Structural equation modelling analysis of evolutionary and ecological patterns in Australian Banksia

Evolutionary history of species, their geographic ranges, ecological ranges, genetic diversity, and resistance to pathogen infection, have been viewed as being mutually linked through a complex network of interactions. Previous studies have described simple correlations between pairs of these factors, while rarely separated the direct effects among multiple interacting factors. This study was to separate the effect of multiple interacting factors, to reveal the strength of the interactions among these factors, and to explore the mechanisms underlying the ecological and evolutionary processes shaping the geographic range, genetic diversity and fitness of species. I assembled comparative data on evolutionary history, geographic range, ecological range, genetic diversity, and resistance to pathogen infection for thirteen Banksia species from Australia. I used structural equation modelling to test multivariate hypotheses involving evolutionary history, geographic range, genetic diversity and fitness. Key results are: (1) Species with longer evolutionary times tend to occupy larger geographic ranges; (2) higher genetic diversity is directly associated with longer flowering duration in Banksia; and (3) species with higher genotypic diversity have higher level of resistance to infection caused by the pathogen Phytophthora cinnamomi, whereas heterozygosity has the opposite relationship with capacity of resistance to the infections caused by this pathogen. These results revealed a mutually linked and complex network of interactions among gene, species, environment and pathogen in evolutionary and ecological scales. These findings also have great practical significance and help to provide preemptive management options in pathogen control.     

不同坡位沙棘光合日变化及其主要环境因子

沙棘是我国干旱半干旱地区重要的生态经济树种,被广泛应用于黄土高原造林活动中。为探明不同坡位沙棘光合特征及影响沙棘光合作用的主要环境因子,在沙棘生长旺盛期分坡位测定光合特性及环境因子日变化进程,并采用通径分析法分析各环境因子对沙棘净光合速率的直接和间接影响。结果表明：1、各环境因子之间存在相互作用,光合有效辐射是空气温度变化的主要驱动因子,而空气温度变化引起的空气密度变化对空气相对湿度和CO2浓度有显著影响。在上、中和下坡位环境变化可以分别解释85.6%、86.0%和 55.22%净光合速率的变异。2、下坡位沙棘净光合速率最小,日均值为9.38μmol/m2/s,上、中坡位分别为14.22μmol/m2/s,15.94μmol/m2/s。3、10:00之前中上坡位沙棘水分利用效率明显高于下坡位,但3坡位沙棘水分利用效率日均值无明显差异。4、上坡位净光合速率主要受到光合有效辐射、空气相对湿度的影响;中坡位光合有效辐射仍为主要环境因子,此外空气温度和空气湿度之间的相互作用对净光合速率也有一定影响,为主要限制因子;下坡位影响沙棘光合速率主导因素为光合有效辐射。5、沙棘在10:00之前光合有效辐射和空气湿度较高而空气温度较低的环境下,净光合速率和水分利用效率最高。作为阳生物种,沙棘需要足够的光照维持生长,而以往研究表明适度水分胁迫可以提高沙棘光合过程中对水的利用效率。本研究所选流域年降水量535mm,中上坡位水分胁迫并非十分严重。因此,种植于中上坡位的沙棘即可接受足够光照（特别是10:00以前的光照）进行光合保证生长速率,又能在光合过程中保持较高水分利用效率,符合干旱半干旱地区生态经济发展的需求。     

硬头鳟幼鱼部分形态性状和体重的关系

随机选取116尾硬头鳟(Oncorhynchus mykiss)幼鱼,测量其体长、体高、体厚、头长、眼径和眼间距、体重7个性状,计算各性状间的相关系数,采用通径分析方法计算以表型形态性状为自变量对体重作因变量的通径系数、决定系数及复相关指数,对各性状的影响大小进行剖析,明确影响硬头鳟幼鱼体重的主要外部形态性状,为硬头鳟...     

