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361.
Hybrid zones are often found in areas where the environmental characteristics of native habitat of both parental species meet.
One of the plausible mechanisms that maintain species distinctiveness, or limit hybridization, is the existence of local species-specific
preferences for the natal habitat type. We evaluated this hypothesis for two passerine bird species, the pied Ficedula hypoleuca and collared flycatcher F. albicollis, in their narrow hybrid zone in Central Europe. Both species have quite distinct habitat distributions, and they have also
been reported to differ in their foraging niches. In a series of aviary experiments, we demonstrated that both species show
distinct preferences for trees from their native area. The pied flycatcher preferred coniferous vegetation, while the collared
flycatcher favored deciduous vegetation. In addition, both species differed in foraging substrate preferences. The pied flycatcher
preferred to forage in the lower strata on the ground than the canopy, whereas the collared flycatcher foraged more at the
canopy level. Both males and females of each species were highly consistent in their preference patterns. Due to the widespread
nature of hybrid zones as places with transitional habitat features and the well-known habitat tight associations of various
animal taxa with particular habitat types, we propose that habitat preferences might be an important and common mechanism
that enhances the formation of conspecific pairs. 相似文献
362.
Although mate guarding as prevention of extra-pair copulation is common among birds, evidence for aggressive behaviour involving
physical contact related to mate guarding in passerines is scarce and cases of the presence of one partner directly influencing
the aggressiveness of the other are lacking. We investigated the intra-specific territorial behaviour of male meadow pipits
(Anthus pratensis; Passeriformes: Motacillidae) at the beginning of the breeding season by placing a pipit model accompanied by an intra-specific
song playback in the territory of socially paired males and compared the responses of males whose mates were physically present
during trials with those whose females were out of sight. The level of aggression of males was significantly higher in the
presence of the female; half of the males in this group physically attacked the model (the most intense and risky aggressive
behaviour). Physical attacks did not occur among males whose female was absent during the trial; response to the playback
by most of these males was only weak. This pattern may be related to the prevention of extra-pair copulation; if the risks
involved in the conflict are outweighed by potential loss of paternity, such aggressive mate guarding may pay off. The apparently
overlooked effect on the territorial behaviour of a partner’s passive physical presence during conflict should be further
evaluated because it may be important for the design and interpretation of results of behavioural experiments. 相似文献
363.
Adam Dušek Luděk Bartoš František Sedláček 《Behavioral ecology and sociobiology》2011,65(12):2209-2217
The issue of adaptive adjustment of offspring sex ratio (proportion of male births) in polytocous mammals, producing several
offspring per litter, is controversial because females of these species can maximize their fitness mainly by adjusting offspring
number. To address this issue, we examined the effect of maternal condition at mating, experimentally decreased by pre-mating
food restriction, on the sex ratio variation in 137 female mice. We tested two basic sex allocation hypotheses plausible for
polytocous mammals: (1) the Myers hypothesis, predicting that cheaper sex should be favored in poor environmental conditions
to maximize offspring number; and (2) the Williams hypothesis, predicting maximum fitness returns by adjusting size- and sex-specific
composition of the litter according to the maternal condition. The food-restricted mothers produced larger litters with a
higher proportion of cheaper daughters than the control mothers. By contrast, the control mothers optimized size and sex composition
of the litter according to their weight at mating. In addition, the offspring of the food-restricted mothers suffered less
from pre-weaning mortality than those of the control mothers. Therefore, when comparing the groups, the Myers hypothesis had
a general significance while the Williams hypothesis was plausible only for the control mothers. Furthermore, some of the
food-restricted mothers partly coped with the pre-mating food restriction and increased the proportion of sons in the litter
with the increasing maternal weight loss (during the period of food restriction). The sex ratio variation was thus a result
of three sex allocation strategies depending on the maternal condition at mating. 相似文献
364.
365.
