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71.
72.
Tug-of-war over reproduction in a cooperatively breeding cichlid 总被引:1,自引:0,他引:1
In group-living animals, dominants may suppress subordinate reproduction directly and indirectly, thereby skewing reproduction
in their favour. In this study, we show experimentally that this ability (‘power’) is influenced by resource distribution
and the body size difference between unrelated dominants and subordinates in the cichlid Neolamprologus pulcher. Reproduction was strongly skewed towards the dominant female, due to these females producing more and larger clutches and
those clutches surviving egg eating better than those of subordinate females, but was not so when subordinates defended a
patch. If breeding shelters were provided in two patches, subordinate females were more likely to exclusively defend a patch
against the dominant female and breed, compared to when the same breeding resource was provided in one patch. Relatively large
subordinate females were more likely to defend a patch and reproduce. Females also directly interfered with each other’s reproduction
by eating the competitors’ eggs, at which dominants were more successful. Although dominant females benefited from subordinate
females due to alloparental care and an increase in egg mass, they also showed costs due to reduced growth in the presence
of subordinates. The results support the view that the dominant’s power to control subordinate reproduction determines reproductive
partitioning, in agreement with the predictions from tug-of-war models of reproductive skew. 相似文献
73.
Warish Ahmed Qian Zhang Satoshi Ishii Kerry Hamilton Charles Haas 《Environmental monitoring and assessment》2018,190(2):105
Potable and non-potable uses of roof-harvested rainwater (RHRW) are increasing due to water shortages. To protect human health risks, it is important to identify and quantify disease-causing pathogens in RHRW so that appropriate treatment options can be implemented. We used a microfluidic quantitative PCR (MFQPCR) system for the quantitative detection of a wide array of fecal indicator bacteria (FIB) and pathogens in RHRW tank samples along with culturable FIB and conventional qPCR analysis of selected pathogens. Among the nine pathogenic bacteria and their associated genes tested with the MFQPCR, 4.86 and 2.77% samples were positive for Legionella pneumophila and Shigella spp., respectively. The remaining seven pathogens were absent. MFQPCR and conventional qPCR results showed good agreement. Therefore, direct pathogen quantification by MFQPCR systems may be advantageous for circumstances where a thorough microbial analysis is required to assess the public health risks from multiple pathogens that occur simultaneously in the target water source. 相似文献
74.
Brian Anderson Bryn Phillips John Hunt Katie Siegler Jennifer Voorhees Kelly Smalling Kathy Kuivila Mary Hamilton J. Ananda Ranasinghe Ron Tjeerdema 《Environmental monitoring and assessment》2014,186(3):1801-1814
Recent and past studies have documented the prevalence of pyrethroid and organophosphate pesticides in urban and agricultural watersheds in California. While toxic concentrations of these pesticides have been found in freshwater systems, there has been little research into their impacts in marine receiving waters. Our study investigated pesticide impacts in the Santa Maria River estuary, which provides critical habitat to numerous aquatic, terrestrial, and avian species on the central California coast. Runoff from irrigated agriculture constitutes a significant portion of Santa Maria River flow during most of the year, and a number of studies have documented pesticide occurrence and biological impacts in this watershed. Our study extended into the Santa Maria watershed coastal zone and measured pesticide concentrations throughout the estuary, including the water column and sediments. Biological effects were measured at the organism and community levels. Results of this study suggest the Santa Maria River estuary is impacted by current-use pesticides. The majority of water samples were highly toxic to invertebrates (Ceriodaphnia dubia and Hyalella azteca), and chemistry evidence suggests toxicity was associated with the organophosphate pesticide chlorpyrifos, pyrethroid pesticides, or mixtures of both classes of pesticides. A high percentage of sediment samples were also toxic in this estuary, and sediment toxicity occurred when mixtures of chlorpyrifos and pyrethroid pesticides exceeded established toxicity thresholds. Based on a Relative Benthic Index, Santa Maria estuary stations where benthic macroinvertebrate communities were assessed were degraded. Impacts in the Santa Maria River estuary were likely due to the proximity of this system to Orcutt Creek, the tributary which accounts for most of the flow to the lower Santa Maria River. Water and sediment samples from Orcutt Creek were highly toxic to invertebrates due to mixtures of the same pesticides measured in the estuary. This study suggests that the same pyrethroid and organophosphate pesticides that have been shown to cause water and sediment toxicity in urban and agriculture water bodies throughout California, have the potential to affect estuarine habitats. The results establish baseline data in the Santa Maria River estuary to allow evaluation of ecosystem improvement as management initiatives to reduce pesticide runoff are implemented in this watershed. 相似文献
75.
Youngchul Byun Ian P. Hamilton Xin Tu Dong Nam Shin 《Environmental science and pollution research international》2014,21(13):8052-8058
This study examines gaseous chlorinated species generated from the reaction of sulfur dioxide (SO2) with sodium chlorite powder (NaClO2(s)) to obtain insight into the propensity of this process to enhance NO and Hg0 oxidation. A packed bed reactor containing NaClO2(s) was used and the reaction temperature was set to 130 °C. Initially, we determined that the presence of SO2 enhances the oxidation of NO and Hg0 by reaction with NaClO2(s). We then introduced NO2 into the gas mixture as a radical scavenger and determined that the chlorinated species generated by the reaction of SO2 with NaClO2(s) are OClO, Cl, ClO, and Cl2. Based on these results, we suggest that such gaseous chlorinated ones are responsible for the enhancement of NO and Hg0 oxidation. 相似文献
76.
