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221.
In this commentary, we discuss recent experiments on the reliability of bird song as a signal of aggressive intent during
territorial conflicts. We outline relevant theoretical views on honest signaling, highlighting the vulnerability handicap
hypothesis as a possible explanation for soft song’s reliability in predicting attack. We also sketch possible methods of
testing whether soft song agrees with key predictions of the vulnerability handicap hypothesis. Finally, we suggest possible
empirical refinements that may be useful in future studies of signals of intent, both in birds and in animals broadly. In
particular, we argue that future studies of intent should strive to incorporate the following elements into their experimental
design: (1) multi-modal signal components, (2) interaction dynamics, and (3) minimal time intervals. Simulated exchanges using
dynamically interactive models may provide a powerful means of incorporating all three of these design features simultaneously.
相似文献
Mark E. LaidreEmail: |
222.
Lauryn Benedict 《Behavioral ecology and sociobiology》2008,62(6):983-988
Previous studies suggest that extrapair young are very rare or absent in socially monogamous avian species that produce vocal
duets. These results are generally consistent with functional hypotheses suggesting that duets may signal commitment between
partners, or aid males as a paternity guard to ensure genetic as well as social monogamy. Additionally, species that exhibit
social monogamy with the same partner across multiple breeding seasons tend to exhibit low levels of extrapair paternity,
so duetting species that mate for life may be particularly likely to exhibit genetic monogamy. This study examined the social
and genetic mating systems of California towhees (Pipilo crissalis), a duetting species thought to have life-long pair bonds. Observation of a color-banded population confirmed that California
towhees exhibit long-term social monogamy. Known social families were genotyped at four microsatellite loci with high allelic
diversity. Unexpectedly, paternity exclusion indicated that at least 13 of 31 (42%) nests contained extrapair young. All chicks
exhibited maternal alleles, but 21 of 81 (26%) young were not the offspring of social fathers. Thus, in contrast to previous
work, this study documents high frequencies of extrapair young among socially monogamous duetting birds with long-term pair
bonds. 相似文献
223.
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225.
Previous work has shown that arsenic can accumulate in drinking water distribution system (DWDS) solids (Lytle et~al., 2004) when arsenic is present in the water. The release of arsenic back into the water through particulate transport and/or
chemical release (e.g. desorption, dissolution) could result in elevated arsenic levels at the consumers' tap. The primary
objective of this work was to examine the impact of pH and orthophosphate on the chemical release (i.e. desorption) of arsenic
from nine DWDS solids collected from utilities located in the Midwest. Arsenic release comparisons were based on the examination
of arsenic and other water quality parameters in leach water after contact with the solids over the course of 168~hours. Results
showed that arsenic was released from solids and suggested that arsenic release was a result of desorption rather than dissolution.
Arsenic release generally increased with increasing initial arsenic concentration in the solid and increasing pH levels (in
the test range of 7 to 9). Finally, orthophosphate (3 and 5 mg PO4/L) increased arsenic release at all pH values examined. Based on the study results, utilities with measurable levels of arsenic
present in their water should be aware that some water quality changes can cause arsenic release in the DWDS potentially resulting
in elevated levels at the consumer's tap. 相似文献
226.
Current demand analysis methods do not formally cover the case of chronic deficits in quantity or quality of water and sanitation
services. These services include drinking water supply (DWS), wastewater and sewage treatment (WST), and municipal solid waste
management (MSW). Formal analysis of this case would, at minimum, define the deficit state and evaluate appropriate options
for reducing it. This paper proposes for a formal analytical model for municipal sanitation systems (MSS) that operate with
deficits in at least one of the constituent services of DWS, WST, or MSW. The model introduces definitions and notation for
describing the deficit state for conducting demand analysis on municipal sanitation systems. This model of demand analysis
for systems with chronic deficits will hereinafter be referred to as deficit analysis. A case study for Bacoor, Philippines is presented as an example. 相似文献
227.
228.
James V. Briskie Robert Montgomerie Tarmo Põldmaa Peter T. Boag 《Behavioral ecology and sociobiology》1998,43(3):181-190
In species where females copulate with more than one male during a single breeding attempt, males risk investing in offspring
that are not their own. In the polygynandrous Smith's longspur (Calcarius pictus), females copulate sequentially with one to three males for each clutch of eggs and most of these males later assist in feeding
the young. Using multilocus DNA profiling, we determined that there was mixed paternity in >75% of broods (n=31) but that few offspring (<1% of 114 nestlings) were sired by males outside the polygynandrous group. Male feeding rate
increased significantly with the number of young sired, with males siring four nestlings feeding the brood at double the frequency
of males siring only a single nestling. However, male Smith's longspurs appear to show a graded adjustment of paternal care
in response to paternity only when other males are available to compensate for reduced care: feeding rate did not vary in
relation to paternity when only one male provisioned young at the nest. There was no evidence that males could recognise their
own offspring within a brood and feed them preferentially. The number of offspring sired by each male was significantly correlated
with the number of days spent copulating with the attending female: on average, a male sired one offspring for every 2 days
of copulatory access. If males use their access to females to estimate paternity (and thereby decide on their subsequent level
of parental investment), a positive relationship is expected between the amount of female access and the subsequent feeding
rate to the nestlings. Nonetheless, male feeding effort was only weakly correlated with female access and more study is needed
to determine how males estimate their paternity in a brood.
Received: 1 June 1997 / Accepted after revision: 1 April 1998 相似文献
229.
An air quality monitoring network (AQMN) usually performs the basic function of assessment of regional air quality and demonstration of compliance with ambient air quality standards in an urban area. Different pollutants, however, may present different characteristic variabilities due to their specific emission patterns, rates of diffusion, and transport and transformation behaviors. But the costs of siting in a pollutant-specific monitoring network would be higher than that for a common network with respect to several pollutants monitored simultaneously. This paper presents a survey of multi-pollutant design principles and optimal searches for siting patterns of an AQMN using both simulation and optimization models as a combined tool. While conservative, quasi-stable, and reactive pollutants are considered in the design principles, cost, coverage effectiveness, and spatial correlation characteristics are included in the multi-criteria decision making process. For illustrative purpose, a series of technical settings and two types of objectives were examined in the case study for the city of Kaohsiung in Taiwan. 相似文献
230.
生命线工程网络抗震可靠性分析方法的比较研究 总被引:2,自引:0,他引:2
生命线工程网络抗震可靠性分析是进行生命线工程系统规划、设计、改造与优化的基础。因此 ,寻找一种高效的适应性强的系统可靠性分析方法对实际工程应用具有重要的意义。本文主要介绍两种高效的网络系统两终端连通可靠性分析方法———递推分解算法和有序二分决策图算法。首先 ,分别对两种算法的原理及实现过程进行了详细的论述和说明 ,并且用c语言编制了二分决策图算法的计算程序。然后 ,利用这两种方法及随机模拟算法对 2 0个以往研究中的经典算例和两个实际工程网络———河南省电力网和上海市浦西供水管网 ,进行了网络系统抗震连通可靠性分析。通过对实例分析结果的比较研究 ,得到了一些经验性的结论 ,以期为优化设计工程网络时选择系统可靠性的分析工具提供参考。研究表明 ,由于递推分解算法具有适应性强和能够求得问题近似解的优点 ,因此有良好的实际工程应用前景。 相似文献