Inbreeding in a lek-mating ant species, Pogonomyrmex occidentalis

In this paper we have two goals. First, we examine the effects of sample size on the statistical power to detect a given amount of inbreeding in social insect populations. The statistical power to detect a given level of inbreeding is largely a function of the number of colonies sampled. We explore two sampling schemes, one in which a single individual per colony is sampled for different sample sizes and a second sampling scheme in which constant sampling effort is maintained (the product of the number of colonies and the number of workers per colony is constant). We find that adding additional workers to a sample from a colony makes it easier to detect inbreeding in samples from given number of colonies; however, adding more colonies rather than more workers per colony always gives greater power to detect inbreeding. Because even relatively large amounts of sib-mating generate relatively small inbreeding coefficients, detection of even substantial deviations from random mating will require very large samples. Second, we look at the amount of inbreeding in a large population of the western harvest ant, Pogonomyrmex occidentalis. We find deviations from Hardy-Weinberg equilibrium equivalent to approximately 27% sib-mating in our population ( f = 0.09). Review of past studies on the population structure of other Pogonomyrmex species suggests that inbreeding may be a regular feature of the mating system of these ants. Although P. occidentalisis a swarm-mating species, there are a number of features of its population biology which suggest that the effective population size may be small. These include topographical variation that potentially breaks the population into demes, variation in the reproductive output of colonies, and variation in the size of reproductives produced by colonies. Received: 6 May 1996 / Accepted after revision: 6 October 1996     

Is the environment becoming more hazardous?—A global survey 1947 to 1980

This paper examines the assertion that natural disasters are increasingly destructive using evidence from disaster reports during the period 1947–1980. The criteria for judging the impact of a given natural disaster are chiefly loss of life and the extent of the geographical area affected. In spite of uneveness and bias in the reporting of sudden impact disasters the conclusions are that both the frequency of disasters and number of people killed are increasing. Further research into the social consequences of disasters and the need for disaster preparedness training programmes are recommended.     

Earthquake hazard and vulnerability in the northeastern Mediterranean: the Corinth earthquake sequence of February-March 1981

Population density, building type and earthquake magnitude are the main factors on which the total building damage following an earthquake depend. For the Greece - Turkey region quantitative relations between these factors have been developed, which, in spite of the inaccuracies in the available data, allow crude estimates of the damage following a particular size earthquake to be made. This is demonstrated retrospectively for the Gulf of Corinth earthquakes in 1981.     

Demographic impact of introducing modern medicine to a subsistence-level agrarian population: A simulation

Typical of many peasant communities in the Third World, the highland Indian population of Nuñoa, Peru operates close to its capacity for providing members with adequate nutrition. High birth and mortality rates maintain population stability in groups such as this. The introduction of modern medical services could decrease mortality and stimulate population growth, thus upsetting stability of the population size.Development of Third World countries includes improving health of subsistence-level populations by providing modern medical services. However, such changes would have secondary effects which should be anticipated. Using the Nuñoa population as a representative data base, and making a number of simplifying assumptions to increase the generality of this case, a simulation model has been devised to explore some of the consequences of introducing modern medical services.The model predicts that decreased mortality would initiate population growth. Some growth would be supported by changes in individual consumption patterns. But unless decreases in birth rate stabilized the population, it would increase beyond the level sustainable by local resources. Starvation or emigration would cause the population to crash. The model identifies several strategies for reducing birth rate sufficiently to avoid a population crash. Despite these strategies, increased equilibrium size of population would reduce per capita consumption. Since the population lives at the subsistence level, hardship, hunger, and even starvation could result. Thus, introduction of modern medical services could involve a trade-off between short-term improvements in health and. long-term economic hardship for the population. The model suggests that improved well-being of the population would require not only modern medical services but also (a) reduced birth rates; and (b) the improved technology necessary to increase food production.     

Managing brown bears and wilderness recreation on the Kenai Peninsula,Alaska, USA

The Russian River-Cooper Lake-Resurrection River trail system, on the Kenai Peninsula, Alaska, traverses essential brown bear habitat. To set management guidelines for this area, the trail system was monitored using questionnaire cards and electronic trail counters from 1984 through 1987. This helped to determine the extent and type of human use and human-bear encounters in the area. Management recommendations were intended to reduce the potential displacement of brown bears by hikers and to inform wilderness users of the proper camping techniques to avoid attracting bears to the campsite. An average of 5800 visitors hiked or camped along the trail system each year. Encounters between hikers and brown bears averaged 7/yr while encounters with black bears averaged 35/yr. Minor problems occurred with both the electronic trail counters and the questionnaire. Modilications to these methods are discussed. A Limits of Acceptable Change format should be considered for the trail system to determine the character and future direction of recreational activities and monitoring of the trail system should continue in the future.     

