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排序方式: 共有113条查询结果,搜索用时 15 毫秒
21.
Jocelyn R Holt Lina Bernaola Kadie E Britt Chirs McCullough Morgan Roth Jennie Wagner Max Ragozzino Leslie Aviles Zhilin Li Forest Huval Manoj Pandey Benjamin W Lee Megan Asche Abigail Hayes Abigail Cohen Adrian Marshall Hannah E Quellhorst Rachel V Wilkins Valerie Nguyen Jacqueline Maille Rachel K Skinner John J Ternest Sarah Anderson Scott W Gula Kayleigh Hauri Julius Eason Megan Mulcahy Scott Lee James Michael Villegas Patricia Shorter 《Journal of insect science (Online)》2020,20(5)
Every year, the Student Debates Subcommittee (SDS) of the Student Affairs Committee (SAC) for the annual Entomological Society of America (ESA) meeting organizes the Student Debates. This year, the SAC selected topics based on their synergistic effect or ability to ignite exponential positive change when addressed as a whole. For the 2019 Student Debates, the SAC SDS identified these topic areas for teams to debate and unbiased introduction speakers to address: 1) how to better communicate science to engage the public, particularly in the area of integrated pest management (IPM), 2) the influential impacts of climate change on agriculturally and medically relevant insect pests, and 3) sustainable agriculture techniques that promote the use of IPM to promote food security. Three unbiased introduction speakers gave a foundation for our audience to understand each debate topic, while each of six debate teams provided a strong case to support their stance or perspective on a topic. Debate teams submitted for a competitive spot for the annual ESA Student Debates and trained for the better part of a year to showcase their talents in presenting logical arguments for a particular topic. Both the debate teams and unbiased introduction speakers provided their insight toward a better understanding of the complexities of each topic and established a foundation to delve further into the topics of science advocacy and communication, climate change, and the many facets of integrated pest management. 相似文献
22.
Direct observation of the detailed conformational fluctuations of a single protein molecule en route to its folded state has so far been realized only in silico. We have used single-molecule force spectroscopy to study the folding transitions of single calmodulin molecules. High-resolution optical tweezers assays in combination with hidden Markov analysis reveal a complex network of on- and off-pathway intermediates. Cooperative and anticooperative interactions across domain boundaries can be observed directly. The folding network involves four intermediates. Two off-pathway intermediates exhibit non-native interdomain interactions and compete with the ultrafast productive folding pathway. 相似文献
23.
A diameter increment model is developed and evaluated for individual trees of ponderosa pine throughout the species range in the United States using a multilevel linear mixed model. Stochastic variability is broken down among period, locale, plot, tree and within-tree components. Covariates acting at tree and stand level, as breast height diameter, density, site index, and competition indices are included in the model as fixed effects in order to explain residual variability. The data set used in this study came from long-term permanent research plots in even-aged, pure stands both planted and of natural origin. The data base consists of six levels-of-growing stock studies supplemented by initial spacing and other permanent-plot thinning studies for a total of 310 plots, 34,263 trees and 153,854 observations. Regression analysis is the preferred technique used in growth and yield modeling in forestry. We choose the mixed effects models instead of the regression analysis approach because it allows for proper treatment of error terms in a repeated measures analysis framework. Regional growth and yield models exist for ponderosa pine. However, data collection and analysis procedures differ. As a result, comparisons of growth responses that may be due to geographic variation of the species are not possible. Our goal is to present a single distance-independent diameter increment model applicable throughout the geographic range of ponderosa pine in the United States and by using only data from long-term permanent plots on sites capable of the productivity estimated by Meyer [Meyer, W.H., 1938. Yield of Even-Aged Stands of Ponderosa Pine. US Department of Agriculture Technical Bulletin 630]. 相似文献
24.
Ane T Laugen Georg H Engelhard Rebecca Whitlock Robert Arlinghaus Dorothy J Dankel Erin S Dunlop Anne M Eikeset Katja Enberg Christian Jørgensen Shuichi Matsumura Sébastien Nusslé Davnah Urbach Loїc Baulier David S Boukal Bruno Ernande Fiona D Johnston Fabian Mollet Heidi Pardoe Nina O Therkildsen Silva Uusi‐Heikkilä Anssi Vainikka Mikko Heino Adriaan D Rijnsdorp Ulf Dieckmann 《Fish and Fisheries》2014,15(1):65-96
Managing fisheries resources to maintain healthy ecosystems is one of the main goals of the ecosystem approach to fisheries (EAF). While a number of international treaties call for the implementation of EAF, there are still gaps in the underlying methodology. One aspect that has received substantial scientific attention recently is fisheries‐induced evolution (FIE). Increasing evidence indicates that intensive fishing has the potential to exert strong directional selection on life‐history traits, behaviour, physiology, and morphology of exploited fish. Of particular concern is that reversing evolutionary responses to fishing can be much more difficult than reversing demographic or phenotypically plastic responses. Furthermore, like climate change, multiple agents cause FIE, with effects accumulating over time. Consequently, FIE may alter the utility derived from fish stocks, which in turn can modify the monetary value living aquatic resources provide to society. Quantifying and predicting the evolutionary effects of fishing is therefore important for both ecological and economic reasons. An important reason this is not happening is the lack of an appropriate assessment framework. We therefore describe the evolutionary impact assessment (EvoIA) as a structured approach for assessing the evolutionary consequences of fishing and evaluating the predicted evolutionary outcomes of alternative management options. EvoIA can contribute to EAF by clarifying how evolution may alter stock properties and ecological relations, support the precautionary approach to fisheries management by addressing a previously overlooked source of uncertainty and risk, and thus contribute to sustainable fisheries. 相似文献
25.
