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51.
William Post 《Behavioral ecology and sociobiology》1994,35(6):401-407
Female boat-tailed grackles (Quiscalus major) nest in colonies, and apparently settle independently of male activities. Associations between colony females may be mutually beneficial (cooperative hypothesis) or females may be penalized by associating (competitive hypothesis). Contrary to predictions based on either cooperative or competitive behavior, (1) reproductive success was not related to colony size nor to internest distance; (2) intracolony nesting synchronies were the same as those of the whole population, and within colonies, there was no relationship between the timing and spacing of nearest-neighbor nests; and (3) already established females were only occasionally aggressive toward females attempting to settle near them, and their aggressive response was independent of their stage of nesting. The results suggest that females act independently of each other and do not affect each other's fitness (neutral female hypothesis). Colonies may be neutral aggregations in sites secure from ground predators. Although females benefit by co-occupying predator-free sites, advantages and disadvantages of colomality do not appear to be related to intrasexual association. 相似文献
52.
Social animals often use vocal communication signals that contain individual signatures. As bats emit echolocation calls several
times per second to orient in space, these might seem ideal candidates for conveying the caller's individual identity as a
free by-product. From a proximate perspective, however, coding of caller identity is hampered by the simple acoustic structure
of echolocation signals, by their task-specific design and by propagation loss. We investigated the occurrence of individual
signatures in echolocation calls in individually marked, free-living Bechstein's bats (Myotis bechsteinii) in a situation with defined social context in the field. The bats belonged to two different colonies, for both of which
genetic data on relatedness structure was available. While our data clearly demonstrate situation specificity of call structure,
the evidence for individual-specific signatures was relatively weak. We could not identify a robust and simple parameter that
would convey the caller's identity despite the situation-specific call variability. Discriminant function analysis assigned
calls to call sequences with good performance, but worsened drastically when tested with other sequences from the same bats.
Therefore, we caution against concluding from a satisfactory discrimination performance with identical training and test sequences
that individual bats can reliably be told apart by echolocation calls. At least the information contained in a single call
sequence seems not to be sufficient for that purpose. Starting frequencies did give the best discrimination between individuals,
and it was also this parameter that was correlated with genetic relatedness in one of our two study colonies. Echolocation
calls could serve as an additional source of information for individual recognition in Bechstein's bats societies, while it
is unlikely that a large number of individuals could be reliably identified in different situations based on echolocation
alone. 相似文献
53.
54.
Five 14C-labelled polychlorinated biphenyls: 2,4′,5-trichlorobiphenyl, 2,2′,4,5′-tetrachlorobiphenyl, 2,2′,4,5,5′-pentachlorobiphenyl, 2,2′,3,4,4′-pentachlorobiphenyl and 2,2′,4,4′,5,5′-hexachlorobiphenyl were administered orally to bile-cannulated rats. The activity secreted in the bile, excreted in the feces and the urine was determined. Residues of radioactivity in certain tissues and the carcass were also measured.The trichlorobiphenyl showed the highest absorption (93.8%±5.4) from the gastrointestinal tract and biliary secretion of radioactivity (87.6%±6.1 of the dose). The hexachlorobiphenyl showed the lowest absorption and biliary secretion, 28.2%±1.4 and 18.6%±1.3, respectively. The urinary excretion was low and the radioactive residues in the eviscerated carcasses increased with the chlorine content of the biphenyls. 相似文献
55.
