首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
The ability of an animal to acquire, process and learn from information in their environment is thought to be fundamental to fitness. We currently have a poor understanding of the learning ability of young animals within the first few months of their life, the types of learning they use and the extent of their learning ability. Furthermore, an animal’s developmental environment, such as nest incubation temperature, may profoundly influence motor and cognitive skills. We first tested the ability of hatchling three-lined skinks (Bassiana duperreyi) incubated at ‘hot’ and ‘cold’ temperatures to solve an instrumental (motor) task before assessing their ability to learn colour associations in a multi-stage instrumental task, with a choice reversal. While 53 (88.3 %) lizards successfully completed the training phase, 14 (46.7 %) of the ‘hot’ incubated and none of the ‘cold’ incubated lizards successfully completed the instrumental task. Thirteen of these lizards rapidly learnt to discriminate colours, and this culminated in eight individuals successfully completing a choice reversal. Hatchling B. duperreyi demonstrated surprisingly rapid learning, and these results highlight the potentially important role of cognition during development and ultimately, in fitness.  相似文献   

3.
Different mechanisms operating downstream from high temperature processes lead to the formation of polychlorinated dibenzo(p) dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Independent of the level of concentration, these mechanisms lead to comparable PCDD/F patterns, as has been observed from the proportion of single congeners to the total of 17 2,3,7,8-Cl-substituted congeners or to the individual homologous groups related to the sum of the homologous tetra to octa CDD/F groups. A comparison of these so-called “combustion profiles” with the congeners Heats of Formation (HoF), as calculated via semiempirical molecular orbital methods, may provide an idea of the course of thermodynamical forced reaction.  相似文献   

4.
5.
Australia has a long history of metal mining and smelting. Extraction and processing have resulted in elevated levels of toxic metals surrounding mining operations, which have adverse health effects, particularly to children. Resource companies, government agencies and employees often construct ‘myths’ to down play potential exposure risks and responsibility arising from operating emissions. Typical statements include: contaminants are naturally occurring, the wind blows emissions away from residential areas, contaminants are not bioavailable, or the problem is a legacy issue and not related to current operations. Evidence from mining and smelting towns shows that such ‘myths’ are exactly that. In mining towns, the default and primary defence against contamination is that elevated metals in adjacent urban environments are from the erosion and weathering of the ore bodies over millennia—hence ‘naturally occurring’. Not only is this a difficult argument to unravel from an evidence-based perspective, but also it causes confusion and delays remediation work, hindering efforts to reduce harmful exposures to children. An example of this situation is from Broken Hill, New South Wales, home to one of the world’s largest lead–zinc–silver ore body, which has been mined continuously for over 130 years. Environmental metal concentration and lead isotopic data from soil samples collected from across Broken Hill are used to establish the nature and timing of lead contamination. We use multiple lines of evidence to unravel a ‘miner’s myth’ by evaluating current soil metal concentrations and lead isotopic compositions, geological data, historical environmental assessments and old photographic evidence to assess the impacts from early smelting along with mining to the surface soils in the city.  相似文献   

6.
This commentary highlights multivariate tools that have been used by evolutionary biologists in the study of syndromes and their evolution and discusses the insights that these methods provide into evolutionary processes relative to the metric ‘syndrome deviation’ that has recently been proposed by Herczeg and Garamszegi (Behav Ecol Sociobiol 66:161–169, 2012). We clarify that non-zero phenotypic correlations arise from the joint influences of within- and between-individual correlations, whereas only non-zero between-individual correlations represent behavioural syndromes, and discuss how acknowledgement of this subtle difference between phenotypic and between-individual correlations affects the applicability of syndrome deviation for the study of behavioural syndromes.  相似文献   

7.
Communal nesting can help defray the high cost of endothermic heat production in cold environments, but such social behavior is generally thought to be incompatible with the persistent defense of exclusive territories in typically ‘asocial’ animals. We examined the propensity for communal nesting in female red squirrels (Tamiasciurus hudsonicus), which maintain individual year-round territories, through intensive monitoring of litters over 22 years and by radio-tracking females during 3 years in late winter/early spring. Communal nesting was exceptionally rare during lactation: of 1,381 litters tracked to emergence, we observed a single instance in which two closely related (r?=?0.5) females pooled their litters into a single nest. In contrast, nest sharing between 2–3 females was relatively common in the late winter/early spring, prior to mating; at least 12 of 63 females (19 %) engaged in communal nesting during a year of systematic tracking of radio-collared females from late February to April. Communal nesting occurred more frequently when temperatures were colder, suggesting that such aggregations might function to reduce thermoregulatory costs. These social associations were typically, though not exclusively, between closely related individuals (r?≥?0.25 for seven of eight cases; mother–daughter dyads: four of eight), suggesting this cooperative behavior might evolve through kin selection and/or may reflect extended parental care. Our results demonstrate that female red squirrels engage in communal nesting, typically with closely related kin, despite a dispersed population structure that stems from the persistent defense of individual territories.  相似文献   

