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Sperm competition and the level of polyandry in a bushcricket with large nuptial gifts 总被引:4,自引:0,他引:4
Leon?R.?HockhamEmail author Jefferson?A.?Graves Michael?G.?Ritchie 《Behavioral ecology and sociobiology》2004,57(2):149-154
Variation in paternity due to sperm competition or post-copulatory female choice has a major influence on animal mating system evolution and on the levels of genetic variability in natural populations. However, there are relatively few studies comparing the outcome of sperm-competition experiments in the laboratory with natural variation in polyandry among families from the field. In the bushcricket Ephippiger ephippiger, females mate multiply, and the males provide them with a large, nutritious, and probably expensive, donation at mating. We examined paternity in a series of laboratory matings, where females mated with two males, and amongst a series of families collected from a natural population. In the laboratory, paternity was highly bimodally distributed: 24% of families had offspring fathered by the first male to mate, 68% by the second male (in only 8% was paternity shared). In the field, paternity was more mixed: only 27% of families had a single father, 14% had more than two fathers, whilst 59% had two fathers. While unsuccessful matings may contribute to the highly biased paternity in the laboratory, they cannot fully explain the high incidence of complete P2 families. Nonrandom sperm utilisation is therefore likely. Greater sperm mixing in the field probably results from females mating with more males, but the distribution of paternity also reflects an active process of nonrandom sperm utilisation. Confidence of paternity due to last male advantage may be relatively high in this species, and therefore may have facilitated the evolution of the large spermatophore in E. ephippiger.Communicated by D. Gwynne 相似文献
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Ai Leon Kazunori Kohyama Kazuyuki Yagi Yusuke Takata Hiroshi Obara 《Mitigation and Adaptation Strategies for Global Change》2017,22(1):85-98
Cultivated wetland rice fields are a source of methane (CH4) emissions. To estimate CH4 emissions and develop policies to reduce such emissions, information on water management at the farm level is crucial. It is known that farmers implement midseason drainage (MD) to increase rice yields and save water. However, little is known about whether MD is carried out in soils where CH4 emissions are high and how part-time status will influence management. The objective of this study is to identify factors that determine MD implementation using a binomial logistic regression model based on a farm-level survey in Japan and to indicate possible changes in estimates of CH4 emissions, accounting for current water management practices. The implementation rates were significantly higher where the soil types were classified as having the potential for high CH4 emissions. Under current water management practices, the duration of MD and the percentage of continuous flooding were 5 to 7 days longer and approximately 7 % higher, respectively, than the values used by the Greenhouse Gas Inventory Office of Japan, which in turn are used to report greenhouse gas emissions to the United Nations Framework Convention on Climate Change. By accounting for current water conditions with the Tier 2 method, this study indicates that national estimates of CH4 emissions from rice straw application areas could be lowered by 12.7 %. These results may contribute to the development of a mitigation policy that will help to further reduce CH4 emissions. 相似文献
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Leon H.H. Tan 《Local Environment》2013,18(6):529-539
Community gardens offer a space that allows facilitation of leisure activities, encourages interaction within different factions in a community and helps forge a sense of belonging towards the overall community. Using the case study of “Community in Bloom” (CIB) programme initiated by the National Parks Board of Singapore, this article highlights how such community gardens are also viewed by some as exclusionary spaces due to their close links with government apparatus. More broadly, it argues that a constrained civic activism not only affects the extent to which these gardens can forge communal bonds, but they also challenge their integral spirit. Despite promising signs of politically opening up in the early 2000s, the soft authoritarianism of the Singaporean state continues to be wary of non-governmental sanctioned community projects and civic activism. This attitude may prove to be resilient in the foreseeable future, thereby preventing the “CIB” programme from truly blossoming. 相似文献
45.
Inge F. Goldstein Leon Landovitz Gloria Block 《Journal of the Air & Waste Management Association (1995)》2013,63(2):148-152
Some preliminary analyses of data selected from three years of smoke shade and sulfur dioxide measurements from the forty air monitoring stations in New York City are presented. The purpose of these analyses is to investigate the spatial-temporal variation in concentration of these pollutants throughout the five boroughs of the city. Air pollution health effects studies in New York City have often used city-wide daily morbidity or mortality statistics and related them to air pollution levels obtained from a single monitoring station. The question of whether readings at one station in New York City can adequately represent the air pollution exposure for the population in the five boroughs is examined in this paper. Some samples of correlation matrices of daily pollution averages obtained from the forty air monitoring stations are presented to illustrate the day-to-day variation in pollution in various sections of New York City. It was found that interstation correlations are not high enough to justify the use of one central pollution measuring station as representative of a large metropolitan area. Sulfur dioxide correlates better between stations than smoke shade; this may reflect the different nature and spatial distribution of sources of the two pollutants. Close proximity of stations, or the fact that they were at similar heights above street or sea level did not necessarily lead to higher correlation coefficients. 相似文献
46.
Leon J. Dolislager 《Journal of the Air & Waste Management Association (1995)》2013,63(7):775-783
Abstract The U.S. Environmental Protection Agency (EPA) mandated the use of oxygenated gasoline beginning in the winter of 1992 to reduce the unhealthful carbon monoxide concentrations in many urban areas. The California Air Resources Board (CARB), weighing the potential effects of the program on other pollutants, implemented a modified version of the federal wintertime oxygenated fuels program. In California, the number of violations of the carbon monoxide air quality standard during the three winters associated with the program was dramatically lower than during any winter prior to the program. Because meteorological conditions during the program were very favorable for dispersion of pollutants, any analysis of the impacts of the program must account for the influence of variable meteorological conditions. Analyses of ambient pollutant concentrations suggest that most of the air quality improvement was due to increased atmospheric dispersion. The analyses presented here account for the large influence of meteorology on ambient concentrations and indicate that California’s modified oxygenated fuels program was responsible for an approximately 5–10% reduction in mean ambient carbon monoxide concentrations, depending on the statistical approach used. 相似文献
47.
Ottewill GA Reade GW Campbell SA de Leon CP Walsh FC 《Journal of environmental monitoring : JEM》2005,7(10):943-949
An environmental electrochemistry workshop program on metal ion removal is described. The program was designed for undergraduate students in chemistry, chemical engineering or environmental science and teaches environmental electrochemistry through a combination of hands-on experiments, understanding of research concepts, completion of project reports and in class discussion. The students are encouraged to quantitatively describe the performance of the electrochemical cells (containing 2-D and 3-D carbon cathodes) and to consider the advantages and shortcomings of electrochemical routes to environmental treatment. 相似文献
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