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101.
Does living in elevated CO2 ameliorate tree response to ozone? A review on stomatal responses 总被引:1,自引:0,他引:1
Short-term elevated O3 reduces photosynthesis, which reduces stomatal conductance (g(s)) in response to increased substomatal CO2 concentration (Ci). Further exposure causes stomata to become sluggish in response to environmental stimuli. Exposure to elevated CO2 stimulates rapid stomata closure in response to increased Ci. This reduction in g(s) may not be sustained over time as photosynthesis down-regulates and with it, g(s). The relationship between g(s) and photosynthesis may not be constant because stomata respond more slowly to environmental changes than photosynthesis, and because elevated CO2 may alter guard cell sensitivity to other signals. Also, reduced stomatal density (and g(s)) in response to long-term CO2 enrichment suggests sustained reduction in g(s). Elevated CO2 is believed to ameliorate the deleterious O3 effects by reducing g(s) and thus the potential O3 flux into leaves. Confirmation that g(s) acclimation to CO2 enrichment does not lessen over time is critical for developing meaningful O3 flux scenarios. 相似文献
102.
Fabiola?G.?Arcos Ilie?S.?Racotta Elena?Palacios Ana?M.?IbarraEmail author 《Marine Biology》2005,148(2):339-346
Besides some mammals and a few model organisms, the presence of genetic variation in ovary or gonad development at ages before that of reproduction has not been established for marine oviparous species nor has the correlation with reproductive traits at maturity. In this investigation, ovary development was evaluated for genetic variability in a full-sib family structured population of subadult shrimp. The numbers of each oocyte type that were present were counted, measured, and used to evaluate the following traits: total oocyte number, mean oocytes diameter, and ovary maturity (OM). The total ovary area was also measured for each female. Genetic variation was assessed through the estimation of the parameter ‘heritability’. The heritability (h
2) of total number of oocytes was zero, but large heritability values were seen for mean oocytes diameter (h
2=0.57±0.27) and OM (h
2=0.71±0.26). Family means correlations between traits in subadults with traits measured in their full-sibs when adults (days to first spawn, total number of spawns, total fecundity, and fecundity at first spawn) indicated the existence of some significant associations between reproductive traits at the two ages. These findings point toward an early genetic determination of reproductive capacity in this crustacean. 相似文献
103.
Ilya A. Volodin Vera A. Matrosova Roland Frey Julia D. Kozhevnikova Inna L. Isaeva Elena V. Volodina 《Die Naturwissenschaften》2018,105(7-8):40
Non-hibernating pikas collect winter food reserves and store them in hay piles. Individualization of alarm calls might allow discrimination between colony members and conspecifics trying to steal food items from a colony pile. We investigated vocal posture, vocal tract length, and individual acoustic variation of alarm calls, emitted by wild-living Altai pikas Ochotona alpina toward a researcher. Recording started when a pika started calling and lasted as long as possible. The alarm call series of 442 individual callers from different colonies consisted of discrete short (0.073–0.157 s), high-frequency (7.31–15.46 kHz), and frequency-modulated calls separated by irregular intervals. Analysis of 442 discrete calls, the second of each series, revealed that 44.34% calls lacked nonlinear phenomena, in 7.02% nonlinear phenomena covered less than half of call duration, and in 48.64% nonlinear phenomena covered more than half of call duration. Peak frequencies varied among individuals but always fitted one of three maxima corresponding to the vocal tract resonance frequencies (formants) calculated for an estimated 45-mm oral vocal tract. Discriminant analysis using variables of 8 calls per series of 36 different callers, each from a different colony, correctly assigned over 90% of the calls to individuals. Consequently, Altai pika alarm calls are individualistic and nonlinear phenomena might further increase this acoustic individualization. Additionally, video analysis revealed a call-synchronous, very fast (0.13–0.23 s) folding, depression, and subsequent re-expansion of the pinna confirming an earlier report of this behavior that apparently contributes to protecting the hearing apparatus from damage by the self-generated high-intensity alarm calls. 相似文献
104.
