Spermatophore characteristics in bushcrickets vary with parasitism and remating interval

Male bushcrickets provide females with a nuptial gift, a spermatophore, which is transferred to females at mating. The spermatophore consists of a gelatinous mass, the spermatophylax, and the sperm-containing ampulla. Male spermatophore size is positively correlated with insemination rate and female refractory period and therefore with male reproductive success. In this study, we examined spermatophylax weight, ampulla weight and sperm number in males of Poecilimon mariannae parasitized by the acoustically orienting fly Therobia leonidei. We show that in parasitized males, spermatophylax weight decreases with the level of parasitism. In line with the hypothesis that parasitism is a cost to reproduction, we found that spermatophylax weight was reduced at remating. In contrast, the replenishment of the spermatophylax in unparasitized males was complete after 2 days and was increased no further after 3 days. Both sperm number and ampulla weight showed an increase over time since last mating and sperm production was estimated at a constant rate of 500,000 per day in all individuals, regardless of parasitism. The allocation of investment in components of the spermatophore varies greatly with parasitism and remating. Both factors had rather independent effects on spermatophore constitution, revealing functional constraints acting on spermatophore characteristics in bushcrickets, which are important for understanding the selection pressures working on its components. Received: 13 September 1999 / Received in revised form: 4 February 2000 / Accepted: 13 March 2000     

大力发展循环经济 抢占国际竞争高地

中国在后国际金融危机时代要保持国民经济持续稳定快速增长,必须大力发展循环经济,全面提升国际竞争力。中国经济所处的发展阶段决定了不仅要在包括战略性新兴产业的高新技术领域抢占国际竞争的制高点,更要在国内市场需求快速增长的传统产业领域,通过自主创新抢占国际竞争的制高点。     

厌氧氨氧化菌与其他细菌之间的协同竞争关系

随着污水脱氮行业的蓬勃发展,各种新工艺、新理论层出不穷.厌氧氨氧化(Anammox)工艺以其独特的优点脱颖而出,成为最具应用前景的新工艺.厌氧氨氧化菌作为该过程的执行者目前已发现5属17种,本文主要对5属17种的厌氧氨氧化菌进行总结,并对厌氧氨氧化菌种内关系中的群体感应系统进行详细介绍,此外还介绍了厌氧氨氧化菌与硝化菌、反硝化菌以及厌氧甲烷氧化菌之间的协同与竞争关系.最后给出常见竞争因素对厌氧氨氧化种群结构的影响,通过控制竞争因素来实现对厌氧氨氧化种群结构的调节.本文将厌氧氨氧化菌微生物生态学与厌氧氨氧化污水处理工艺相结合,为厌氧氨氧化工艺在污水生物处理中的应用提供理论依据.     

Mate replacement in experimentally widowed collared flycatchers (Ficedula albicollis): determinants and outcomes

There is increasing evidence that sexual selection may be intense even in socially monogamous birds, resulting from both mate choice and sperm competition. We studied these two modes of sexual selection experimentally by removing paired male collared flycatchers, Ficedula albicollis, from their mates for 2 days and investigating the factors that influenced the likelihood of a replacement male appearing and how the removals influenced paternity. Replacement males (usually neighbouring males) appeared at 81% (n = 37) of nests where males were removed. The likelihood of this appearance was unaffected by the probable reproductive value of the female's clutch to the replacing male. A replacement was, however, less likely when the original male had a large forehead patch, a trait previously shown to be subject to sexual selection in this population. Experimental removal of males increased the level of sperm competition: 74% of experimental broods were multiply sired, compared to 29% of unmanipulated broods in a previous study. Only two factors predicted how paternity was shared between males: removed males fathered more young if removed closer to laying, and if they had larger forehead patches. The former result is consistent with last-male sperm precedence determining paternity, whereas the latter adds to other evidence that forehead patch size is the target of female preference in this species. Our results suggest that females exert some control over male replacement, and also that they may influence the fertilisation success of males by behavioural means. Received: 15 July 1998 / Received in revised form: 16 March 1999 / Accepted: 28 March 1999     

When females should contest for food – testing hypotheses about resource density, distribution, size, and quality with Hanuman langurs (Presbytis entellus)

Predictions of ecological models on female social relationships (van Schaik 1989) and their links with food distribution and the potential competitive regime are used to analyze the feeding and spatial behavior, and resource density, size, distribution, and quality in a forest population of Hanuman langurs (Presbytis entellus). In contrast to other populations, and assumptions on folivorous primates, the females of this population exhibit a linear dominance hierarchy. The langurs concentrated their feeding on three key resources with a low density and clumped distribution. Two out of the three key resources contained significantly higher levels of extractable protein and soluble sugar than other food plants, indicating high spatial variability of food quality. Even the mature leaves of the most preferred food plant were about twice as nutritious as those from other food plants. Group spread was small and only a single high-quality resource was used at a time. Finally, even rich resources could accommodate only a subset of a group. These findings fit predictions made for the prevalence of within-group contest competition. Given the observed food distribution and phytochemical heterogeneity of mature foliage, even females of folivorous species should contest for food. The effect of female dominance rank on size and composition of feeding parties also agrees with this prediction. A comparison with data from another forest population, where female dominance relations are weakly developed, revealed a clear-cut difference in the use and abundance of resources. It is argued that between-population differences in female social relationships within a species may be viewed as adaptive responses to local habitat conditions. Received: 1 August 1997 / Accepted after revision: 7 December 1997     

