Climate change and tree genetic resource management: maintaining and enhancing the productivity and value of smallholder tropical agroforestry landscapes. A review     

Ian K. Dawson  Barbara Vinceti  John C. Weber  Henry Neufeldt  Joanne Russell  Ard G. Lengkeek  Antoine Kalinganire  Roeland Kindt  Jens-Peter B. Lilles?  Jim Roshetko  Ramni Jamnadass 《Agroforestry Systems》2011,81(1):67-78

Anthropogenic climate change has significant consequences for the sustainability and productivity of agroforestry ecosystems upon which millions of smallholders in the tropics depend and that provide valuable global services. We here consider the current state of knowledge of the impacts of climate change on tree genetic resources and implications for action in a smallholder setting. Required measures to respond to change include: (1) the facilitated translocation of environmentally-matched germplasm across appropriate geographic scales, (2) the elevation of effective population sizes of tree stands through the promotion of pollinators and other farm management interventions; and (3) the use of a wider range of ??plastic?? species and populations for planting. Key bottlenecks to response that are discussed here include limitations in the international exchange of tree seed and seedlings, and the absence of well-functioning delivery systems to provide smallholders with better-adapted planting material. Greater research on population-level environmental responses in indigenous tree species is important, and more studies of animal pollinators in farm landscapes are required. The development of well-functioning markets for new products that farmers can grow in order to mitigate and adapt to anthropogenic climate change must also consider genetic resource issues, as we describe.  相似文献   

Analysis of selected drug formulations for volatile nitrosamines     

B A Dawson  R C Lawrence 《Journal of the Association of Official Analytical Chemists》1987,70(3):554-556

A number of selected drug formulations on the Canadian market were analyzed for N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) content by using a gas chromatograph interfaced to a thermal energy analyzer (GC/TEA). Of the 34 formulations analyzed, NDMA was found in 21 at levels up to 12 ppb and NDEA was found in 11 at levels up to 0.6 ppb. In many cases, the drug entity in the formulation did not contain the precursors for the observed nitrosamines.  相似文献   

2,4-D metabolism: pathway of degradation of chlorocatechols by Arthrobacter sp     

Tiedje JM  Duxbury JM  Alexander M  Dawson JE 《Journal of agricultural and food chemistry》1969,17(5):1021-1026

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Liquid chromatographic determination of rotenone in fish, crayfish, mussels, and sediments   总被引：2，自引：0，他引：2  

V K Dawson  J L Allen 《Journal of the Association of Official Analytical Chemists》1988,71(6):1094-1096

An analytical procedure is described for determining residues of rotenone in fish muscle, fish offal, crayfish, freshwater mussels, and bottom sediments. Tissue samples were extracted with ethyl ether and extracts were cleaned up by gel permeation chromatography and silica gel chromatography. Sediment samples were extracted with methanol, acidified, partitioned into hexane, and cleaned up on a silica gel column. Rotenone residues were quantitated by liquid chromatography, using ultraviolet (295 nm) detection. Recoveries from sediment samples fortified with rotenone at 0.3 microgram/g were 80.8%, whereas recoveries from tissue samples fortified with 0.1 microgram/g ranged from 87.7 to 96.8%. Samples fortified with 0.3 microgram/g and stored at -10 degrees C for 6 months before analysis had recoveries ranging from 83.2 to 90.5%. Limits of detection were 0.025 microgram/g for sediments and 0.005 microgram/g for tissue samples.  相似文献   

Long-distance plant dispersal and habitat fragmentation: identifying conservation targets for spatial landscape planning under climate change   总被引：1，自引：0，他引：1  

Richard G. Pearson  Terence P. Dawson 《Biological conservation》2005,123(3):389-401

