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301.
Paula A. White 《Behavioral ecology and sociobiology》2008,62(3):377-361
Among spotted hyenas, Crocuta crocuta, neonatal aggression in twins is a well-known phenomenon and serves to establish intra-litter dominance soon after birth.
As the stronger more aggressive cub presumably attains dominance over its twin, intra-litter dominance presents mothers with
an ideal opportunity to assess individual cub fitness and, thereafter, to selectively favor one cub over the other. This study
quantified maternal response to sibling conflict in 26 sets of twins born to 16 wild-living females to determine whether mothers
of different social ranks exhibited favoritism towards sons or daughters, or in the case of same-sex twins, the dominant or
subordinate cub. Maternal response to sibling conflict did not vary with litter sex composition, suggesting that mothers do
not favor offspring of one sex over the other. All mothers intervened when their cubs fought and sometimes punished their
cubs. Higher-ranking mothers more often punished both cubs, while lower-ranking mothers were more selective and punished the
dominant cub. Where sibling aggression was most extreme, rather than favor the dominant sibling, mothers of all ranks made
concessions to the subordinate cub that included procuring private nursing bouts for the subordinate and temporarily housing
twins in separate dens, presumably to decrease sibling conflict. These findings represent a complex example of parent–offspring
conflict and support both the insurance cub hypothesis and resource tracking hypothesis that mothers endeavor to keep all
offspring alive for as long as possible in the event that the dominant sibling dies or that resources provide for the rearing
of twins.
This contribution is part of the special issue “Sibling competition and cooperation in mammals” (guest editors: Robyn Hudson
and Fritz Trillmich). 相似文献
302.
303.
Marco Antonio Leonel Caetano Douglas Francisco Marcolino Gherardi Gustavo de Paula Ribeiro Takashi Yoneyama 《Ecological modelling》2009,220(19):2536-2542
The recent global financial crisis has highlighted the need for balanced and efficient investments in the reduction of the greenhouse effect caused by emissions of CO2 on a global scale. In a previous paper, the authors proposed a mathematical model describing the dynamic relation of CO2 emission with investment in reforestation and clean technology. An efficient allocation of resources to reduce the greenhouse effect has also been proposed. Here, this model is used to provide estimates of the investments needed in land reforestation and in the adoption of clean technologies for an optimum emission and abatement of CO2, for the period of 1996–2014. The required investments are computed to minimize deviations with respect to the emission targets proposed in the Kyoto Protocol for European Countries. The emission target can be achieved by 2014 with investments in reforestation peaking in 2004, and a reduction of the expected GDP of 42%, relative to 2006. Investments in clean technology should increase between 2008 and 2010 with maximum transfer figures around 70 million American dollars. Total (cumulative) costs are, however, relatively high depending on the price of carbon abatement and the rate at which the expected CO2 concentration in the atmosphere should be reduced. Results highlight the advantages for policy makers to be able to manage investments in climate policy more efficiently, controlling optimum transfers based on a portfolio of actions that tracks a pre-defined CO2 concentration target. 相似文献
304.
