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41.
Kevin J. McGraw Elizabeth A. Tourville Michael W. Butler 《Behavioral ecology and sociobiology》2008,62(12):1991-2002
Interest in animal carotenoids, especially in birds, has exploded in recent years, and so too have the methods employed to
investigate the nature and function of these pigments. Perhaps the most easily and commonly performed procedure in this work
has been the determination of carotenoid concentration from avian plasma. Over the past 20 years of research on avian carotenoids,
numerous methods have been used to extract carotenoids from bird plasma, all of which have differed in several important parameters
(e.g., number and types of solvents used, degree of mixing/centrifugation). However, to date, no study has systematically
compared these methods to determine if any of them are more effective than others for recovering any or all types of carotenoids
present. We undertook such an investigation on plasma samples from two bird species (house finch, Carpodacus mexicanus, and mallard, Anas platyrhynchos) using five of the most commonly employed methods for extracting carotenoids from avian plasma: (1) acetone-only, (2) methanol-only,
(3) ethanol-only, (4) ethanol + hexane, and (5) ethanol + tert butyl methyl ether. We also manipulated the amount of time that extracts were centrifuged, which has varied tremendously
in previous studies, to evaluate its importance on carotenoid recovery. We found that all methods equally recovered the polar
xanthophylls (lutein and zeaxanthin), but that the methanol-only procedure poorly recovered non-polar carotenoids (less β-carotene
in both species and less β-cryptoxanthin in house finches) compared to the other methods. These results suggest that the data
accumulated to date on xanthophyll plasma carotenoids in birds should be comparable across studies and species despite the
different chemical extraction methods used. However, care should be taken to use relatively strong organic solvents for fully
recovering non-polar carotenoids. We also found no effect of centrifugation duration (1 vs. 10 min at 10,000 rpm) on carotenoid
recoveries, demonstrating that researchers can save considerable time by centrifuging for a much shorter time period than
is typically used. 相似文献
42.
Improving Community-Based Conservation Near Protected Areas: The Importance of Development Variables
Balint PJ 《Environmental management》2006,38(1):137-148
Community-based conservation projects implemented in conjunction with protected area management often struggle to meet expectations.
This article argues that outcomes will improve if project leaders pay closer attention to four development indicators—rights,
capacity, governance, and revenue—that are often taken for granted or considered beyond the scope of local conservation projects.
I make the case for focusing on these variables in four steps. First, I distinguish community-based conservation linked to
protected area management from community-based institutions studied by scholars of the commons. Second, I draw on the theory
and practice of international development to highlight the central relevance of the variables highlighted in this article
to development projects at all levels. Third, I discuss the four variables in some detail, considering problems of definition
and measurement and reviewing possible interactions among them. Fourth, to illustrate the influence of the variables in particular
cases, I review outcomes from community-based conservation projects implemented near protected areas in El Salvador and Zimbabwe. 相似文献
43.
Kinship and aggression: do house sparrows spare their relatives? 总被引:1,自引:0,他引:1
Zoltán Tóth Veronika Bókony Ádám Z. Lendvai Krisztián Szabó Zsolt Pénzes András Liker 《Behavioral ecology and sociobiology》2009,63(8):1189-1196
Kin-selection theory predicts that relatedness may reduce the level of aggression among competing group members, leading to
indirect fitness benefits for kin-favoring individuals. To test this hypothesis, we investigated whether relatedness affects
aggressive behavior during social activities in captive house sparrow (Passer domesticus) flocks. We found that sparrows did not reduce their aggression towards kin, as neither the frequency nor the intensity of
fights differed between close kin and unrelated flock-mates. Fighting success was also unrelated to kinship and the presence
of relatives in the flock did not influence the birds’ dominance rank. These results suggest that the pay-offs of reduced
aggression towards kin may be low in non-breeding flocks of sparrows, e.g. due to competition among relatives as predicted
by a recent refinement of kin-selection theory. Our findings indicate that the significance of kin selection may be restricted
in some social systems such as winter aggregations of birds.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
44.
