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41.
P.R. Lecavalier I. Chu D. Villeneuve V.E. Valli 《Journal of environmental science and health. Part. B》2013,48(5):951-961
Abstract The objective of the present study was to assess the potential interactive effects of two Great Lakes chemical contaminants, hexachlorobenzene (HCB) and mercury (HgCl2). Groups of 10 female Sprague‐Dawley rats were administered by gavage single doses of HCB (400, 600 mg/kg b.w. in corn oil), HgCl2 (10.0, 12.5 mg/kg b.w. aqueous) or combinations of both followed by observation for clinical signs of toxicity for 14 days. Five animals from treatment groups died before the termination of the study; one animal each in 600 mg HCB, 400 mg HCB + 10 mg HgCl2, and 600 mg HCB + 10 mg HgCl2, and two animals in 600 mg HCB + 12.5 mg HgCl2. The surviving animals were necropsied at the termination of the study, and hematological, clinical chemistry, histopathological and tissue residue analyses were performed. Relative liver weights were increased in both low and high dose groups of HCB but not in animals treated with HgCl2 alone. Co‐administration of HgCl2 did not alter the HCB effects on the liver weight of the animals. Serum cholesterol levels were increased in all the groups receiving HCB but not HgCl2. No interactive effects on other serum parameters were seen in animals administered with both chemicals. Mild to moderate morphological changes occurred in the liver, thyroid, thymus, ovary and bone marrow of rats exposed to HCB or HCB + HgCl2, and in the kidney of HgCl2 or HgCl2 + HCB treated animals. More severe histological changes occurred in the groups receiving both chemicals. The histological effects appeared to be additive. It was concluded that co‐administration with HCB and HgCl2 resulted in additive effects in some of the endpoints measured but no synergism or antagonism was observed. 相似文献
42.
T. B. Kalinnikova I. A. Krasnoperova T. M. Gainutdinov S. V. Sadykova M. Kh. Gainutdinov 《Russian Journal of Ecology》2005,36(2):109-114
The thermal resistance of Daphnia magna Straus is a trait depending on the interaction between individuals. The group effect is expressed in D. magna as both a decrease in thermal resistance and a marked individual differentiation with respect to thermal resistance. Two types of interactions between individual D. magna have been found: (1) the release of an unidentified factor decreasing thermal resistance (without noticeably changing the phenotypic variability of this trait) into the medium and (2) a decrease in the thermal resistance of individuals poorly adapted to heat stress, with the thermal resistance of well-adapted individuals (determined by the dependence of thermal resistance on interactions between individuals) remaining the same or even slightly increasing.Translated from Ekologiya, No. 2, 2005, pp. 126–131.Original Russian Text Copyright © 2005 by Kalinnikova, Krasnoperova, T. Gainutdinov, Sadykova, M. Gainutdinov. 相似文献
43.
河水-地下水交互作用对河流水质净化、流域水生态健康和河岸土地合理规划具有重要意义.本文以广州市流溪河为研究对象,实时监测河水和河岸带地下水基本理化指标并采集水样和土样进行水体主离子、氮形态、金属离子浓度、氘(δD)氧(δ~(18)O)同位素和土壤渗透系数(K)测试分析.结果表明:监测期间以河水侧向补给地下水为主,对地下水水位的影响范围在距河岸10 m内;距河岸1 m处地下水溶解氧(DO)浓度、电导率(EC)和氧化还原电位(ORP)变化明显,变异系数(n=7)分别为30.9%、42.0%和44.4%.河水和河岸带地下水水化学类型均为HCO_3-Ca型,受碳酸盐岩风化控制.河水入渗补给地下水初期,河岸带含水层向还原环境转化(ORP平均下降92.25 mV),非饱和带Mn氧化物发生还原性溶解,地下水中Mn~(2+)浓度逐渐增加并达最大值(0.52 mg·L~(-1));基于δD、δ~(18)O和Cl~-浓度的混合模型估算的河水对距河岸5 m处地下水的贡献率分别为10.4%、11.6%和11.5%,表明监测断面河水-地下水交互边界约在距河岸5 m处. 相似文献
44.
We examine the role of spatial interactions in conservation easements placed on prairie pothole habitat in western Canada. One of the goals of the conservation easement program we study is to protect contiguous habitat. We identify endogenous spatial interactions among conservation easements and government protected land, independent of spatially correlated landscape features and local economic shocks that influence easement enrollment. We present evidence that easements increase the likelihood of subsequent easements on neighboring land. Government-protected land appears to have little effect on the location of conservation easements. These results imply that conservation agencies have leveraged past conservation investment to enroll more contiguous habitat in permanent easements through a combination of targeting and positive social interactions among neighboring landowners. 相似文献
45.
