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The UK population of the Spotted Flycatcher Muscicapa striata has declined markedly in the last 30 years but there have been few recent studies of the species. This study examined the relationship between nest success and the predominant habitat type around Spotted Flycatcher nests in two contrasting areas of England. A breeding population in eastern England, a region where numbers of Spotted Flycatchers are known to have decreased dramatically in recent decades, was compared with another in southwest England, where numbers have remained stable or even increased. Whilst there was no difference in breeding success between the two study areas, there were significant differences between habitats, with garden nests more successful than those in farmland or woodland, at both egg and chick stages. Estimates of productivity per nesting attempt were also lower in farmland and woodland, with nests in gardens fledging twice as many chicks as those in either woodland or farmland. The proximate cause of lower success in farmland and woodland was higher nest predation rates during both egg and chick stages. In terms of nesting success, farmland and woodland appear to be similar in quality for this species, but both appear to be suboptimal habitats when compared with gardens, providing evidence of a problem on the breeding grounds for this species, in at least these two habitats. 相似文献
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OLIVIER BROENNIMANN WILFRIED THUILLER†‡ GREG HUGHES‡§ GUY F. MIDGLEY‡ J. M. ROBERT. ALKEMADE§ ANTOINE GUISAN 《Global Change Biology》2006,12(6):1079-1093
We modelled the future distribution in 2050 of 975 endemic plant species in southern Africa distributed among seven life forms, including new methodological insights improving the accuracy and ecological realism of predictions of global changes studies by: (i) using only endemic species as a way to capture the full realized niche of species, (ii) considering the direct impact of human pressure on landscape and biodiversity jointly with climate, and (iii) taking species' migration into account. Our analysis shows important promises for predicting the impacts of climate change in conjunction with land transformation. We have shown that the endemic flora of Southern Africa on average decreases with 41% in species richness among habitats and with 39% on species distribution range for the most optimistic scenario. We also compared the patterns of species' sensitivity with global change across life forms, using ecological and geographic characteristics of species. We demonstrate here that species and life form vulnerability to global changes can be partly explained according to species' (i) geographical distribution along climatic and biogeographic gradients, like climate anomalies, (ii) niche breadth or (iii) proximity to barrier preventing migration. Our results confirm that the sensitivity of a given species to global environmental changes depends upon its geographical distribution and ecological proprieties, and makes it possible to estimate a priori its potential sensitivity to these changes. 相似文献
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We have studied four strains of Tetrahymena thermophila , each of which expresses a different allele of the SerH gene and produces a distinctive surface protein of the immobilization antigen (i-antigen) class. Following exposure of the strains to [3 H]ethanolamine or [3 H]myristic acid, a protein corresponding in molecular mass to the characteristic i-antigen for that strain became highly labeled, as determined by mobility in sodium dodecylsulfate-polyacrylamide eiectrophoresis gels. Furthermore, antibodies raised to the i-antigens of the T. thermophila strains selectively immunoprecipitated radioactive proteins having molecular mass identical to that of the i-antigen characteristic for that particular strain. The lipid moieties labeled by [3 H]myristate were not susceptible to hydrolysis by exogenous phosphatidylinositol-specific phospholipase C from bacteria. However, when protein extraction was carried out in the absence of phospholipase C inhibitors, radioactive fatty acids derived from [3 H]myristate were rapidly cleaved from the putative i-antigens. On the basis of available data, it was concluded that T. thermophila i-antigens contain covalently-Iinked glycosyl-phospha-tidylinositol anchors. 相似文献
76.
