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 31 毫秒
1.
The occurrence of wild foxes in suburbia is discussed. It is shown that in London breeding populations of foxes are found 5 km from the city centre, and in the last 3 years foxes have been recorded in the very centre of the city. The fox population in London is shown to be heavily dependent on residential habitats for both daytime harbourage and when selecting sites for natal earths. The fox population is unevenly distributed in London, with a marked clumping of the adult population during most of the year. The age structure of the population is presented, and these data are compared with data for other canid populations. Conclusions are drawn as to the effects of conventional control techniques on the age structure of a fox population.  相似文献   

2.
According to development of the city, it has been revealed that demographic characteristics and living condition, as well as health status, have been differentiated among areas within it. On the causal relationships between urban growth and health, the present study shows no evidence, but a significant correlation between population density and demographic characteristics, and health, especially in maternal child health, have been observed in the same city (Takemoto et al., 1988). Considering the regionalization of characteristics in man and his environment within a city, public health activities based on the assessment of health needs in each community should be developed in urbanized society.  相似文献   

3.
The work is devoted to analysis of various methods of assessment and control of house dust mites population and mite allergens in city dwellings using own results and the literature data. Data about in-house dust mites biology and ecology, mechanisms of their migration and circulation in modern city conditions are presented. The comparison of several methods of mites number assessment and mite allergens exposure (classical acarological analysis, colorimetric method of guanine detection in house dust, immunochemical methods) has been performed and their advantages and disadvantages analyzed. As choice of adequate avoidance measures is one of the key question, various such measures (mechanical, physical and chemical) have been compared.  相似文献   

4.
Golubeva NA  Zhigachev AI 《Genetika》2007,43(8):1079-1083
The population of domestic cats from the city of Armavir has been examined. A high frequency of gene O was revealed in the population. Differences among three subpopulations estimated using two genetic distances showed heterogeneity of the Armavir cat population. The extreme samples showed highly significant differences (P < 0.01; chi2[6] = 24.67), likely explained by the structural features of the synantropous population and human-driven frequency- dependent selection operating in it. The feline population of Armavir underwent significant changes during the past two decades. The d(ij) coefficient in it was 0.093; D(p) = 0.05. The frequencies of genes orange and Long-hair have increased in the general population. The frequency of gene dilution has decreased. These changes may have occurred because of genetic exchange with purebred domestic cats that have become more popular as pets in the recent years.  相似文献   

5.
Several single nucleotide polymorphisms (SNPs) in the Mu Opioid Receptor gene (OPRM1) have been identified and associated with a wide variety of clinical phenotypes related both to pain sensitivity and analgesic requirements. The A118G and other potentially functional OPRM1 SNPs show significant differences in their allele distributions among populations. However, they have not been properly addressed in a population genetic analysis. Population stratification could lead to erroneous conclusions when they are not taken into account in association studies. The aim of our study was to analyze OPRM1 SNP variability by comparing population samples of the International Hap Map database and to analyze a new population sample from the city of Corrientes, Argentina. The results confirm that OPRM1 SNP variability differs among human populations and displays a clear ancestry genetic structure, with three population clusters: Africa, Asia, and Europe-America.  相似文献   