Reductions in global bee populations are threatening the pollination benefits to both the planet and people. Whilst the contribution of bee pollination in promoting sustainable development goals through food security and biodiversity is widely acknowledged, a range of other benefits provided by bees has yet to be fully recognised. We explore the contributions of bees towards achieving the United Nation’s Sustainable Development Goals (SDGs). Our insights suggest that bees potentially contribute towards 15 of the 17 SDGs and a minimum of 30 SDG targets. We identify common themes in which bees play an essential role, and suggest that improved understanding of bee contributions to sustainable development is crucial for ensuring viable bee systems. 相似文献
46.
47.
Gabriel?Ramos-FernándezEmail author José?L.?Mateos Octavio?Miramontes Germinal?Cocho Hernán?Larralde Bárbara?Ayala-Orozco 《Behavioral ecology and sociobiology》2004,55(3):223-230
Scale invariant patterns have been found in different biological systems, in many cases resembling what physicists have found in other, nonbiological systems. Here we describe the foraging patterns of free-ranging spider monkeys (Ateles geoffroyi) in the forest of the Yucatan Peninsula, Mexico and find that these patterns closely resemble what physicists know as Lévy walks. First, the length of a trajectorys constituent steps, or continuous moves in the same direction, is best described by a power-law distribution in which the frequency of ever larger steps decreases as a negative power function of their length. The rate of this decrease is very close to that predicted by a previous analytical Lévy walk model to be an optimal strategy to search for scarce resources distributed at random. Second, the frequency distribution of the duration of stops or waiting times also approximates to a power-law function. Finally, the mean square displacement during the monkeys first foraging trip increases more rapidly than would be expected from a random walk with constant step length, but within the range predicted for Lévy walks. In view of these results, we analyze the different exponents characterizing the trajectories described by females and males, and by monkeys on their own and when part of a subgroup. We discuss the origin of these patterns and their implications for the foraging ecology of spider monkeys.Communicated by D. Watts 相似文献
48.
Bo Terning Hansen Lars Erik Johannessen Tore Slagsvold 《Behavioral ecology and sociobiology》2007,61(8):1203-1209
Imprinting plays a key role in the development of species recognition, with young imprinting upon the morphological characters
of their parents. However, the potential role that cultural transmission might play in species recognition remains largely
uninvestigated. Great tits (Parus major) and blue tits (Cyanistes caeruleus) do not normally perceive each other as sexual competitors or potential partners. However, after reciprocal interspecific
cross-fostering, both species may perceive individuals of the foster species as potential rivals or mates. Although the experience
of being raised by heterospecifics clearly has affected the species recognition of cross-fostered birds, some of them breed
naturally with conspecifics. The offspring of such cross-fostered birds (OCF) are hence raised by parents that look like ordinary
conspecifics but display deviant species recognition as compared to controls in terms of aggressive response towards rivals.
Comparing the aggressive behavior of OCF, cross-fostered birds and controls towards territorial intruders may thus help tease
apart the influence of morphological vs behavioral cues of parents in the development of offspring species recognition. To
this end, we compared birds from all three treatments with respect to their aggressive response to territorial intruders of
both species during the breeding season. OCF and controls did not differ in their pattern of response towards heterospecific
and conspecific stimuli. Compared to cross-fostered birds, OCF and controls showed less aggression towards heterospecific
intruders, while the response towards conspecific intruders did not differ between treatments. These results demonstrate that
both tit species imprint on the morphological characters of their parents, but that parental behavior is not important for
the development of species recognition in terms of aggressive response towards territorial intruders. 相似文献
49.
Summary Chemical analysis of each individual leaf of fivePlantago lanceolata (Plantaginaceae) plants showed that iridoid glycoside content increased from undetectable in the oldest photosynthetic leaves to over 9% dry weight in the youngest leaves. The relative proportion of the two iridoid glycosides inP. lanceolata also changed with leaf age: older leaves had significantly more aucubin, whereas the youngest leaves had primarily or solely catalpol. Oviposition tests with femaleJunonia coenia (Nymphalidae) butterflies, showed that they laid most of their eggs on new leaves. 相似文献
50.
In signalling interactions, animals can directly address information to a specific individual. Vocal overlapping is such a
signalling strategy used in songbirds, anurans, and insects. In songbirds, numerous studies using high rates of song overlap
to simulate an escalating situation have shown that song overlapping is perceived as a threatening signal by interacting and
by listening (eavesdropping) individuals, indicating a high social relevance of song overlapping. Here we present a playback
experiment on nocturnally singing male territorial nightingales (Luscinia megarhynchos). Using three different rates of song overlap (1, 25, or 50%), we tested whether or not lower levels of song overlapping
act as a signal of aggressive intent and if birds would increase the intensity of their response with increasing level of
song overlapping. Subjects did not vary song duration in response to the different playback treatments but increasingly interrupted
their singing with increasing overlap by the three playback treatments. The effects persisted even after the playback ceased
to overlap and switched to an alternating singing mode. These results expand on previous studies by showing that song overlapping
is interpreted as an aggressive signal even when it is used at low or moderate levels. They suggest that, within the range
tested here, increasing levels of song overlapping are perceived to be increasingly aggressive. 相似文献