Morphological variation of Keratella cochlearis (Rotatoria) in a shallow, eutrophic subtropic Chinese lake

The duration of occurrence of two morphological forms of Keratella cochlearis varied seasonally in Lake Donghu, a shallow eutrophic lake in China. The total lengths of both K cochlearis tecta and K cochlearis cochlearis were negatively correlated with the water temperature. Total length of K cochlearis tecta may also have been influenced by the degree of eutrophication or available food.

Morphological variability between wild populations and inbred stocks of a Chinese minnow, Gobiocypris rarus

Gobiocypris rarus, a small, native cyprinid fish, is currently widely used in research on fish pathology, genetics, toxicology, embryology, and physiology in China. To develop this species as a model laboratory animal, inbred strains have been successfully created. In this study, to explore a method to discriminate inbred strains and evaluate inbreeding effects, morphological variation among three wild populations and three inbred stocks of G. rarus was investigated by the multivariate analysis of eight meristic and 30 morphometric characters. Tiny intraspecific variations in meristic characters were found, but these were not effective for population distinction. Stepwise discriminant analysis and cluster analysis of conventional measures and truss network data showed considerabe divergence among populations, especially between wild populations and inbred stocks. The average discriminant accuracy for all populations was 82.1% based on conventional measures and 86.4% based on truss data, whereas the discriminant accuracy for inbred strains was much higher. These results suggested that multivariate analyses of morphometric characters are an effective method for discriminating inbred strains of G. rarus. Morphological differences between wild populations and inbred strains appear to result from both genetic differences and environmental factors. Thirteen characters, extracted from stepwise discriminant analysis, played important roles in morphological differentiation. These characters were mainly measures related to body depth and head size.

Dietary-morphological relationships of fishes in Liangzi Lake, China

Species in Liangzi Lake were clustered into four trophic groups: Hemiramphus kurumeus and Hemiculter bleekeri bleekeri fed predominantly on terrestrial insects; Carassius auratus auratus and Abbottina rivularis on non-animal food; Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva and Toxabramis swinhonis on cladocerans or copepods; Culterichthys erythropterus on decapod shrimps. Gut length, mouth width, mouth height, gill raker length and gill raker spacing, varied widely among species. With the exception of three species pairs (H. swinhonis, C. glurinus; C. erythropterus, H. kurumeus; T. swinhonis, H. bleekeri bleekeri), principal components analysis of morphological variables revealed over-dispersion of species. Canonical correspondence analysis of dietary and morphological data revealed five significant dietary-morphological correlations. The first three roots explained > 85% of the total variance. The first root reflected mainly the relationship of gut length to non-animal feud, with an increase in gut length associated with an increase in non-animal food. The second root was influenced strongly by the relationship of the gill raker spacing to consumption of copepods, with an increase in gill raker spacing associated positively with copepods in the diet. The third root was influenced by the relationship of mouth gape to consumption of fish and decapod shrimps, with an increase in mouth gape associated with more fish and decapod shrimps in the diet. These significant dietary-morphological relationships supported the eco-morphological hypotheses that fish morphology influence food use, and morphological variation is important in determining ecological segregation of co-existing fish species. (C) 2001 The Fisheries Society of the British Isles.