Climate change presents a potentially severe threat to biodiversity. Species will be required to disperse rapidly through fragmented landscapes in order to keep pace with the changing climate. An important challenge for conservation is therefore to manage landscapes so as to assist species in tracking the environmental conditions to which they are adapted. Here we develop a stochastic spatially explicit model to simulate plant dispersal across artificial fragmented landscapes. Based on certain assumptions as to the dispersal mechanism, we assess the impact that varying potential for rare long-distance dispersal (LDD) has on the ability to move over landscapes with differing spatial arrangements of suitable habitat (clumped versus fragmented). Simulations demonstrate how the relative importance of landscape structure in determining migration ability may decrease as the potential for LDD increases. Thus, if LDD is the principal mechanism by which rapid large-scale migrations are achieved, strategically planned networks of protected habitat may have a limited impact on rates of large-scale plant migrations. We relate our results to conventional principles for conservation planning and the geometric design of reserves, and demonstrate how reversal of these principles may maximise the potential for conservation under future climates. In particular, we caution against the justification of large-scale corridors on grounds of climate change since migration along corridors by standard dispersal mechanisms is unlikely to keep pace with projected change for many species. An improved understanding of the dispersal mechanisms by which species achieve rapid migrations, and the way that these processes are affected by patterns of landscape fragmentation, will be important to inform future conservation strategies.  相似文献   

Effects of feeding different concentration and forms of zinc on the performance and tissue mineral status of broiler chicks     

Ao T  Pierce JL  Pescatore AJ  Cantor AH  Dawson KA  Ford MJ  Paul M 《British poultry science》2011,52(4):466-471

1. Two studies were conducted to investigate the effect of feeding different concentration and forms of zinc (Zn) on the performance and tibia Zn status of broiler chicks.

2. In Experiment 1, chicks fed on the control or the diet supplemented with 12?mg of Zn as sulphate had lower feed intake, weight gain and tibia Zn content than other treatment groups. Chicks given 12 and 24?mg of organic Zn in starter and grower phases, respectively, had the same performance and tibia Zn content as those fed 40?mg of Zn as sulphate and the same performance but higher tibia Zn content than those given 12?mg of Zn as organic over the 42?d.

3. In Experiment 2, chicks given 24?mg organic Zn had greater weight gain than chicks fed on the other treatment diets in the starter period. Chicks fed on the control diet had lower tibia Zn content than chicks fed other treatment diets. Chicks given 80?mg Zn as sulphate had higher tibia Zn content than chicks fed the other treatment diets except those given 40?mg of Zn as sulphate.

4. The results from these trials indicate that feeding lower concentration of Zn as organic form may better promote the growth performance of broiler chicks.  相似文献   

Reference intervals for hematologic and coagulation tests in adult alpacas (Vicugna pacos)     

Dawson DR  DeFrancisco RJ  Stokol T 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2011,40(4):504-512

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Seed exchanges,a key to analyze crop diversity dynamics in farmer-led on-farm conservation     

Mathieu Thomas  Julie C. Dawson  Isabelle Goldringer  Christophe Bonneuil 《Genetic Resources and Crop Evolution》2011,58(3):321-338

Sustainable management of genetic resources is a crucial issue in the global context of food security. On-farm conservation is now widely acknowledged as a relevant strategy to reach this goal because it maintains evolutionary forces within and between the different components of the agricultural system. Seed exchanges between farmers play a key role in this process but are complicated to study over different agricultural contexts. This review begins by illustrating how interdisciplinary approaches combining ethnobotany and genetics helps provide a detailed analysis of the role of social and genetic dynamic interactions related to seed exchanges in traditional farming systems with farmer-led on-farm conservation. Secondly, the evolution of crop genetic diversity management is described in the context of industrialized farming systems. We follow the evolution of crop biodiversity perception by involved actors using a socio-historical perspective. After the agricultural shift from a traditional to a productivist model, recent social developments such as citizen science and participatory research movements are emerging and are strongly concerned by the question of biodiversity. These emerging trends which recognize and value seed exchanges between farmers show similarities to farmer-to-farmer seed exchanges in traditional farming systems. To what extent are these systems comparable? To fully benefit from studies in both traditional and industrialized contexts, it will be critical to develop an interdisciplinary framework to rigorously compare seed exchange systems and more generally farmer-led on-farm conservation strategies in diverse agricultural systems.  相似文献   

The use of a delayed hypersensitivity test and long-acting oxytetracycline in a flock affected with ovine enzootic abortion     

A J Wilsmore  M Dawson  M J Arthur  D C Davies 《The British veterinary journal》1986,142(6):557-561

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Laparoscopic Insemination of Seasonally Anoestrous Ewes by a Simplified Method under Field Conditions     

B Kühholzer  U Besenfelder  S Müller  HD Reichenbach  G Brem 《Reproduction in domestic animals》1997,32(6):309-312

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