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41.
ANTHONY RAVEL LAURENT MARIVAUX RODOLPHE TABUCE MUSTAPHA BEN HAJ ALI EL MABROUK ESSID MONIQUE VIANEY‐LIAUD 《Palaeontology》2012,55(5):1035-1041
Abstract: Among the new dental remains from the late Early Eocene of Chambi (Kasserine area, Tunisia) is a large‐sized upper molar of a new bat species, Witwatia sigei nov. sp. (Chiroptera, Vespertilionoidea, Philisidae), described herein. The locality of Chambi has revealed evidence for an early appearance of two modern microchiropteran superfamilies in Africa: Dizzya exsultans, a Philisidae, which is considered to be an archaic Vespertilionoidea, and an indeterminate Rhinolophoidea. In addition to D. exsultans, the new species, W. sigei, is the second representative of the Philisidae in this locality. W. sigei extends back to the late Early Eocene the occurrence of the genus Witwatia, which was previously only reported from the early Late Eocene of the Fayum (BQ‐2, Egypt). By analogy with the largest extant microbats, the large size of Witwatia suggests a tendency to the opportunistic diet of this taxon, thereby contrasting with the strict insectivory characterizing primitive bats found in other continents in the same epoch. 相似文献
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An overview of models of stomatal conductance at the leaf level 总被引:4,自引:0,他引:4
GAËLLE DAMOUR THIERRY SIMONNEAU HERVÉ COCHARD LAURENT URBAN 《Plant, cell & environment》2010,33(9):1419-1438
Stomata play a key role in plant adaptation to changing environmental conditions as they control both water losses and CO2 uptake. Particularly, in the context of global change, simulations of the consequences of drought on crop plants are needed to design more efficient and water‐saving cropping systems. However, most of the models of stomatal conductance (gs) developed at the leaf level link gs to environmental factors or net photosynthesis (Anet), but do not include satisfactorily the effects of drought, impairing our capacity to simulate plant functioning in conditions of limited water supply. The objective of this review was to draw an up‐to‐date picture of the gs models, from the empirical to the process‐based ones, along with their mechanistic or deterministic bases. It focuses on models capable to account for multiple environmental influences with emphasis on drought conditions. We examine how models that have been proposed for well‐watered conditions can be combined with those specifically designed to deal with drought conditions. Ideas for future improvements of gs models are discussed: the issue of co‐regulation of gs and Anet; the roles of CO2, absissic acid and H2O2; and finally, how to better address the new challenges arising from the issue of global change. 相似文献
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JEAN‐MARC LIMOUSIN LAURENT MISSON ANNE‐VIOLETTE LAVOIR NICOLAS K. MARTIN SERGE RAMBAL 《Plant, cell & environment》2010,33(5):863-875
Seasonal drought can severely impact leaf photosynthetic capacity. This is particularly important for Mediterranean forests, where precipitation is expected to decrease as a consequence of climate change. Impacts of increased drought on the photosynthetic capacity of the evergreen Quercus ilex were studied for two years in a mature forest submitted to long‐term throughfall exclusion. Gas exchange and chlorophyll fluorescence were measured on two successive leaf cohorts in a control and a dry plot. Exclusion significantly reduced leaf water potential in the dry treatment. In both treatments, light‐saturated net assimilation rate (Amax), stomatal conductance (gs), maximum carboxylation rate (Vcmax), maximum rate of electron transport (Jmax), mesophyll conductance to CO2 (gm) and nitrogen investment in photosynthesis decreased markedly with soil water limitation during summer. The relationships between leaf photosynthetic parameters and leaf water potential remained identical in the two treatments. Leaf and canopy acclimation to progressive, long‐term drought occurred through changes in leaf area index, leaf mass per area and leaf chemical composition, but not through modifications of physiological parameters. 相似文献
44.
