Effects of stream-crossing by a pipeline on the benthic macroinvertebrate communities of a small mountain stream

Aquatic environmental impact associated with stream-crossing by a pipeline was monitored at Archibald Creek, B.C. for two years. Water chemistry and benthic macroinvertebrates were used as monitoring tools. Results indicated that impacts arising from stream-crossing were short-term and non-residual.Funded by a contract from Canadian Arctic Gas Study Limited, calgary, to Aquatic Environments Limited, Calgary.Aquatic Environments Limited, Calgary.Aquatic Environments Limited, Calgary.     

Female‐driven intersexual coevolution in beetle genitalia

Genital coevolution is a pervasive phenomenon as changes in one sex tend to impose fitness consequences on the other, generating sexual conflict. Sexual conflict is often thought to cause stronger selection on males due to the Darwin–Bateman's anisogamy paradigm. However, recent studies have demonstrated that female genitalia may be equally elaborated and perform diverse extra‐copulatory functions. These characteristics suggest that female genitals can also be primary targets of selection, especially where natural selection acts on female‐exclusive functions such as oviposition. Here, we test this hypothesis in a statistical phylogenetic framework across the whole beetle (Coleoptera) phylogeny, investigating whether coevolution of specific genital traits may be triggered by changes in females. We focus on traits of the proctiger, which composes part of the male terminalia and the female ovipositor. Our results present a comprehensive case of male–female genital coevolution and provide solid statistical evidence for a female‐initiated coevolutionary process where the vast majority of evolutionary transitions in males have occurred only after changes in females. We corroborate the hypothesis that female traits may change independently and elicit counter‐adaptations in males. Furthermore, by showing a consistent pattern across the phylogeny of the most diverse group of animals, our results suggest that this female‐driven dynamics may persist through long time scales.     

中美减排二氧化碳的GDP溢出模拟

基于气候保护模型(State-contingent模型与Demeter模型)和GDP溢出模型(Mundell-Fleming模型),对中美两国在实施控制性气候保护措施之后所导致的GDP溢出影响的变化进行了模拟分析。结果表明,美国实行控制性减排政策对于中国的GDP溢出影响与不实施任何减排的情况相比,两者的差别并不明显,但是这种影响经历一个从负向到正向逐步上升的发展趋势,虽然中国实行控制性减排政策对于美国GDP溢出的影响,相比美国对于中国的影响,所导致的GDP溢出影响更小,但是也同样表现出了一个从负溢出到正溢出的过程。这一结果表明一国的控制性气候保护政策从长远来看会对另一国的经济发展产生正向的溢出。同时,针对两种情况,即不考虑他国GDP溢出影响和考虑他国GDP溢出影响,分别模拟计算了中美两国的GDP,进而对两种情况下的差额结果进行对比,分析了中美相互之间GDP溢出量的大小。结果发现,美国对中国GDP溢出影响要大于中国对美国的GDP溢出。     

Kgtests: a simple Excel Macro program to detect signatures of population expansion using microsatellites

A simple Microsoft Excel Macro application (kgtests) that performs the k and g tests for detecting population expansion is described. The application, being an Excel Macro, facilitates the ease of preparation of the input file and makes it possible to use the application in any machine that can run Excel.     

松嫩草地牛粪中大型节肢动物种类组成及种群动态变化

研究并分析了松嫩草地牛粪中大型节肢动物种类组成及动态变化.结果表明,在草地牛粪中共调查到大型节肢动物7目20科43种,以鞘翅目、膜翅目和双翅目为主.依其食性不同,分为粪食性型(8科19种)、腐食性型(4科4种)、植食性型(4科6种)、捕食性型(5科11种)、杂食性型(2科5种)、尸食性型(1科1种)和寄生性型(1科1种).根据鞘翅目金龟总科中营粪食性型生活的粪甲虫对牛粪利用方式的不同,分为外生粪甲虫(6种)、内生粪甲虫(5种)、远生粪甲虫(2种)和偷窃寄生粪甲虫(1种).除了双顶嗡蜣螂,牛粪中大型节肢动物数量与鲜牛粪重量具有显著正相关关系(p＜0.01).粪食性型种类数和个体数量随鲜牛粪堆置时间的延长而迅速减少,7d后消失,其个体总数量与鲜牛粪堆积时间呈显著的负相关关系(p＜0.01),而与牛粪含水量呈显著正相关关系(p＜0.01),各种大型节肢动物因其食性不同在鲜牛粪中占据不同的生态位.鲜牛粪中大型节肢动物以粪食性型占绝对优势,而干牛粪中则以捕食性型和杂食性型为主.牛粪中大型节肢动物种群季节动态变化受温度、降水量与牛粪含水量影响,鲜牛粪中大型节肢动物优势种为直蜉金龟(69.25%)和肖秋家蝇与东方角蝇幼虫(25.12%).4、5、6月份和9月份,优势种为直蜉金龟,7月和8月份,优势种为蝇幼虫.     