Dietary-morphological relationships of fishes in Liangzi Lake, China

Species in Liangzi Lake were clustered into four trophic groups: Hemiramphus kurumeus and Hemiculter bleekeri bleekeri fed predominantly on terrestrial insects; Carassius auratus auratus and Abbottina rivularis on non-animal food; Hypseleotris swinhonis, Ctenogobius giurinus, Pseudorasbora parva and Toxabramis swinhonis on cladocerans or copepods; Culterichthys erythropterus on decapod shrimps. Gut length, mouth width, mouth height, gill raker length and gill raker spacing, varied widely among species. With the exception of three species pairs (H. swinhonis, C. glurinus; C. erythropterus, H. kurumeus; T. swinhonis, H. bleekeri bleekeri), principal components analysis of morphological variables revealed over-dispersion of species. Canonical correspondence analysis of dietary and morphological data revealed five significant dietary-morphological correlations. The first three roots explained > 85% of the total variance. The first root reflected mainly the relationship of gut length to non-animal feud, with an increase in gut length associated with an increase in non-animal food. The second root was influenced strongly by the relationship of the gill raker spacing to consumption of copepods, with an increase in gill raker spacing associated positively with copepods in the diet. The third root was influenced by the relationship of mouth gape to consumption of fish and decapod shrimps, with an increase in mouth gape associated with more fish and decapod shrimps in the diet. These significant dietary-morphological relationships supported the eco-morphological hypotheses that fish morphology influence food use, and morphological variation is important in determining ecological segregation of co-existing fish species. (C) 2001 The Fisheries Society of the British Isles.

藏麻黄与丽江麻黄的形态及遗传变异研究

麻黄属(Ephedra)起源较早，该属植物的形态性状极度退化或简化，可用于经典分类学的有价值的性状非常有限。分布于青藏高原的藏麻黄（E. saxatilis）和丽江麻黄（E. likiangensis）二者间形态相似，性状变异连续，很难分辨，但被《中国植物志》中、英文版作两个种处理。 本文对藏麻黄和丽江麻黄的七个居群、151个个体的叶、雌球花和节间长等形态学性状进行了分析，发现各性状的变异情况在群体间无明显差异。同时我们还对154个个体的叶绿体DNA trnT-trnF和 trnS-trnfM区进行了序列分析，两个片段的联合矩阵长1382bp，共有29个变异位点，其中有9个碱基变异和2个indel，可划分为H1、H2和H3三种单倍型。这3种单倍型在丽江麻黄中均有分布，但藏麻黄仅含H1和H2。 综合来自形态学和分子方面的证据，我们发现藏麻黄和丽江麻黄的关系非常近缘，因此建议予以合并。同时本文还以膜果麻黄（E. przewalskii）为外类群，从谱系生物地理学角度探讨了三种叶绿体单倍型的进化关系，发现H2最原始，分布最广;H1与其它两种单倍型间的序列差异较大，可能是较进化的类型。此外，无性克隆的繁殖方式可能是导致Ephedra单倍型非常简单的重要原因之一。

