Agonistic behavior of the crayfish Euastacus armatus and Cherax destructor

The intra- and interspecific agonistic behavior of Euastacus armatus and Cherax destructor from northeastern Victoria were examined. While the agonistic patterns of E. armatus appeared similar to those shown by most crayfish, individuals of C. destructor execute an unusual, highly stylized cheliped “punch” behavior during strong interactions, along with the other behaviors seen in many species. Juvenile C. destructor exhibited gregarious behavior, tending to co-occupy burrows and being physically near each other. Tests showed that the white chelipeds which are characteristic of mature E. armatus affect the outcome of aggressive interactions. When individuals had their chelipeds whitened, they won agonistic interactions more often. This result held for both intraspecific pairings and size-matched pairings with individuals of C. destructor. Individuals of C. destructor won the majority of size-matched pairings with non-whitened individuals of E. armatus.     

庞泉沟国家自然保护区森林群落木本植物种间关系的分析

应用基于二元数据的χ²检验、方差比率法和基于数量数据的Pearson相关系数检验及Spearman秩相关系数检验等数量方法,研究了庞泉沟国家级自然保护区(东经111°22′～111°33′,北纬37°45′～37°55′）森林群落（海拔1 600～2 430 m）21个优势种的种间关系。结果表明：研究区域内森林群落优势种群的种间关系较为松散（χ²_0.95N＜W＜χ²_0.05N）,种的分布相对独立,森林群落总体处于稳定阶段;但局部地段优势种群间存在着一定程度的竞争。位于山体中下部的群丛组Ⅰ、群丛组Ⅱ的总体关联性存在一定程度的负关联,但未达到显著水平; 位于山体上部的群丛组Ⅲ的总体关联性为无关联,种间关系较为松散。随着海拔的升高,三个群丛组的联结指数(VR)呈上升趋势,χ²检验显著率和Spearman秩相关检验的正负关联比有所增加,负显著率都明显下降,正显著率有升高的趋势,说明随着海拔的升高,种间关系表现为无关联,森林群落也趋于稳定。应用方差比率法与χ2检验、Pearson相关系数检验和Spearman秩相关系数检验较为清晰地揭示了庞泉沟自然保护区森林群落的种间关系。这四种方法可以互相弥补彼此的不足,结合使用效果更好。本研究结果支持随着群落演替进程的发展,群落结构及其种类组成将逐渐趋于完善和稳定,群落种群总体种间关系也将向着无关联发展的观点。     

Quantitative and qualitative differences in morphological traits revealed between diploid Fragaria species

BACKGROUND AND AIMS: The aims of this investigation were to highlight the qualitative and quantitative diversity apparent between nine diploid Fragaria species and produce interspecific populations segregating for a large number of morphological characters suitable for quantitative trait loci analysis. METHODS: A qualitative comparison of eight described diploid Fragaria species was performed and measurements were taken of 23 morphological traits from 19 accessions including eight described species and one previously undescribed species. A principal components analysis was performed on 14 mathematically unrelated traits from these accessions, which partitioned the species accessions into distinct morphological groups. Interspecific crosses were performed with accessions of species that displayed significant quantitative divergence and, from these, populations that should segregate for a range of quantitative traits were raised. KEY RESULTS: Significant differences between species were observed for all 23 morphological traits quantified and three distinct groups of species accessions were observed after the principal components analysis. Interspecific crosses were performed between these groups, and F2 and backcross populations were raised that should segregate for a range of morphological characters. In addition, the study highlighted a number of distinctive morphological characters in many of the species studied. CONCLUSIONS: Diploid Fragaria species are morphologically diverse, yet remain highly interfertile, making the group an ideal model for the study of the genetic basis of phenotypic differences between species through map-based investigation using quantitative trait loci. The segregating interspecific populations raised will be ideal for such investigations and could also provide insights into the nature and extent of genome evolution within this group.     