8.
In East Africa, spotted hyenas live in large clans in a highly structured society dominated by females. A clan is a fission-fusion society where members are often solitary or in small groups. Spotted hyenas have a ritualized greeting during which two individuals stand parallel and face in opposite directions. Both individuals usually lift their hind leg and sniff or lick the anogenital region of the other. The unique aspect of greetings between individuals is the prominent role of the erect penis in animals of both sex. Female spotted hyenas have fused outer labiae and a pseudo-penis formed by the clitoris which closely resembles the male penis and can be erected. During greetings subordinates signalled submission with gestures which were not necessarily reciprocated by the dominant participant. Asymmetries were most pronounced in greetings between adult females where the probability of asymmetries increased with the divergence in rank between partners. Greetings between adult females and males were uncommon and restricted to males above median rank, principally the alpha male. Models of primate affiliative behavior assume that benefits derived from social relationships with different individuals are not equal and that individuals are selected to maximize the benefits they receive from social relationships with others. The observed distribution of greetings between partners of different rank matched the predictions of these models. An examination of non-adaptive hypotheses on the evolution of the pseudo-penis demonstrated that the conventional scenario linking (initial) virilization of female genitalia with selection for female dominance does not explain either the initial virilization, nor the evolution of the pseudo-penis to its current form and use. We sketch a new scenario that links (1) initial virilization to the occurrence of neonatal siblicide amongst members of a twin litter, and (2) costs of maintenance, pseudo-penile control over copulation and male submission. Our analysis confirms previous adaptive hypotheses on the function of the pseudo-penis in greetings and suggests new hypotheses to account for hitherto unexplained features. Correspondence to: M.L. East  相似文献   

9.
Following the 2004 tsunami disaster in Sri Lanka, it was apparent that mapping the coast’s vulnerability was essential for future protection of the local populations. We therefore developed a prototype ‘Coastal-hazard GIS’ for Sri Lanka so as to provide an effective tool for decision makers to limit the impact of natural coastal hazards such as sea level rise, tsunamis, storm surges and coastal erosion, and thus protect the exposed assets (population, property, settlements, communications networks, etc.). The prototype was developed on a pilot site in Galle through building up homogeneous data on the land/sea interface from studies conducted on the exposure of the coastal populations, the aim being to enable an evaluation of the hazards combined with the vulnerability and thus an analysis of the risks. Coastal risk scenarios are developed so as to estimate the impacts and consequences of an event (tsunami, storm, etc.) on the assets, the principle behind this being that if, in general, the coastal hazard cannot be decreased, then a better knowledge of it through simulation should make it possible to limit the vulnerability and thus the risk. The Coastal-hazard GIS will also provide a planning tool in terms of locating new settlements, expanding urban areas, siting coastal protection works, etc.  相似文献   

10.
The paper examines the way in which the term ‘sustainable development’ has been used. Beginning with a short review of responses to a publication of the author's on sustainable development, it goes on to explore the different assumptions behind the discussion of the concept, and the different dimensions of sustainability: economic, political and epistemological. It is argued that, like the environment itself, the concept of sustainable development is a contested domain. We can learn from exploring the way the concept is used and contested.  相似文献   

11.
The photolysis of Phorate(I) (0,0‐diethyl S‐ethyl thiomethyl phosphordithioate) has been studied as a thin film on a glass surface and in a solution of methanol‐water (60:40) by ultraviolet light (λ > 290 nm). The rate of disappearance of Phorate in the solution show first order Kinetics with a rate constant of 4.9 × 10–5 S –1. The half‐life of (I) exposed on a glass surface is found to be 5 hours. The structure of the major photoproducts were characterised by 1H NMR and mass spectroscopy.  相似文献   

12.
Ranked set sampling can be useful when measurements are expensive but units from the popu- lation can be easily ranked. In this situation one may draw k units from the population, rank them, select one on which to make the expensive measurement, draw another k units, rank them, select one, and so on. The method was originally suggested by McIntyre (1952) in connection with pasture yields and is obviously applicable in other situations as well. Dell and Clutter (1972) and Patil et al. (1994) explain the basics from a classical point of view. Our aim is to examine the procedure from a Bayesian point of view, determine whether ranked set sampling provides advantages over simple random sampling and explore some optimality questions  相似文献   