高山松（Pinus densata）同倍性杂交物种形成的生态遗传学研究

种间杂交在自然界中普遍存在。杂交可以为群体带来多方面的遗传改变，具有重要的进化生物学意义。越来越多的证据表明，同倍性杂交物种形成是一种重要物种形成途径，在动、植物物种进化中扮演着重要的角色。同倍性杂交物种形成意味着一个稳定的、可育的、与亲本种间形成生殖隔离的杂种群体建立起来，但不改变染色体的数目。这种生殖隔离被认为是通过快速的染色体重组、生态分化、或空间分离形成的。对于现存杂交种的对比分析和对同倍性杂交物种形成的理论模拟都表明，适应性分化和生态转变在同倍性杂交物种形成中起着至关重要的作用。来自于生态成种的研究也表明生态选择自身就可以导致生殖隔离的形成和新物种的形成。尽管如此，我们对同倍性杂交物种形成过程的研究仍然较多地关注于染色体重组及相应的遗传效应；对于自然选择，特别是生态选择在同倍性杂交成种过程中的作用模式缺乏全面地了解。 本研究以同倍性杂交种－高山松为研究对象，利用地理信息学技术、基于天然群体取样的性状对比分析和人工杂交手段，全面地定量描述了高山松及其亲本种间的生态分化、生态转变下的天然群体生殖适应性、以及生态选择下的形态变异和种间杂交可配性。以此探讨了高山松的杂交成种过程，生态转变和自然选择的重要性以及它们与杂交种适应性、形态变异和生殖隔离之间的关系。利用地理信息学手段，对高山松及其亲本种间的生态分化对比分析表明：高山松与其亲本种间形成了明显的生态转变；在自然选择的作用下，高山松已经具备了对于青藏高原东南缘横断山区高山地带独特的生态适应性；相对于亲本种，它的适应性特征体现为混合型，在某些性状上它高出亲本种的适应性，在另一些性状上，它体现出居中、较低或者类似于亲本种适应性；高山松适生区由于地形地貌的复杂性，往往不连续，呈间断状。基于四个反映结实效率的性状、小孢子母细胞减数分裂异常现象及花粉萌发率在种间的对比分析表明，这些反映生殖状态的指标，在三个种及群体间并没有显著差异；相对于亲本种的天然群体，居于青藏高原的高山松群体，表现出了正常的授粉效率和生殖适应性。高山松天然群体正常的生殖效率表明，它经历了生态转变过程中的选择作用，已经具备了在新生境下，繁殖发展下去的生殖适应性。 在大规模群体取样的基础上，通过对反映植物个体发育和营养状态的球果和针叶形态性状的对比分析，我们发现，高山松及其亲本种间的形态变异存在以下特征：第一，绝大多数性状，在种间和种内群体间都存在着显著的差异，并且大部分性状的差异主要体现在种间；第二，高山松在大部分形态性状上介于两个亲本种之间，少数性状表现为超亲分离、类似于某个亲本或无种间差别；第三，在多数性状上，和亲本种相比，高山松群体都拥有较大的变异幅度。第四，在临近亲本种的群体中，高山松的形态特征更类似于所临近的亲本种。上述形态变异特征及其与气象、土壤、经纬度、海拔等因子间普遍的相关性，意味着生态选择在高山松成种过程中起了重要作用。总的来说，形态性状变异的总体模式揭示出：高山松在选择作用下的遗传和表型的精炼过程中已经形成了自身适应于高原环境的、稳定而有效的形态发育模式和资源利用方式，甚至是恰当的防御机制。 本研究通过云南松×油松的单交实验和油松×高山松部分双列杂交实验，检验了高山松及其亲本种间的杂交可配性。结果表明，就平均水平而言，高山松及其亲本种间的种间杂交结实可配性低于种内杂交，但个别种间杂交组合的结实可配性可能高于种间杂交；高山松及其亲本种间正在或已经形成了部分的合子后生殖障碍；现存的高山松群体及其亲本种间的生态地理隔离可能是很有效的生殖隔离形式，一方面做为合子前生殖隔离，它能避免种间相互传粉、阻碍种间杂交的发生，另一方面做为合子后生殖隔离，它能清除掉可能存在的劣势回交产物。 综合已有的证据，我们提出了高山松同倍性杂交物种形成模型：高山松的同倍性杂交成种是与青藏高原隆升过程以及隆升过程中所产生的全新生态空间紧密相关的；青藏高原隆升导致了生态环境的剧变，创造了全新的生态位，在选择的作用下，拥有综合了双亲遗传基础的杂种基因型开始占领这个全新的生态位；在分化的生态选择的持续作用下，杂种基因型在新的生境下稳定下来，形成了独立于亲本种的资源利用方式、形态特征和繁育系统，具备了完善的生殖和生态适应性；此时，一个与亲本种间以生态隔离存在的同倍性杂交种－高山松形成了；随着分化的生态选择的持续进行,高山松与亲本种间的内在生殖隔离不断加强。