6.
The effect of raw city wastewater irrigation on biodiversity and population densities of a cycloheximide-resistant (CH) fungal community was studied in 13 field soils receiving either raw city wastewater or normal irrigation, and in raw city wastewater in the Nablus area, using the hair baiting technique (HBT) and a surface soil dilution plating (SSDP) technique. Three of these fields [one had been receiving raw city wastewater for more than ten years and was designated a heavily polluted field, and the other 2 were cultivated for the first time and were either irrigated with raw city wastewater (newly polluted field) or normal irrigation water (nonpolluted)], were sampled 4–7 times over a 9-month period. The other ten fields, which had been under raw city wastewater irrigation for more than 10 years, were sampled only once. Fifty-seven CH-resistant species belonging to 18 genera were recovered, of which 49 species were recovered from soil habitats and 28 species from raw city wastewater. The HBT had shown to be more efficient in the isolation of pathogenic and potentially pathogenic fungi including dermatophytes. A higher percentage of this group of fungi was recovered from the three main field soils studied using HBT (70% of all isolates), than the SSDP (35.5%); no dermatophytes were recovered by the SSDP method. Two dermatophytes (Microsporum gypseum, and Trichophyton ajelloi), and five more fungi (Arthroderma cuniculi, A. curreyi, Chrysosporium keratinophilum, C. tropicum, and C. pannorum), were recovered from these habitats. Wastewater irrigation seemed to have affected the fungal population densities, with the highest population densities being found in the heavily polluted field soil, while lower population densities were found in the nonpolluted field soil. Increases in organic matter were also observed as a result of sewage effluent irrigation. However, basic similarities in the biodiversity of CH-resistant fungal communities existed in nonpolluted and polluted field soils, and raw city wastewater. Comparable numbers of fungal species were recovered from the three main field soils. The species most commonly found in those habitats included: Alternaria alternata, Aspergillus candidus, Geotrichum candidum, and Paecilomyces lilacinus. Field soils receiving either raw city wastewater or normal irrigation water, were found to be rich in pathogenic and potentially pathogenic CH-resistant fungi, including dermatophytes, with raw city wastewater yielding the highest percentage (81%), followed by the newly wastewater irrigated field (77.7%), the nonpolluted field (67%), and the heavily polluted field (63.4%). Hygienic measures should therefore be taken to control the spread of these fungi in the environment of human communities, and to avoid mycotic infections among farmers. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

7.
不同生境中橘小实蝇种群动态及密度的差异   总被引:1,自引:0,他引:1  
郑思宁 《生态学报》2013,33(24):7699-7706
为揭示不同生境条件对橘小实蝇种群动态及密度的影响,通过设置橘小实蝇诱捕器,对2008-2009年福州地区不同生境条件下的橘小实蝇种群动态进行了监测。结果表明:(1)各寄主的转色成熟期是该果园橘小实蝇发生的高峰期。(2)在瓜果的成熟期,果园内橘小实蝇的种群数量要高于果园周边丛林的种群数量;成熟期过后,果园内部的种群数量小于果园周边丛林。(3)山谷生境橘小实蝇种群数量明显高于山脊生境,沿河生境则要明显高于非沿河生境。(4)城区的橘小实蝇的发生期早于乡村,且发生量要大于乡村。  相似文献   

8.
Land use associations and changes in population indices were assessed for an urban population of raccoons (Procyon lotor) in Baltimore, Maryland (USA), from January 1984 to December 1987. Records were examined for 1,458 raccoons trapped alive and removed dead from city streets during, and after, the peak of a rabies epizootic. The distribution of raccoons was associated with single-unit residential areas primarily along the northern and western perimeter of the city. Beginning in March 1985 an ending in May 1987, an epizootic of raccoon rabies spread through Baltimore, ultimately resulting in the identification of 95 rabid raccoons. Within the study interval, annual numbers of trapped raccoons remained stable from 1984 to 1986, before showing a marked decline in 1987. The number of raccoons removed as vehicle mortalities (road-kills) varied little from 1984-1985 but declined in the last 2 yr of study. Numbers of other road-killed species did not decrease concurrently, suggesting a specific decrease in the urban raccoon population. The rabies epizootic, in conjunction with the increased city and private control, appears to have contributed to a decline in the number of raccoons in Baltimore.  相似文献   

