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51.
Patterns of courtship behavior and ejaculate characteristics in male red-winged blackbirds 总被引:1,自引:0,他引:1
David F. Westneat Lisa A. McGraw Jennifer M. Fraterrigo Tim R. Birkhead F. Fletcher 《Behavioral ecology and sociobiology》1998,43(3):161-171
Sperm competition in birds is likely to have important effects on the behavior and physiology of reproduction in both sexes.
For males, such competition should select for large sperm reserves and behavioral adjustment of copulation when reserves are
low. We investigated both these possibilities in free-living red-winged blackbirds (Agelaius phoeniceus), a highly polygynous species with apparently strong sperm competition. We found that the recent copulatory behavior of males
did not affect the propensity to copulate with a model female. Ejaculates collected from individual males at 1-h intervals
showed no evidence of sperm depletion, yet repeated ejaculates collected less than 10 min apart did. Male ejaculate size was
significantly larger if it was the first one of the day (i.e., after an overnight rest). The average ejaculate size was 12.5
(±12.5 SD) million sperm. Males captured during the breeding season had an average of 111.7 (±52.8) million sperm stored in
their seminal glomera. Because males average a peak copulation rate of six per female per day, in one day a male might utilize
all the sperm in his seminal glomera if more than two females on his territory are fertilizable. We hypothesize that polygyny
and sperm competition in this species have combined to select for rapid replenishment of the seminal glomera throughout the
day, in contrast to other species that have been studied. Testis size and sperm reserves of male red-winged blackbirds are
intermediate between monogamous species and species with intense sperm competition. Several possible explanations for this
are discussed.
Received: 21 October 1997 / Accepted after revision: 15 February 1998 相似文献
52.
There has been a considerable debate about the individual and organizational benefits of competition. Adopting a person–environment fit perspective, this research examined the influence of competition as an interaction between trait competitiveness and competitive climate. Using a sample of information technology workers, competitive climate was considered as both an individual level variable and a workgroup variable. Results show that the effect of competitive climate depended on trait competitiveness and the level at which climate was assessed for four of the outcomes assessed: job satisfaction, organizational commitment, job dedication, and supervisor‐rated task performance. In general, the effect of competitive climate was more negative for individuals lower in trait competitiveness. Competitive psychological climate was associated with greater stress regardless of the level of trait competitiveness but was not directly related to self‐rated task performance. Findings suggest that managers should be cautious in encouraging competitive climate. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
53.
Fletcher David Dillingham Peter W. Zeng Jiaxu 《Environmental and Ecological Statistics》2019,26(4):367-384
Environmental and Ecological Statistics - Model averaging is commonly used to allow for model uncertainty in parameter estimation. As well as providing a point estimate that is a natural compromise... 相似文献
54.
A monitoring and evaluation program was undertaken, involving six different styles of evaluation to determine whether a low-cost, eight month education campaign that operated within a small commercial district was successful at changing people's behavior and reducing stormwater litter loads. This project also tested newly developed guidelines for monitoring and evaluating all types of non-structural stormwater quality best management practices (BMPs). The project evaluated: the extent and quality of the campaign's implementation; the degree to which it changed the awareness, attitudes, self-reported behavior and actual behavior of merchants and the public; and the nature of changes in stormwater litter loads. Overall, the education campaign produced mixed results, with the net result being modestly positive. Specifically, it was: unsuccessful at significantly influencing the knowledge or attitudes of merchants or the public; modestly successful at influencing the behavior of merchants and the public; and modestly successful at reducing litter loads in stormwater. At a theoretical level, the project highlights how using different 'styles' of BMP evaluation can help to build a more complete picture of a BMP's performance. At a practical level, the project helped to improve the monitoring and evaluation guidelines and produced evidence-based design guidelines for future campaigns that aim to reduce littering in commercial areas. 相似文献
55.