预防压疮管理路径表的设计与应用

目的:探讨压疮管理的方法和路径。方法:制定并应用神经外科压疮管理路径表。选择2010年3月至2011年3月神经外科入院的1400例患者,分为对照组与观察组,观察组755例,入院后常规护理基础上应用路径表;对照组为645例,常规护理。结果:对照组645例患者中,发生压疮例数Ⅱ期压疮5例;观察组755例患者中,发生Ⅰ期压疮1例。P<0.05,有显著统计学意义。结论:应用压疮管理路径表可以预防神经外科患者压疮的发生,有效降低患者压疮发生率。     

Review: Depth, navigation and orientation in crabs: Angular acceleration, gravity and hydrostatic pressure sensing during path integration

This review shows how well the published work on the neural basis of balance and hydrostatic pressure reception in crabs agrees with the analyses and models of path integration. Fiddler crabs allow analyses at the level of behaviour. With considerable accuracy, they continuously show the direction to home with their body orientation and use idiothetic path integration to calculate a home vector from the internal measurements of their locomotion. All crabs have a well-developed vestibular system in the statocyst with horizontal and vertical canals which is used for angular acceleration sensing and depth reception. Large identified interneurones abstract the component of angular acceleration in one of the three orthogonal planes. These have properties consistent with a key role in path integration, combining vestibular and proprioceptor information with a central excitatory drive from the hemiellipsoid bodies. They have been monitored during walking, swimming and even in freefall for a 22 s period in parabolic flight.     

大菱鲆幼鱼表型形态性状与体重之间的关系

随机选取1120尾3月龄大菱鲆幼鱼,测量其体长、全长、体高、头长、吻尖至鳃裂前缘长、尾柄长、尾柄高、体厚、体重等9个性状,计算各性状间的相关系数,采用通径分析方法计算以表型形态性状为自变量对体重作依变量的通径系数、决定系数及复相关指数, 对各性状的影响大小进行剖分,明确影响大菱鲆三月龄幼鱼体重的主要外部形态性状,为大菱鲆选育提供理论依据和理想的测度指标.结果表明:所测各表型性状与体重之间的相关系数均达到极其显著水平(P＜0.01＝;全长对体重的直接影响(R=0.702)最大, 对体重的决定程度(R2=51.84%)最高,是影响体重的主要因素;体高、体厚对体重的直接作用 (0.211 ,0.094)相对较小,主要通过体长的间接作用(0.5558,0.4342)影响体重.所选表型性状对体重的回归系数R2=0.911,表明所选性状是影响体重的主要性状.利用逐步回归分析方法建立以体长、体高、体厚为自变量估计体重的多元回归回归方程为:y=-6.216 1.294x1 0.518x2 1.293x3[动物学报 54(3):540-545,2008].     

Restoration of a species‐rich flood meadow by topsoil removal and diaspore transfer with plant material

Abstract. In previous studies, limited dispersal was revealed to be the main obstacle to restoration of species‐rich flood‐meadows along the northern Upper Rhine in Germany. To overcome dispersal limitation we transferred freshly mown plant material from species‐rich sources to a restoration site on a former arable field. Before plant material application, topsoil was removed to accelerate nutrient impoverishment and create favourable conditions for seedling recruitment. Topsoil removal led to a drastic reduction in organic matter and essential mineral nutrients to the level of target communities (P) or even below (N, K). At a removal depth of 30 cm content of the soil seed bank that comprised exclusively of annual arable weeds, ruderals and some common grassland species, declined by 60 ‐ 80%, while at a removal depth of 50 cm the seed bank was almost completely eliminated. With few exceptions, all species recorded in source plant material were found established at the restoration site. However, the overall correlation between seed content in plant material and establishment success was not very high. Vegetation development at the restoration site was characterized by a rapid decline in arable weeds and ruderals, while resident grassland species and species transferred with plant material increased rapidly from the third year onwards. After four years as many as 102 species were established that could be exclusively attributed to plant material transfer, among them many rare and highly endangered plants. Establishment of species from plant material was most successful in regularly flooded plots, due to the suppression of competitors as well as the creation of favourable moisture conditions for seedling emergence. Diaspore transfer with plant material proved to be an extremely successful method in restoring species‐rich grassland. However, high quality of plant material and suitable site conditions with low competition in early stages of succession seem to be essential prerequisites.     