Dorota Siuta Adam S. Markowski M. Sam Mannan 《Journal of Loss Prevention in the Process Industries》2013,26(3):418-426
The dynamic development of the LNG sector increases the risk of major accidents. Uncontrolled releases of LNG during the processes of manufacturing, distribution, storage, and regasification can pose a serious threat to people, facilities, and the environment. Therefore, an important goal is to determine hazard zones and the extent of potential consequences associated with a release of LNG. The key issue is to estimate these with the least level of uncertainty. The largest part of uncertainty comes from the modeling of LNG release sources and performing dispersion calculations. It is connected with the application of different mathematical models, the adoption of a number of simplifying assumptions, approximations, empirical relations, constants, and a lack of knowledge.This paper proposes a general procedure for calculating the release rate and duration time of the LNG release, pool spreading, vaporization, as well as dispersion, taking into consideration the uncertainty. The procedure consists of two parts. The first part concerns the sensitivity analysis to identify the most uncertain parameters of the LNG source term and dispersion models. The second part applies to two techniques used to include the uncertainty aspects of fuzzy sets and the Monte Carlo method for calculating hazard zones. In order to provide a basis for comparison between these two approaches, the shape of the membership functions used in the fuzzy methods are the same as the shape of the probability density function used in the Monte Carlo simulation. The case study, concerning an LNG release, illustrates the application of the proposed techniques. 相似文献
366.
Wim Bonckaert Adam Tofilski Fabio S. Nascimento Johan Billen Francis L. W. Ratnieks Tom Wenseleers 《Behavioral ecology and sociobiology》2011,65(4):633-640
In insect societies, workers often try to challenge the reproductive monopoly of the queen by laying their own eggs. Successful
worker reproduction, however, is frequently prevented by queen policing or worker policing, whereby either the mother queen
or non-reproductive workers selectively kill worker-laid eggs. Recently, a third mechanism—“selfish” worker policing—has also
been described in which the workers selectively police worker-laid eggs but also lay eggs themselves. Here, we present results
from the monogynous wasp Dolichovespula norwegica, which show that all three kinds of policing—queen policing, worker policing and “selfish” worker policing—co-occur. The
net effect of these three kinds of policing collectively favoured the queen’s reproduction, as within 1 day 44% of the worker-laid
eggs versus only 8% of the queen-laid eggs were eaten. Of the worker-laid eggs that were killed by workers, approximately
two thirds were eaten by the reproductive workers even though these made up only a small proportion, 8%, of the work force.
This means that policing workers obtained both direct fitness benefits as well as indirect (inclusive) fitness. In addition,
we show that worker policing was carried out by a limited, specialised set of workers that was estimated to constitute approximately
one quarter of the whole colony and of which 66% were non-reproductive. 相似文献
367.
M. Kirchner T. Faus-Kessler W. Levy S. Bernhöft A. Zsolnay C. Belis W. Moche M. Uhl K.-W. Schramm 《Environmental pollution (Barking, Essex : 1987)》2009,157(12):3238-3247
In forest soils along vertical profiles located in different parts of the Alps, concentrations of persistent organic pollutants (POPs), namely organochlorine pesticides (OCPs) like dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCH), heptachlor, aldrin, dieldrin and mirex, were measured. Though local characteristics of the sites are influenced by numerous factors like orographic and meteorological parameters, forest stand characteristics and humus parameters, we ascertained a marked vertical increase of concentrations of some organochlorine compounds in the soil. On the basis of climatological values of each site, we found that the contamination increase with altitude can be ascribed to a certain ‘cold condensation effect’. In addition, the perennial atmospheric deposition of POPs is controlled by precipitation. Other key parameters explaining the accumulation of POPs are the soil organic carbon stocks, the turnover times, the re-volatilisation and degradation processes, which vary with altitude. 相似文献
368.
