Anadromy,potamodromy and residency in brown trout Salmo trutta: the role of genes and the environment

Brown trout Salmo trutta is endemic to Europe, western Asia and north-western Africa; it is a prominent member of freshwater and coastal marine fish faunas. The species shows two resident (river-resident, lake-resident) and three main facultative migratory life histories (downstream–upstream within a river system, fluvial–adfluvial potamodromous; to and from a lake, lacustrine–adfluvial (inlet) or allacustrine (outlet) potamodromous; to and from the sea, anadromous). River-residency v. migration is a balance between enhanced feeding and thus growth advantages of migration to a particular habitat v. the costs of potentially greater mortality and energy expenditure. Fluvial–adfluvial migration usually has less feeding improvement, but less mortality risk, than lacustrine–adfluvial or allacustrine and anadromous, but the latter vary among catchments as to which is favoured. Indirect evidence suggests that around 50% of the variability in S. trutta migration v. residency, among individuals within a population, is due to genetic variance. This dichotomous decision can best be explained by the threshold-trait model of quantitative genetics. Thus, an individual's physiological condition (e.g., energy status) as regulated by environmental factors, genes and non-genetic parental effects, acts as the cue. The magnitude of this cue relative to a genetically predetermined individual threshold, governs whether it will migrate or sexually mature as a river-resident. This decision threshold occurs early in life and, if the choice is to migrate, a second threshold probably follows determining the age and timing of migration. Migration destination (mainstem river, lake, or sea) also appears to be genetically programmed. Decisions to migrate and ultimate destination result in a number of subsequent consequential changes such as parr–smolt transformation, sexual maturity and return migration. Strong associations with one or a few genes have been found for most aspects of the migratory syndrome and indirect evidence supports genetic involvement in all parts. Thus, migratory and resident life histories potentially evolve as a result of natural and anthropogenic environmental changes, which alter relative survival and reproduction. Knowledge of genetic determinants of the various components of migration in S. trutta lags substantially behind that of Oncorhynchus mykiss and other salmonines. Identification of genetic markers linked to migration components and especially to the migration–residency decision, is a prerequisite for facilitating detailed empirical studies. In order to predict effectively, through modelling, the effects of environmental changes, quantification of the relative fitness of different migratory traits and of their heritabilities, across a range of environmental conditions, is also urgently required in the face of the increasing pace of such changes.     

猪的基因图谱及数量性状位点定位

在人类基因组计划的带动下,猪的遗传连锁图谱和细胞遗传学图谱有了较大的进步,利用目前猪基因组图谱的研究成果,通过基因组扫描法和候选基因法,可以对猪重要经济性状的主效基因位点进行区域定位,进而图位克隆,找到主效基因,为现代遗传育种奠定理论基础。     

长期氮添加对典型草原植物多样性与初级生产力的影响及途径

氮(N)沉降对陆地生态系统的结构和功能已产生了重要的影响, N也是中国北方草原植物生长和初级生产力的主要限制性元素。物种多样性和功能多样性是揭示生物多样性对生态系统功能维持机制的关键指标, 然而, 关于长期N添加下草原物种多样性与功能多样性的关系, 及其对初级生产力的影响途径及机制, 尚不十分清楚。为此, 该研究依托在内蒙古典型草原建立的长期N添加实验平台, 实验处理包括1个完全对照(不添加任何肥料)和6个N添加水平(0、1.75、5.25、10.50、17.50和28.00 g·m^-2·a^-1), 研究了长期N添加对典型草原物种多样性、功能多样性和初级生产力的影响大小及途径。结果表明: 1) N添加显著降低了典型草原的物种丰富度和Shannon-Wiener指数, 但对功能多样性(包括功能性状多样性指数和群落加权性状值)无显著的影响。2)结构方程模型分析表明, 功能多样性主要受物种丰富度的影响, 但是物种多样性减少并没有导致功能多样性降低, 其原因主要是功能群组成发生了改变, 即群落内多年生根茎禾草所占比例显著增加, 以致群落加权性状值变化不大。3) N通过影响物种丰富度和功能群组成, 间接影响群落加权性状值, 进而影响群落净初级生产力。其中, 群落加权性状值是最重要的影响因子, 可解释48%的初级生产力变化, 表明初级生产力主要是由群落内优势物种的生物量及功能性状所决定, 因此该研究的结果很好地支持了质量比假说。     