濒危植物秦岭冷杉的种实特性和幼苗适应性

　　秦岭冷杉(Abies chensiensis)是松科冷杉属常绿乔木，我国国家二级濒危植物，主要分布在我国的秦岭。迄今为止，国内外有关秦岭冷杉的研究鲜有报道。本文研究了核心分布区和边缘区秦岭冷杉的结实特性、球果和种子的形态变异、种子萌发特性及幼苗的最初生长和适应状况，并通过与同属非濒危物种巴山冷杉相关特性的比较研究，初步探讨了秦岭冷杉的繁殖生物生态学特性, 为全面揭示秦岭冷杉濒危机制奠定基础。 　　与冷杉属其他种相比，核心区秦岭冷杉种子较大，出种量也较高，但空粒率很高，达到88%以上;边缘分布区的空粒率更达到95%以上，反映出极高的败育率。秦岭地区秦岭冷杉结实量和结实率随海拔高度升高而减少;同时，两个海拔高度的对比表明，低海拔秦岭冷杉具有较大的球果和种子，饱满度高。表明在其垂直分布范围内，低海拔地段更适合秦岭冷杉的生长和发育。 　　核心区（即秦岭地区）的秦岭冷杉球果和种子的绝大部分指标均值显著大于边缘区（即神农架地区）。相同海拔条件下，秦岭冷杉绝大部分球果和种子形态指标在地区间、地区内种群间、种群内部均有显著差异，约85%的变异来自地区内个体间和个体内，说明秦岭冷杉的球果和种子形态特征变化受遗传控制更显著。人工林与天然林相比，大部分人工林球果和种子指标均值和变异幅度大于天然林，表明通过人为经营可以改善秦岭冷杉的一些生殖性状。 　　秦岭冷杉具有浅休眠，除经典的冷层积方法可以打破休眠外，适当的物理、化学方法处理，如流动水冲洗、适宜浓度硝酸钾、赤霉酸浸种也可以起到相似的作用。各种促进萌发的方法所得到的最大萌发率间没有显著差异。核心区种子萌发率显著高于边缘区;此外，核心区种子在萌发速度和进程上也要显著高于边缘区，这也表明核心区秦岭冷杉活力更高。同样，由于巴山冷杉较高的饱满度，同等条件下，巴山冷杉种子萌发率约三倍于秦岭冷杉种子。 　　野外幼苗的适应性研究主要通过播种后观测出苗率及幼苗在各种环境条件下的存活率、生长状况来进行。通过一年的观测发现，秦岭冷杉野外种子出苗率平均只有16.9%，一年后幼苗死亡率高于50%。 林窗中、土壤覆盖厚度2~3cm的苗床中种子出苗率最高;较深土壤厚度出苗率低说明秦岭冷杉土壤种子库对更新贡献较小。层积30天种子出苗率高于未处理的种子，但对生长率没有影响。林外苗床中幼苗生长率较高。矿质土壤基质上幼苗生长率明显高于林地中。

Factors affecting leaf morphology: a case study of Ranunculus natans C. A. Mey. (Ranunculaceae) in the arid zone of northwest China

In order to examine the role of environmental factors affecting foliar morphology, we performed a case study of leaf morphological variation of Ranunculus natans found in the arid zone of northwest China. We found that foliar phenotypic variation differed significantly between populations. We described substantial positive correlations between altitude and leaf area (LA) as well as leaf perimeter (LP), and also between longitude and number of teeth, along with dissection index (DI). The pH, conductivity, and salinity of the environment caused a significant decrease in both LA and LP. Ranked in terms of their impacts on leaf morphology, the six selected factors were: altitude > pH > conductivity > salinity > longitude > latitude. We found that foliar morphological variations are functional responses to water-quantity factors (e.g., altitude and longitude at regional scales) and water-availability relation factors (e.g., pH, conductivity, and salinity at local scales), rather than to temperature-relation factors (latitude). Therefore, altitude and longitude, along with pH, conductivity, and salinity, are the main factors that significantly influence foliar morphology in the arid zone of China. We found that main factors played major roles in plant phenotypic plasticity in a complex ecosystem, although different combinations and interactions of environmental and geographical factors in each local environment may obscure the general trends in trait changes along environmental gradients.

