Feeding Patterns in Different Size Larvae of Walleye Pollack, Theragra chalcogramma (Pallas, 1814) on the Shelf of Western Kamchatka

The stomach contents were examined in 373 walleye pollack larvae of different sizes. The diet of pollack larvae included more than 20 plankters of different sizes. Phytoplankton was the major food source of 4- to 6-mm-long larvae. The proportion of phytoplankton in the larval diet decreased as the larvae grew, and the late larval stages shifted entirely to a diet of zooplankton. As the larvae increased in size, the spectrum of food organisms changed from smaller to larger sizes. In the larvae 4 to 31 mm long, the length of prey varied from 0.1 (Coscinodiscus) to 6.0 mm (Neocalanus plumchrus). The average daily repleteness of pollack larvae varied from 32 to 210. The minimum repleteness was registered in 4- to 6-mm-long larvae with mixed feeding (endogenous and exogenous); in 30- to 35-mm-long fish the repleteness was the greatest. The daily food rations calculated for the most abundant size groups of larvae ranged from 4.3 to 6.6% of their body weight.     

Emergence pattern,microhabitat choice,and population structure of the Maghribian endemic Gomphus lucasii Selys, 1849 (Odonata: Gomphidae) in northeastern Algeria

Emergence of Gomphus lucasii Selys, 1849, an unstudied Maghreb endemic, was synchronised by overwintering in the final stadium in the Seybouse River in northeastern Algeria. Regular collections revealed that half of the annual population emerged during 10 days, showing a typical ‘spring species’ emergence pattern. Sex ratio was slightly male biased (51%). Males and females did not differ in vertical stratification. Emergence support choice was not random, but rather depended on support height, body size, and daily population density. Mortality was caused mainly by ants, although deformity of tenerals and bird predation were also important factors. Gomphus lucasii has been assessed as vulnerable (International Union for Conservation of Nature (IUCN) Red List), and the information provided in our study will be helpful in future conservation efforts.     

刺槐叶瘿蚊越冬幼虫空间格局及抽样调查技术

本文采用聚集指标法分析了刺槐叶瘿蚊Obolodiplosis robiniae(Haldemann)越冬幼虫的空间分布格局,结果表明:刺槐叶瘿蚊越冬幼虫在林间呈聚集分布;其聚集的原因与刺槐叶瘿蚊自身的行为习性有关或由刺槐叶瘿蚊本身与环境的异质性共同作用所造成。采用"z"字型、平行线、棋盘式、大五点、对角线5种抽样方法估计林间刺槐叶瘿蚊越冬幼虫虫口密度,确定对角线法调查15样方为最佳抽样方法。对土壤不同深度土层中越冬幼虫数量调查,明确最适取样深度为3cm。同时利用Iwao回归建立了理论抽样数量模型:n=t2/D2(1.1957/x珋+0.8905)。利用过筛手检和过筛水漂2种方法检数土中幼虫,对检出刺槐叶瘿蚊越冬幼虫虫量及检虫时间进行了对比分析,结果表明过筛水漂法检虫较为可取。     

松材线虫病发生点格局及影响因素

松材线虫病在中国大陆造成了巨大的生态与经济价值损失,南方地区尤为严重,分析松材线虫病空间分布、量化环境因素对其发生的影响对于松材线虫病的防控整治具有重要意义。本研究以江西省赣州市南康区松材线虫病为研究对象,采用核平滑密度、Ripley’s K函数、点过程模拟等空间点格局分析方法,探讨了区域松材线虫病发生的空间格局及其对环境变量的响应。结果表明: 研究区松材线虫病的发生不是随机分布,而是存在显著的空间聚集区。地形因子、植被因子和人类活动因子是影响松材线虫病空间异质性分布的主要因素。空间点格局分析表明,海拔、坡度、距最近道路距离、道路密度、距最近居民点距离、郁闭度和植被类型对松材线虫病的发生具有重要影响。在森林病害管理中,除了加强因人类活动引起病害传播源的管控外,还应该考虑地形、植被类型等特征进行松材线虫病害的综合预警监测。     

