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41.
42.
Amanda D. Melin Linda M. Fedigan Chihiro Hiramatsu Shoji Kawamura 《Behavioral ecology and sociobiology》2008,62(5):659-670
Many species of platyrrhine primates are characterised by sex-linked color vision polymorphism. This presents an opportunity
to study the biology and ecology of individuals with different phenotypes living in the same group. Several evolutionary processes
could maintain polymorphic genes in populations. In this study, we evaluate the hypothesis that foraging niche divergence
among monkeys explains the presence of multiple color vision phenotypes. Specifically, we test whether dichromats and trichromats
differ in foraging time devoted to cryptic vs brightly colored resources. We did not find any differences in foraging time
spent on different food types by dichromatic and trichromatic monkeys in two groups of white-faced capuchins (Cebus capucinus) living in a tropical dry forest. We conclude that in so far as these variables are concerned, niche divergence does not
likely explain color vision polymorphism in our study population. 相似文献
43.
呼吸防护用品符合人的形态与生理特征,才能保证其防护效果和舒适性。笔者从人体的面部形态与生理机能角度,分析了呼吸防护用品与人体的适配性,系统提出密合性、呼吸阻力、死腔、视野等呼吸防护用品的人机工效学问题。该论文取得的成果,对进一步丰富呼吸防护用品人机工效学研究内容,指导呼吸防护用品的设计与生产,提升我国呼吸防护用品的防护效果与核心竞争力,以期发挥积极的推动作用。 相似文献
44.
The Canary Islands are home to a guild of endemic, threatened bird-pollinated plants. Previous work has suggested that these
plants evolved floral traits as adaptations to pollination by flower specialist sunbirds, but subsequently, they appear to
have co-opted generalist passerine birds as sub-optimal pollinators. To test this idea, we carried out a quantitative study
of the pollination biology of three of the bird-pollinated plants, Canarina canariensis (Campanulaceae), Isoplexis canariensis (Veronicaceae) and Lotus berthelotii (Fabaceae), on the island of Tenerife. Using colour vision models, we predicted the detectability of flowers to bird and
bee pollinators. We measured pollinator visitation rates, nectar standing crops as well as seed-set and pollen removal and
deposition. These data showed that the plants are effectively pollinated by non-flower specialist passerine birds that only
occasionally visit flowers. The large nectar standing crops and extended flower longevities (>10 days) of Canarina and Isoplexis suggests that they have evolved a bird pollination system that effectively exploits these low frequency non-specialist pollen
vectors and is in no way sub-optimal. Seed set in two of the three species was high and was significantly reduced or zero
in flowers where pollinator access was restricted. In L. berthelotii, however, no fruit set was observed, probably because the plants were self-incompatible horticultural clones of a single
genet. We also show that, while all three species are easily detectable for birds, the orange Canarina and the red Lotus (but less so the yellow-orange Isoplexis) should be difficult to detect for insect pollinators without specialised red receptors, such as bumblebees. Contrary to
expectations if we accept that the flowers are primarily adapted to sunbird pollination, the chiffchaff (Phylloscopus canariensis) was an effective pollinator of these species. 相似文献
45.
46.
(1.南京信息工程大学 大气物理学院,江苏 南京 210044;2.南京信息工程大学 地理科学学院,江苏 南京 210044;3.南京信息工程大学 应用气象学院,江苏 南京 210044) 相似文献
47.
Albert Llausàs Michael Buxton Ruth Beilin 《Journal of Environmental Planning and Management》2016,59(7):1304-1322
Building on the scientific literature, this article first summarises the socio-environmental impacts of land-use change expected to occur in high amenity Australian peri-urban areas, involving in particular, the effects of land development on agriculture, biodiversity, landscape character, bushfire risk and social factors. Second, the current spatial planning framework and its distribution in seven municipalities in Victoria, Australia, is critically analysed, and records of approved planning permits are related to this framework to assess the challenges posed by peri-urban growth. We argue that the current planning framework supports a static approach which does not address foreseen challenges and lacks strategic power. Both the strategic framework and the development approval process lead to unanticipated, cumulative impacts and contestation. A more coordinated, less urban-centric approach to planning and the introduction of rural land-use plans would substantially address some of the issues encountered. 相似文献
48.
本文以某学院6号楼为例,研究标识设置对教学楼通道疏散能力影响,测定了不同标识设置情况楼道人流时程,结果表明:自然状态人流速峰值66.8人/min,持时2.823min,拥堵明显;立体标识使人流速峰值提升3%,使峰值持时缩短51.65%,墙面平铺张贴标识使人流速峰值提升1%,使持时缩短44.07%,立体标识优于墙面平铺张贴标识;早期疏导标识使人流速峰值提升6%,使持时缩短60.93%,使峰值出现时刻比自然状态提前约31%,疏散效果明显。同时本文分析了现有标识设置的问题和弊端。 相似文献
49.
A. Gumbert 《Behavioral ecology and sociobiology》2000,48(1):36-43
It is usually assumed that the choice behavior of bees for floral colors is influenced by innate preferences only for the
first flower visits prior to any experience. After visits to rewarding flowers bees learn to associate their colors with a
reward. This learning process leads to an acquired preference for the trained colors that has been believed to dominate over
previous experiences and over innate preferences. This work investigates how bumble bees (Bombus terrestris) chose among artificial flowers of different colors after they had been extensively trained to other colors. The bees chose
novel colors according to their similarity to the trained color if the trained color was similar to some of the test colors.
This was true also if trained colors and test colors were well distinguished, so their color choice reflected generalization
between colors. If the test colors were so different from the trained color that no generalization took place, choice behavior
was not affected by the trained color and reflected innate preferences. The differences in choice frequencies could not be
explained by physical properties of the test colors other than the dominant wavelength, a parameter taken to reflect hue perception.
Preferred dominant wavelengths correspond to those observed in naive bumble bees and honeybees. Thus bumble bees show innate
preferences for certain colors not only prior to color learning but also after intensive learning when choosing among very
different novel colors. Color choice among similar colors, however, is controlled by generalization from the learned color.
Received: 9 November 1999 / Received in revised form: 19 March 2000 / Accepted: 31 March 2000 相似文献
50.
青鳉鱼在饮用水安全领域具有很高的应用价值,其鱼鳍的活动状态可以反映水质的污染状况。但由于技术条件的限制,传统的方法无法实时而有效地提取到这些特征。针对这个问题,提出了一种可以高效识别并测量青鳉鱼胸、尾鳍摆动频率和幅值的计算机视觉算法。其中,为了快速地提取到这2个细节,自动阈值分割、帧差法、背景差分法、重心法、图像卷积和骨架细化等耗时极短的图像处理方法被应用到这项研究当中。初步试验显示这种算法在应用过程中是高效而可行的。它可以被广泛地应用到水环境监测领域,如研究有毒物质对青鳉鱼行为特性的影响和评估水环境的危险程度。 相似文献