MARINA DMITRENOK LUCA PUGLISI LAURENT DEMONGIN GILLIAN GILBERT MARCIN POLAK & VINCENT BRETAGNOLLE 《Ibis》2007,149(1):37-44
Biometrics, plumage and bare-part colour of 87 Great Bitterns Botaurus stellaris from the UK, France, Italy, Poland and Belarus, of known sex (sexed by behaviour, DNA or dissection), were analysed to provide reliable sexing and ageing criteria for this little-known species, and to investigate geographical variation in biometrics. Four parameters were analysed: bill length, tarsus, wing length and body weight. We found little (though significant) geographical variation across Europe, but this was not clinal and we cannot exclude variation in measurement technique among observers. Males were significantly larger than females for all biometric parameters: a discriminant function based on these parameters was able to sex correctly all individuals. Body weight varied with season, especially for males. During the breeding period, lore colour was also a reliable sex-criterion. Ageing proved more difficult and required a combination of iris colour (which darkens with age) and flight-feather moult. From this, the largest sample size of known-age Great Bitterns, we conclude that most previously published criteria for age determination of this species were wrong. 相似文献
45.
DANIEL EPRON YANN NOUVELLON†‡ PHILIPPE DELEPORTE†‡ SUSPENS IFO† GUY KAZOTTI† ARMEL THONGO M'BOU† WELCOME MOUVONDY† LAURENT SAINT ANDRE‡ OLIVIER ROUPSARD‡ CHRISTOPHE JOURDAN‡ OLIVIER HAMEL‡ 《Global Change Biology》2006,12(6):1021-1031
Soil CO2 efflux was measured in clear‐cut and intact plots in order to quantify the impact of harvest on soil respiration in an intensively managed Eucalyptus plantation, and to evaluate the increase in heterotrophic component of soil respiration because of the decomposition of harvest residues. Soil CO2 effluxes showed a pronounced seasonal trend, which was well related to the pattern of precipitation and soil water content and were always significantly lower in the clear‐cut plots than in the intact plots. On an annual basis, soil respiration represented 1.57 and 0.91 kgC m?2 yr?1 in intact and clear‐cut plots, respectively. During the first year following harvest, residues have lost 0.79 kgC m?2 yr?1. Our estimate of heterotrophic respiration was calculated assuming that it was similar to soil respiration in the clear‐cut area except that the decomposition of residues did not occur, and it was further corrected for differences in soil water content between intact and clear‐cut plots and for the cessation of leaf and fine root turnover in clear cut. Heterotrophic respiration in clear‐cut plots was estimated at 1.18 kgC m?2 yr?1 whereas it was only 0.65 kgC m?2 yr?1 in intact plots (41% of soil respiration). Assumptions and uncertainties with these calculations are discussed. 相似文献
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47.
Leaf structure and chemical composition as affected by elevated CO2 : genotypic responses of two perennial grasses 总被引:2,自引:2,他引:0
Genotypic variability was studied in two Mediterranean grass species, Bromus erectus and Dactylis glomerata , with regard to the response to CO2 of leaf total non-structural carbohydrate concentration ([TNC]lf ), specific leaf area (SLA), and leaf carbon and nitrogen concentrations ([C]lf and [N]lf , respectively). Fourteen genotypes of each species were grown together on intact soil monoliths at ambient and elevated CO2 concentrations (350 and 700 μmol mol−1 , respectively). In both species, the most consistent effect of elevated CO2 was an increase in [TNC]lf and a decrease in leaf nitrogen concentration when expressed either as total dry mass [Nm ]lf , structural dry mass [Nm st]lf or leaf area [Na ]lf . The SLA decreased only in D. glomerata , due to an accumulation of total non-structural carbohydrates and to an increase in leaf density. No genotypic variability was found for any variable in B. erectus , suggesting that genotypes responded in a similar way to elevated CO2 . In D. glomerata , a genotypic variability was found only for [Cst], [Nm ]lf , [Nm st]lf and [Na ]lf . Since [Nm ]lf is related to plant growth and is a strong determinant of plant–herbivore interactions, our results suggest evolutionary consequences of elevated CO2 through competitive interactions or herbivory. 相似文献
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