Tony J. Ward Raymond F. Hamilton Jr. Garon C. Smith 《Journal of the Air & Waste Management Association (1995)》2013,63(7):1007-1013
Abstract The city of Missoula is located in a high mountain valley (elevation 3200 ft) in western Montana and contains one of the largest populations in the entire Rocky Mountain Region completely enclosed by mountains. During the 2000/2001 Missoula Valley Sampling Program, ambient levels of 61 semivolatile organic compounds (SVOCs) and 54 volatile organic compounds (VOCs) were originally quantified before refining the analytical program to 28 of the most prominent SVOCs and VOCs found in the Missoula Valley airshed. These compounds were measured over 24-hr periods at two locations throughout an entire year. This study provides the first, comprehensive appraisal of the levels of SVOCs and VOCs measured simultaneously throughout all four seasons at two locations in the Missoula Valley, including those levels measured during the 2000 Montana wildfire season. Generally, SVOC levels were comparable between both sides of the Missoula Valley. However, there were nearly double the amount of VOCs measured at the more urban Boyd Park site compared with the rural Frenchtown sampling site, a result of the greater number of automobiles on the eastern side of the Valley. SVOCs and VOCs were measured at their highest levels of the sampling program during the winter. Forest fire smoke samples collected during the summer of 2000 showed significant increases in SVOC phenolic compounds, including phenol, 2-methylphenol, 4-methylphenol, and 2,4-dimethylphenol. Although there were modest increases in some of the other SVOCs and VOCs measured during the fire season, none of the increases were as dramatic as the phenolics. 相似文献
77.
Andrew J. McElrone Jason G. Hamilton Mihai Aldea Evan H. DeLucia 《Environmental pollution (Barking, Essex : 1987)》2010,158(1):108-114
Atmospheric CO2 concentrations are predicted to double within the next century and alter climate regimes, yet the extent that these changes will affect plant diseases remains unclear. In this study conducted over five years, we assessed how elevated CO2 and interannual climatic variability affect Cercospora leaf spot diseases of two deciduous trees. Climatic data varied considerably between the five years and altered disease expression. Disease incidence and severity for both species were greater in years with above average rainfall. In years with above average temperatures, disease incidence for Liquidambar styraciflua was decreased significantly. When significant changes did occur, disease incidence and severity always increased under elevated CO2. Chlorophyll fluorescence imaging of leaves revealed that any visible increase in disease severity induced by elevated CO2 was mitigated by higher photosynthetic efficiency in the remaining undamaged leaf tissue and in a halo surrounding lesions. 相似文献
78.
人群感知是气候变化适应行为形成的重要信息基础,基于对中国北方草地草甸草原、典型草原、荒漠草原、草原化荒漠、沙地、农牧交错带等地区1292个牧户的问卷访谈,分2轮调查研究了不同草地类型地区牧民对气候变化的感知,与气候实值比较分析,并研究了牧民气候变化感知的偏差途径,结果表明:1980~2009年间研究区温度变化倾向率为0.63℃/10a(P0.05);温度较强的趋势性与牧民对其感知的分歧存在偏差,降水无明显变化与不同地区牧民感知明确的趋势性判断存在偏差;受草场变化等环境信息的传导是气候变化感知偏差形成的重要原因,其中,降水感知与环境感知之间具有较强的关系,存在明显的传导过程,而温度感知的传导性不明显;通过Probit模型分析显示,气候变化传导感知与否主要与牧户距离行政中心距离、户主年龄、教育背景、载畜水平、草畜资源等因素有关. 相似文献
79.
Kaninga Belinda Lark R. Murray Chishala Benson H. Maseka Kakoma K. Sakala Godfrey M. Young Scott D. Tye Andrew Hamilton Elliott M. Watts Michael J. 《Environmental geochemistry and health》2021,43(9):3699-3713
Environmental Geochemistry and Health - A field experiment was undertaken on farmers’ fields adjacent to a large mine tailings dam in the Zambian mining town of Kitwe. Experimental plots were... 相似文献
80.
In the UK, there now exist hundreds of low-carbon community groups (LCCGs) that aim to decrease collective resource consumption and/or generate renewable energy through diverse social and environmental interventions. These groups have in recent years become the subject of political attention and funding schemes, underpinned by beliefs that LCCGs are key to fostering resilience to climate change and meeting national-level greenhouse gas emission reduction targets. While previous research into LCCGs has focused on drivers, barriers and outcomes of LCCG action, there is now growing policy and academic interest in groups' capacities for, and uses of, monitoring and evaluation (M&E) processes and tools. However, little is known about the experiences, opportunities and potential challenges for LCCGs undertaking M&E. In response, this paper draws on a Knowledge Exchange project that explored M&E processes and tools with a sample of UK LCCGs. It outlines the benefits and drawbacks of groups' attempts to achieve change and to account for their outcomes and/or impacts, individually, and as part of a wider movement. It argues that, while M&E could be one way for groups to “scale up” their impact without losing their grounding in place and community, issues of capacity, resources and utility remain paramount. 相似文献