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51.
Martin R. Billingham Tiago Simões Thorsten B. H. Reusch Ester A. Serrão 《Marine Biology》2007,152(4):793-801
The spatial distribution of genetic variability depends on the spatial patterns of clonal and sexual reproduction, gene flow,
genetic drift and natural selection. Species with restricted dispersal may exhibit genetic structuring within populations
with immediate neighbours being close relatives, and may show differentiation among populations. Genetic structuring of a
species may have important genetic, evolutionary and ecological consequences including distance-dependent mating success.
In this study we used microsatellite markers to show that clones of Zostera marina in a population in the Ria Formosa, Portugal, were aggregated and covered distances of up to 3–4 m. Clones within 4 m of
each other exhibited significant and positive coancestry values, reflecting the limited seed dispersal of this species. Hand-pollinations
between near (0–10.9 m), intermediate (11–32 m) and far (15 km) individuals resulted in similar levels of seed set, although
the near pollinations had higher, although not statistically significant, levels of seed abortion during maturation. Seeds
from intermediate-distance pollinations had a significantly higher proportion of seeds germinate and shorter germination time
than both the near and far seeds. Similarly, the average number of seedlings produced per pollination, used as an overall
estimate of fitness, was significantly greater for the intermediate distance when compared to both near and far pollinations.
These results suggest that the genetic structuring observed may result in both inbreeding and outbreeding depression, which
gives rise to an intermediate optimal outcrossing distance. 相似文献
52.
A new methodology to evaluate the overall environmental hazard of unknown mixtures, based on bioconcentration potential and toxicity, was developed using a combination of two methodologies: 1) the estimation of the octanol-water partition coefficient (K(ow)) using reverse-phase high performance liquid chromatography (RP-HPLC) and 2) the toxicity identification evaluation (TIE). Forty seven compounds with known K(ow) and different molecular structures where used for the calibration of the log K(ow) in relation to the retention time in reverse-phase high performance liquid chromatography (RP-HPLC). A linear regression with an R(2)=0.81 and an sd=0.69 was established between log K(ow) and RP-HPLC retention time. This K(ow) estimation method was furthermore validated using seven additional compounds, showing acceptable estimations of the log K(ow) of unknown substances. Two different mixtures were tested, one containing 3,4 Dichloroaniline, Diazinon and 4-Nonylphenol and another one containing a mixture of 16 pesticides. Both mixtures were first tested as a whole effluent and then fractionated and tested, using a miniaturized Daphnia magna test. An equation is presented, that combines both methodologies and establishes a relative hazard index RHI, ranging from 1 to 10 for any particular mixture of chemicals. The results show how the method presented can refine the security factors that could be included in the environmental risk assessment of effluents in the future. 相似文献
53.
Marco Antonio DS Guidugli-Lazzarini KR do Nascimento AM Simões ZL Hartfelder K 《Die Naturwissenschaften》2008,95(10):953-961
The switch from within-hive activities to foraging behavior is a major transition in the life cycle of a honeybee (Apis mellifera) worker. A prominent regulatory role in this switch has long been attributed to juvenile hormone (JH), but recent evidence
also points to the yolk precursor protein vitellogenin as a major player in behavioral development. In the present study,
we injected vitellogenin double-stranded RNA (dsVg) into newly emerged worker bees of Africanized genetic origin and introduced them together with
controls into observation hives to record flight behavior. RNA interference-mediated silencing of vitellogenin gene function shifted the onset of long-duration flights (>10 min) to earlier in life (by 3–4 days) when compared with sham
and untreated control bees. In fact, dsVg bees were observed conducting such flights extremely precociously, when only 3 days
old. Short-duration flights (<10 min), which bees usually perform for orientation and cleaning, were not affected. Additionally,
we found that the JH titer in dsVg bees collected after 7 days was not significantly different from the controls. The finding
that depletion of the vitellogenin titer can drive young bees to become extremely precocious foragers could imply that vitellogenin
is the primary switch signal. At this young age, downregulation of vitellogenin gene activity apparently had little effect on the JH titer. As this unexpected finding stands in contrast with previous results
on the vitellogenin/JH interaction at a later age, when bees normally become foragers, we propose a three-step sequence in
the constellation of physiological parameters underlying behavioral development.