9.
House Sparrow was the most abundant bird species near human habitat until few years back. But from the mid of twentieth century, the declining trend of House Sparrow has been reported from various countries. It has already been red listed in Netherlands and UK. Researches indicate the declining trend of House Sparrow in different cities of India like Delhi, Mumbai and Bengaluru. A 3-month wide survey has been conducted to get a preliminary idea about the distributional trend of House Sparrow in greater Kolkata. Depending on nature of urbanization and human habitat, greater Kolkata, has been subdivided into four regions (Planned City, Highly dense city, Medium dense city and Low dense city regions). In high density urban region the avian density recoded was highest, although avian diversity was maximum in medium and low dense city regions and minimum in planned city. Among 20 observational units of planned city region, House Sparrow has been noticed in 6 units and crow in all units. Among 115 observational units of rest of the regions of greater Kolkata, House Sparrow was observed in 79 units and crow in 98 units. The preliminary information revealed from this survey indicates towards negative relationship between urbanization and House Sparrow population in greater Kolkata and this negative influence is maximum in planned urban region. The presence of sufficient number of House Sparrow in any region indicates environmental stability of that region. So the declining trend of House Sparrow population in greater Kolkata, particularly in planned city region, indirectly gives the evidence of serious environmental degradation.  相似文献   

10.
Marriage records of six raions (districts) of Udmurtia and the city of Glazov (a total of 10,518 records) have been used to calculate marriage-migration parameters. The endogamy indices of the rural and urban Udmurt populations are 0.59 (from 0.48 to 0.76 in individual districts) and 0.29, respectively, and those of the rural and urban Russian populations are 0.33 and 0.47, respectively. The mean ethnic assortativeness values are 1.05 and 0.89 for the rural and urban Udmurt populations, respectively, and 2.13 and 1.44 for the rural and urban Russian populations, respectively. The parameters of isolation by distance for the rural Udmurt population are the following: sigma = 52.4, a = 0.00035, and b = 0.012; those for the urban Udmurt population are 54.1, 0.00020, and 0.010, respectively.  相似文献   

11.
Wildlife inhabiting urban environments exhibit drastic changes in morphology, physiology, and behavior. It has often been argued that these phenotypic responses could be the result of micro‐evolutionary changes following the urbanization process. However, other mechanisms such as phenotypic plasticity, maternal effects, and developmental plasticity could be involved as well. To address maternal effects as potential mechanisms, we compared maternal hormone and antibody concentrations in eggs between city and forest populations of European blackbirds (Turdus merula), a widely distributed species for which previous research demonstrated differences in behavioral and physiological traits. We measured egg and yolk mass, yolk concentrations of androgens (androstenedione [A4], testosterone [T], 5α‐dihydrotestosterone [5α‐DHT], and immunoglobulins [IgY]) and related them to population, clutch size, laying order, embryo sex, and progress of breeding season. We show (a) earlier onset of laying in the city than forest population, but similar egg and clutch size; (b) higher overall yolk androgen concentrations in the forest than the city population (sex‐dependent for T); (c) greater among‐female variation of yolk T and 5α‐DHT concentrations in the forest than city population, but similar within‐clutch variation; (d) similar IgY concentrations with a seasonal decline in both populations; and (e) population‐specific positive (city) or negative (forest) association of yolk A4 and T with IgY concentrations. Our results are consistent with the hypotheses that hormone‐mediated maternal effects contribute to differences in behavioral and physiological traits between city and forest individuals and that yolk androgen and immunoglobulin levels can exhibit population‐specific relationships rather than trade‐off against each other.  相似文献   

12.
The relationships between the health of Pinus sylvestris trees and stands and the levels of anthropogenic stress and fragmentation of habitats have been studied based on the example of pine stands of natural origin in Yekaterinburg and its vicinity (48 sampling plots located at different distances from the center of the city). The distances from the city center and from the boundary of a built-up area to a sampling plot and the population density around this plot are taken to characterize the level of anthropogenic stress. The area and perimeter of a forest site; the distance from the boundary of a sampling plot to the forest edges; and the shape of forest edges are used to characterize the level of fragmentation of habitats. We have found that the average morphological metrics of trees have slight changes, while the traits of tree health are significantly altered under urban environment. The overall performance of stands decreases by 22–35% in the urbanization gradient. The health of stands is most substantially influenced by the forest-site area. The population density around sampling plots and the distance of these plots from the megalopolis center have a lower effect on the health of trees and stands. Fragmentation of forests in the city leads to a decrease in the size of forest sites, which causes a decrease in wood stocks and the diameter and height of trees and the deterioration of their health. The lowest area of the forest to make it sustain an urban environment is about 30 ha. The untransformed core of forest is located no less than 70 m from the forest edge.  相似文献   