三种瓢虫集团内捕食卵对初龄幼虫生长发育的影响

种内和种间捕食卵现象常见于对食蚜瓢虫的研究报道中。源自亚洲、入侵北美和欧洲的异色瓢虫(Harmonia axyridis)由于卵含有生物碱而被认为可能是威胁本土瓢虫生存的原因,但该推测只有在明确异色瓢虫在原产地是否对本土瓢虫具有类似负面影响后,才能确证。通过饲喂实验,旨在明确异色瓢虫在原产地是否对本土七星瓢虫(Coccinella septempunctata)和龟纹瓢虫(Propylea japonica)具有食卵负面作用,为揭示异色瓢虫入侵机理提供依据。实验中用蚜虫(对照)和3种瓢虫卵对瓢虫初孵1龄幼虫进行饲喂处理,观察幼虫生长发育指标。对瓢虫初龄幼虫存活表现的分析结果表明:(1)龟纹瓢虫初孵幼虫取食同种卵和七星瓢虫卵后存活至2龄的比率均高于取食异色瓢虫卵的近7倍;(2)七星瓢虫幼虫取食异色瓢虫卵未存活到2龄,但取食其他瓢虫卵和蚜虫后85%以上个体存活至2龄;(3)异色瓢虫初孵幼虫取食同种和其他2种瓢虫卵后有90%以上存活至2龄。龟纹瓢虫和七星瓢虫1龄幼虫取食异种卵比同种卵后的发育历期显著延长,但异色瓢虫并未表现出差异。龟纹瓢虫和异色瓢虫1龄幼虫取食同种和异种卵后的体增重相同,但七星瓢虫取食龟纹瓢虫卵后体增重比取食同种卵减小。研究结果说明,异色瓢虫卵对七星瓢虫和龟纹瓢虫初孵幼虫的生存具有负面影响,反之不然。所以,取食异色瓢虫卵本身并非是导致北美和欧洲本土瓢虫数量减少的原因。     

元宝山南方红豆杉种群结构——Ⅱ、高度结构

在资源调查的基础上选择样地 ,采用样方调查法研究红豆杉种群高度结构 ,结果表明南方红豆杉种群是通过茎干萌生幼苗 (构件 )来延续和扩大的 ,其结构为塔型 ,存活曲线为中间微凸而近于直线 ,是稳定型种群结构。幼苗幼树级占 95.3% ,其次为高度 9.1～ 11m的成年树级 ,占 1.6 %。为了扩大和延续 ,南方红豆杉种群通过大量萌生 (繁殖 )构件并进行自我调节 ,使幼树幼苗有较高的死亡率 ;种群个体进入优势层后 ,高度生长缓慢 ,而径向生长加快 ,因此 9.1～ 11m级数量增多。种间种内竞争的结果形成南方红豆杉种群世代不同大小个体的高度结构。南方红豆杉种群高度与胸径的关系为幂函数相关关系 ,高度与年龄 (<6 0 a)的关系为线性相关关系     

Herbivorous insect species in the tree canopy of a relict South African forest

Abstract.

• 1 The herbivorous insects on twelve species of evergreen broadleafed trees were repeatedly sampled over a period of 11 months in a small relict forest on the east coast of South Africa. This extraordinarily speciose forest patch has an unusually high proportion of endemic tree species, some of which are extremely rare.
• 2 The insect herbivore fauna (number of species) seems to be markedly depauperate compared to that reported on native, broadleafed trees from other parts of the world. Some possible reasons for this are discussed.
• 3 The total number of herbivorous insect species on each tree species was strongly correlated with the local relative abundance of the host plant species.
• 4 There was no relationship between the total number of insect herbivore species on each tree species and the relative taxonomic isolation of the trees. The proportion of seemingly unique (= specialist) herbivorous insect species (i.e. those that occurred on one tree species only) was greatest on taxonomically isolated trees.
• 5 A fundamental deficiency in the interpretation of the data in this study, and of many other similar studies that report on the number of insect species on plants, is discussed, namely the lack of clarity on the closeness of the association between individual insect herbivore species and their respective host plants.

     

围封与放牧管理对高寒草甸植物功能性状和功能多样性的影响

植物功能性状能够响应生存环境的变化并直接决定着生态系统功能。为了揭示围封与放牧管理对物种共存和驱动群落构建的影响机理,该研究以青藏高原东缘高寒草甸为对象,分析了围封与放牧处理对植物功能性状和功能多样性的影响。结果显示:(1)在群落水平,放牧显著降低了比叶面积和植物高度;在物种水平,放牧群落中多数杂类草比叶面积减小,而莎草类和禾草类的比叶面积在处理间无显著差异。(2)叶干物质含量与比叶面积在围封和放牧处理中均呈显著负相关关系,在放牧处理中,叶干物质含量与植物高度呈显著的二次函数关系,即随着叶干物质含量的增大,植物高度先减小后增大;在同等比叶面积的情况下,与围封相比,放牧降低了叶干物质含量;在相同叶干物质含量的情况下,与围封相比,放牧降低了植物高度。(3)放牧在总体上降低了种间性状的平均差异,植物性状表现出趋同响应,具体表现为放牧减小了叶干物质含量和植物高度的种间差异;与围封相比,放牧显著提高了功能均匀度,减小了功能分离度。研究表明,不同植物种对放牧的响应模式存在差异,放牧降低了种间对光资源的竞争,可能增加了对土壤养分的竞争,放牧驱动群落构建的过程中,土壤养分是非常重要的作用因子,说明放牧影响物种共存依赖于对多种资源的竞争。     