Pius Lee Youhua Tang Daiwen Kang Jeff McQueen Marina Tsidulko Ho-Chun Huang Sarah Lu Mary Hart Hsin-Mu Lin Shaocai Yu Geoff DiMego Ivanka Stajner Paula Davidson 《Environmental Fluid Mechanics》2009,9(1):23-42
Discrepancies in grid structure, dynamics and physics packages in the offline coupled NWS/NCEP NAM meteorological model with
the U.S. Environmental Protection Agency Community Multiscale Air Quality (CMAQ) model can give rise to inconsistencies. This
study investigates the use of three vertical mixing schemes to drive chemistry tracers in the National Air Quality Forecast
Capability (NAQFC). The three schemes evaluated in this study represent various degrees of coupling to improve the commonality
in turbulence parameterization between the meteorological and chemistry models. The methods tested include: (1) using NAM
predicted TKE-based planetary boundary height, h, as the prime parameter to derive CMAQ vertical diffusivity; (2) using the NAM mixed layer depth to determine h and then proceeding as in (1); and (3) using NAM predicted vertical diffusivity directly to parameterize turbulence mixing
within CMAQ. A two week period with elevated surface O3 concentrations during the summer 2006 has been selected to test these schemes in a sensitivity study. The study results are
verified and evaluated using the EPA AIRNow monitoring network and other ozonesonde data. The third method is preferred a
priori as it represents the tightest coupling option studied in this work for turbulent mixing processes between the meteorological
and air quality models. It was found to accurately reproduce the upper bounds of turbulent mixing and provide the best agreement
between predicted h and ozonesonde observed relative humidity profile inferred h for sites investigated in this study. However, this did not translate into the best agreement in surface O3 concentrations. Overall verification results during the test period of two weeks in August 2006, did not show superiority
of this method over the other 2 methods in all regions of the continental U.S. Further efforts in model improvement for the
parameterizations of turbulent mixing and other surface O3 forecast related processes are warranted. 相似文献
305.
Top predators are critical to ecosystem function, exerting a stabilising effect on the food web. Brown skuas are opportunistic predators and scavengers. Although skuas are often the dominant land-based predator at seabird colonies, this is the first detailed study of their movements and activity during breeding. The study was carried out at Bird Island, South Georgia (54°00′S, 38°03′W), in the austral summer of 2011/2012 and included GPS data from 33 breeding adults tracked during the late incubation and early chick-rearing periods. Brown skuas spent on average more than 80 % of time in the territory, and it was extremely rare for both partners to leave the territory simultaneously. Much more time was spent foraging at the coast than in penguin colonies and, based on saltwater immersion data, adults never foraged at sea. None of the tracked birds appeared to specialise in catching small petrels at night. Fewer foraging trips were made per day, and hence, more time was spent in the territory, during incubation than chick-rearing. Despite the pronounced sexual size dimorphism, there were no effects of sex on territorial attendance, foraging time or habitat use. Skuas at Bird Island show higher territorial attendance and are less likely to leave the territory unattended than those breeding elsewhere, suggesting closer proximity to more diverse or abundant food resources than at other colonies. The results tie in with previous diet studies, indicating that brown skuas at this site feed mostly on seal placentae and carrion and that birds may rely on a broader range of food resources as the season progresses. 相似文献
306.
Paula Adánez Sanjuán Juan F. Llamas Borrajo Juan Locutura Rupérez Angel García Cortés 《Environmental geochemistry and health》2014,36(6):1129-1150
Overbank and stream sediments have been studied in the Community of Madrid. Four vertical profiles have been sampled corresponding to Guadarrama, Jarama, and finally Manzanares River, where two profiles have been studied upstream (El Pardo profile) and downstream (Rivas profile) Madrid city. Sieved samples (<63 µm) were subjected to total (ICP-MS/ICP-OES and INAA) and partial analysis (ICP-MS). AMS radiocarbon dating techniques revealed a young age (170 ± 40 years BP) at 2.40–2.65 m depth for Rivas profile. It has not been possible to detect pristine or pre-industrial overbank sediments, since in the rest of the studied profiles, anthropogenic wastes were found even in the lower levels. Three main sources of sediment have been detected in the area. Granitic and arkosic geology, located in the northern part of Madrid (U, Th, W, K, Na, or rare earth elements); clays located in the southeast of Madrid (Ni, Cr, or V), and finally an anthropogenic source has been identified (Au, Ag, Pb, Zn, or Sb) in Rivas profile. The influence of the anthropogenic activity has been established based on the contents distribution of contaminant elements in the profile. This can be associated to the growth of industrial activities and population in the city of Madrid during the last decades. The comparison of the profiles by a k-means cluster analysis showed some similarities for these samples that could have analogous sources (anthropogenic and geological). 相似文献
307.