Assessing the correlations and selection criteria between different traits in wheat salt-tolerant genotypes

Salinity is one of the largest stresses blocking horizontal and vertical expansion in agricultural lands. Establishing salt-tolerant genotypes is a promising method to benefit from poor water quality and salinized lands. An integrated method was developed for accomplishing reliable and effective evaluation of traits stability of salt-tolerant wheat. The study aims were to estimate the genetic relationships between explanatory traits and shoot dry matter (SDM), and determine the traits stability under three salinity levels. Morphophysiological and biochemical traits were evaluated as selection criteria for SDM improvement in wheat for salinity tolerance. Three cultivars and three high-yielding doubled haploid lines (DHLs) were used. Three salt (NaCl) levels (control (washed sand), 7 and 14 dS m⁻¹) were applied for 45 days (at the first signs of death in the sensitive genotypes). All morphophysiological traits gradually decreased as salinity levels increased, excluding the number of roots. Decreases were more visible in sensitive genotypes than in tolerant genotypes. All biochemical traits increased as salinity levels increased. Variance inflation factors (VIFs) and condition number exhibited multicollinearity for membrane stability index and polyphenol oxidase activity. After their removal, all VIFs were <10, thereby increasing path coefficient accuracy. Total chlorophyll content (CHL) and catalase (CAT) provided significant direct effects regarding genetic and phenotypic correlations for the three salinity levels and their interactions in path analysis on SDM, indicating their stability. CHL and CAT had high heritability (>0.60%) and genetic gain (>20%) and highly significant genetic correlation, co-heritability, and selection efficiencies for SDM. CHL and CAT could be used as selection criteria for salinity tolerance in wheat-breeding programs. The tolerated line (DHL21) with the check cultivar (Sakha 93) can be also recommended as novel genetic resource for improving salinity tolerance of wheat.     

玉米茎秆细胞壁和组织构建对抗压强度的影响

耐密抗倒伏玉米品种是玉米育种的重要方向,探究影响玉米茎秆抗压强度的机制是培育玉米新品种的重要途径。本实验采用组织化学、显微观察的方法研究了10个玉米品种茎秆的形态结构、解剖特征和细胞壁的化学组成,并分析了这些变量之间的相关性,结果表明:茎的皮层/半径、厚壁组织比例、机械组织比例和纤维素含量、木质素含量与抗压强度呈极显著正相关关系;薄壁组织比例、茎长/茎粗、维管束个数与抗压强度呈极显著负相关关系。利用共线性诊断和逐步线性回归分析发现,影响茎秆抗压强度的主要因素为皮层/半径、机械组织比例、维管束个数、纤维素含量和木质素含量。利用通径分析进一步定量研究了这5个变量与抗压强度之间的直接作用和间接作用,明确了决定玉米茎秆抗压强度的主要因素为纤维素含量、木质素含量和单位面积维管束个数。本实验还建立了玉米茎微观结构与细胞壁化学构成的数学模型,为进一步揭示玉米茎微观力学形成机理提供了思路,进而为耐密抗倒伏玉米育种提供了研究方向。     

Three-dimensional orientation in desert ants: context-independent memorisation and recall of sloped path segments

Desert ants (Cataglyphis fortis) navigate by a combination of path integration and landmark-based route memories. Their ability to correct sloped path segments to their ground distances enables them to orientate accurately even in undulating terrain. In this study, we tested whether or not ants incorporate vertical components of an itinerary into their route memory in similar ways as they do with visual landmarks and horizontal changes of direction. In two separate experiments, we trained desert ants to walk over artificial hills and later tested their acceptance of slopes within novel contexts. In the first paradigm, ants had to traverse a hill only on their outbound run, but not on their homebound trip. In a follow-up experiment, we confronted ramp-trained animals with descents in a completely new temporal and spatial context. The animals transferred their newly acquired acceptance of slopes from the outbound to the homebound run as well as to novel foraging trips. Cataglyphis obviously dissociates the experience of sloped path segments from the original context in which they appeared, thus reducing their significance as a navigational aid.