Large variability in ambient ozone sensitivity across 19 ethylenediurea-treated Chinese cultivars of soybean is driven by total ascorbate 总被引:2,自引:0,他引:2
The sensitivity of Chinese soybean cultivars to ambient ozone(O3) in the field is unknown,although soybean is a major staple food in China. Using ethylenediurea(EDU) as an O3 protectant, we tested the gas exchange, pigments, antioxidants and biomass of 19 cultivars exposed to 28 ppm·hr AOT40(accumulated O3 over an hourly concentration threshold of40 ppb) over the growing season at a field site in China. By comparing the average biomass with and without EDU, we estimated the cultivar-specific sensitivity to O3 and ranked the cultivars from very tolerant( 10% change) to highly sensitive( 45% change), which helps in choosing the best-suited cultivars for local cultivation. Higher lipid peroxidation and activity of the ascorbate peroxidase enzyme were major responses to O3 damage, which eventually translated into lower biomass production. The constitutional level of total ascorbate in the leaves was the most important parameter explaining O3 sensitivity among these cultivars. Surprisingly, the role of stomatal conductance was insignificant. These results will guide future breeding efforts towards more O3-tolerant cultivars in China, while strategies for implementing control measures of regional O3 pollution are being implemented. Overall, these results suggest that present ambient O3 pollution is a serious concern for soybean in China, which highlights the urgent need for policy-making actions to protect this critical staple food. 相似文献
105.
Federico Luchi Valeria Vigni Riccardo Basosi Elena Busi 《Environmental monitoring and assessment》2011,177(1-4):151-163
The identification of an indicator for monitoring pesticides is a very effective analytical approach because it allows one to schedule and simplify the analytical routine. In this study, a new indicator has been designed, which has to be able to define a scale of priorities in the pesticides monitoring. A starting equation was developed involving the escaping tendency of a given substance from a phase (based on the Mackay model I level). The reliability of the indicator was tested by application to a model system, consisting of a defined and limited area, choosing water as matrix over a period of 6 years. A group of marker compounds was also defined to implement the predictive efficacy of the indicator. The results obtained by modeling were compared to those obtained by experimentation of the same model system. The indicator was subsequently and appropriately modified creating a new equation, including a kinetic factor, which considers the environmental degradation processes. The effect of the rectified indicator was consistent with the sales data list of compounds, when applied to the markers. The indicator developed in this study, tested as a model on specific area-phase-period (Province of Siena, water phase, 2000?C2006), is applicable to any other area-phase-period, adjusting the partition value of the Mackay model for the case under study. 相似文献
106.
107.
Elena Cantarello Claude E. Steck Paolo Fontana Diego Fontaneto Lorenzo Marini Marco Pautasso 《Die Naturwissenschaften》2010,97(3):265-271
Recent large-scale studies have shown that biodiversity-rich regions also tend to be densely populated areas. The most obvious
explanation is that biodiversity and human beings tend to match the distribution of energy availability, environmental stability
and/or habitat heterogeneity. However, the species–people correlation can also be an artefact, as more populated regions could
show more species because of a more thorough sampling. Few studies have tested this sampling bias hypothesis. Using a newly
collated dataset, we studied whether Orthoptera species richness is related to human population size in Italy’s regions (average
area 15,000 km2) and provinces (2,900 km2). As expected, the observed number of species increases significantly with increasing human population size for both grain
sizes, although the proportion of variance explained is minimal at the provincial level. However, variations in observed Orthoptera
species richness are primarily associated with the available number of records, which is in turn well correlated with human
population size (at least at the regional level). Estimated Orthoptera species richness (Chao2 and Jackknife) also increases
with human population size both for regions and provinces. Both for regions and provinces, this increase is not significant
when controlling for variation in area and number of records. Our study confirms the hypothesis that broad-scale human population–biodiversity
correlations can in some cases be artefactual. More systematic sampling of less studied taxa such as invertebrates is necessary
to ascertain whether biogeographical patterns persist when sampling effort is kept constant or included in models. 相似文献
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