Vertebrate exploitation of pulsed marine prey: a review and the example of spawning herring

Short-term bursts of prey availability occur in many ecosystems and have potential important consequences for both predator biology and ecosystem function. Examples of prey ‘pulses’ in marine ecosystems include spawning runs of several anadromous and marine fishes, horseshoe crab spawning, and salmonid juvenile outmigrations, which are exploited by numerous species of vertebrate predators. In a few cases, the fitness or demographic consequences of such predator–prey interactions are known or inferred, but too often that information remains unknown. We explored the extent of temporal and spatial variation in one example of a pulsed marine resource: the spawning of Pacific herring (Clupea pallasii). Spawning herring provide a rich, aggregated resource to which dozens of species of vertebrate predators often exhibit strong numerical responses. However, the spawning events are often variable in both time (annual differences of several to many weeks) and space (both regional and more local differences in size and timing of events). Such variability must affect more mobile predators less than area-restricted predators, and thus its effect would vary not only among species but also within species, depending on constraints of the predator life history. Unpredictability of the prey concentrations, whatever their proximate causes, may contribute to maintenance of metapopulations of prey such as herring, if unpredictability lessens the impact of predation.     

An insight into the genetic polymorphism among European populations of Lactuca serriola assessed by AFLP

Prickly lettuce (Lactuca serriola) is world-wide distributed and very variable species generally considered as a progenitor of the cultivated lettuce (Lactuca sativa). Altogether, 50 populations of L. serriola were characterized by means of amplified fragment length polymorphism (AFLP) and by isozyme analysis. Relationships among individuals and populations were examined by applying the unweighted pair-group method with the arithmetic averages (UPGMA) clustering algorithm, principal coordinate analysis (PCA) and the Nei's gene diversity index. The studied set of populations split into three main groups based on the AFLP polymorphism analysis. The first group contained L. sativa (control). The second group comprised two L. serriola accessions; one of them was identified as L. serriola f. integrifolia and the other as a mixture of two L. serriola forms. The largest and the most diverse third group contained the remaining L. serriola accessions. The population clustering corresponded approximately to their geographical distribution in Europe. At least five distinct geographic groups were recognised: 1) Northern European; 2) Slovenian; 3) very heterogeneous Central and Western European (mostly north of the Alps); 4) Mediterranean; 5) prevalence of L. serriola f. integrifolia, mostly comprising accessions from the United Kingdom and the Netherlands. This study showed that accessions originating in various eco-geographical conditions of Europe differ significantly in their genetic and protein polymorphism, as well as in morphology. Some European L. serriola populations (e.g. from Scandinavia and United Kingdom/British Isles/) seems to be isolated and homogeneous; in contrast, populations occurring in Central Europe are very diverse and genetically overlapping.     

广西千层塔资源调查研究

通过对广西千层塔主要分布区10个野外样点和总样方量30.5 km~2的调查,结合6个标本馆45份千层塔馆藏标本及现有文献的研究表明:千层塔在广西主要分布在桂东北、桂东南等地,实际分布生境总面积约1886.3 km~2;野外生物量调查得到了千层塔在不同地理区域的生物量分布格局,并结合科学评估方法对样方调查结果和间接推导数据的权重分析及环境参数进行评估,初步确定广西千层塔天然生物量为413.1 t;进一步考虑人为采集能力的前提下,估测广西千层塔的理论可采量20.6 t。千层塔资源分布分散,且主要分布在自然保护区和风景区范围内,因此,不宜大规模开采,应进一步寻找科学合理的途径解决资源紧缺问题。     

Situation exploitation: higher male mating success when female resistance is reduced by feeding

Optimal male and female mating rates rarely coincide. Males often shift the rate in their favor by either increased signaling and by overcoming female resistance to copulation. The concept of sensory exploitation posits that males produce signals that mimic naturally selected benefits and so deceitfully attract females. However, males also have to overcome female resistance to actual copulation. Males may do so by copulating during situations when the female's ability to resist is decreased because of competing naturally selected demands. Males of the common bedbug, Cimex lectularius , an obligate blood feeder, mate at a rate, and in a manner that is harmful to females. Females have to feed regularly to produce eggs, and during feeding female body volume increases by 300%. Choice trials using unfed and either fed or experimentally enlarged but unfed females showed that the increased postfeeding body volume of females attracted more male mating attempts, strongly reduced female resistance to male mating attempts and resulted in a net increase in female mating rate. Our results, therefore, suggest that males have increased mating success in a situation that females cannot avoid because it is naturally selected. Such "situation exploitation" of low resistance may be a common phenomenon.     

Mode de vie à Isernia La Pineta (Molise, Italie). Stratégie d’exploitation du Bison schoetensacki par les groupes humains au Paléolithique inférieur

The site of Isernia La Pineta (Molise, Italie) is characterized by the presence of a rich faunal assemblage related to a very abundant lithic industry in several archaeosurfaces dated between 600,000 and 700,000 BP. A specific archaeozoological study has been carried out on Bison schoetensacki specimens that are the most represented taxon in each archaeological level, followed by rhinoceros, elephant, bear and cervid. The quantitative et qualitative analysis of the faunal remains, the age profiles and the identification of anthropic modifications have allowed to better understand the exploitation strategies adopted by humans in the site and to underline a selective hunting of population of bison, related to the age of the individuals.     