Aysu Akalin Kemal Yildirim Christopher Wilson Onder Kilicoglu 《Journal of environmental psychology》2009
In this study, five different sets of single-family house façades from private suburban cooperative housing developments in Ankara, Turkey, were analyzed; with each set comprising one example each of minimum, intermediate and maximum complexity. Although the houses in each set had the same appearance when they were first built, their façades have since been altered by their owners. The main hypothesis of the study was that preference rates would be high for intermediately altered houses by showing the existence of a U-shaped relationship. On the other hand, it was hypothesized that perceived complexity and perceived impressiveness would have a linear relationship, with perceived complexity increasing and perceived impressiveness decreasing as the complexity level changed. In terms of these two basic hypotheses, it was also assumed that there would be a difference in the ratings of particular respondent groups with different backgrounds. Thus, a questionnaire was given to 100 undergraduate students of the Architecture and Engineering Departments of Gazi University, Ankara (41 from architecture and 59 from engineering). These students were asked to rate a total of 15 photographs from five housing sites with the help of five-point semantic differential scales under three headings; namely: Preference: beautiful – ugly, warm – cold, pleasant – unpleasant; Complexity: unimposing – imposing, simple – complex; and Impressiveness: impressive – unimpressive. The results proved the existence of a U-shaped relationship between complexity and preference criteria. That is, façades representing an intermediate level of complexity were favored over less and more complex ones. The façades that seemed the most impressive were the most complex ones, but these, however, were not the most preferred. Amongst these results, it was also noted that the architecture students replied in a more critical way than the engineering students as they criticized what they saw as negative design decisions. 相似文献
45.
Data on polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) concentrations from Stockholm, Sweden, indoor microenvironments were combined with information from detailed questionnaires regarding the sampling location characteristics, including furnishing and equipment present. These were used to elucidate relationships between possible flame-retarded sources and the contaminant concentrations found in air and dust. Median concentration ranges of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD from all microenvironments were 19-570, 1.7-280, 29-3200 and < 1.6-2 pg/m3 in air and 22-240, 6.1-80, 330-1400 and 45-340 ng/g in dust, respectively. Significant correlations were found between concentrations of some PBDEs and HBCD in air and/or dust and the presence of electronic/electrical devices, foam furniture, PUF mattresses and synthetic bed pillows in, as well as floor area and construction year of the microenvironment. Car interiors were a source to indoor air in dealership halls. Using median and maximum concentrations of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD in air and dust, adult and toddler (12-24 months) intakes from inhalation and dust ingestion were estimated. Toddlers had higher estimated intakes of ΣPenta-, ΣDecaBDE and HBCD (7.8, 43, 7.6 ng/d, respectively) from dust ingestion than adults (5.8, 38, 6.0 ng/d, respectively). Air inhalation in offices was also an important exposure pathway for ΣPenta-, ΣOcta- and ΣDecaBDE in adults. For ΣPentaBDE and HBCD, air inhalation and dust ingestion play minor roles when compared to previously published Swedish dietary intakes (median exposures). However, in worst case scenarios using maximum concentrations, dust ingestion may represent 77 and 95% of toddler intake for ΣPentaBDE and HBCD, respectively. 相似文献
46.
Testosterone and the allocation of reproductive effort in male house finches (Carpodacus mexicanus) 总被引:9,自引:1,他引:8
Testosterone has been proposed to serve as the mediator that controls the relative effort that an individual male bird will
devote to mating effort versus parental effort. Here, we demonstrate a testosterone-influenced trade-off between parental
and mating efforts in male house finches. Male house finches with experimentally elevated testosterone fed nestlings at a
significantly lower rate, but sang at a higher rate than males without manipulated testosterone levels. Females mated to testosterone-implanted
males fed nestlings at a significantly higher rate than females mated to males without testosterone implants, resulting in
similar feeding rates for both treated and untreated pairs. The effects of testosterone on male house finches, however, were
not as dramatic as the effects of testosterone observed in some other socially monogamous species of birds. Because extra-pair
copulations are uncommon in house finches and males provide substantial amounts of parental care, these more modest effects
may be due to differences in how the allocation of reproductive effort affects the costs and benefits of different reproductive
behaviors.
Received: 6 June 2000 / Accepted: 17 July 2000 相似文献
47.