骨质疏松症易感基因BDNF的遗传学关联分析及功能研究

为探索脑源性神经营养因子BDNF基因与中国汉族人群骨密度(bone mineral density, BMD)的关系,解析该基因调节骨质疏松症的功能机制,进而为中国汉族人群的骨质疏松症的防治提供依据。本研究从我国陕西地区征集了1300例汉族样本,并测量髋部/脊椎骨密度。选取BDNF基因上的14个标签SNPs进行基因分型,与1300例样本BMD进行关联分析,发现8个SNPs与髋部/脊椎BMD显著关联(P < 0.05)。其中,SNP rs16917237同时与髋部和脊椎骨密度关联,经Bonferroni校正后仍表现出显著性(0.05/14 = 0.0036)。整合连锁不平衡和单体型分析、表观功能注释、表达数量基因座分析、代谢通路分析进一步探索BDNF基因调节骨质疏松症的机制。构建小鼠前成骨细胞系(MC3T3-E1)人骨形态形成蛋白(rhBMP-2)诱导分化模型,利用小干扰RNA(siRNA)敲除BDNF。结果显示：14个SNPs位于同一单体型内;rs16917237在成骨细胞中表现出较强的激活型组蛋白H3K4me1、H3K4me3、H3K27ac修饰信号以及P300结合信号,表明其在成骨细胞中可能具有调控活性;rs16917237在11个组织中均能显著影响BDNF基因表达;BDNF基因位于与成骨细胞增殖分化相关的MAPK通路中;BDNF敲低能够显著降低MAPK通路中与成骨分化相关的CREB 基因mRNA和蛋白表达水平,提示其可能通过调控CREB表达进而影响成骨分化。生物信息学分析和功能实验结果一致,表明BDNF基因可能是影响骨质疏松症的重要功能基因。     

基于Voronoi图的群落优势树种种内种间竞争

在浙江天目山国家级自然保护区内,选择典型常绿阔叶林设置样地,样地大小100m×100m。用全站仪测定每株树木坐标(x,y,z)。首先,用优势度分析法确定群落优势树种。其次,提出基于Voronoi图的V_Hegyi竞争指数,并对Hegyi、APA和V_Hegyi三种竞争指数进行比较分析。最后,采用V_Hegyi竞争指数分析常绿阔叶林的种内、种间竞争关系。结果表明:常绿阔叶林群落共有11个优势树种即细叶青冈(Cyclobalanopsis myrsinaefolia)、青冈(Cyclobalanopsis glauca)、短尾柯(Lithocarpus brevicau-datus)、豹皮樟(Litsea coreana)、白栎(Quercus fabri)、天目木姜子(Litsea auriculata)、黄连木(Pistacia chinensis)、榉树(Zelkovaschneideriana)、杉木(Cunninghamia lanceolata)、枫香(Liquidambar formosana)和黄檀(Dalbergia hupeana)。比较分析认为,V_Hegyi竞争指数既克服了用固定半径圆确定竞争单元的尺度不统一缺陷,又可进行种内、种间竞争分析,并保持竞争排序的稳定性,因此是优于Hegyi和APA的更合适的竞争指数,所以选择V_Hegyi竞争指数进行优势树种竞争分析。常绿阔叶林优势树种的种内竞争比种间竞争激烈。种内竞争最激烈的优势树种细叶青冈、青冈和短尾柯与其它优势树种的种间竞争强度也是最高的。反之,种内、种间竞争都较弱的优势树种包括豹皮樟、白栎、天目木姜子、黄连木、榉树、杉木、枫香和黄檀。多数优势树种存在1个主要竞争树种,很少有超过3个以上的情形。细叶青冈是群落最占优势的树种,具有最强烈的种内竞争。同时,也是所有其它优势树种的最大竞争者。     

Competitive strategies between Anastrepha fraterculus and Anastrepha obliqua (Diptera: Tephritidae) regulating the use of host fruits

Interspecific competition between individuals of different species can result in reductions in their fecundity, growth or survival, reflecting differential exploitation of resources that become intensified due to spatial co-occurrence, ecological similarity and increased population densities. As two species cannot occupy the same niche, coexistence is only possible if the available resources are used in non-overlapping manners such as niche partitioning or the use of refuges. Among agricultural insect pests, such as fruit flies of the family Tephritidae, competitive interactions can result in competitive displacement, host changes, or the expansion or restriction of the numbers of hosts utilized that can have negative consequences for human agricultural activities. We evaluated the competitive interactions between two fruit fly species of the genus Anastrepha, Anastrepha obliqua (Macquart, 1835) and Anastrepha fraterculus (Wiedmann, 1830), on their respective preferred hosts (mangoes and guava). Experiments of larval competition and competition for ovipositioning sites by adult females were performed to compare the parameters of larval development time, numbers of pupae and emerged adults and numbers of ovipositions in the presence or absence of interspecific competition. We observed that the interactions between those species were asymmetrical and hierarchical, and our results suggest a competitive displacement of A. fraterculus by A. obliqua when those two species are present on the same fruit, whether mangoes or guavas.