Kari E. Gunson Anthony P. Clevenger Adam T. Ford John A. Bissonette Amanda Hardy 《Environmental management》2009,44(2):268-277
Wildlife-vehicle collisions (WVCs) pose a significant safety and conservation concern in areas where high-traffic roads are
situated adjacent to wildlife habitat. Improving transportation safety, accurately planning highway mitigation, and identifying
key habitat linkage areas may all depend on the quality of WVC data collection. Two common approaches to describe the location
of WVCs are spatially accurate data derived from global positioning systems (GPS) or vehicle odometer measurements and less
accurate road-marker data derived from reference points (e.g., mile-markers or landmarks) along the roadside. In addition,
there are two common variable types used to predict WVC locations: (1) field-derived, site-specific measurements and (2) geographic
information system (GIS)-derived information. It is unclear whether these different approaches produce similar results when
attempting to identify and explain the location of WVCs. Our first objective was to determine and compare the spatial error
found in road-marker data (in our case the closest mile-marker) and landmark-referenced data. Our second objective was to
evaluate the performance of models explaining high- and low-probability WVC locations, using congruent, spatially accurate
(<3-m) and road-marker (<800-m) response variables in combination with field- and GIS-derived explanatory variables. Our WVC
data sets were comprised of ungulate collisions and were located along five major roads in the central Canadian Rocky Mountains.
We found that spatial error (mean ± SD) was higher for WVC data referenced to nearby landmarks (516 ± 808 m) than for data
referenced to the closest mile-marker data (401 ± 219 m). The top-performing model using the spatially accurate WVC locations
contained all explanatory variable types, whereas GIS-derived variables were only influential in the best road-marker model
and the spatially accurate reduced model. Our study showed that spatial error and sample size, using road-marker data for
ungulate species, are important to consider for model output interpretation, which will impact the appropriate scale on which
to apply modeling results. Using road-marker references <1.6 km or GPS-derived data locations may represent an optimal compromise
between data acquisition costs and analytical performance.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
369.
Jason W. Kelsey Ilya B. Slizovskiy Richard D. Peters Adam M. Melnick 《Environmental pollution (Barking, Essex : 1987)》2010,158(6):2251-2257
Laboratory experiments were conducted to assess the effects of soil sterilization on the bioavailability of spiked p,p′-DDE and anthracene to the earthworms Eisenia fetida and Lumbricus terrestris. Physical and chemical changes to soil organic matter (SOM) induced by sterilization were also studied. Uptake of both compounds added after soil was autoclaved or gamma irradiated increased for E. fetida. Sterilization had no effect on bioaccumulation of p,p′-DDE by L. terrestris, and anthracene uptake increased only in gamma-irradiated soils. Analyses by FT-IR and DSC indicate sterilization alters SOM chemistry and may reduce pollutant sorption. Chemical changes to SOM were tentatively linked to changes in bioaccumulation, although the effects were compound and species specific. Artifacts produced by sterilization could lead to inaccurate risk assessments of contaminated sites if assumptions derived from studies carried out in sterilized soil are used. Ultimately, knowledge of SOM chemistry could aid predictions of bioaccumulation of organic pollutants. 相似文献
370.
Justin S. Rogers Kenneth W. Potter Adam R. Hoffman John A. Hoopes Chin H. Wu David E. Armstrong 《Journal of the American Water Resources Association》2009,45(3):628-640
Abstract: In 2006, we collected flow, sediment, and phosphorus (P) data at stream locations upstream and downstream of a small degraded wetland in south‐central Wisconsin traversed by a stream draining a predominantly agricultural watershed. The amount of sediment that left the wetland in the two largest storms, which accounted for 96% of the exported sediment during the observation period, was twice the amount that entered the wetland, even though only 50% of the wetland had been inundated. This apparently anomalous result is due to erosion of sediment that had accumulated in the low‐gradient channel and to the role of drainage ditches, which trapped sediment during the wetland‐filling phase. In the case of total P, the inflow to the wetland approximately equaled the outflow, although the wetland sequestered 30% of the incoming dissolved reactive P. The discrepancy is almost certainly due to net export of sediment. Many wetlands in the glaciated midwestern United States are ditched and traversed by low‐gradient channels draining predominantly agricultural areas, so the processes observed in this wetland are likely to be common in that region. Knowledge of this behavior presents opportunities to improve water quality in this and similar regions. 相似文献