大连市6种园林树种的光合固碳释氧特性

以大连市园林6种常用园林树种为研究材料,利用LI-6400便携式光合测定仪测定树木的光合生理生态指标,对6种树种的光合固碳释氧能力、光响应参数以及光合速率影响因子进行分析。结果表明:在不同季节同种植物的单位叶面积固碳释氧能力表现为夏季最强。日均单位叶面积固碳释氧能力由强到弱为龙爪槐(Sophora japonica var.pendula)合欢(Albizia julibrissin)光叶榉(Zelkova serrata)槲树(Quercus dentata)悬铃木(Platanus acerifolia)枫杨(Pterocarya stenoptera);日均单株固碳释氧能力由强到弱为悬铃木槲树合欢光叶榉枫杨龙爪槐。气孔导度、蒸腾速率、光合有效辐射和大气CO2浓度是影响光合速率的主要因子。悬铃木、合欢对环境的适应能力较强。根据树种的固碳释氧能力及生理特性,建议在大连地区进行绿化时优选悬铃木、合欢,槲树、龙爪槐也可作为高固碳树种推广。     

长白山不同演替阶段森林植物功能性状及其与地形因子间的关系

植物功能性状是近年来生态学研究的热点。不同种群功能性状的差异决定竞争优势,导致群落结构和性质发生改变,进而演替。以长白山森林演替过程中4个阶段的典型群落为研究对象,分析了长白山地区森林不同层次优势种的茎叶功能性状之间的关系、功能性状与地形因子的关系,并对不同演替阶段群落功能性状进行了比较。结果发现,比叶面积(SLA)与叶氮浓度(LNC)和茎磷浓度(SPC)正相关,与叶干物质质量(LDMC)负相关;叶厚度(LT)与LDMC负相关;LNC与LPC、SNC和LDMC呈正相关;茎氮浓度(SNC)与茎磷浓度(SPC)正相关;茎组织密度(STD)与LNC、SNC正相关。通过灰色关联度分析发现,海拔对SLA、LNC、LPC、STD、SPC影响最大;坡向对于LT、LDMC影响最大;坡位对SNC影响最大。各演替群落间的乔木层功能性状均有显著差异,灌木层的功能性状无显著差异,而草本层除了LDMC、LPC、SNC有显著差异外,其它指标均无显著差异;SLA、STD、LNC随演替的进行呈现明显增加趋势,LDMC、LPC随演替呈减少的趋势。LDMC和SLA是能体现群落演替差异的主要功能性状。     

水稻苗期耐旱性基因位点及其互作的分析

随着全球水资源的日益贫乏和旱灾的日趋严重,水稻耐旱性的研究越来越重要,对籼稻窄叶青8号（ZYQ8）和粳稻京系17（JX17）以及由它们构建的加倍单倍体（DH）群体,参照国际水稻研究所的耐旱鉴定方法,在苗期进行断水,调查期耐旱性,利用该群体的分子连锁图谱进行数量性状座位（QTL）区间作图分析,共检测到2个耐旱的QTL（qDT-5和qDT-12),分别位于第5染色体的GA41-GA257之间的和第12染色体的RG457-Y12817R之间,这两个QTL的加性效应均来自ZYQ8的等位基因,用Epistat软件检测到2个单位点,即GA257和Y12817R,与区间作图分析的结果一致,Epistat还检测到与GA257互作的3个位点（RG541、G318和G192,分别位于第1、4和8染色体上）和与Y12817R互作的1个位点（CT234,位于第3染色体上）。     

Effects of size,neighbors, and site condition on tree growth in a subtropical evergreen and deciduous broad‐leaved mixed forest,China

Successful growth of a tree is the result of combined effects of biotic and abiotic factors. It is important to understand how biotic and abiotic factors affect changes in forest structure and dynamics under environmental fluctuations. In this study, we explored the effects of initial size [diameter at breast height (DBH)], neighborhood competition, and site condition on tree growth, based on a 3‐year monitoring of tree growth rate in a permanent plot (120 × 80 m) of montane Fagus engleriana–Cyclobalanopsis multiervis mixed forest on Mt. Shennongjia, China. We measured DBH increments every 6 months from October 2011 to October 2014 by field‐made dendrometers and calculated the mean annual growth rate over the 3 years for each individual tree. We also measured and calculated twelve soil properties and five topographic variables for 384 grids of 5 × 5 m. We defined two distance‐dependent neighborhood competition indices with and without considerations of phylogenetic relatedness between trees and tested for significant differences in growth rates among functional groups. On average, trees in this mixed montane forest grew 0.07 cm year^?1 in DBH. Deciduous, canopy, and early‐successional species grew faster than evergreen, small‐statured, and late‐successional species, respectively. Growth rates increased with initial DBH, but were not significantly related to neighborhood competition and site condition for overall trees. Phylogenetic relatedness between trees did not influence the neighborhood competition. Different factors were found to influence tree growth rates of different functional groups: Initial DBH was the dominant factor for all tree groups; neighborhood competition within 5 m radius decreased growth rates of evergreen trees; and site condition tended to be more related to growth rates of fast‐growing trees (deciduous, canopy, pioneer, and early‐successional species) than the slow‐growing trees (evergreen, understory, and late‐successional species).     