A simple method for screening antimicrobial compounds with application to plant disease and fruit quality

Aims:  It is often difficult to extrapolate information from a Petri dish and apply it to commercial applications as with antimicrobial assays. Often large volumes of commodities are used for a virtually untested protocol and result in an unnecessary expenditure of time and materials. An intermediate method, where experimental compounds could be tested directly on a specific commodity without expending large quantities of either sample or compound, would be practical and economical.
Methods and Results:  A method was developed that employs the use of a small experimental chamber in which pieces of natural materials (e.g. fruit) can be tested with antimicrobial compounds. This method uses a type of autoclavable incubation chamber with a filter paper base, hydrating sponge pieces and a sterile glass sample platform. The chamber offers a sterile, controlled environment and can be manipulated to serve a number of studies.
Conclusion:  The chamber results are more analogous to what happens on whole fruit than the Petri dish.
Significance and Impact of the Study:  This method is presently used to screen for antimicrobial compounds and treatments needed to control serious economic pests compromising Florida's agriculture.     

河口盐沼植物对大型底栖动物群落的影响

通过对长江口崇明东滩盐沼海三棱燕草带大型底栖无脊椎动物进行取样调查,研究了不同盐沼底栖动物群落结构及其多样性特征,分析了盐沼植物群落特征与底栖动物群落的关系。研究发现。（1）沿着河口盐沼海拔梯度,从低位盐沼到高位盐沼,底栖动物群落结构及多样性具有明显的梯度变化;（2）盐沼植被与底栖动物群落有密切的关系,尤其是植株高度,地下部分生物量与底栖动物密度,Shannon-Weiner多样性指数,物种丰度的相关性最显著。（3）盐沼植被影响底栖动物群落,是由于植物的地下部分和地下部分结构导致盐沼生境结构复杂,增加了沉积物表层环境的结构异质性,使生境多样化,给底栖动物提供大量生活空间,（4）不同盐沼带海三陵蔗草群落的差异,提供了盐沼表层地貌的变化,这种变化及植物结构的复杂化,在这一些动物提供拓殖地的同时,也为底栖动物躲避捕食者提供了避护所;（5）盐沼植被可以改变口潮滩生境中的沉积环境,并通过消浪、缓流及调节有机质的输入动态和沉积作用而影响底栖动物群落的组成和结构。     

Application of response surface method to evaluate the cytotoxic potency of Ulva fasciata Delile,a marine macro alga

Bioprospecting of marine natural products has recently produced a substantial number of drug candidates. Ulva fasciata Delile, belonging to the family Ulvaceae, is a green marine macro alga that grows profusely on the coastal seashore of South India. In the present study, we investigated the in vitro cytotoxic potential of a methanolic extract of U.fasciata Delile (MEUF) using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay against human colon carcinoma (HT-29), human hepatocyte carcinoma (Hep-G2), and human breast carcinoma (MCF-7) cell lines. Response surface methodology (RSM) was applied using central-composite experimental design (CCD) to obtain optimum combined effect of concentration and cancer cells with highest cytotoxicity. The effect of concentration, cancer cell lines as independent variables on absorbance (OD), percent cell survival and percent cell inhibition as dependent variables was investigated. Maximum cytotoxic activity of MEUF was established for Hep-G2 with lowest OD or percent cell survival; highest percent cell inhibition with significant difference (p > 0.05) was compared to HT-29 and MCF-7.     