Morphological and molecular phylogenetic analysis of two Saprolegnia sp (Oomycetes) isolated from silver crucian carp and zebra fish

Two Saprolegnia isolates, JY isolated from silver crucian carp (Carassius auratus gibelio Bloch) and BMY isolated from zebra fish (Brachydanio rerio Hamilton) came from infections occurring concurrently in different locations in China. To confirm whether the two isolates were from the same Saprolegnia clone, comparative studies have been carried out based on their morphological, physiological and molecular characteristics. Observations showed that morphologically (both asexual and sexual organs) the two isolates were broadly similar and both isolates under-went repeated zoospore emergence. Comparing 704 base pairs of internal transcribed spacer (ITS) region and the 5.8S rDNA, we found isolates JY and BMY shared an identical ITS sequence with a minor variation (99.6 % similarity). Forty available sequences for representatives Saprolegnia spp. belonged to four phylogenetically separate clades. The two studied isolates fell within clade I that comprised a group of isolates which showed almost an identical ITS sequence but had been identified as a number of different morphological species. our findings suggest that isolates JY and BMY appear to belong to the S. ferax clade and this clade (1) contains a number of closely related phylogenetic species. This is distinct from the more common fish pathogenic isolates, which belong to the S. parasitica clade (III) and are characterized by having cysts decorated by bundles of long hooked hairs and two further clades (II and IV) containing largely saprotrophic or soil born species. (C) 2009 Published by Elsevier Ltd on behalf of The British Mycological Society.

Molecular phylogenetics of the family Cyprinidae (Actinopterygii : Cypriniformes) as evidenced by sequence variation in the first intron of S7 ribosomal protein-coding gene: Further evidence from a nuclear gene of the systematic chaos in the family

The family Cyprinidae is the largest freshwater fish group in the world, including over 200 genera and 2100 species. The phylogenetic relationships of major clades within this family are simply poorly understood, largely because of the overwhelming diversity of the group; however, several investigators have advanced different hypotheses of relationships that pre- and post-date the use of shared-derived characters as advocated through phylogenetic systematics. As expected, most previous investigations used morphological characters. Recently, mitochondrial DNA (mtDNA) sequences and combined morphological and mtDNA investigations have been used to explore and advance our understanding of species relationships and test monophyletic groupings. Limitations of these studies include limited taxon sampling and a strict reliance upon maternally inherited mtDNA variation. The present study is the first endeavor to recover the phylogenetic relationships of the 12 previously recognized monophyletic subfamilies within the Cyprinidae using newly sequenced nuclear DNA (nDNA) for over 50 species representing members of the different previously hypothesized subfamily and family groupings within the Cyprinidae and from other cypriniform families as outgroup taxa. Hypothesized phylogenetic relationships are constructed using maximum parsimony and Basyesian analyses of 1042 sites, of which 971 sites were variable and 790 were phylogenetically informative. Using other appropriate cypriniform taxa of the families Catostomidae (Myxocyprinus asiaticus), Gyrinocheilidae (Gyrinocheilus aymonieri), and Balitoridae (Nemacheilus sp. and Beaufortia kweichotvensis) as outgroups, the Cyprinidae is resolved as a monophyletic group. Within the family the genera Raiamas, Barilius, Danio, and Rasbora, representing many of the tropical cyprinids, represent basal members of the family. All other species can be classified into variably supported and resolved monophyletic lineages, depending upon analysis, that are consistent with or correspond to Barbini and Leuciscini. The Barbini includes taxa traditionally aligned with the subfamily Cyprininae sensu previous morphological revisionary studies by Howes (Barbinae, Labeoninae, Cyprininae and Schizothoracinae). The Leuciscini includes six other subfamilies that are mainly divided into three separate lineages. The relationships among genera and subfamilies are discussed as well as the possible origins of major lineages. (c) 2008 Published by Elsevier Inc.

