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191.
For wolves (Canis lupus) scats play an important function in territorial marking behaviour. Depositing scats at strategic sites such as crossroads and on conspicuous substrates probably increases their effectiveness as visual and olfactory marks. It is therefore likely that scats will be deposited, and will accumulate, at particular crossroads where the probability of being detected by other wolves is greatest. To check this hypothesis, a wolf population in NW Spain was studied for two consecutive years, from May 1998 to March 2000, and the spatial distribution of 311 scats detected along roads (both at and away from crossroads) was analysed. This study was conducted over an area of 12,000 ha in Montes do Invernadeiro Natural Park. The results confirm that wolves preferably deposit their scats at crossroads (60.1%) and on conspicuous substrates (72.1%). Significantly more scats were found at intersections with numerous, easily passable roads connecting distant territories. Thus, wolves preferably deposit their faeces at crossroads with high accessibility and driveability. The larger the surface area of the crossroads, the more scats were found. Crossroads are therefore highly strategic points that facilitate the detection of scats. 相似文献
192.
193.
Martínez-de la Puente J Merino S Tomás G Moreno J Morales J Lobato E Martínez J 《Die Naturwissenschaften》2011,98(2):99-106
Parasites are undoubtedly a biotic factor that produces stress. Heat shock proteins (HSPs) are important molecules buffering cellular damage under adverse conditions. During the breeding season, blue tit Cyanistes caeruleus (L.) adults are affected by blood parasites, nest-dwelling parasites and biting flies, potentially affecting their HSP-mediated responses. Here, we treated females with primaquine to reduce blood parasites and fumigated nests with permethrin to reduce nest-dwelling parasites to test whether these treatments affect HSP60 level during the breeding season. Medicated females, but not controls, had a significant reduction of the intensity of infection by Haemoproteus spp. blood parasites. However, final intensity of infection did not differ significantly between groups, and we did not find an effect of medication on change in HSP60 level. Fumigation reduced the abundance of nest-dwelling parasites (mites, fleas and blowfly larvae) and engorged biting midges in nests. Females breeding in non-fumigated nests increased HSP60 levels during the season more than those breeding in fumigated nests. Furthermore, the change in HSP60 level was positively correlated with the abundance of biting midges. These results show how infections by nest ectoparasites during the breeding period can increase the level of HSPs and suggest that biting midges impose physiological costs on breeding female blue tits. Although plausible, the alternative that biting midges prefer to feed on more stressed birds is poorly supported by previous studies. 相似文献
194.
Javier González-Benito Gustavo LannelongueDolores Queiruga 《Journal of Cleaner Production》2011,19(14):1622-1630
This article analyzes the combined effects of stakeholder pressure and the implementation of environmental management systems on organizations’ environmental behaviors. Beyond their individual effects, the implementation of an environmental management system should enhance the effect of stakeholder pressure on environmental imbalance, defined as the divergence between what the organization does and what it should do. Information collected from 3748 industrial plants in seven countries provides empirical evidence that supports the study propositions. Therefore, this study contributes to both the debate about the effectiveness of environmental management systems and the effort to explain the complex relationship between organizations and their stakeholders in environmental matters. 相似文献
195.
Francisco J. Goin Marcelo F. Tejedor Laura Chornogubsky Guillermo M. López Javier N. Gelfo Mariano Bond Michael O. Woodburne Yamila Gurovich Marcelo Reguero 《Die Naturwissenschaften》2012,99(6):449-463
We describe two isolated molariforms recovered from early–middle Eocene (early Lutetian) levels of northwestern Patagonia, Argentina. Comparisons with major lineages of therian and non-therian mammals lead us to refer them to a new genus and species of Gondwanatheria (Allotheria). There is a single root supporting each tooth that is very short, wide, rounded, and covered by cementum; the steep sidewalls, lack of a neck between the crown and root, and the heavily worn stage in both molariforms suggest that they were of a protohypsodont type. Both teeth are strongly worn at their centers, all along their length, with the labial edge less worn than the lingual; they show strong transverse crests that alternate with lingual grooves. The protohypsodont aspect of the teeth, as well as the strong, transverse crests, are suggestive of sudamericid affinities; on the other hand, the thin enamel layer and the occlusal pattern formed by the crests and grooves shows more similarities to molariform teeth of the Ferugliotheriidae. The new taxon adds evidence regarding the (1) extensive radiation of the Gondwanatheria throughout the Southern Hemisphere, (2) persistence of several lineages well after the Cretaceous/Paleogene boundary, and (3) early evolution of hypsodont types among South American herbivorous mammals. 相似文献
196.
Here, we provide evidence for a wavelength-dependent effect of light on magnetic compass orientation in Pelophylax perezi (order Anura), similar to that observed in Rana catesbeiana (order Anura) and Notophthalmus viridescens (order Urodela), and confirm for the first time in an anuran amphibian that a 90° shift in the direction of magnetic compass
orientation under long-wavelength light (≥500 nm) is due to a direct effect of light on the underlying magnetoreception mechanism.
Although magnetic compass orientation in other animals (e.g., birds and some insects) has been shown to be influenced by the
wavelength and/or intensity of light, these two amphibian orders are the only taxa for which there is direct evidence that
the magnetic compass is light-dependent. The remarkable similarities in the light-dependent magnetic compasses of anurans
and urodeles, which have evolved as separate clades for at least 250 million years, suggest that the light-dependent magnetoreception
mechanism is likely to have evolved in the common ancestor of the Lissamphibia (Early Permian, ~294 million years) and, possibly,
much earlier. Also, we discuss a number of similarities between the functional properties of the light-dependent magnetic
compass in amphibians and blue light-dependent responses to magnetic stimuli in Drosophila melanogaster, which suggest that the wavelength-dependent 90° shift in amphibians may be due to light activation of different redox forms
of a cryptochrome photopigment. Finally, we relate these findings to earlier studies showing that the pineal organ of newts
is the site of the light-dependent magnetic compass and recent neurophysiological evidence showing magnetic field sensitivity
in the frog frontal organ (an outgrowth of the pineal). 相似文献
197.