Global grass (Poaceae) success underpinned by traits facilitating colonization,persistence and habitat transformation

Poaceae (the grasses) is arguably the most successful plant family, in terms of its global occurrence in (almost) all ecosystems with angiosperms, its ecological dominance in many ecosystems, and high species richness. We suggest that the success of grasses is best understood in context of their capacity to colonize, persist, and transform environments (the “Viking syndrome”). This results from combining effective long‐distance dispersal, efficacious establishment biology, ecological flexibility, resilience to disturbance and the capacity to modify environments by changing the nature of fire and mammalian herbivory. We identify a diverse set of functional traits linked to dispersal, establishment and competitive abilities. Enhanced long‐distance dispersal is determined by anemochory, epizoochory and endozoochory and is facilitated via the spikelet (and especially the awned lemma) which functions as the dispersal unit. Establishment success could be a consequence of the precocious embryo and large starch reserves, which may underpin the extremely short generation times in grasses. Post‐establishment genetic bottlenecks may be mitigated by wind pollination and the widespread occurrence of polyploidy, in combination with gametic self‐incompatibility. The ecological competitiveness of grasses is corroborated by their dominance across the range of environmental extremes tolerated by angiosperms, facilitated by both C₃ and C₄ photosynthesis, well‐developed frost tolerance in several clades, and a sympodial growth form that enabled the evolution of both annual and long‐lived life forms. Finally, absence of investment in wood (except in bamboos), and the presence of persistent buds at or below ground level, provides tolerance of repeated defoliation (whether by fire, frost, drought or herbivores). Biotic modification of environments via feedbacks with herbivory or fire reinforce grass dominance leading to open ecosystems. Grasses can be both palatable and productive, fostering high biomass and diversity of mammalian herbivores. Many grasses have a suite of architectural and functional traits that facilitate frequent fire, including a tufted growth form, and tannin‐like substances in leaves which slow decomposition. We mapped these traits over the phylogeny of the Poales, spanning the grasses and their relatives, and demonstrated the accumulation of traits since monocots originated in the mid‐Cretaceous. Although the sympodial growth form is a monocot trait, tillering resulting in the tufted growth form most likely evolved within the grasses. Similarly, although an ovary apparently constructed of a single carpel evolved in the most recent grass ancestor, spikelets and the awned lemma dispersal units evolved within the grasses. Frost tolerance and C₄ photosynthesis evolved relatively late (late Palaeogene), and the last significant trait to evolve was probably the production of tannins, associated with pyrophytic savannas. This fits palaeobotanical data, suggesting several phases in the grass success story: from a late Cretaceous origin, to occasional tropical grassland patches in the later Palaeogene, to extensive C₃ grassy woodlands in the early–middle Miocene, to the dramatic expansion of the tropical C₄ grass savannas and grasslands in the Pliocene, and the C₃ steppe grasslands during the Pleistocene glacial periods. Modern grasslands depend heavily on strongly seasonal climates, making them sensitive to climate change.     

The effects of sex and season on the metal levels and proximate composition of red mullet (Mullus barbatus Linnaeus 1758) caught from the Middle Black Sea

The effects of seasonal and sexual differences on the levels of macro, trace element, and toxic metal levels in Mullus barbatus were investigated using the ICP-MS. The quantity relationships of macro elements were found as K>P>Na>Ca>Mg for male, P>K>Na>Ca>Mg in female; the quantity relationships of trace elements were determined as Fe>Zn>Mn>Mo>Se>Cu>Ni>Co in male, Fe>Zn>Mn>Se>Cu>Ni>Mo>Co in female; and the quantity relationship of toxic elements were found as As>Pb>Cd in both male and female. Macro, trace, and toxic metal levels showed no significant differences (p > .05) in terms of sexuality, but demonstrated seasonal differences (p > .05). Overall, the highest level of macro elements was determined in the autumn, while the high level of trace elements was measured in the winter. The As, Cd, and Pb levels in the muscle tissue of red mullet fish were higher than acceptable limits. However, when the Estimated Daily Intake (EDI) and Estimated Weekly Intake (EWI) of both toxic metals are considered, they appear to be below acceptable limits. As a result, it was determined that the red mullet had been contaminated with toxic metals (Cd and Pb) but their levels according to EDI and EWI were below the limit.