A single oral dose of [14C] 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) was administered to conventional and bile-duct cannulated male Sprague-Dawley rats. Tissue disposition, excretion and metabolism was determined. BTBPE is a low-volume brominated flame retardant used in resins or plastics, and toxicity data in peer-reviewed journals is extremely limited. BTBPE was fairly insoluble in lipophilic solutions, which made dose preparation difficult. The great majority of 14C (>94%) was excreted in the feces of both groups of rats at 72 h, and tissue retention was minimal. Lipophilic tissues contained the highest concentrations of BTBPE, e.g. thymus, adipose tissue, adrenals, lung, and skin. Metabolites were excreted in the urine, bile and feces, but at a very low level. Fecal metabolites were characterized as monohydroxylated, monohydroxylated with debromination, dihydroxylated/debrominated on a single aromatic ring, monohydroxylated on each aromatic ring with accompanying debromination, and cleavage on either side of the ether linkage to yield tribromophenol and tribromophenoxyethanol. Despite a limited quantity of stable metabolites extractable in the feces, non-extractable 14C levels were relatively high (39% of the 0-24 h fecal 14C), which suggested that BTBPE could be metabolically activated in the rat and covalently bound to fecal proteins and/or lipids. It was concluded that limited absorption and metabolism of BTBPE would occur by ingestion in mammals. 相似文献
56.
Müller K Pelzing M Gnauk T Kappe A Teichmann U Spindler G Haferkorn S Jahn Y Herrmann H 《Chemosphere》2002,49(10):1247-1256
An increasing percentage of agricultural land in Germany is used for oil seed plants. Hence, rape has become an important agricultural plant (in Saxony 1998: 12% of the farmland) in the recent years. During flowering of rape along with intensive radiation and high temperatures, a higher production and emission of biogenic VOC was observed. The emissions of terpenes were determined and more importantly, high concentrations of organic carbonyl compounds were observed during this field experiment. All measurements of interest have been carried out during two selected days with optimal weather conditions. It is found that the origin or the mechanism of formation of different group of compounds had strong influence on the day to day variation of their concentrations. The emission flux of terpenes from flowering rape plants was determined to be 16–32 μg h−1 m−2 (30–60 ng h−1 per g dry plant––540–1080 ng h−1 per plant), in total. Limonene, -thujene and sabinene were the most important compounds (about 60% of total terpenes). For limonene and sabinene reference emission rates (MS) and temperature coefficients were determined: βlimonene=0.108 K−1 and MS=14.57 μg h−1 m−2; βsabinene=0.095 K−1 and MS=5.39 μg h−1 m−2.
The detected carbonyl compound concentrations were unexpectedly high (maximum formaldehyde concentration was 18.1 ppbv and 3.4 ppbv for butyraldehyde) for an open field. Possible reasons for these concentrations are the combination of primary emission from the plants induced by high temperature and high ozone stress, the secondary formation from biogenically and advected anthropogenically emitted VOC at high radiation intensities and furthered by the low wind speeds at this time. 相似文献
57.
Few studies have evaluated PCB concentrations in alligators. This is the first comparison of PCB concentrations in alligators eggs from the southeastern United States. Eggs were collected from Bear Island and Winyah Bay, South Carolina and from the Rockefeller Wildlife Refuge, Louisiana. Mean PCB concentrations in eggs from Bear Island (333 ng/g) were the same (P > 0.45) as those found at the Rockefeller Wildlife Refuge (218 ng/g). However, eggs from Winyah Bay contained 3176 ng/g PCBs which is higher (P < 0.008) than concentrations from the other two sites. These data indicate the ubiquitous nature of PCBs and their bioaccumulation even in remote habitats. 相似文献
58.