西湖引水治理后的底栖动物群落

１９９５年１月－１９９６年１２月对西湖底栖大型无脊椎动物群落进行了连续监测与研究,共发现大型底栖无脊椎动物２６种,其中寡毛类６种,多毛类１种,水生昆虫９种,蛭类,线虫和无节蠕虫各１种。     

人口增长对经济发展的影响

本文提出了人类社会生产的两个方面即物质生产、人口生产,指出人口生产必须与社会经济发展相一致,如果人口生产过多人口增长过快,就会影响社会经济的发展,因此我国必须对人口进行控制,实行计划生育.     

Ecological and hormonal correlates of antipredator behavior in adult Belding’s ground squirrels (Spermophilus beldingi)

Predator–prey relationships provide an excellent opportunity to study coevolved adaptations. Decades of theoretical and empirical research have illuminated the various behavioral adaptations exhibited by prey animals to avoid detection and capture, and recent work has begun to characterize physiological adaptations, such as immune reactions, metabolic changes, and hormonal responses to predators or their cues. A 2-year study quantified the activity budgets and antipredator responses of adult Belding’s ground squirrels (Spermophilus beldingi) living in three different California habitats and likely experiencing different predation pressures. At one of these sites, which is visually closed and predators and escape burrows are difficult to see, animals responding to alarm calls remain alert longer and show more exaggerated responses than adults living in two populations that likely experience less intense predation pressure. They also spend more time alert and less time foraging than adults at the other two sites. A 4-year study using noninvasive fecal sampling of cortisol metabolites revealed that S. beldingi living in the closed site also have lower corticoid levels than adults at the other two sites. The lower corticoids likely reflect that predation risk at this closed site is predictable, and might allow animals to mount large acute cortisol responses, facilitating escape from predators and enhanced vigilance while also promoting glucose storage for the approaching hibernation. Collectively, these data demonstrate that local environments and perceived predation risk influence not only foraging, vigilance, and antipredator behaviors, but adrenal functioning as well, which may be especially important for obligate hibernators that face competing demands on glucose storage and mobilization.     

Which regional features of Danish agriculture favour the corn bunting in the contemporary farming landscape?

Corn buntings Miliaria calandra were abundant throughout arable agricultural landscapes in Europe, but have catastrophically declined since the mid 1970s with changes in farming practice and now give serious conservation cause for concern. Corn buntings declined in Denmark during 1976–1993, but (almost unique in Europe) have since increased (by up to 11% per annum) in some areas without specific conservation recovery actions. Based on breeding bird surveys in the mid 1990s, highest corn bunting densities occurred on mixed agriculture in west Denmark (Jylland); the species was rarer or absent in regions of highest arable land cover. Corn bunting density and extent of rotational and permanent grassland were correlated, but not with spring sown barley (all known to constitute important corn bunting winter habitat). The extent of spring barley rapidly declined in Denmark during the 1980s, but since 1990, most counties have since shown 2–3% annual increases in this crop, except in Nordjylland, where high densities of corn buntings have remained stable. Elsewhere in Jylland, corn buntings have increased in counties supporting highest densities during the mid 1990s, contrasting stable or declining trends in south and east Denmark where densities were originally lower. After dramatic decreases everywhere in Denmark, corn buntings retain highest breeding densities associated with mixed agriculture, especially where grassland and spring sown barley remained in greatest extent. Although purely based on land use correlation and bird surveillance, these results show an association between mixed farming and favourable conservation status of a species now red-listed throughout much of Europe. Further investigations of habitat use at small spatial scales and throughout the annual cycle are urgently required to better enlighten specific recommendations for wider applicability of guidelines for corn bunting recovery actions elsewhere.     

多级曝气-固定化优势微生物强化固定生物膜处理工艺的应用

广州白云山一峰污水处理工程采用了新型污水处理工艺-多级曝气-微生物制剂强化固定生物膜处理工艺,对该工艺的特点及设计体会进行了讨论。设计进水COD、BOD5、SS、NH3-N、TP、动植物油为400～600mg/L、300～400mg/L、250～400mg/L、20～30mg/L、3～5mg/L、70～100 mg/L,出水为90mg/L、20mg/L、10mg/L、10mg/L、0.5mg/L、10 mg/L。实际运行结果表明：主要出水指标COD、BOD5、SS、NH3-N、TP、动植物油的去除率分别可达到88.1%、94.4%、97.9%、88.6%、94.6%、91.5%。该工艺具有占地少、建设成本低、结构简单、施工容易、能耗低、噪声低、运行可靠、稳定达标、剩余污泥极少、运行成本底、维护简便等优点。