David Santos Marco Antonio and Karina Rosa Guidugli-Lazzarini contributed equally to the present study. 相似文献
54.
Pedro Simões Kristof De Witte Rui Cunha Marques 《Waste management (New York, N.Y.)》2010,30(6):1130-1137
This research computes the influence of the operational environment on the efficiency of the Portuguese urban solid waste services. A sample of 29 solid waste utilities encompassing the whole continental country was used for this purpose. Particularly, we apply the non-parametric double bootstrap model to estimate the effect of various explanatory factors on robust data envelopment analysis estimates. In general, we find a significant influence of the environmental context on the solid waste utilities’ performance. The environmental context is characterized by gross domestic product per capita, distance to treatment facilities, population density, regulation, type of management, composting and incineration services. 相似文献
55.
Ricardo Lavandier Natalia Quinete Rachel Ann Hauser-Davis Patrick Simões Dias Satie Taniguchi Rosalinda Montone Isabel Moreira 《Chemosphere》2013,90(9):2435-2443
Polychlorinated biphenyls (PCBs) and Polybrominated Diphenyls Ethers (PBDEs) are two highly lipophilic classes of persistent organic pollutants able to resist degradation and with the ability to bioaccumulate through the food chain. In Brazil, there are still few studies on PCBs and PBDEs in aquatic organisms. In this study, we determined the levels of PBDEs and PCBs in three different fish species from the Ilha Grande Bay, located in the southern state of Rio de Janeiro, Brazil. PBDEs levels were very low, with values below the limit of quantification. PCBs concentrations ranged from 2.29 to 27.60 ng g?1 ww in muscle and from 3.41 to 34.22 ng g?1 ww in liver of the three investigated fish species. Significant positive correlations were established between PCBs concentration and fish biometric variables in mullet (length and lipid content) and a statistically significant change between seasons in croaker was observed. 相似文献
56.
Aliste Marina Pérez-Lucas Gabriel Vela Nuria Garrido Isabel Fenoll José Navarro Simón 《Environmental science and pollution research international》2020,27(7):7222-7233
Environmental Science and Pollution Research - We have demonstrated the potential leaching of eight compounds, one insecticide (flonicamid) and seven fungicides (myclobutanil, penconazole,... 相似文献
57.
Teodoro Filipe Simões Soares Liliane Catone Filgueiras Jefferson Gonçalves de Azevedo Eduardo Ribeiro Patiño-Agudelo Álvaro Javier Adarme Oscar Fernando Herrera da Silva Luis Henrique Mendes Gurgel Leandro Vinícius Alves 《Environmental science and pollution research international》2022,29(18):26425-26448
Environmental Science and Pollution Research - A new one-pot synthesis method optimized by a 23 experimental design was developed to prepare a biosorbent, sugarcane bagasse cellulose succinate... 相似文献
58.
Multi-process herbicide transport in structured soil columns: experiments and model analysis 总被引:3,自引:0,他引:3
Model predictions of pesticide transport in structured soils are complicated by multiple processes acting concurrently. In this study, the hydraulic, physical, and chemical nonequilibrium (HNE, PNE, and CNE, respectively) processes governing herbicide transport under variably saturated flow conditions were studied. Bromide (Br-), isoproturon (IPU, 3-(4-isoprpylphenyl)-1,1-dimethylurea) and terbuthylazine (TER, N2-tert-butyl-6-chloro-N4-ethyl-1,3,5-triazine-2,4-diamine) were applied to two soil columns. An aggregated Ap soil column and a macroporous, aggregated Ah soil column were irrigated at a rate of 1 cm h(-1) for 3 h. Two more irrigations at the same rate and duration followed in weekly intervals. Nonlinear (Freundlich) equilibrium and two-site kinetic sorption parameters were determined for IPU and TER using batch experiments. The observed water flow and Br- transport were inversely simulated using mobile-immobile (MIM), dual-permeability (DPM), and combined triple-porosity (DP-MIM) numerical models implemented in HYDRUS-1D, with improving correspondence between empirical data and model results. Using the estimated HNE and PNE parameters together with batch-test derived equilibrium sorption parameters, the preferential breakthrough of the weakly adsorbed IPU in the Ah soil could be reasonably well predicted with the DPM approach, whereas leaching of the strongly adsorbed TER was predicted less well. The transport of IPU and TER through the aggregated Ap soil could be described consistently only when HNE, PNE, and CNE were simultaneously accounted for using the DPM. Inverse parameter estimation suggested that two-site kinetic sorption in inter-aggregate flow paths was reduced as compared to within aggregates, and that large values for the first-order degradation rate were an artifact caused by irreversible sorption. Overall, our results should be helpful to enhance the understanding and modeling of multi-process pesticide transport through structured soils during variably saturated water flow. 相似文献
59.