Konrad Müller Matthias Pelzing Thomas Gnauk Anett Kappe Ulrich Teichmann Gerald Spindler Sylvia Haferkorn Yvonne Jahn Hartmut Herrmann 《Chemosphere》2002,49(10)
An increasing percentage of agricultural land in Germany is used for oil seed plants. Hence, rape has become an important agricultural plant (in Saxony 1998: 12% of the farmland) in the recent years. During flowering of rape along with intensive radiation and high temperatures, a higher production and emission of biogenic VOC was observed. The emissions of terpenes were determined and more importantly, high concentrations of organic carbonyl compounds were observed during this field experiment. All measurements of interest have been carried out during two selected days with optimal weather conditions. It is found that the origin or the mechanism of formation of different group of compounds had strong influence on the day to day variation of their concentrations. The emission flux of terpenes from flowering rape plants was determined to be 16–32 μg h−1 m−2 (30–60 ng h−1 per g dry plant––540–1080 ng h−1 per plant), in total. Limonene, α-thujene and sabinene were the most important compounds (about 60% of total terpenes). For limonene and sabinene reference emission rates (MS) and temperature coefficients were determined: βlimonene=0.108 K−1 and MS=14.57 μg h−1 m−2; βsabinene=0.095 K−1 and MS=5.39 μg h−1 m−2.The detected carbonyl compound concentrations were unexpectedly high (maximum formaldehyde concentration was 18.1 ppbv and 3.4 ppbv for butyraldehyde) for an open field. Possible reasons for these concentrations are the combination of primary emission from the plants induced by high temperature and high ozone stress, the secondary formation from biogenically and advected anthropogenically emitted VOC at high radiation intensities and furthered by the low wind speeds at this time. 相似文献
59.
Busch G Lammel G Beese FO Feichter J Dentener FJ Roelofs GJ 《Environmental science and pollution research international》2001,8(2):95-102
A global assessment of the impact of the anthropogenic perturbation of the nitrogen and sulfur cycles on forest ecosystems is carried out for both the present-day [1980-1990] and for a projection into the future [2040-2050] under a scenario of economic development which represents a medium path of development according to expert guess [IPCC IS92a]. Results show that forest soils will receive considerably increasing loads of nitrogen and acid deposition and that deposition patterns are likely to change. The regions which are most prone to depletion of soils buffering capacity and supercritical nitrogen deposition are identified in the subtropical and tropical regions of South America and Southeast Asia apart from the well known 'hotspots' North-Eastern America and Central Europe. The forest areas likely to meet these two risks are still a minor fraction of the global forest ecosystems, though. But the bias between eutrophication and acidification will become greater and an enhanced growth triggered by the fertilizing effects of increasing nitrogen input cannot be balanced by the forest soils nutrient pools. Results show increasing loads into forest ecosystems which are likely to account for 46% higher acid loads and 36% higher nitrogen loads in relation to the 1980-1990 situation. Global background deposition of up to 5 kg N ha-1 a-1 will be exceeded at more than 25% of global forest ecosystems and at more than 50% of forest ecosystems on acid sensitive soils. More than 33% of forest ecosystems on acid sensitive soils will receive acid loads which exceeds their buffering capacity. About 25% of forest areas with exceeded acid loads will receive critical nitrogen loads. 相似文献
60.
Gerald Spindler Konrad Müller Hartmut Herrmann 《Environmental science and pollution research international》1999,6(2):89-94
Aerosol filter samples have been collected nearby the industrialised basin of Leipzig in Saxony (Germany) at the research station Melpitz of the Institut für Troposphärenforschung e.V. (IfT). Time series (1992–1998) and a three year comparison (1995–1997) of two different aerosol filter sampling systems, the Sierra-Andersen-PM 10 high volume sampler (daily sample, PM 10 inlet) and the Rupprecht and Patashnik Co. Inc. Model Partisol 2000 (weekly sample, PM 10 and PM 2.5 inlet) are presented and discussed. The comparison of the different sampling systems and strategies yields small differences between the daily and weekly samples for mass and different ions, which may be influenced by sampling duration and flow rates. A general trend of change in aerosol composition was observed: Soot and Sulphate concentrations decreased whereas Nitrate and Ammonium concentrations increased. During summers the mass of coarse particles is higher than in other seasons. One reason could be found in the occurence of longer periods of dry ground surfaces enabling reemission of crustal and biological material. The time series have been integrated in a longer historical aerosol mass trend for Saxony and do show a good agreement. Since 1990 a significant downward trend in gravimetric mass concentration was found. 相似文献