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211.
Toby J. Hibbitts Martin J. Whiting Devi M. Stuart-Fox 《Behavioral ecology and sociobiology》2007,61(8):1169-1176
Many species possess multiple sexually dimorphic traits, which incorporate different sensory modalities (e.g., acoustic, olfactory
and visual), although their relative roles in sexual selection and in determining reproductive success are still poorly understood
for most taxa. We assessed the role of multiple male traits, including one acoustic (dominant call frequency) and one visual
(yellow throat patch) trait, in residency advertisement, contest behavior, and breeding success in barking geckos (Ptenopus garrulus garrulus). We show that male barking geckos maintain largely exclusive home ranges, with a trend for larger males to maintain larger
home ranges. We also show that larger males have a lower dominant calling frequency. When aggressive behavior was elicited
in the field using a recorded call of average frequency, resident males with low frequency calls were more likely to respond
aggressively and charge the speaker compared to males with high frequency calls. However, body size and small relative throat
patch size, rather than call frequency, were the best predictors of overall aggressiveness. Body size was also the best predictor
of whether males bred. We suggest that call frequency in this crepuscular species constitutes an effective long-range signal
of body size, used by males for remote rival assessment and to advertise home range boundaries in low-light environments. 相似文献
212.
Abstract: The primary goals of reserve selection are to represent all chosen units of biodiversity and to ensure their long-term persistence while minimizing costs. We considered two simple proxies of species persistence: a time series of point-count data to calculate abundance and a time series of presence–absence data to calculate permanence (a measure of consistent occupancy over time). Using two 10-year intervals of data from the North American Breeding Bird Survey, we compared the performance of each measure at predicting persistence 18 years later. For nonrare species, abundance and permanence predicted persistence similarly well. We performed complementarity-based reserve selections with data on species abundance and permanence (from 1970 to 1979) and then evaluated the effectiveness of the reserve networks at maintaining species populations and efficiency in land use (data from 1997 to 2006). Abundance proved a better predictor of future local persistence than permanence, which justifies the relatively larger financial and temporal costs of collecting a time series of point-count data to estimate abundance. If future extinction events were used as a measure of reserve-network effectiveness, the performance of abundance and permanence did not differ markedly. Nevertheless, when future abundance, which is a more sensitive measure of network effectiveness, was used, abundance was significantly better than permanence at selecting longer-term, high-quality, species-specific habitat but required larger reserves to do so . 相似文献
213.
214.
Variations in land requirements for meat production 总被引:2,自引:0,他引:2
Production of meat requires substantial amounts of feed grains which in turn require vast amounts of land. Future population growth and increase in consumption will raise the demand for meat and with it the land required for meat production. This paper analyses the various factors that affect land requirements for meat production. Meat production by Dutch broilers, pigs and beef cattle on their current feeds are compared and options for change are evaluated with respect to their nutritional needs. Differences in land requirements of a factor of 3 were found between different agricultural production systems and feeds as well as between types of livestock. It is shown that broilers have the lowest land requirement while beef cattle have the highest. The variation in feed crop yields between agricultural systems is discussed. It is concluded that due to the large variation within the system there is potential for reduction in the land requirements for meat production. 相似文献
215.
工业化学品的日益增多和广泛使用,给环境带来了很大的压力。工业化学品的风险评价问题,对环境管理至为重要,国家环保局及国内的工业企业正在讨论有关化学品毒性的控制问题。该文讨论了化学品风险评价的常用术语及基本程序,对生态毒性在评价中的地位特别予以强调,并提出了与其相关的评价程序,即理化参数分析;毒性扫描;亚急性毒性试验和慢性毒性试验或微生态系统试验。 相似文献
216.
Living Amidst Large Wildlife: Livestock and Crop Depredation by Large Mammals in the Interior Villages of Bhadra Tiger Reserve,South India 总被引:7,自引:0,他引:7
Conflict with humans over livestock and crops seriously undermines the conservation prospects of India's large and potentially
dangerous mammals such as the tiger (Panthera tigris) and elephant (Elephas maximus). This study, carried out in Bhadra Tiger Reserve in south India, estimates the extent of material and monetary loss incurred
by resident villagers between 1996 and 1999 in conflicts with large felines and elephants, describes the spatiotemporal patterns
of animal damage, and evaluates the success of compensation schemes that have formed the mainstay of loss-alleviation measures.
Annually each household lost an estimated 12% (0.9 head) of their total holding to large felines, and approximately 11% of
their annual grain production (0.82 tonnes per family) to elephants. Compensations awarded offset only 5% of the livestock
loss and 14% of crop losses and were accompanied by protracted delays in the processing of claims. Although the compensation
scheme has largely failed to achieve its objective of alleviating loss, its implementation requires urgent improvement if
reprisal against large wild mammals is to be minimized. Furthermore, innovative schemes of livestock and crop insurance need
to be tested as alternatives to compensations. 相似文献
217.
规划环境影响评价是以可持续发展的思想为出发点,通过调整规划布局或规模从规划源头预防环境污染和生态破坏。文章探讨了化工建设规划的生态环境影响评价理论和方法学体系,并以武汉化工新城为例,对该理论方法体系进行探讨。 相似文献
218.
以资源、能源为依托的工业结构和粗放的增长方式是内蒙古工业的主要特点,也是实现节能减排目标的瓶颈。通过淘汰落后生产能力、加快接续产业发展、推动资源型产业发展高端和集成产品、促进节能减排技术的研发和应用、发展循环经济以及建立配套的政策、法规体系,力促内蒙古工业实现节能减排目标,走出一条资源节约与环境友好的新型发展道路。 相似文献
219.
随着我国规模化畜禽养殖业的发展,畜禽养殖面源污染已超过工业源和生活源污染,成为最大的污染源,也成为"十二五"污染减排的重点。本文从规模化畜禽养殖面源污染影响因素分析着手,提出基于监测数据的"产生-削减-面源体现系数法"的畜禽养殖面源污染总量测算方法,并给出了计算公式和总量测算流程,最后以内江市规模化畜禽养猪场为例,介绍了总量测算过程,给出了内江市规模化养猪场面源污染总量。 相似文献
220.
Airborne particulate matter from livestock production systems: A review of an air pollution problem 总被引:5,自引:0,他引:5
María Cambra-López André J.A. Aarnink Salvador Calvet 《Environmental pollution (Barking, Essex : 1987)》2010,158(1):1-17
Livestock housing is an important source of emissions of particulate matter (PM). High concentrations of PM can threaten the environment, as well as the health and welfare of humans and animals. Particulate matter in livestock houses is mainly coarse, primary in origin, and organic; it can adsorb and contain gases, odorous compounds, and micro-organisms, which can enhance its biological effect. Levels of PM in livestock houses are high, influenced by kind of housing and feeding, animal type, and environmental factors. Improved knowledge on particle morphology, primarily size, composition, levels, and the factors influencing these can be useful to identify and quantify sources of PM more accurately, to evaluate their effects, and to propose adequate abatement strategies in livestock houses. This paper reviews the state-of-the-art of PM in and from livestock production systems. Future research to characterize and control PM in livestock houses is discussed. 相似文献