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591.
592.
Walter D. Koenig Eric L. Walters Joey Haydock 《Behavioral ecology and sociobiology》2011,65(12):2229-2238
Social dominance confers potential advantages in terms of access to superior resources, habitats, and breeding opportunities.
In the cooperatively breeding acorn woodpecker (Melanerpes formicivorus), within-brood dominance among juveniles is correlated with relative body size as nestlings. Capitalizing on this relationship,
we investigated the fitness consequences of dominance by means of paired comparisons of broodmates. We found that (1) larger
fledglings retained at least some of their size advantage as adults; (2) overwinter survival of larger, dominant fledglings
was significantly greater than subordinates, but was not relatively greater when resources were poor than when they were good;
(3) among birds surviving their first winter, there were no differences vis-à-vis dominance in terms of the proportion of
birds acting as helpers or inheriting their natal territory. However, larger, dominant males were present in the study area
longer than subordinates, suggesting that they either survived better or were more successful at gaining reproductive opportunities;
(4) if only one male broodmate became a helper instead of dispersing, he was significantly more likely to be the smaller subordinate,
consistent with the view that helping is a best-of-a-bad-job strategy; and (5) there were no significant differences in reproductive
success among pairs of male broodmates that cobred together as adults, consistent with prior work failing to detect a phenotypic
correlation of reproductive skew. Our results indicate that within-brood dominance relationships established as juveniles
have significant effects on first-year survivorship and at least some aspects of adult fitness. 相似文献
593.
Thimonier A Kull P Keller W Moser B Wohlgemuth T 《Environmental monitoring and assessment》2011,174(1-4):47-63
At Swiss long-term forest ecosystem research sites, ground vegetation was assessed during the period 1994-2003/2008 following two approaches: (1) visual assessment of the cover of species occurring in sixteen 1 m(2) quadrats, distributed over a 43 × 43 m area, and (2) phytosociological relevés in concentric circular plots of 30, 200, and 500 m(2). We first compared the two approaches with respect to diversity assessment. The number of species recorded in the 16 quadrats was in general higher than in the 30 m(2) plot and it represented 42% to 108% of the number of species recorded in the 500 m(2) plot. In a second step, we tested whether any temporal trends were apparent. In a few cases, a decrease or increase in Landolt's mean indicator values for light, nitrogen availability, soil pH, soil moisture, or temperature was found to be significant. However, these changes were usually restricted to one approach or one area. The only clear trend was detected in an unmanaged former coppice beech stand, for which all survey approaches indicated canopy closure. At another site, vegetation reacted to the local opening of the canopy following windthrow. In a third step, we compared the leaf area index (LAI), measured with an LAI-2000 instrument (Licor, Inc.) over each quadrat, with the indicator value of the vegetation for light (L). Within a site, there was no clear relationship between LAI and L values per quadrat. In contrast, across all sites, the relationship between LAI and L, averaged per site for all available years, was highly significant. 相似文献
594.
Gabriela Rosiles-González Gerardo Ávila-Torres Oscar A. Moreno-Valenzuela Gilberto Acosta-González Rosa María Leal-Bautista Cinthya D. Grimaldo-Hernández Judith K. Brown Cristóbal Chaidez-Quiroz Walter Q. Betancourt Charles P. Gerba Cecilia Hernández-Zepeda 《Food and environmental virology》2017,9(4):487-497
The Yucatan Peninsula of Mexico hosts a karst aquifer system that is the only source of freshwater for the area; however, it is vulnerable to human-mediated contamination. Pepper mild mottle virus (PMMoV) is one of the most abundant RNA viruses associated with human feces, making it a viable indicator for tracking fecal pollution in aquatic environments, including groundwater. In this study, groundwater samples collected from a karst aquifer from fresh and brackish water locations were analyzed for fecal indicator bacteria, somatic and male F+ specific coliphages, and PMMoV during the rainy and dry seasons. Total coliform bacteria were detected at all sites, whereas Escherichia coli were found at relatively low levels <40 MPN/100 ml. The highest average concentrations of somatic and male F+ specific coliphages were 920 and 330 plaque forming units per 100 ml, respectively, detected in freshwater during the rainy season. PMMoV RNA was detected in 85% of the samples with gene sequences sharing 99–100% of nucleotide identity with PMMoV sequences available in GenBank. Quantification of PMMoV genome copies (GC) by quantitative real-time PCR indicated concentrations ranging from 1.7 × 101 to 1.0 × 104 GC/L, with the highest number of GC detected during the rainy season. No significant correlation was observed between PMMoV occurrence by season or water type (p > 0.05). Physicochemical and indicator bacteria were not correlated with PMMoV concentrations. The abundance and prevalence of PMMoV in the karst aquifer may reflect its environmental persistence and its potential as a fecal indicator in this karst aquifer system. 相似文献
595.