Cameron S. Fletcher Alicia N. Rambaldi Felix Lipkin Ryan R. J. McAllister 《Regional Environmental Change》2016,16(4):1023-1034
The distribution of risk of coastal inundation, and the potential benefits of adapting to protect against inundation, vary greatly both within and between coastal communities. This diversity is a result of physical factors, such as the risk of storm surge, sea level rise projections, and the topography of the landscape, as well as socio-economic factors, such as the level of development, and the capacity within the community to adapt. Despite this strong local variation, various communities share common characteristics that constrain or enable different adaptation options in different situations. Understanding these drivers is likely to be important in engaging coastal communities in the discussion around adaptation and may provide new insights into which adaptation options are suitable for each of our at-risk coastal communities. We performed a property-level analysis of 6 suburb-sized case studies distributed along the coast of Queensland, Australia. We assessed the potential economic costs of inundation events now and in the future under sea level rise projections, and the potential avoided costs following adaptation to protect against inundation. We went beyond this to estimate the distribution of risk in each community and compared the potential costs of adaptation with the capacity of the community to pay for their implementation. We used these insights to propose a typology of coastal communities based on their exposure to total inundation risk, the distribution of that risk within the community, and their capacity to adapt. 相似文献
56.
Most water management studies concentrate on the inter-temporal allocation problem or, more recently, spatial dynamics - but not both. While early spatial-temporal studies focused on the allocation of water quantity, this paper presents an approach to water quality analysis that incorporates both spatial and temporal dynamics in a watershed framework. The acid mine drainage (AMD) problem in the Cheat River watershed of West Virginia, USA, serves as a case study and provides an opportunity to test the modeling approach developed. The empirical models are written in General Algebraic Modeling System (GAMS) and solved using the CPLEX mixed integer programming package. The results suggest that available investments should be concentrated in heavily impaired stream segments. The model can be used to assess the economic implications of alternative watershed Total Maximum Daily Load (TMDL) implementation or other management strategies. 相似文献
57.
Influence of plant growth stage and season on the release of root phenolics by mulberry as related to development of phytoremediation technology 总被引:1,自引:0,他引:1
The phenolics released by red mulberry (Morus rubra L.) roots at different growth stages within a season were quantified and the makeup of phenols analyzed by reverse-phase high performance liquid chromatography (RP-HPLC). The data show that total phenols released into the soil solution increased continuously from an early vegetative stage to leaf senescence, indicating their accumulation in the rhizosphere. From the RP-HPLC analysis of the butanol-extractable phenolics at various growth stages, there appears to be a massive release of an assortment of less polar phenolics into the rhizosphere at the end of the season accompanying leaf senescence. The rhizosphere phenolics may create an environment suitable for the biodegradation of recalcitrant environmental pollutants, by selectively fostering the growth of some, while inhibiting the growth of other microbes. 相似文献
58.
59.
60.
A. Azapagic Z. Chalabi T. Fletcher C. Grundy M. Jones G. Leonardi O. Osammor V. Sharifi J. Swithenbank A. Tiwary S. Vardoulakis 《Process Safety and Environmental Protection》2013,91(6):508-520
This paper presents a new decision-support methodology and software tool for sustainable management of urban pollution. A number of different methods and tools are integrated within the same platform, including GIS, LCA, fate and transport modelling, health impact assessment and multi-criteria decision analysis. The application of the framework is illustrated on a case study which investigates the environmental and health impacts of pollution arising from different industrial, domestic and transport sources in a city. The example city chosen for the study is Sheffield, UK, and the main pollutants considered are NOx, SO2 and PM10. The results suggest that the absence of the current large industrial sources in the city would lead to a 90% reduction of the SO2 and 70% of the NO2 ground concentrations, consequently preventing 27 deaths and 18 respiratory hospital admissions per annum for a population of 500,000. Based on the total annual mortality and hospital admissions in Sheffield for the year of the assessment, this means that 0.53% of premature deaths and 0.49% of respiratory hospital admissions would be prevented by the estimated reduction in air pollution. 相似文献