Jacques D Simůnek J Mallants D van Genuchten MT 《Journal of contaminant hydrology》2006,88(3-4):197-218
One possible way of integrating subsurface flow and transport processes with (bio)geochemical reactions is to couple by means of an operator-splitting approach two completely separate codes, one for variably-saturated flow and solute transport and one for equilibrium and kinetic biogeochemical reactions. This paper evaluates the accuracy of the operator-splitting approach for multicomponent systems for typical soil environmental problems involving transient atmospheric boundary conditions (precipitation, evapotranspiration) and layered soil profiles. The recently developed HP1 code was used to solve the coupled transport and chemical equations. For steady-state flow conditions, the accuracy was found to be mainly a function of the adopted spatial discretization and to a lesser extent of the temporal discretization. For transient flow situations, the accuracy depended in a complex manner on grid discretization, time stepping and the main flow conditions (infiltration versus evaporation). Whereas a finer grid size reduced the numerical errors during steady-state flow or the main infiltration periods, the errors sometimes slightly increased (generally less than 50%) when a finer grid size was used during periods with a high evapotranspiration demand (leading to high pressure head gradients near the soil surface). This indicates that operator-splitting errors are most significant during periods with high evaporative boundary conditions. The operator-splitting errors could be decreased by constraining the time step using the performance index (the product of the grid Peclet and Courant numbers) during infiltration, or the maximum time step during evapotranspiration. Several test problems were used to provide guidance for optimal spatial and temporal discretization. 相似文献
60.
Romain Amiot Delphine Angst Serge Legendre Eric Buffetaut François Fourel Jan Adolfssen Aurore André Ana Voica Bojar Aurore Canoville Abel Barral Jean Goedert Stanislaw Halas Nao Kusuhashi Ekaterina Pestchevitskaya Kevin Rey Aurélien Royer Antônio Álamo Feitosa Saraiva Bérengère Savary-Sismondini Jean-Luc Siméon Alexandra Touzeau Zhonghe Zhou Christophe Lécuyer 《Die Naturwissenschaften》2017,104(5-6):47
Oxygen isotope compositions of bone phosphate (δ18Op) were measured in broiler chickens reared in 21 farms worldwide characterized by contrasted latitudes and local climates. These sedentary birds were raised during an approximately 3 to 4-month period, and local precipitation was the ultimate source of their drinking water. This sampling strategy allowed the relationship to be determined between the bone phosphate δ18Op values (from 9.8 to 22.5‰ V-SMOW) and the local rainfall δ18Ow values estimated from nearby IAEA/WMO stations (from ?16.0 to ?1.0‰ V-SMOW). Linear least square fitting of data provided the following isotopic fractionation equation: δ18Ow = 1.119 (±0.040) δ18Op ? 24.222 (±0.644); R 2 = 0.98. The δ18Op–δ18Ow couples of five extant mallard ducks, a common buzzard, a European herring gull, a common ostrich, and a greater rhea fall within the predicted range of the equation, indicating that the relationship established for extant chickens can also be applied to birds of various ecologies and body masses. Applied to published oxygen isotope compositions of Miocene and Pliocene penguins from Peru, this new equation computes estimates of local seawater similar to those previously calculated. Applied to the basal bird Confuciusornis from the Early Cretaceous of Northeastern China, our equation gives a slightly higher δ18Ow value compared to the previously estimated one, possibly as a result of lower body temperature. These data indicate that caution should be exercised when the relationship estimated for modern birds is applied to their basal counterparts that likely had a metabolism intermediate between that of their theropod dinosaur ancestors and that of advanced ornithurines. 相似文献