳核Fos-ir阳性细胞表达,但却降低了黑质区Fos-ir和Fos-ir/TH-ir的细胞表达。Apomorphine增加了禁食诱导的沙鼠的贮食行为,且降低伏隔核和尾壳核Fos-ir阳性细胞表达。这些结果表明,中脑DA系统参与调节了禁食条件下长爪沙鼠的贮食行为。     

放牧对布氏田鼠主要食物选择的影响

动物的食物选择受食物资源量、质量和喜好度决定。尽管放牧可减少鼠类的喜食植物的数量和质量,但其如何影响鼠类的食物选择尚不清楚。本研究于2014年5月至10月,在内蒙古锡林郭勒盟锡林浩特市毛登牧场的大型试验围栏内进行了布氏田鼠的食物选择实验。利用大型实验围栏内5年连续放牧处理所构建的植被变化条件,采用扣笼试验,调查了布氏田鼠对其三种主要植物的取食情况。研究发现：连续放牧后,糙隐子草的盖度增加,而羊草、克氏针茅盖度降低;糙隐子草的盖度显著高于羊草、克氏针茅,成为各季节的优势植物种类。放牧对布氏田鼠取食羊草、克氏针茅和糙隐子草的绝对取食频次均无显著影响。在季节上,布氏田鼠对克氏针茅和糙隐子草的取食在三个季节均无差异,但布氏田鼠对羊草取食的绝对频次夏季显著高于春季和秋季;布氏田鼠对三种植物的喜好程度依次为羊草>克氏针茅>糙隐子草,但季节和放牧因素对布氏田鼠对这三种植物的喜好度无显著影响。结果表明,布氏田鼠的食物选择及食物组成相对稳定,表现为其对放牧或季节因素造成的喜食植物资源量的变化具有很好的适应性,推测是其调整取食努力来实现食物组成的平衡。