湿法脱硫技术在高含硫燃煤机组上的应用 总被引:1,自引:0,他引:1
龙源自主知识产权湿法烟气脱硫技术在高含硫燃煤机组上的应用,经过168 h试运行及一系列相关试验.探索了石膏浆液的最高合理密度范围.结果表明,机组燃用设计及校核煤种有较大裕度,具有一定的借鉴意义. 相似文献
48.
Gabriele Gerlach 《Behavioral ecology and sociobiology》1996,39(3):159-170
Emigration in small mammals may be strongly related to social factors, but direct observations of emigrants are rare. Feral
house mice (Mus domesticus) were studied using a population cage system that allowed continuous observation of individually marked animals. Mice that
left their natal cage and took up residence in cages that could only be reached by crossing a water barrier were defined as
emigrants. Six pairs of house mice with their litters were placed in the system, and data on aggressive interactions, body
weight, reproduction, mortality and emigration were collected daily. Both sexes emigrated, but males did so twice as often
as females. Population density was not correlated with the frequency of aggression, and had no effect on the weight of emigrating
individuals. Male emigrants suffered more aggression before emigration than their non-emigrant brothers of the same age; they
were aggressively driven out by other males, predominantly by the father. Female emigration depended on the female’s chances
of reproduction. The probability of a female reproducing decreased with increasing birth order. Females born in a late litter,
who therefore had only a low chance of reproduction, dispersed earlier than those of early litters. Resident males were reproductively
suppressed. Male offspring had two different strategies for attaining top rank. They could develop rapidly and reach sexual
maturity early on, but face competition with the father, risking being forced to emigrate. Alternatively, they could develop
slowly, stay within their family and wait for a chance to take over the dominant position. It is concluded that emigration
in male and female feral house mice is caused by intrasexual competition.
Received: 13 July 1995/Accepted after revision: 8 June 1996 相似文献
49.
As with many farmland bird species, the house sparrow Passer domesticus is declining in Europe, mainly due to intensification of agriculture reducing nest sites and food supplies. During 2002–2005,
we studied the population size and nest site characteristics of house sparrows breeding within white stork Ciconia ciconia nests in a large area of agricultural landscape within western Poland. To explain sparrow density within stork nests, we
examined characteristics of white stork nests (position, age, productivity) and the farm type around the nest. House sparrow
density was greatest in the longest established (and hence larger) white stork nests located on traditionally managed farms.
Two recent changes appear to have adverse effects on house sparrows. The first is the intensification of farming and the second
is active management of white stork nests on electric poles to reduce nest size and thus avoid both disruption to the electrical
supply and electrocution of white storks. Because the white stork has such a high profile in Poland, there are numerous schemes
to conserve and enhance this species. In conclusion, we clearly show that protecting one species can have valuable, although
unplanned, benefits to another species of conservation interest, the house sparrow. 相似文献
50.
Secondary sexual characters often provide indicators of a male’s resistance to infectious diseases to rivals and potential
mates, but it is unclear why. It is often suggested that males honestly signal their health due to energetic and other physiological
trade-offs between investing into secondary sexual traits vs resistance to infectious diseases. Our aim was to determine whether
such a trade-off exists using wild-derived male house mice (Mus domesticus). We exposed male mice to female scent, a manipulation that induces elevations in testosterone concentration and the expression
of a variety of testosterone-mediated secondary sexual traits, and tested whether this sexual stimulation impaired the males’
ability to resolve or cope with an experimental infection (Salmonella enterica). We kept the males on a controlled diet to prevent them from compensating by eating more food. We found that sexually stimulated
males were able to control bacterial growth as effectively as sham-stimulated controls; however, to do so, they lost more
body mass during infection compared to the controls. In contrast, we found no evidence that sexual stimulation reduced the
body mass of uninfected male mice. These results indicate that males’ responses to female odor are not immunosuppressive per
se, yet they increase the energetic costs of controlling infection. Our findings support the idea that there is a physiological
trade-off between secondary sexual signaling vs resistance to infectious diseases and suggest that studies using only immunocompetence
assays might fail to detect such energetic trade-offs.
We dedicate this paper to the late Professor Chris Barnard who conducted pioneering research on this topic. 相似文献