Sperm allocation in an uncertain world

Models of optimal sperm allocation are constructed using stochastic dynamic programming techniques, yielding predictions about sperm allocation when males mate sequentially, breeding time is finite, sperm stores are limited and females vary in quality. The models suggest that uncertainty of future reproductive opportunities should favour withholding of sperm, so that males tend to allocate less (for a given level of stored sperm) earlier in the breeding season. This effect is more pronounced the greater the variance in female quality. We also show that while allocation will be influenced by mate value, it is not necessarily optimal to allocate preferentially to high-quality females, since the benefits of a higher-quality mate may be offset by increased risk of rejection of sperm or higher sperm competition. The relationship between mate quality and level of allocation will depend strongly on the amount of remaining stored sperm, with males whose supplies are depleted being more likely to favour lower-quality partners. Received: 12 September 1997 / Accepted after revision: 28 June 1998     

环渤海地区主要港口竞争力评价

随着经济中心的不断东移，东北亚以其独特的地缘优势和经济互补优势正逐渐成为世界经济的新增长点，依托港口优势发展腹地经济也成为各大港口研究的重要课题。引入因子分析方法，以环渤海地区港口群为研究对象，利用2009年统计数据对影响港口竞争力指标进行处理并横向比较，得出港口竞争力排名，同时进行了分析。结果表明，青岛、天津、大连三大港口竞争力最强，但大连港稍显落后。在三大子港口群中，山东子港口群综合优势显著，辽宁子港I：3群存在腹地经济落后、恶性竞争等问题，津冀港口群受行政区划限制，港口资源整合困难。     

Managing for biodiversity from the electric utilities' perspective

The quality and sustainability of the natural environment is a matter of inestimable value and is critical to public health and welfare. All species have a purpose, and they exist for the betterment of other species. It is, therefore, incumbent on all humans to do their part in the preservation of this vast, diverse ecosystem called Earth. All humans are the beneficiaries, the ultimate customers, of a sound environment—water that is safe to drink, air that can be breathed, and soil that will sustain crops. There must be a commitment to leaving a clean and healthy planet for generations to follow, an earth which is enhanced, not diminished, by humans' presence.     

Herbaceous Covers to Control Tree Invasion in Rights-of-Way: Ecological Concepts and Applications

In northeastern America, thousands of kilometers of utility rights-of-way (ROWs) have to be managed to prevent the establishment of a tall vegetation cover that does not comply with safety and maintenance regulations. Recent decades have seen the emergence of ecologically based vegetation control strategies to reduce environmental impacts as well as maintenance costs. One such strategy is to take advantage of competitive herbaceous covers to limit tree invasion. This approach, however, as well as its fundamental underlying principles, has been little scrutinized. In this article, (1) we present the main ecological concepts supporting the use of a herbaceous cover to limit tree invasion, emphasizing naturally forested ecosystems of northeastern America. They include reported evidence of stable plant communities and an overview of potential underlying mechanisms of inhibition. (2) We then review field applications, specifically testing the ability of seeded herbaceous covers to control tree invasion in ROWs. (3) We discuss unresolved issues relevant to management and research. The available evidence suggests that seeding herbaceous covers in ROWs can help control tree invasion, but many issues still limit broad-scale applications. The various interactions that govern plant community dynamics are far from being fully understood, so selecting species still largely depends on an empirical approach. Patterns of resistance to tree invasion must be investigated over a wide range of spatial, historical, and environmental contexts to determine effective management and seeding practices that will lead to broad-scale applications. We suggest establishing communities rather than single dominant species and using as much as possible native species to limit risks of invasion.Published online     

Establishment and Growth of Experimental Grass Species Mixtures on Coal Mine Sites Reclaimed with Municipal Biosolids

The Surface Mining Control and Reclamation Act of 1977 requires that coal mine sites in the United States be reclaimed to establish vegetative cover that is diverse, native, and capable of plant succession. However, there is a question as to whether vegetation established on coal mine sites reclaimed with biosolids is diverse and capable of plant succession. The influx of nutrients with the addition of biosolids leads to long-term dominance by early-successional species, most notably grasses, and consequently, a low establishment of woody and volunteer species. Additionally, many grass species commonly planted in reclamation have aggressive growth habits that lead to their dominance in coal mine plant communities. The establishment and growth of selected grass mixes was evaluated to determine whether alternative grass mixes would be less competitive with woody and volunteer species as compared to commonly used grass mixes. Percent vegetative cover, species richness, and the survival of direct-seeded woody species were assessed for each treatment grass mixture. It was found that Poa compressa and a mixture of P. compressa, Panicum virgatum, and Trifolium repens provided adequate coverage while still allowing the highest species richness and survival of woody species. Use of these species mixtures in coal mine reclamation with biosolids in the eastern United States would likely lead to establishment of a more species-rich plant community with a greater woody species component while still providing erosion control and site protection.