13.
14.
The issue of municipal solid waste (MSW) arisings has received great attention recently since it is not only a by-product of economic activity but also serves as an input to the economy through material or energy recovery. The main focus of this study is cultural formation and especially the current picture of waste culture and public perception across European Union (EU) member states. Thus, this study will first evaluate environmental efficiency with data envelopment analysis (DEA) based on five parameters: waste, gross domestic product (GDP), labour, capital, and population density for 22 EU Member States and for the years 2005, 2010 and 2015 in order to evaluate which Member States are more efficient. Then the efficiency results are contrasted to Hofstede’s and Schwartz’s cultural dimensions on STATA with the use of regression modelling. Results show that for year 2005 no significant relationship is noticed for both cultural models, whereas for years 2010 and 2015 there appears to be a significant connection. The above-mentioned findings can be associated with the financial crisis that has hit Europe after 2008 making people more sceptical, while EU legislations have laid out some important directives in the field of waste management. Finally, along with the factors above, EU has faced severe environmental challenges due to waste arisings, as well as accidents and injuries for people working in this sector, which in turn have widely modified EU’s waste culture as supported by this study’s results.  相似文献   

15.
Investment in small scale irrigation (SSI) is crucial to sustain food security and livelihoods of smallholders. In Ethiopia, the government and development partners show a growing interest in developing irrigation projects. The success of irrigation projects is determined by governance and socio-cultural contexts. Yet the lack of thorough understanding of the challenging contexts undermines the efforts to achieve sustainability outcomes in irrigation projects. This article identifies the challenging contexts to irrigation projects, examines how the challenging contexts influence the effectiveness of irrigation projects, and indicates ways of improving the effectiveness of irrigation projects under the existing challenging contexts. Data were collected between April and December 2011 in three regional states of Ethiopia using in-depth interviews and focus group discussions. The lack of governance capacity and accountability are critical challenges for the sustainability of the irrigation projects. In addition, the poor consideration of local knowledge and the use of top-down approaches in planning and implementing the irrigation projects, and lack of equitable access to the irrigation schemes result in poor ownership of projects among farmers. Improving the funding scheme to support long-term capacity building at national and local levels, and in understanding the socio-cultural contexts of the intervention areas; planning irrigation projects with due consideration of the existing challenging contexts, and with active engagement of the local community, are important for the long-term viability and sustainability of irrigation projects.  相似文献   

16.
ABSTRACT

This paper argues that new land conflict frontiers are emerging in the context of renewable energy production. The novel aspect of these frontiers is a ‘green’ framing of the use of land considered ‘degraded’, expressing it as a climate protection strategy, and consequently causing similar dynamics of conflict in different regions. With reference to political ecology debates on the notion of frontiers, we analyze the social conflicts over palm oil production for biodiesel and wind energy development in Brazil and Mexico, respectively. We show that green narratives, understood as forms of knowledge production concerning the protection of the climate and sustainable development, not only represent legitimization strategies for new land grabs, but also come with their own dynamics of social conflict and their own constellations of actors.  相似文献   

17.
The release of nutrients on wetting (‘the Birch effect’) is well documented for terrestrial soils. The effect for aquatic sediments has received much less attention. An extreme drawdown event in a large reservoir during a period of drought presented an opportunity to test whether or not reflooding dried sediments would be a source of nutrients to the overlying water column. Wetting and drying history influences the release of ammonium, but not oxides of nitrogen, organic nitrogen, filterable reactive phosphorus or total phosphorus, from dried sediments following re-wetting. Dried reservoir sediments that have never, or have only rarely, been desiccated since the 1920s produced a pulse of ammonium on re-inundation. Conversely, dried sediments from parts of the reservoir that undergo frequent wetting and drying cycles do not release substantial amounts of ammonium on rewetting.  相似文献   

18.
19.
从嫁接方法、嫁接时间、砧木径级等方面探讨了日本红枫‘珊瑚阁’嫁接繁殖技术,结果表明:切接法嫁接日本红枫‘珊瑚阁’成活率高于撕皮嵌接法,嫁接时间以2月日本红枫‘珊瑚阁’腋芽未萌动时为佳,砧木地径越粗越有利于嫁接后接穗的生长,嫁接后需注意嫁接口的保湿遮阴.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号