Influences of chronic contamination of oil field exploitation on soil nematode communities at the Yellow River Delta of China

Oil production related activities have led to many environmental problems. Around 80% of the total output of crude oil is generated from terrestrial oilfields in the world. However, the impact of oil exploitation procedures on soil animal communities has not been fully understood. This study investigated the responses of soil nematode communities to the oil exploitation activities in the Yellow River Delta of China. By setting 10 oilfield sites and 5 relatively uncontaminated sites (controls), we found that the content of soil total petroleum hydrocarbons (TPH) was significantly higher at oilfield sites than at controls. With a longer oil exploitation history, the content of soil TPH increased. Soil nematode community structure at oilfield sites was largely different from that at controls. Soil nematodes were significantly less abundant but more diverse at oilfield sites than at controls. The proportions of fungal feeders were significantly lower at oilfield sites than at controls, attaining only half of those at controls. The nematode trophic diversity and genus number negatively correlated with the duration of petroleum exploitation history. This study elucidated the difference in soil nematode communities caused by oilfield exploitation and indicated that the nematode diversity was most obviously influenced by the soil TPH content and the oil exploitation history.     

宁夏野生食用植物资源的调查与信息数据库的建立

通过野外调查与室内工作相结合,对宁夏野生食用植物资源进行调查与统计,建立宁夏野生食用植物资源数据库,并提出了宁夏野生食用植物资源开发和利用存在的问题。结果初步调查到宁夏野生食用资源植物共计74科186属348种10类,其中饮料及野果类植物与野菜植物具有一定的开发潜力,应该在这些野生食用资源植物中进行进一步的筛选,最终主要集中于人工驯化与栽培上。此外针对宁夏野生食用植物资源开发和利用面临的问题,需加强对宁夏野生食用植物资源状况的调查,并进行深入的研究,在前面所做的基础研究上,筛选特色的野生食用资源植物进行合理的开发和利用,之后对筛选出的野生食用资源植物进行人工栽培等工作,在土地可持续利用的前提下,研究野生食用资源植物与其他栽培作物间作的模式,同时在发展过程中通过收集珍贵濒危野生植物资源植物的种质资源,而对其加以保护。     

Strategies of survival and resource exploitation in the Antarctic fellfield ecosystem

Antarctic fellfields present organisms with a heterogeneous habitat characterised by a wide variety of environmental stresses. These include low temperatures, limited moisture availability, frequent and often rapid freeze‐thaw and hydration‐dehydration cycles, exposure to high photosynthetic photon flux density and ultraviolet (uv) irradiance, seasonal snow cover, high winds, cryoturbation and, depending on location south of the Antarctic Circle, considerable daylight in summer. Most of these factors vary both predictably and unpredictably in spatial and temporal planes. In response to this adverse environment, fellfield organisms have developed a variety of strategies to overcome physiological stress and to exploit the limited resources available during the short austral growing season. A high degree of synchronisation exists, so that investment in non‐essential activity and adaptations is minimised. Here, we review the combined suites of co‐adapted traits used by different fellfield taxa to achieve energy acquisition, growth and reproduction under adverse levels of two principal limiting factors: low temperatures and the scarcity of water. To this end, a detailed characterisation of the Antarctic fellfield microenvironment is followed by a synthesis of available data on the morphology, physiology, life history and behaviour of successful Antarctic flora and fauna. Tolerance of low temperatures by fellfield organisms is achieved by elevation of standard metabolism, production and accumulation of cryoprotectants, supercooling, melanic pigmentation, behavioural avoidance, compact growth forms and synchronised reproduction and extended life cycles. Low moisture conditions are overcome by dehydration resistance, anhydrobiosis, development of resting stages and by behavioural avoidance of desiccating conditions. Occupancy of the Antarctic fellfield habitat is considered to require the ability to respond rapidly to ephemeral resources and to tolerate severe environmental stresses. During summer, organisms rely on opportunism to maintain a positive energy balance. During winter, resistance adaptations are used to withstand the potentially lethal climate, especially in habitats not protected by snow cover. This deterministic framework has led to the selection of species that are genetically and physiologically pre‐adapted for resource acquisition yet sufficiently robust to withstand cold and desiccation stresses. Non‐adapted taxa fail to become established. Despite the environmental selection pressures, available evidence suggests that colonisation of the fellfield habitat has not required the evolution of any adaptations, only the refinement of those already possessed to an extent by some temperate forms. This has led to the convergence of survival strategies. It is hypothesised that, in the short term, the majority of Antarctic fellfield biota are able to absorb the predicted effects of a changing climate by their high levels of physiological tolerance and life‐cycle flexibility.     

峨眉山野生药用蕨类植物资源及其开发利用

峨眉山中药材以其品种多、质优量大、历史悠久而驰名中外,素有“天然药园”之称。其野生药用蕨类植物有38科148种,占全国该类植物资源总科数的97%、总种数的80%左右。本文对药用蕨类植物的生境、分布、药用部位、功效等作了初步分析,并对合理开发利用提出了建议。     

石油烃的厌氧生物降解对油藏残余油气化开采的启示

利用微生物将油藏中难以动用的原油就地转化为甲烷,以天然气的形式开采、或作为战略资源就地储备,从而大幅度提高油气资源的利用率,是当前国际上研究的前沿课题。本文综述了石油烃厌氧生物降解转化为甲烷的菌群结构、反应热力学和反应动力学等基础科学问题的最新研究进展,讨论了油藏残余油气化开采技术的可行性及开发潜力,提出了该技术进一步研究的方向。