The spiny,thorny and prickly plants in the flora of Israel

To examine whether spininess evolved at random or differently in various life forms and plant organs, we characterized spiny, thorny and prickly organs in the entire wild flora of Israel (294 such species). Of the species, 63.3% defended their reproductive organs (the most‐defended organ) and 67.0% defended various non‐reproductive organs. Ninety‐three species defended both their reproductive organs and at least one other part; 48.3% defended their leaves and 36.4% their stems and branches. Spiny wings defended stems and branches only in herbaceous (annual or perennial) species. There were clear differences between the life forms. Annuals and perennial herbs defended mostly their reproductive organs (95.7 and 83.0%, respectively), dwarf shrubs defended mostly their leaves (54.2%) and shrubs and trees mostly their branches (89.7 and 76.2%, respectively). Trees do not defend their reproductive organs by associated sharp appendages. The differences in defence on various organs among different life forms may influence the results of meta‐analysis studies of the optimal defence allocation if such differences are not taken into account. We noted spine, thorn and prickle colours for 167 species with yellow, red, orange and white being the dominant, supporting hypotheses about spines being visually aposematic. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 344–352.     

Bumble bee pollen use and preference across spatial scales in human‐altered landscapes

相似文献   

The influence of water level on macrophyte growth and trophic interactions in eutrophic Mediterranean shallow lakes: a mesocosm experiment with and without fish

1. Water‐level fluctuations are typical of lakes located in the semi‐arid Mediterranean region, which is characterised by warm rainy winters and hot dry summers. Ongoing climate change may exacerbate fluctuations and lead to more severe episodes of drought, so information on the effects of water level on the functioning of lake ecosystems in such regions is crucial. 2. In eutrophic Lake Eymir, Turkey, we conducted a 4‐month (summer) field experiment using cylindrical 0.8‐m‐ (low‐water‐level) and 1.6‐m‐deep (high‐water‐level) mesocosms (kept open to the sediment and atmosphere). Fish (tench, Tinca tinca, and bleak, Alburnus escherichii) were added to half of the mesocosms, while the rest were kept fishless. Ten shoots of Potamogeton pectinatus were transplanted to each mesocosm. 3. Sampling for physicochemical variables, chlorophyll a (chl‐a), zooplankton and per cent plant volume inhabited (PVI%) by macrophytes was conducted weekly during the first 5 weeks, and subsequently biweekly. Macrophytes were harvested on the last sampling date. During the course of the experiment, the water level decreased by 0.41 ± 0.06 m. 4. Throughout the experiment, fish affected zooplankton abundance (?), nutrient concentrations (+), chl‐a (+) and water clarity (?) most strongly in the low‐water‐level mesocosms and the zooplankton community shifted towards dominance of small‐sized forms. The fishless mesocosms had a higher zooplankton/phytoplankton ratio, suggesting higher grazing. 5. Greatest macrophyte growth was observed in the low‐water‐level fishless mesocosms. However, despite high nutrient concentrations and low water clarity, macrophytes were also abundant in the fish mesocosms and particularly increased following a water‐level decrease from midsummer onwards. Macrophyte growth was poor in the high‐water‐level mesocosms, even in the fishless ones with high water clarity. This was ascribed to extensive periphyton development reducing light availability for the macrophytes. 6. Our results indicate that a reduction in water level during summer may help maintain the growth of macrophytes in Mediterranean eutrophic shallow lakes, despite a strong negative effect of fish predation on water clarity. It is therefore probable that an expected negative effect of global climate change on water clarity because of eutrophication and enhanced top‐down control of fish may be, at least partly, counteracted by reduced water level, provided that physical disturbance is not severe.     

Imagination and Creativity in Childhood

A reflexological study of child development was first attempted by Academician V. M. Bekhterev in a series of studies published in Vestnik psikhologiya from 1908 onward. (1) An independent reflexology department was established at the Petrograd Pedological Institute in 1922. Here, under the direction of Bekhterev and Department Head N. Shchelovanov and their colleagues (Director M. P. Denisova, N. L. Figurin, Director A. M. Lukina, Director V. N. Dobrokhotova, Director Z. F. Khlestova), a systematic investigation was carried out that involved continuous observation and recording of all the responses of children to external and internal stimuli, as well as the reflexological experiment and other methods. An extremely large amount of factual data was accumulated (over 4,000 pages of daily reports and protocols of experiments involving infants up to the age of six months who were under the care of the Infant Department of the Institute). The present report is a summary of analyses of only a part of these factual data.     

WILL BIOMEDICAL ENHANCEMENTS UNDERMINE SOLIDARITY,RESPONSIBILITY, EQUALITY AND AUTONOMY?

Prominent thinkers such as Jurgen Habermas and Michael Sandel are warning that biomedical enhancements will undermine fundamental political values. Yet whether biomedical enhancements will undermine such values depends on how biomedical enhancements will function, how they will be administered and to whom. Since only few enhancements are obtainable, it is difficult to tell whether these predictions are sound. Nevertheless, such warnings are extremely valuable. As a society we must, at the very least, be aware of developments that could have harmful consequences. Indeed, if important values were to be jeopardized, we should take appropriate measures to protect them. This paper focuses on four central values: solidarity, personal responsibility, equality and autonomy. It delineates the conditions under which biomedical enhancements would undermine these values. It also details the circumstances under which these values would be unaffected by enhancements as well as those under which they would be promoted. Specifying these conditions is valuable; it would enable society to prepare appropriate ethical guidelines and policy responses in advance.