川滇高山栎种群不同海拔空间格局的尺度效应及个体间空间关联

川滇高山栎灌丛(Quercus aquifolioides)是我国西南高山典型的植被类型,研究其空间格局对于研究种群的生态学过程有重要意义。为了弄清川滇高山栎种群空间格局及其个体间空间关联对海拔,尺度和大小级等因素的响应情况,研究中应用点格局分析的方法,在巴郎山沿高山栎分布海拔范围设置4个海拔梯度,并根据体积大小将高山栎分为4个大小级等级,比较不同海拔、不同尺度、不同大小级间的高山栎种群空间格局及个体间空间关联。结果表明,川滇高山栎种群空间格局及其个体间关联与空间尺度、植株形体大小和海拔梯度密切相关:在小尺度上,种群趋向于聚集分布,个体间有较强的空间关联,随着空间尺度的增大,种群逐渐趋于随机分布,个体间空间关联减弱,区域无关联;个体间形体差异越小,个体间正关联就越强,个体间形体差异越大,正关联就越弱,负关联就越强;海拔因子对聚集分布的聚集规模和个体间关联的关联程度有较大影响。     

空间分布型的形成过程研究

具合影个研究了广义空间分布型和复合空间分布型的形成问题,解释了空间分布型的形成机理,并给出了１１种广义空间分布型和９种复事空间分布型;同时提出了空间分布型的３种判定方法：扩散系数法、空间相关法和参数变动法,它们以可用于区分常见的空间分布型,也可以用于判定分布型的形成过程;为研究空间分布型的形成机理和变化规模提供了有力的手段。以马尾松毛虫的空间分布型的研究结果表明,马尾松毛虫幼虫的空间分布型是复合负     

子午岭油松林灌木层主要树种的空间分布格局和种间关联性研究

对子午岭油松林的主要物种进行实地调查,并根据林下灌木层各物种的重要值确定主要树种,然后用聚集强度指数、x2值和关联度指数对林下灌木层主要树种的空间分布格局和种间关联性进行分析.结果显示:(1)13个主要树种中除辽东栎的K值和CA值小于0外,其余种群皆表现为K>0,C>1,CA>0,I>0,m*/m>0;(2)x2检验显示,大多数树种种间关联性不显著;(3)种间关联度分析显示,树种呈正联结的共计36对,呈负联结的也有36对,有6对是关联强度低的种对.结果表明,在子午岭油松林中辽东栎与其它树种相比,具有广泛均匀分布的倾向,与其它树种之间存在强烈的竞争关系,辽东栎树种具有一定的种间竞争扩张优势.     

沙棘木蠹蛾的幼虫空间分布与抽样技术

利用常用的聚集度指标 ,对沙棘木蠹蛾HolcocerushippophaecolusHua ,Chou ,FangetChen幼虫的分布进行了分析。结果显示 ,该幼虫的空间分布格局为聚集型分布。通过Iwao的m - x回归检验方程 ,确定了其最适抽样数和最佳样方大小。采用对角线、之字型、五点式、棋盘式和平行线等 5种抽样方法对沙棘木蠹蛾幼虫的抽样技术分别进行了研究 ,结果表明 :最佳的抽样方法为棋盘式。     

水稻与蔬菜/玉米邻作下稻纵卷叶螟幼虫和食虫沟瘤蛛的空间格局与变异

应用地统计学的原理和方法研究了水稻与白瓜、番茄及玉米等邻作生境内稻纵卷叶螟幼虫和食虫沟瘤蛛的空间格局与变异.结果表明:整个水稻生长过程中稻纵卷叶螟幼虫和食虫沟瘤蛛的空间分布基本为聚集分布,且两者的空间相关变程范围分别为1.91～182.57m和3.70～9.70m;种群密度的等值线图表明,两者在空间及时间上的吻合程度高,说明食虫沟瘤蛛对稻纵卷叶螟幼虫有较强的追随效应和控制作用;不同邻作模式下以白瓜邻作水稻田的控制效果最佳.     

Food preferences of tanypodinae larvae (Diptera: Chironomidae)

Analyses of the gut contents of larvae of three species of Tanypodinae, collected from four sites in north-east England and Scotland, invariably showed small particles (1–10 µm²), predominantly of detritus, to be more abundant than large particles (10–100 µm²), mostly algae and diatoms. No animal remains, such as carapaces, head capsules and chaetae, or vascular plant fragments were found in any of the intestines. In contrast, food-choice and growth experiments suggested that animal food (particularly Tubificidae and Chironominae larvae) was important in the tanypod diet. In the food-choice experiments, six different foods offered to small (4–7 mm long) and to large (8–12 mm long) larvae of Procladius choreus Meigen, were chosen in the following order: live Tubificidae spp.; detritus; live Chironominae larvae; a mixture of algae and diatoms; live Ostracoda spp.; and live Cladocera spp. However, when the results of the individual choices were examined, it was clear that the small larvae had consumed greater amounts of the small types of food (i.e. detritus, algae and diatoms) in comparison to the large larvae. In the growth experiment, those larvae of P. choreus reared solely on Tubificidae, detritus or Chironominae larvae thrived, while those fed on algae and diatoms, ostracods or cladocerans grew more slowly and fewer survived the experimental period.It was concluded that although Tanypodinae larvae are primarily predators with definite food preferences in ideal foraging conditions, in adverse conditions they will utilize a range of available stand-by foods, the most important of which appears to be detritus.     