Recruitment dynamics are challenging to assess or predict because of the many underlying drivers that vary in their relevance over time and space. Stock size, demographic and trait composition, condition and distribution of spawning fish and the spatio‐temporal dynamics of trophic and environmental interactions all influence recruitment processes. Exploring common patterns among stocks and linking them to potential drivers may therefore provide insights into key mechanisms of recruitment dynamics. Here, we analysed stock‐recruitment data of 64 stocks from the north‐east Atlantic Ocean for common trends in variation and synchrony among stocks using correlation, cluster and dynamic factor analyses. We tested common trends in recruitment success for relationships with large‐scale environmental processes as well as stock state indicators, and we explored links between recruitment success and demographic, environmental and ecological variables for a subset of individual stocks. The results revealed few statistically significant correlations between stocks but showed that underlying common trends in recruitment success are linked to environmental indices and management indicators. Statistical analyses confirmed previously suggested relationships of environmental–ecological factors such as the subpolar gyre and Norwegian coastal current with specific stocks, and indicated a large relevance of spawning stock biomass and demographics, as well as predation, whereas other suggested relationships were not supported by the data. Our study shows that despite persistent challenges in determining drivers of recruitment due to poor data quality and unclear mechanisms, combining different data analysis techniques can improve our understanding of recruitment dynamics in fish stocks. 相似文献
26.
27.
Fabian Runge Marco Thines 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(2):147-156
Oomycetes contain some of the economically most important pathogens of flowering plants. Most have a rather narrow host range,
often being restricted to single host species. In downy mildews and other obligate biotrophic plant parasites, like powdery
mildews and rusts, delimitating species on grounds of morphological characteristics is often hardly possible and thus often
based on only subtle differences. This has led to the widespread application of a broad species concept for these organisms.
Consequently, despite the fact that morphological differences were reported for Pseudoperonospora cubensis from different host species, the corresponding new pathogen species were not accepted as being independent, and the host
range of Pseudoperonospora cubensis is reported to encompass more than 50 host species in the Cucurbitaceae in temperate to tropical climates. However, recent
studies have reported narrow host ranges for other downy mildew genera and advocated a narrow species concept. Here, we report
successful colonisation of five different tribes of the Cucurbitaceae by a strain of Pseudoperonospora cubensis and demonstrate that the host matrix has a major impact on the morphology of the pathogen. On the basis of five morphological
criteria significant differences could be found for all hosts. These differences were more pronounced in phylogenetically
unrelated than in related hosts. Our results provide evidence for a broad host range of Pseudoperonospora cubensis and demonstrate that species delimitation based on morphological characters is not feasible in Pseudoperonospora on Cucurbitaceae. Also in other biotrophic plant pathogens, the situation could be similar, thus necessitating thorough morphological,
molecular phylogenetic and cross inoculation experiments for species recognition. 相似文献
28.
S R van Amstel M Henton M A Witcomb B Fabian P Vervoort 《The Onderstepoort journal of veterinary research》1987,54(4):551-552
Bacterial isolations from tracheal and bronchial washes obtained with the aid of a fibreoptic endoscope were carried out over a 7 month period in a feedlot on calves suffering from acute pneumonic pasteurellosis. Pasteurella haemolytica and Pseudomonas aeruginosa represented the majority of isolates. Antibiotic sensitivities of the Pasteurella isolates are reported on. 相似文献
29.
Gabriela Palomino Fabian Contreras Adolfo Sanchez Carlos Rosas 《Journal of the World Aquaculture Society》2001,32(2):167-176
This present study was designed to investigate the effects of stocking density and water exchange on the growth rate, survival and performance index of L. setiferus postlarvae under controlled laboratory conditions. The experiment was done with postlarvae (PL10 to PL40) at densities of 50, 150, 250 and 350 shrimp/m2 and various different water exchanges rate per day (0, 6, 12 and 18%). The maximum growth rate was obtained for shrimp with 12% water exchange per day at all densities. A reduction of the maximum growth rate was observed in relation to density with the highest values in shrimp stocked in a density of 50 and 150 shrimp/m2 (mean value of 0.53 mg/d) and the lowest in shrimp stocked in a density of 350 shrimp/m2 (0.24 mg/d). The multiple regression equation obtained to relate performance index (growth rate* survival : PI), shrimp density (X1 ) and water exchange (X2 ) was: PI = 0.31 + (0.001) X1 + 0.039 X2 + 2.28 × 10−6 X1 2 + (−0.0017) X2 2 + (0.000026)X1 X2 , R 2 = 0.78; P > 0.03. According to this equation the optimum shrimp density-water exchange comhination was between 5 to 12% of water exchange at stocking density of between 50 and 150 shrimp/m2 . Salinity, ammonia-N and nitrite-N increased according to the time spent in tanks without water exchange. With no (0%) water exchange, water quality parameters measured were outside the optimum for L. setiferus postlarvae. The use of optimum density and water exchange in a nursery system for L. setiferus with optimum variables established is proposed. 相似文献
30.