A, assimilation ratea, fractionation against 13C for CO2 diffusion through airb, net fractionation against 13C during CO2 fixationCa, ambient CO2 concentrationCc, CO2 concentration at the chloroplastCi, intercellular CO2 concentrationD, vapour pressure deficitEn, needle transpiration rateEp, whole plant water usegw, leaf internal transfer conductance to CO2gs, stomatal conductance to water vapourL, projected leaf areaNUE, nitrogen use efficiencyPEP, phosphoenolpyruvateRubisco, ribulose-1,5-biphosphate carboxylaseTDR, time domain reflectometryWUE, water use efficiencyΔ, carbon isotope discriminationδ13C, carbon isotope abundance parameterδ13Ca, carbon isotopic composition of atmospheric CO2θ, volumetric soil water contentThe effect of nitrogen stress on needle δ13C, water-use efficiency (WUE) and biomass production in irrigated and dry land white spruce (Picea glauca (Moench) Voss) seedlings was investigated. Sixteen hundred seedlings, representing 10 controlled crosses, were planted in the field in individual buried sand-filled cylinders. Two nitrogen treatments were imposed, nitrogen stressed and fertilized. The ranking of δ13C of the crosses was maintained across all combinations of water and nitrogen treatments and there was not a significant genetic versus environmental interaction. The positive relationships between needle δ13C, WUE and dry matter production demonstrate that it should be possible to use δ13C as a surrogate for WUE, and to select for increased WUE without compromising yield, even in nitrogen deficient environments. Nitrogen stressed seedlings had the lowest needle δ13C in both irrigated and dry land conditions. There was a positive correlation between needle nitrogen content and δ13C that was likely associated with increased photosynthetic capacity. There was some indication that decreased nitrogen supply led to increased stomatal conductance and hence lower WUE. There was a negative correlation between intrinsic water use efficiency and photosynthetic nitrogen use efficiency (NUE). This suggests that white spruce seedlings have the ability to maximize NUE when water becomes limited. There was significant genetic variation in NUE that was maintained across treatments. Our results suggest that in white spruce, there is no detectable effect of anaplerotic carbon fixation and that it is more appropriate to use a value of 29‰ (‘Rubisco only’) for the net discrimination against 13C during CO2 fixation. This leads to excellent correspondence between values of Ci/Ca derived from gas exchange measurements or from δ13C. 相似文献
77.
The uptake of the non-metabolizable glucose analogue, 2-deoxy-d -glucose (DOG) has been followed in isolated cotyledons of Ricinus communis L. Within 2 min of immersion in a labelled DOG medium, DOG phosphate (DOG-P) was detectable in the tissue. DOG uptake was relatively rapid for 30 min after which it slowed down but nevertheless continued for many hours; DOG was eventually accumulated against a concentration gradient. Internal DOG-P concentration also rose for the first 30 min, but then reached a plateau. The relationship between uptake and external concentration was close to linear during the first hour, and subsequently curvilinear. Analysis of “wash-out” curves indicated that after very rapid exit from the surface and free space of the tissue, the half-time for exit of the remaining 85% of the absorbed DOG was approximately 250 min. By comparison, the half-time for exit of sorbitol was 30 min. No DOG-P could be detected in the wash-out solutions. When cotyledons were transferred to labelled medium after preloading in non-labelled DOG, the specific activity of the internal DOG pool rose faster than that of the DOG-P. Both curves flattened out when their specific activity was less than half that of the external medium. Addition of d -glucose to the medium depressed DOG-P formation, but only when the incubation period was less than 45 min. Arguments are presented for concluding (a) that DOG uptake is mediated by a specific uptake mechanism; (b) that more than one internal DOG pool is involved; and (c) that the observed phosphorylation is not a necessary step in the entry process into either of the pools, whether the latter are in series or in parallel. 相似文献
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DENIS MAGNE PHILIPPE LACUBE ADELA ANGOULVANT LEILA MELIANI FRANCOISE BOTTEREL MARIE-ELISABETH BOUGNOUX CHRISTIAN CHOCHILLON MURIEL CORNET ERIC DANNAOUI ANNICK DATRY JEAN DUNAND GUY GALEAZZI CLAIRE BOUGES-MICHEL HELENE YERA CLAUDINE SARFATI PATRICIA ROUX 《The Journal of eukaryotic microbiology》2006,53(S1):S106-S107