Javier Balbontín Anders P. Møller Ignacio G. Hermosell Alfonso Marzal Maribel Reviriego Florentino de Lope 《Behavioral ecology and sociobiology》2009,63(8):1197-1205
Dispersal is an important factor that determines the degree of gene flow and, hence, the degree of differentiation among populations.
Using two long-term datasets on natal philopatry and short-distance dispersal in barn swallows Hirundo rustica from Denmark and Spain, we evaluated the fitness costs and benefits and test a number of predictions about the functional
significance of dispersal. The proportion of philopatric individuals was more than six times larger in Spain than in Denmark,
with a higher rate of philopatry in males than in females. Dispersal propensity decreased in both populations during the course
of the study. Males from the more philopatric Spanish population lived longer when philopatric rather than dispersing while
that was not the case for either sex of the less philopatric Danish population. There were large differences in dispersal
propensity among cohorts and breeding sites, suggesting that sites differed in their suitability as sites for immigrants.
We found no evidence consistent with the mate competition hypothesis suggesting that males in better condition or with larger
condition-dependent secondary sexual characters were more likely to be philopatric. These findings suggest that there is a
high degree of intraspecific variation in dispersal propensity between populations, probably relating to local differences
in costs and benefits of philopatry and dispersal. 相似文献
198.
Exposure to uranium (U) is an occupational hazard to workers who continually handle it and an environmental risk to the population at large. Adverse effects of U on different tissues, particularly kidneys, have been reported. The aim of the present study was to investigate whether U might produce damage to the rat submandibular gland (SMG). Uranyl nitrate (UN) was used to evaluate the secretory responses to norepinephrine (NE) or to the parasympathomimetic agent, methacholine (MC), along with some morphological and histological parameters. In addition, the presence of U in saliva was determined by atomic absorption spectrometric techniques. Results indicate that intraperitoneal (i.p.) injection of a single dose of UN (2 or 4 mg kg?1) induced a functional decrease in the induced secretory responses in the rat SMG, demonstrating for the first time that U interferes with salivary secretion. Moreover, salivary responses to MC as well as to NE were decreased after UN administration, in time- and dose-dependent manner, displaying a higher diminution after 7 days post injection. In agreement with the functional studies, the injection of UN produced morphological alterations of SMG, consisting in a reduction of mean acinar area and a marked vacuolization. Data indicate that UN produced an adverse effect in a dose- and time-dependent manner on SMG function and morphology. Furthermore, it was shown that U was incorporated in saliva and therefore, these findings may contribute to create a useful, noninvasive method to detect the exposure to U. 相似文献
199.
Javier Esquer Christian Vaeza-Gastélum Arne Remmen Clara R. Alvarez-Chávez Luis Eduardo Velázquez 《国际发展与全球生态学杂志》2013,20(3):259-268
This paper aims to present the relevant results of a Life Cycle Assessment (LCA) study conducted on printed matter under a sheet-fed offset printing process by a company located in northwestern Mexico. Different scenarios were simulated in order to support decisions related to the improvement of environmental performance along the production processes. The study design was based on the European Platform on Life Cycle Assessment (EPLCA), which is in line with the ISO 14040 and 14044:2006 standards on LCA. The scope of the study was cradle-to-gate, with emphasis on the production of printed matter. The method chosen for the impact assessment was Impact 2002+ with a combined midpoint–damage approach. The results of the study showed that the major contributors to adverse effects were, primarily electricity consumption followed by paper consumption during the printing operation, as well as consumption of ink to a small degree. As for the plate-making operation along with the generation of secondary products, the result was negative. This is essentially due to involvement of recyclable materials, thus contributing to the prevention of raw material extraction. The smallest impact was observed from processes involving cleaning products and LP gas. The main issues of concern stemming from the results are electricity consumption and printing – both activities dominate almost all the midpoint categories. Generation of secondary products also had a relative environmental impact along the supply chain. Cleaning agents and LP gas did not have a significant impact on the final results of the process. 相似文献
200.
Luz Fernández Candela de la Sota José Celio Silveira Andrade Julio Lumbreras Javier Mazorra 《国际发展与全球生态学杂志》2014,21(3):246-258
In recent years, the concept of sustainable development (SD) has become increasingly recognized and important. Within organizations, SD is often portrayed as a balancing act and requires a combination of three elements to be considered: economy, environment, and society. Traditionally, organizational management research has been focused on economical and environmental fronts. However, social aspects are also important for organizations, especially those in emerging and developing countries. The goal of this article is to investigate the potential of Clean Development Mechanism (CDM) projects to deliver social benefits in Brazil’s hydroelectricity sector. The investigation involved the assessment of 46 registered hydro CDM projects under the Kyoto Protocol in terms of their potential impact on the envisaged social development goals. Two case studies were also examined. Results indicate that organizations managing hydroelectric initiatives in Brazil can provide the pathway toward achieving a number of important social benefits. Successful projects were found to have good community involvement and were managed by both cooperative ventures and money-making corporations. The research also identified several challenges that are hindering hydro CDM projects from delivering more social benefits and enabled a number of recommendations to be extracted for the organizations facing these challenges. 相似文献