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31.
Atmospheric nitrogen deposition in world biodiversity hotspots: the need for a greater global perspective in assessing N deposition impacts 总被引:8,自引:0,他引:8
GARETH K. PHOENIX W. KEVIN HICKS† STEVE CINDERBY† JOHAN C. I. KUYLENSTIERNA† WILLIAM D. STOCK‡§ FRANK J. DENTENER¶ KEN E. GILLER AMY T. AUSTIN ROD D. B. LEFROY†† BEN S. GIMENO‡‡ MIKE R. ASHMORE§§ PHILIP INESON¶¶ 《Global Change Biology》2006,12(3):470-476
Increased atmospheric nitrogen (N) deposition is known to reduce plant diversity in natural and semi‐natural ecosystems, yet our understanding of these impacts comes almost entirely from studies in northern Europe and North America. Currently, we lack an understanding of the threat of N deposition to biodiversity at the global scale. In particular, rates of N deposition within the newly defined 34 world biodiversity hotspots, to which 50% of the world's floristic diversity is restricted, has not been quantified previously. Using output from global chemistry transport models, here we provide the first estimates of recent (mid‐1990s) and future (2050) rates and distributions of N deposition within biodiversity hotspots. Our analysis shows that the average deposition rate across these areas was 50% greater than the global terrestrial average in the mid‐1990s and could more than double by 2050, with 33 of 34 hotspots receiving greater N deposition in 2050 compared with 1990. By this time, 17 hotspots could have between 10% and 100% of their area receiving greater than 15 kg N ha?1 yr?1, a rate exceeding critical loads set for many sensitive European ecosystems. Average deposition in four hotspots is predicted to be greater than 20 kg N ha?1 yr?1. This elevated N deposition within areas of high plant diversity and endemism may exacerbate significantly the global threat of N deposition to world floristic diversity. Overall, we highlight the need for a greater global approach to assessing the impacts of N deposition. 相似文献
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乳酸脱氢酶C4的精子免疫荧光定位特性 总被引:2,自引:0,他引:2
用14个抗小鼠LDH-C4的单克隆抗体对小鼠、树鼯和人精子的LDH-C4进行了间接免疫荧光定位。结果显示:不同的单抗可以结合到小鼠精子表面不同的位置,其中PA1(K021)在尾部,PA2(K022)、PA4和PA5(K023)在中段和尾部,SM1、SM2和PG2的中段,SM3和SM4在顶体,SM5在顶体和赤道板。人和树鼯精子表面的LDH-C4也呈现类似的情况。这些研究表明精子表面的LDH-C4呈现 相似文献
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高寒草甸珠芽蓼抗氧化物质含量的季节变化及与太阳辐射的关系 总被引:10,自引:0,他引:10
对高寒草甸珠芽蓼中几种抗氧化物质含量的季节变化测定发现,珠芽蓼叶片内抗坏血酸、超氧阴离子自由基的相对含量、超氧化物歧化酶的活性以及紫外辐射吸收色素在5月至8月间呈现“拱型”曲线变化,不同物质分别以6、7月份最高,分别与海北站地区的太阳辐射呈现一定的相关性。 相似文献
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Sylvain Laborde Fabrice Dosseville Asma Aloui Helmi BEN SAAD Maurizio Bertollo Laura Bortoli 《Chronobiology international》2013,30(9):1294-1304
ABSTRACTChronotype questionnaires provide a simple and time-effective approach to assessing individual differences in circadian variations. Chronotype questionnaires traditionally focused on one dimension of chronotype, namely its orientation along a continuum of morningness and eveningness. The Caen Chronotype Questionnaire (CCQ) was developed to assess an additional dimension of chronotype that captures the extent to which individual functioning varies during the day (amplitude). The aim of this study was to provide a multilanguage validation of the CCQ in six world regions (Arabic, Dutch, German, Italian, Portuguese and Spanish). At Time 1, a total of 2788 participants agreed to take part in the study (Arabic, n = 731; Dutch, n = 538; German, n = 329; Italian, n = 473; Portuguese, n = 361; Spanish, n = 356). Participants completed an assessment of the CCQ together with the Morningness-Eveningness Questionnaire (MEQ; Horne & Ostberg 1976) as well as questions related to factors theoretically related to chronotype (age, shift work, physical activity, sleep parameters and coffee consumption). One month later, participants again completed the CCQ. Results showed that the two-factor structure (morningness-eveningness and amplitude) of the CCQ could be replicated in all six languages. However, measurement invariance could not be assumed regarding the factor loadings across languages, meaning that items loaded more on their factors in some translations than in others. Test–retest reliability of the CCQ ranged from unacceptable (German version) to excellent (Dutch, Portuguese). Convergent validity was established through small–medium effect size correlations between the morningness-eveningness dimension of the CCQ and the MEQ. Taken together, our findings generally support the use of the translated versions of the CCQ. Further validation work on the CCQ is required including convergent validation against physiological markers of sleep, health and well-being. 相似文献
38.
MANES WYSOKI SHAUL BEN YEHUDA DAVID ROSEN 《Invertebrate reproduction & development.》2013,57(3):217-223
Summary The reproductive behavior of the honeydew moth, Cryptoblabes gnidiella (Millière) (Lepidoptera: Pyralidae), was studied in the laboratory. The sex ratio was 1.1:1, males to females, in both laboratory and field stocks. Most of the females that mated did so during the first night after emergence; males began mating on the following night. Mating occurred 1–2 h before dawn and averaged 100 min. Both sexes mated only once in one night. Most females mated only once in their lifetime, a few mated 2–4 times, whereas males mated up to six times per lifetime. Insects that lived longer also mated more times. When the sex ratio was altered from 3:1 to 1:3, males to females, the percentage of females that mated in one night dropped from 90 to 65, whereas the number of matings per male rose from 0.32 to 2.25. When fresh one-day-old females were provided daily at a ratio of three per male, the males averaged 1.4 matings per lifetime vs. 2.6 with 2- to 3-day-old females. A delay in mating did not affect the percentages of males and females that mated; highest percentages were obtained with 2- to 4-day-old males and females, but a delay in mating resulted in egg fertility dropping from 91 % to 73 %. The preoviposition period lasted a full day after mating, and then most of the eggs were laid during the first night. Average fecundity was 105 eggs per female (maximum: 230). 相似文献
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Abstract: The Jurassic was an important period in the evolution of Testudinata and encompasses the origin of many clades, and this is especially true of Jurassic turtles from Western Europe. A new genus and species of Late Jurassic turtle, Hispaniachelys prebetica gen. et sp. nov. from the upper Oxfordian of the Prebetic (Southern Spain), is described on the basis of postcranial material. The specimen is the only known tetrapod from the Mesozoic of the Prebetic and the oldest turtle from southern Europe. A mosaic of characters indicates this is a new genus: it displays basal features including dorsal epiplastral processes/reduced cleithra, no medial contact of the extragulars and a long first thoracic rib, alongside derived characters including an absence of mesoplastra and the vertebral 3/4 sulcus crossing neural 5. The phylogenetic position of the new taxon is hard to resolve, and it might be either a paracryptodire or a basal testudine, but it is distinct from Plesiochelys. A complex taphonomic history is shown by a range of overlying grazing traces and bioerosion on the carapace. The carapace was subsequently overturned and buried ventrally up, terminating grazing activity, and was then bored by sponges before final burial. Scanning electron microscopy reveals phosphatic microspheroids associated with bacterial decay in the vascular cavities of the cancellous bone, suggesting the carapace may have acted as a closed microenvironment in which decay‐derived authigenic minerals formed. 相似文献