Effect of the variation of temperature on the structural and optical properties of ZnO thin films prepared on Si (111) substrates using PLD

ZnO thin films were prepared on Si (1 11) substrates at various temperatures from 250 to 700 degrees C using pulsed laser deposition (PLD) technique in order to investigate the structural and optical properties of the films. The structural and morphological properties of the films were investigated by XRD and SEM measurements, respectively. The quality of the films was improved with the increase of the temperature. By XRD patterns the FWHMs of the (0 0 2) peaks of the ZnO films became narrower when the temperatures were above 500 degrees C. The FWHMs of the peaks of (0 0 2) of the films were as narrow as about 0. 19 degrees when films were grown at 650 and 700 degrees C. This indicates the superior crystallinity of the films. The optical properties of the films were studied by photoluminescence spectra using a 325 nm He-Cd laser. The two strongest UV peaks were found at 377.9 nm from ZnO films grown at 650 and 700 degrees C. This result is consistent with that of the XRD investigation. Broad bands in visible region from 450 to 550 nm were also observed. Our works suggest that UV emissions have close relations with not only the crystallinity but also the stoichiometry of the ZnO films. (c) 2005 Elsevier Ltd. All rights reserved.

Genetic variation and phylogeographic history of Picea likiangensis revealed by RAPD markers

Repeated cycles of retreat and recolonization during the Quaternary ice ages are thought to have greatly influenced current species distributions and their genetic diversity. It remains unclear how this climatic oscillation has affected the distribution of genetic diversity between populations of wind-pollinated conifers in the Qinghai-Tibetan region. In this study, we investigated the within-species genetic diversity and phylogenetic relationships of Picea likiangensis, a dominant forest species in this region using polymorphic DNA (RAPD) markers. Our results suggest that this species has high overall genetic diversity, with 85.42% of loci being polymorphic and an average expected heterozygosity (H (E)) of 0.239. However, there were relatively low levels of polymorphism at population levels and the differences between populations were not significant, with percentages of polymorphic bands (PPB) ranging from 46.88 to 69.76%, Nei's gene diversity (H (E)) from 0.179 to 0.289 and Shannon's indices (Hpop) from 0.267 to 0.421. In accordance with our proposed hypothesis, a high level of genetic differentiation among populations was detected based on Nei's genetic diversity (G (ST) = 0.256) and AMOVA analysis (Phi (st) = 0.236). Gene flow between populations was found to be limited (Nm = 1.4532) and far lower than reported for other conifer species with wide distribution ranges from other regions. No clusters corresponding to three morphological varieties found in the south, north and west, respectively, were detected in either UPGMA or PCO analyses. Our results suggest that this species may have had different refugia during the glacial stages in the southern region and that the northern variety may have multiple origins from these different refugia.

Morphological Evolution During Synthesis of New AlPO4 Center dot H2O Crystal

A new crystal of aluminophosphate, AIPO(4)(.)H(2)O, is synthesized from two-batch aqueous solution under hydrothermal conditions. Three types of the crystal habits, i.e. the tetragonal double pyramid, the tetragonal prism and the plate-type tetragonal prism, are found from batch-A solution. Two types of the crystal habits, i.e. the hexagonal pyramid and the strip-type tetragonal prism, are found from batch-B solution. The change of crystal morphology is originated from the fluctuation of the synthesis conditions, such as the supersaturation, the temperature and the impurity content. It causes change of the step energies, the defect density and the step roughness, and further, change of the growth rates. Since the crystal morphology is sensitive to the mass transport mechanism, the crystal habits could be changed under the microgravity.

Influences of strain rate and temperature variation on material intrinsic length of plasticity strain gradient theory

Cowper-Symonds and Johnson-Cook dynamic constitutive relations are used to study the influence of both strain rate effect and temperature variation on the material intrinsic length scale in strain gradient plasticity. The material intrinsic length scale decreases with increasing strain rates, and this length scale increases with temperature.