空间非齐次性和扩散行为对种群规模的影响

研究空间环境资源的非齐次和物种的扩散行为对于生物种群的影响.对一个单一物种的模型,结果表明:(1)空间环境的非齐次性能使种群规模变大;(2)总的种群规模会在适度的扩散速率的情况下达到最大值,而极端(过大或过小)的情形会对种群规模产生不利的影响,因此总的种群规模不是关于扩散速率的单调函数.     

基于变异系数的我国城市化地域差异演变研究

利用我国26个省会城市和4个直辖市的市辖区1998～2007年的非农人口和建成区面积统计数据,采用增长率和变异系数等指标对中国的城市化水平格局及地域差异变化进行研究.结果表明:研究期内我国东部城市化水平差异一直明显高于中、西部地区,但东中西部的差异有所缩小;城市化速率呈现明显的地域差异,2003年之前东部城市化速度最快...     

中国人口系统结构的灰色关联分析

根据1998～2003年中国人口数据,利用灰色系统理论和灰色关联分析模型法建立由总人口、城镇人口、乡村人口等17个影响人口增长的关联因素构成的指标体系及灰色关联分析模型,对中国人口系统结构进行关联分析,以期找出影响人口增长的主要因素,为我国人口系统的建模、预测、决策、规划、管理和控制提供了的依据,以便实现人口与资源、环境、经济和社会的可持续发展.运算和系统分析结果显示人口增长的主要影响因素为:女性人口、城乡人口、年龄结构、性别结构和人口自然增长率.其中,15～49岁的育龄妇女、农村人口和人口自然增长率3个因素对总人口和年净增人数影响最大.本文中国人口系统结构的灰色关联分析结果较符合中国人口的实际情况,为中国人口发展与控制的管理决策提供了一种新的有效方法.     

HLA高分辨等位基因多态性及单倍体与广西汉族终末期肾病易感性的相关性分析

为研究广西汉族终末期肾病(End Stage Renal Disease, ESRD)与人类白细胞抗原(Human Leukocyte Antigen, HLA)等位基因及单倍体的关联性,本研究采用聚合酶链反应-序列特异性寡核苷酸(Polymerase Chain Reaction-Sequence Specific Oligonucleotides, PCR-SSO)技术对广西汉族578例终末期肾病患者(ESRD组)进行HLA-A、B和DRB1基因分型,HLA等位基因频率用直接计数法来计算,采用Arlequin 3.5.2.2软件计算单倍型频率,并与1 644例广西汉族健康造血干细胞捐献者(对照组)比较。结果显示,ESRD组HLA-A*11:01、A*02:01、B*13:01、DRB1*12:02、DRB1*04:05、DRB1*14:54和DRB1*11:01的基因频率大于对照组(P<0.05),HLA-A*11:02、A*30:01、A*32:01、B*13:02、B*07:02、DRB1*07:01和DRB1*13:02的基因频率小于对照组(P<0.05)。ESR...     

赫哲人口的现状与发展态势

适度的人口数量,较高的人口素质和合理的人口结构会对民族的进步、社会的可持续发展具有积极的作用。新中国成立后,赫哲人口数量有了很大增加,人口质量也得到一定程度的提高,人口结构趋于合理。但从现状和发展态势看,还存在一定问题。掌握赫哲族人口现状,认清人口发展态势,可为赫哲族发展创造良好的环境,并为国家制定人口较少民族的人口政策以及和谐社会的构建提供相关依据。     

Mortality effects of temperature changes in the United Kingdom

Temperature changes are known to affect the social and environmental determinants of health in various ways. Consequently, excess deaths as a result of extreme weather conditions may increase over the coming decades because of climate change. In this paper, the relationship between trends in mortality and trends in temperature change (as a proxy) is investigated using annual data and for specified (warm and cold) periods during the year in the UK. A thoughtful statistical analysis is implemented and a new stochastic, central mortality rate model is proposed. The new model encompasses the good features of the Lee and Carter (Journal of the American Statistical Association, 1992, 87: 659–671) model and its recent extensions, and for the very first time includes an exogenous factor which is a temperature‐related factor. The new model is shown to provide a significantly better‐fitting performance and more interpretable forecasts. An illustrative example of pricing a life insurance product is provided and discussed.     