紫陀螺菌化学成分及其抑制肿瘤细胞增殖活性的研究

以紫陀螺菌为对象,研究其子实体的化学成分及其抑制肿瘤细胞增殖活性。采用溶剂提取、柱层析和高效液相色谱等方法分离纯化化学成分,通过核磁共振和质谱技术鉴定单体化合物结构,运用结晶紫法评价单体化合物抑制肿瘤细胞增殖活性。从乙酸乙酯提取物中共分离鉴定6个单体化合物,分别为(22E,24R)-麦角甾-5,7,22-三烯-3β-醇(1)、3β,5α-二羟基-(22E,24R)-麦角甾-7,22-二烯-6-酮(2)、(22E,24R)-麦角甾-7,22-二烯-3β,5α,6β-三醇(3)、吲哚-3-甲酸甲酯(4)、4,4-二甲基-1,7-庚二酸(5)和(8E,10E)-12羰基十八碳-8,10-二烯酸(6),其中化合物1为主要成分,相对含量为23.8%。活性测试结果表明3对人乳腺癌细胞株MCF-7 细胞、人胰腺癌细胞株PANC-1细胞和人乳腺癌细胞株MDA-MB-231细胞具有微弱的细胞增殖抑制活性。本研究首次报道了紫陀螺菌化学成分,对深入挖掘其在健康领域中的开发价值具有重要意义。     

节瓜蓟马空间分布图式研究

对节瓜蓟马在节瓜上的空间分布状况进行了调查和分析,结果表明,该虫的空间分布型前期符合奈曼分布,后期符合负二项分布;其空间图式是聚集的,分布的基本成分是个体群;在节瓜不同叶位上分布差异显著。明显向心叶聚集,在瓜栅向光面与背光面虫口比例方面,均以向光面较多。     

嗜热菌PIF1解旋酶的生化活性研究

小整合频率1(petite integration frequency 1,PIF1)解旋酶广泛存在于生物体内,在核酸的代谢过程中发挥着重要作用。近年来,人们已经报道了多种PIF1解旋酶的生化活性及三维结构,但对极端环境下细菌的PIF1解旋酶的报道仍较少。本文利用多种生物化学与生物物理学技术,对黄石热脱硫弧菌PIF1(Ty.PIF1)解旋酶进行了多方面研究。通过原核表达纯化系统,获得了纯度90%以上,均一性好的Ty.PIF1蛋白。Ty.PIF1在溶液中为单体,分子量约为60 kD。Ty.PIF1具有很高的热稳定性,在65 ℃以下时,二级结构保持稳定,大于70 ℃时,二级结构才会发生改变。Ty.PIF1在体外最适解旋温度为45 ℃,并非黄石热脱硫弧菌生存的最适温度,预示着Ty.PIF1在体内发挥活性时,可能需要其他辅助因子的参与。Ty.PIF1的酶活力温度范围较宽,在20~55 ℃均具有解旋活性,在55 ℃能解旋预示了Ty.PIF1具有耐热特性。Ty.PIF1偏向于同含有单链的底物结合,但对单链长度有一定要求,其长度至少大于4 nt;Ty.PIF1也会较好地结合无单链尾链的G₄结构,说明Ty.PIF1可能有专门结合G₄结构的区域。Ty.PIF1能解开一系列带有5′-单链尾链的类似于复制中间体的底物,且对底物结构有一定的偏好性;Ty.PIF1也可以解开含有G₄结构的底物,DNA-RNA杂交链、RNA-loop结构,预示着Ty.PIF1在生物体内有着多种生物学功能。Ty.PIF1解旋带有不同长度5′-单链尾链的双链底物时,尾链长度越长,解旋速率越快,预示着Ty.PIF1可能与Sc.PIF1一样有着较低的解旋持续性。本文将Ty.PIF1的生化活性与其它物种的PIF1解旋酶进行了比较,找出了其中的共性与差异,加深了人们对嗜热菌PIF1解旋酶的认识,为今后研究其它极端环境微生物的PIF1解旋酶提供了一些思路。     

Spatial and temporal abundance,substrate partitioning and species co-occurrence in a guild of Neotropical blackflies (Diptera: Simuliidae)