13.
Kholin SK 《Genetika》2012,48(5):655-659
The frequencies of mutant coat color genes have been estimated in the cat populations of five settlements in Primorskii krai, Russia: two cities (Partizansk and Spassk-Dal'nii), a town (Khorol'), and two villages (Dmitrievka and Brovnichi). The genetic profiles of these populations have been found to be relatively homogenous and to correspond of the cat population of the city of Vladivostok studied earlier. No considerable differences in gene frequencies have been found between urban and rural cat populations. The data suggest a common origin of all domestic cat populations of Primorskii krai.  相似文献   

14.
The gene pool of the entire population of all the 21 raions (districts) of the Belgorod oblast (region) has been studied using anthroponymic data. Considerable geographic variations of the number of surnames and the degree of population subdivision (0.00003 < f(r)* < 0.00125) in the 21 districts have been demonstrated. Districts with low population subdivision levels are mainly located in the central and southwestern raions of the Belgorod oblast, contain an urbanized area (city), and border on Ukraine (they are characterized by a considerable Ukrainian immigration). Urbanization significantly affects the population structure of the Belgorod oblast. In urbanized districts, rural populations lack the relationships between the population size, number of surnames, and population subdivision level (f(r)).  相似文献   

15.
Marriage records of six raions (districts) of Udmurtia and the city of Glazov (a total of 10518 records) have been used to calculate marriage-migration parameters. The endogamy indices of the rural and urban Udmurt populations are 0.59 (from 0.48 to 0.76 in individual districts) and 0.29, respectively, and those of the rural and urban Russian populations are 0.33 and 0.47, respectively. The mean ethnic assortativeness values are 1.05 and 0.89 for the rural and urban Udmurt populations, respectively, and 2.13 and 1.44 for the rural and urban Russian populations, respectively. The parameters of isolation by distance for the rural Udmurt population are the following: σ = 52.4, a = 0.00035, and b = 0.012; those for the urban Udmurt population are 54.1, 0.00020, and 0.010, respectively.  相似文献   

16.
仙湖苏铁野生种群的报道   总被引:8,自引:0,他引:8  
深圳塘朗山分布的仙湖苏铁种群是首次发现的该物种的野生种群,具有极高的研究价值,可填补仙湖苏铁野外研究的空白,但目前已处于濒危状态。笔者对该种群在塘朗山的分布状况以及群落特征作了初步报道.  相似文献   

17.
Urban scaling relations characterizing how diverse properties of cities vary on average with their population size have recently been shown to be a general quantitative property of many urban systems around the world. However, in previous studies the statistics of urban indicators were not analyzed in detail, raising important questions about the full characterization of urban properties and how scaling relations may emerge in these larger contexts. Here, we build a self-consistent statistical framework that characterizes the joint probability distributions of urban indicators and city population sizes across an urban system. To develop this framework empirically we use one of the most granular and stochastic urban indicators available, specifically measuring homicides in cities of Brazil, Colombia and Mexico, three nations with high and fast changing rates of violent crime. We use these data to derive the conditional probability of the number of homicides per year given the population size of a city. To do this we use Bayes' rule together with the estimated conditional probability of city size given their number of homicides and the distribution of total homicides. We then show that scaling laws emerge as expectation values of these conditional statistics. Knowledge of these distributions implies, in turn, a relationship between scaling and population size distribution exponents that can be used to predict Zipf's exponent from urban indicator statistics. Our results also suggest how a general statistical theory of urban indicators may be constructed from the stochastic dynamics of social interaction processes in cities.  相似文献   