Thalita B. Zanoni Eloísa Silva de Paula Guilherme Julião Zocolo Maria Valnice B. Zanoni Danielle Palma de Oliveira 《毒物与环境化学》2013,95(9):1506-1517
Incubation of guanosine and Sudan III induces the formation of a stable adduct, which may be identified using a spectrophotometric technique and mass spectroscopy. The high nucleophilicity of the C8 position and its proximity to N7 makes the site susceptible to a nucleophilic attack, which explains the SN2 reaction detected between guanosine and Sudan III dye. In addition, direct interaction of Sudan III with calf thymus DNA was monitored using a simple spectrophotometric technique. The results presented indicate that a simple modification of the chemical structure of Sudan I (monoazo dye) to Sudan III (diazo dye) markedly alters reactivity towards nitrogenous DNA bases. 相似文献
308.
Ivan Holoubek Jaakko Paasivirta Paula Maatela Mirja Lahtiperä Irena Holoubková Pavel Korínek 《毒物与环境化学》2013,95(2-3):137-154
Different sample preparation methods for the determination of polycyclic aromatic hydrocarbons (PAHs) in lake and river sediments were compared and evaluated. Freeze‐dried sediment materials were extracted using Soxhlet extraction, ultrasonic agitation and digestion with various solvents and solvent mixtures. Similarly, clean‐up methods using various types of sorbents for separation of PAHs tested. The following method gives the best results for the determination of PAHs: freeze‐dried sediment samples were extracted using Soxhlet extractor with dichloromethane (6 hr, dark), extracts were cleanup using Silica gel and a mixture of n‐hexa‐ne‐dichloromethane was used for the elution of PAHs. This method was used for the determination of 7 selected PAHs in sediment samples from Finnish lakes and Czech streams. 相似文献
309.
Phylogeographic patterns in Uca annulipes sampled from 30 locations across an East African latitudinal gradient were investigated using mitochondrial DNA cytochrome
oxidase I sequences and analysed together with patterns of morphometric differentiation. Four hundred and four specimens along
the east African coast were sampled, and 18 haplotypes were encountered. Haplotype and nucleotide diversity values were very
low and the phylogenetic analysis did not reveal any clear phylogeographic structure. Furthermore, the analysis of molecular
variance and pairwise Φ
ST values showed no significant spatial population differentiation. Mismatch analyses and tests of neutrality supported the
hypothesis that this species has undergone a fairly recent demographic expansion. Our results, therefore, failed to demonstrate
significant geographical structure in the pattern of genetic variation, indicating that populations of U. annulipes are capable of extensive gene flow among mangroves along the coast. The genetic structure of this species could be panmictic
due to a high amount of gene flow along the geographical gradient in study during the planktonic larval phase, when larvae
are carried along stream by the dominant currents. Moreover, the morphometric analysis performed did not reveal differences
of shape differentiation according to a geographical pattern, although significant differences among the sampling areas were
found. 相似文献
310.
Sofia Gamito Paula Chainho João Paulo Medeiros João Carlos Marques 《Ecological modelling》2010,221(3):459-466
The brackish water amphipod Corophium orientale is the dominant macroinvertebrate species in the upper Mira estuary, a small mesotidal system located in the southwest coast of Portugal. As climate changes will increase the frequency and intensity of extreme events such as floods and droughts, these will have a negative effect on benthic estuarine invertebrates, namely C. orientale. In order to understand the effects of these events on C. orientale, a dynamic model, based on published information and calibrated with field data, was developed and different scenarios were tested.For model construction, the annual development of three cohorts of C. orientale, their growth rates, and the establishment of the timing of each cohort rise and extinction are introduced. This structure can be repeated indefinitely, for years, and few parameters are required. The model simulations highlight the need for refuge areas that enable a fast recovery of the amphipod population after an extreme event and the recolozination of the affected areas. 相似文献