Blackfly larvae were sampled monthly from two smallNeotropical mountain streams 500 m apart from each other in northernVenezuela during a 15-month period, and ten habitat variables weremeasured at two altitudes (800 and 900 m) to determine local spatialand temporal variations in abundance, stream variables, speciesco-occurrence, and substrate preference within the blackflyguild. The blackfly species composition of each stream was the same,with five species (in order of abundance): Simulium ochraceumWalker s.l., S. paynei Vargas, S. metallicum Bellardicytospecies E, Simulium sp., and S. horacioi Okazawa &Onishi. There were clear differences in community structurebetween streams (not among altitudes), although S. ochraceums.l. was the most abundant species in both habitats. Principal component andcorrelation analyses revealed that structural (great depth, width,flow, and discharge) and chemical (low conductivity) factors werethe stream variables best associated to the spatial distribution ofmost blackfly species. Blackfly abundance was greater in the largerstream. Larvae were most abundant on submerged rocks and fallenleaves, although the patterns of substrate use within the guildrevealed substrate partitioning among most blackfly species.There was one general annual peak of abundance at the end of therainy season. We suggest that blackfly community structure in theseNeotropical headwaters streams, over the small spatial scaleexamined here, is largely influenced by interactions among streamsize and velocity-related factors (width, streamflow, discharge andsubstrate availability-stability) and the rainfall regime.     

老龄阔叶红松林下层木空间分布的生境关联分析

基于老龄阔叶红松林30 hm2(500 m×600 m)固定监测样地,分析了老龄阔叶红松林下层(1 cm≤DBH≤5 cm)14个主要树种(个体数>300)的空间分布与空间距离、地形因子及郁闭度之间关联性。结果显示:(1)14个种都显示出了聚集分布,绝大多数种呈现出了在小距离级上呈显著正空间自相关大距离级上呈现显著负空间自相关的趋势。(2)6个种显示与空间距离显著相关即存在本身的聚集效应,占被检验种的42.86%;7个种显示出与环境(地形、郁闭度)有显著相关性即存在显著的生境偏好,占50%。个体数大于1000的7优势种中有5个种空间分布与生境显著相关,5个种与空间距离显著相关。(3)色木槭、千金榆显示出了对低海拔、向阳坡生境类型的偏好,簇毛槭、花楷槭、毛榛显示出对高海拔、坡度陡、向阴坡生境类型的偏好。这表明,老龄阔叶红松林下层木多数树种为聚集分布,其聚集性的空间分布受生境及自身聚集效应的重要影响。多个树种对同种生境的偏好体现了植物利用资源的相似性和生态位的重叠,对不同生境的偏好体现了物种间的排斥性,这是长期适应不同微环境,利用不同空间资源的结果,也是生态位分离的反映。     

Colonization of perspex strips by larvae of Austrosimulium bancrofti (Taylor) near Ipswich,Queensland

Larvae of the Taxon Austrosimulium bancrofti (Taylor) were collected from perspex strips placed in rapids of the Brisbane River during January (summer) and October (spring). Separation of larvae according to the mixture approach to clustering demonstrated that: a) October cluster I larvae were larger and underwent an additional cluster to those collected in January, b) there was an additional cluster of larvae in each month, which correlated with the percentage of A. bancrofti Ipswich B that were identified cytologically, and c) greater numbers of later cluster larvae were collected from the strips than early clusters.Multivariate analysis demonstrated that distance from the lip of the rapids, strip texture and water velocity had a significant effect on the number of larvae colonizing perspex strips. Numbers increased with: a) decreasing distance from the lip of the rapids, b) increasing surface area of roughened strips and c) water velocity in the range 1.00 < X 1.38ms^–1. The influence of adult female oviposition behaviour, larval behaviour, sampling time and technique are discussed in relation to the parameters that influenced the colonization of artificial substrates.     

Spatial patterns and associations of four species in an old-growth temperate forest

The spatial pattern of a tree species is an important characteristic of plant communities, providing critical information to explain species coexistence. The spatial distribution and association of four different successional species were analyzed among different life-history stages in an old-temperate forest. Significant aggregation patterns were found, and the degree of aggregation decreased with the scales and life-history stages. Significant interspecific spatial associations were detected. In comparing the relationships among the different life-history stages, positive associations were found at small scales in all of the juvenile species pairs. In the adult stage, negative associations were detected in coniferous vs. deciduous species pairs, while the deciduous species pairs, which have identical resource requirements, showed a positive association in this study. The coniferous species pairs showed a positive association at small scales. We infer that seed dispersal, competitive ability, or the requirement for specific topographic and light environments may contribute to the coexistence of these species.