596.
Based on the results from detailed structural and petrological characterisation and on up-scaled laboratory values for sorption and diffusion, blind predictions were made for the STT1 dipole tracer test performed in the Swedish Äspö Hard Rock Laboratory. The tracers used were nonsorbing, such as uranine and tritiated water, weakly sorbing 22Na+, 85Sr2+, 47Ca2+and more strongly sorbing 86Rb+, 133Ba2+, 137Cs+.Our model consists of two parts: (1) a flow part based on a 2D-streamtube formalism accounting for the natural background flow field and with an underlying homogeneous and isotropic transmissivity field and (2) a transport part in terms of the dual porosity medium approach which is linked to the flow part by the flow porosity.The calibration of the model was done using the data from one single uranine breakthrough (PDT3). The study clearly showed that matrix diffusion into a highly porous material, fault gouge, had to be included in our model evidenced by the characteristic shape of the breakthrough curve and in line with geological observations.After the disclosure of the measurements, it turned out that, in spite of the simplicity of our model, the prediction for the nonsorbing and weakly sorbing tracers was fairly good. The blind prediction for the more strongly sorbing tracers was in general less accurate. The reason for the good predictions is deemed to be the result of the choice of a model structure strongly based on geological observation. The breakthrough curves were inversely modelled to determine in situ values for the transport parameters and to draw consequences on the model structure applied. For good fits, only one additional fracture family in contact with cataclasite had to be taken into account, but no new transport mechanisms had to be invoked. The in situ values for the effective diffusion coefficient for fault gouge are a factor of 2–15 larger than the laboratory data. For cataclasite, both data sets have values comparable to laboratory data. The extracted Kd values for the weakly sorbing tracers are larger than Swedish laboratory data by a factor of 25–60, but agree within a factor of 3–5 for the more strongly sorbing nuclides. The reason for the inconsistency concerning Kds is the use of fresh granite in the laboratory studies, whereas tracers in the field experiments interact only with fracture fault gouge and to a lesser extent with cataclasite both being mineralogically very different (e.g. clay-bearing) from the intact wall rock. 相似文献
597.
Sanchez-Azofeifa G. Arturo Skole David L. Chomentowski Walter 《Mitigation and Adaptation Strategies for Global Change》1997,2(2-3):177-189
One of the concerns regarding transformation of land cover in tropical areas has been the large degree of uncertainty associated with both rates of deforestation over time and total deforestation. Special monitoring mechanisms must be taken into consideration if a program toward deforestation control is going to be implemented at the national or regional scale. The premise of this paper is that any attempt to quantify tropical deforestation and deforestation rates—at regional level, by randomly selecting sites within a population of satellite scenes—would require an overwhelming number of samples. This paper suggests a methodological approach for sampling remote sensing databases to be used as part of land use/cover change or joint implementation projects. This paper uses the concept of stratification and persistence as main tools. 相似文献
598.
This paper is concerned with stimulating debate amongst land-use planning practitioners and researchers in relation to the possible consequences of the European Union Water Framework Directive. The potentially far-reaching ramifications for the Town and Country Planning system in England and Wales are examined in detail, presenting the case that planning, at all spatial scales, may have to give both water and environmental concerns greater consideration than has hitherto been the case. Furthermore, in the imminent future the planning system will need to begin the process of formulating policies in line with the aspirations of the Directive. 相似文献
599.
Joe Weston 《Journal of Environmental Planning and Management》2000,43(2):185-203
As an aid to decision making Environmental Impact Assessment (EIA) is seen as a rational and systematic process which is often held to be holistic and proactive in its approach to environmental protection (Glasson et al., 1999). The roots of EIA are firmly located within the 1960s' demand for a more systematic and objective approach to environmental decision making and hence within the rationalist model of decision making theory. This paper examines the key stages of the EIA process to assess how far EIA conforms to the rationalist model today. Most research in EIA decision making has focused on the project authorization process and not the crucial decisions made at the earlier stages of screening and scoping. This study examines those early stages within the context of UK EIA practice. From this examination the paper attempts to locate EIA within decision-making theory. 相似文献
600.