Diet composition of an invasive population of Lithobates catesbeianus (American Bullfrog) from Argentina

The American bullfrog Lithobates catesbeianus has been introduced around the world, with invasive populations reported from almost all South American countries. A population of this species was introduced in the Calingasta department of San Juan province, which is an arid environment in western Argentina. This work provides information on the dietary composition of an invasive population of L. catesbeianus, and compares the degree of dietary overlap between adults and juveniles. Stomach contents of 169 bullfrogs (82 adults and 87 juveniles) were analysed. Adults consumed 40 prey taxa and Hymenoptera (Insecta) was the most numerous prey item (41.8%), followed by Araneae (13.6%) and Aeglidae (13.4%). Juveniles consumed 29 prey taxa and Hymenoptera constituted the highest percentage in prey number (77.2%). The trophic overlap niche index at the same level shows a value of 0.64 overlap in dietary community between adults and juveniles of this bullfrog. Aeglidae was volumetrically the most important trophic item (25.4%), followed by Anura (25.02%). Our results showed that cannibalism in bullfrogs is more common than the consumption of native anurans, coinciding with that reported in other populations of introduced bullfrogs. The high similarity in the diets of both size classes and the association between the size of the predator and prey suggest that the impact caused by bullfrogs throughout their ontogeny is high and probably has an impact on their prey. Freshwater crabs are the main items in the diet of Lithobates catesbeianus in other introduced populations and are usually the most conspicuous at our study site. The crabs in freshwater ecosystems are part of the lowest trophic level in the food chain. The major threats to the southern region’s freshwater crabs include deforestation, farming and exotic species. Lithobates catesbeianus has a generalist diet and high overlap between adults and juveniles.     

Non-invasive genetic study and population monitoring of the brown bear (Ursus arctos) (Mammalia: Ursidae) in Kastoria region – Greece

The brown bear (Ursus arctos) in Greece is considered endangered but little is known about the genetic status and the exact size of local populations. Non-invasive genetic sampling was used in this study to investigate the genetic diversity and genetic structure of the brown bear population in the Kastoria region (northwest Macedonia, Greece) and to estimate its population size. Estimation of demographic parameters was based on innovative, well-evaluated methods that can provide estimates from a single sampling session. DNA was extracted from hairs, scat and blood samples and subsequent amplification of 10 microsatellite loci allowed the identification of a minimum number of 75 living bears in the study area while the mark–recapture-based analysis resulted in a point estimation of 219 individuals. Relatively high diversity values, lack of heterozygosity deficiency as well as estimated effective population size, support the Kastoria bear population having good conservation status.     

浅析河南省城市化的制约因素及对策

从人口流动机制、产业基础、基础设施建设、相关制度安排等方面,探讨了制约河南省城市化水平提高的不利因素,并对其的改进对策和措施进行了论述。     

Natural history of the marsupial Thylamys macrurus (Mammalia,Didelphidae) in fragments of savannah in southwestern Brazil

The objective of this study was to furnish information on the natural history of the Neotropical marsupial Thylamys macrurus in the southern Cerrado of Brazil. A range expansion of the species was observed to the northeast of the Mato Grosso do Sul state, Brazil. Specimens were surveyed in fragments of savannah (40–600 ha) during dry and wet seasons in 2003 and 2004 with live‐trap grids and pitfall lines. With an effort of 9767 trap nights and 2200 pitfall nights, we obtained 102 captures and 49 recaptures of T. macrurus. The data analyzed (57 males and 40 females) showed that males are more abundant in the dry season and females in the wet season. Young were recorded mostly during the wet season. Thylamys macrurus was scansorial, using the floor and the understorey. Sexual dimorphism was recorded, with males being larger than females. Information on ectoparasites is supplied.