猕猴桃观花品种‘江山娇’与中华猕猴桃回交后代的性别分离与开花性状变异

以猕猴桃种间杂种品种‘江山娇’（Actinidia chinensis Planch×A.eriantha Benth）与中华猕猴桃（A.chinensis Planch）雄株杂交得到的杂交后代群体为实验材料,于2012、2013和2016年分别对该群体的雌雄性别比及其开花性状进行了调查。结果表明,杂交群体的雌雄性别比例小于1：1,即雄株偏多。杂交后代的花瓣颜色以红色为基础,但红色的分布区域、深浅及类型出现明显分离。聚类分析显示,这些杂交后代可通过花瓣CMYK色卡取值分为4个类群,其中猩红色与紫罗兰红色2个变异类型与观察表型完全一致。杂交后代群体的始花期、开花天数、花朵大小、开花量及单花花瓣数等性状均出现广泛分离,且因不同年份而出现变化。群体中杂交个体进入始花期的平均时间跨度为14 d,群体的始花期进入高峰时个体平均比例仅占群体的25.5%。2016年群体开花时间最长,最多有47.4%的个体开放10~13 d;2013年杂交群体的开放时间最短,有55.2%的后代开花3~5 d。本研究筛选出一批花瓣数多、花朵较大或单花序花朵较多的优良单株,并在后代群体中共发现21个含不同花数的花序组合类型。     

辽宁和江苏两省杂草稻植物性状多样性

辽宁和江苏两省是我国杂草稻(Oryza sativa f. spontanea)发生最为严重的地区之一, 为明确两省杂草稻识别特征和类型, 我们在两省14个市29个样点采集样品, 与当地栽培水稻品种一并在南京种植, 观测了营养生长期和生殖生长期的23个植物性状。结果表明, 两省杂草稻在营养生长期的1月株高、1月和2月分蘖数, 在生殖生长期的果皮色、谷粒长/宽比、百粒重、落粒性、秆硬度、剑叶宽、剑叶长、有效穗数、50%黄熟、50%黄熟–50%抽穗和全黄熟等性状与相应的当地栽培稻存在差异;主成分1和主成分2组成的二维散点图(累计贡献率达43.24%)也显示出两省杂草稻间以及与栽培稻间的差异性。采用欧氏距离对两省杂草稻进行系统聚类可以将杂草稻分为籼型和粳型。其中辽宁省杂草稻全部聚在粳型类群中, 它们又可细分为两类; 江苏省杂草稻既有粳型, 又有籼型, 其中粳型与辽宁省杂草稻聚在粳型类群中, 籼型又可分为3类。这6个类群分别具有如下突出特点: 第1类为强落粒、粒轻、秆矮、早熟、偏粳等; 第2类为无芒、穗多、强休眠、剑叶窄、偏粳等; 第3类为长芒、弱分蘖、穗少、弱落粒、偏粳等; 第4类为硬秆、剑叶宽、迟熟、强休眠、偏籼等; 第5类为红果皮、粒长、软秆、粒重、偏籼等; 第6类为无芒、株高、穗长、剑叶长、偏籼等。上述杂草稻的形态学指标和类型的研究将为两省开展杂草稻危害防治工作提供理论依据。     

QTL analysis of leaf morphology in tetraploid Gossypium (cotton)

Molecular markers were used to map and characterize quantitative trait loci (QTLs) determining cotton leaf morphology and other traits, in 180 F₂ plants from an interspecific cross between a Gossypium hirsutum genotype carrying four morphological mutants, and a wild-type Gossypium barbadense. The prominent effects of a single region of chromosome 15, presumably the classical ”Okra-leaf” locus, were modified by QTLs on several other chromosomes affecting leaf size and shape. For most traits, each parent contained some alleles with positive effects and others with negative effects, suggesting a large potential for adapting leaf size and shape to the needs of particular production regimes. Twenty one QTLs/loci were found for the morphological traits at LOD≥3.0 and P≤0.001, among which 14 (63.6%) mapped to D-subgenome chromosomes. Forty one more possible QTLs/loci were suggested with 2.0≤LOD<3.0 and 0.001<P≤0.01. Among all of the 62 possible QTLs (found at LOD≥2.0 and P≤0.01) for the 14 morphological traits in this study, 38 (61.3%) mapped to D-subgenome chromosomes. This reinforces the findings of several other studies in suggesting that the D-subgenome of tetraploid cotton has been subject to a relatively greater rate of evolution than the A-subgenome, subsequent to polyploid formation. Received: 26 April 1999 / Accepted: 30 July 1999