18.
A variety of ambient exposure indicators have been used to evaluate the impact of high temperature on mortality and in the identification of susceptible population sub-groups, but no study has evaluated how airport and city centre temperatures differ in their association with mortality during summer. This study considers the differences in temperatures measured at the airport and in the city centre of three Italian cities (Milan, Rome and Turin) and investigates the impact of these measures on daily mortality. The case-crossover design was applied to evaluate the association between daily mean apparent temperature (MAT) and daily total mortality. The analysis was conducted for the entire population and for subgroups defined by demographic characteristics, socioeconomic status and chronic comorbidity (based on hospitalisation during the preceding 2 years). The percentage risk of dying, with 95% confidence intervals (95% CI), on a day with MAT at the 95th percentile with respect to the 25th percentile of the June-September daily distribution was estimated. Airport and city-centre temperature distributions, which vary among cities and between stations, have a heterogeneous impact on mortality. Milan was the city with the greatest differences in mean MAT between airport and city stations, and the overall risk of dying was greater when airport MAT (+47% increase, 95%CI 38-57) was considered in comparison to city MAT (+37% increase, 95%CI 30-45). In Rome and Turin, the results were very similar for both apparent temperature measures. In all cities, the elderly, women and subjects with previous psychiatric conditions, depression, heart and circulation disorders and cerebrovascular disease were at higher risk of dying during hot days, and the degree of effect modification was similar using airport or city-centre MAT. Studies on the impact of meteorological variables on mortality, or other health indicators, need to account for the possible differences between airport and city centre meteorological variables in order to give more accurate estimates of health effects.  相似文献   

19.
Anoplophora glabripennis Motschulsky, a wood borer native to Asia, was recently found in New York City and Chicago. In an attempt to eradicate these beetle populations, thousands of infested city trees have been removed. Field data from nine U.S. cities and national tree cover data were used to estimate the potential effects of A. glabripennis on urban resources through time. For the cities analyzed, the potential tree resources at risk to A. glabripennis attack based on host preferences, ranges from 12 to 61% of the city tree population, with an estimated value of $72 million-$2.3 billion per city. The corresponding canopy cover loss that would occur if all preferred host trees were killed ranges from 13-68%. The estimated maximum potential national urban impact of A. glabripennis is a loss of 34.9% of total canopy cover, 30.3% tree mortality (1.2 billion trees) and value loss of $669 billion.  相似文献   

20.
Analyzing urban green space pattern and eco-network in Hanoi, Vietnam   总被引:2,自引:0,他引:2  
In Hanoi, the capital city of Vietnam, there has recently been a growing awareness about the roles and benefits of greening in urbanized areas. As a result, planners and decision-makers propose a combination of water bodies and green areas, using cultural as well as historic values, in a strategic concept for city planning in Hanoi. This study aims at quantifying the landscape patterns and ecological processes or clearly linking pattern to process to identify green space changes and their driving forces, based on gradient analysis combined with landscape metrics, GIS support, and FRAGSTATS 3.3, from 1996 to 2003. The results of gradient analysis taken four directions show that green spaces have been become more fragmented in this period, especially in the south and west directions. These changes could be caused by land use change, economic growth, population increase, urbanization, and weakness in planning and managing the urban development. From this context, graph theory was also applied to find any eco-networking, by mitigating the fragmentation and enhancing the green space connectivity, as a biodiversity conservation strategy for the city. Analyzing the green network based on graph theory indicates that among six different network scenarios which were produced from several models (Traveling Salesman, Paul Revere, Least Cost to User), network F with 37 links, and gamma (0.07), beta (0.62), cost ratio (0.606), circuitry (0.098) and connectivity (0.398) is the best option for ecological restoration in the Hanoi city. This will be a basis for the 2020 Green Space Planning in Hanoi.  相似文献   

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