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关于综合杂种优势指数的研究 总被引:2,自引:1,他引:1
本文参照综合选择指数的构成,即通过极大化聚合基因型值H=与选择指数I=的相关而得到的ι,对杂种群体的多性状的离中优势值进行分析,得出了评判中的多个性状的选择指数,即文中定义的综合杂种优势指数。本文以35个水稻杂交组合为材料测定了8个数量性状的综合杂种优势指数值和亲本间的遗传距离及典范遗传距离。相关分析表明,产量优势同遗传距离及典范遗传距离的相关性达到了显著水平(0.05),而综合杂种优势指数与这两种遗传距离的相关性达到了极显著水平(0.01)。综合杂种优势指数可以作为测定多个数量性状杂种优势的一个新的参数。 相似文献
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泡桐无性系数量性状的遗传分析和指数选择研究 总被引:3,自引:0,他引:3
以10年的泡桐无性系为材料,对包括材积、胸径、树高以内的8个主要数量性状进行了遗传参数分析,并在相关分析的基础上通过指数选择法,分别对材积、胸径、树高进行了选择指数研究。结果表明:材积的遗传变异系数较大,胸径、叶基宽中等,树高、叶干重等最小。遗传力以材积、胸径、叶柄长最高,叶干重、叶面积、叶基凹入、叶基宽中等,树高最低。多性状选择指数优于单一性状。根据材积、胸径、树高的选择指数,选出了2个材积,胸 相似文献
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通径系数(Wrigt, 1922)在畜禽育种中
的应用日渐增多。通径分析原理、通径系数的基
本概念和性质、以及相关性状的通径分析,都有
了较详细的阐明。目前,在家禽育种中已普遍
应用早期选择指数,而利用通径分析判断性状
之间的最佳组合还少见报道。本文就成都白鸡
的几个重要经济性状对产蛋量的影响进行了通
径分析,并与实际应用早期选择指数的效果作
了比较。 相似文献
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基于植物多度的群落物种组成与环境关联性分析 总被引:1,自引:0,他引:1
揭示群落物种组成与环境的关联性对于理解物种共存机制具有重要意义.传统生态种组划分不仅带有主观性,且难以定量种组-环境的关联程度.本研究以浙江天童31个处于不同生境的植物群落为研究材料,以群落实际物种组成作为研究对象,利用物种多度分别构建了各群落的最大、实际和相对环境选择性指数,并以随机模拟的群落环境关联性作为零假设,通过与实际群落相比较来揭示群落物种组成的环境关联程度;最后,利用环境选择指数(environmental dependence index)与群落生境马氏距离(Mahalanobis distance)的相关分析来确认群落物种组成与环境的关联性.结果表明:最大环境选择指数反映的是现有生境在理论上的最优群落配置组合的环境选择性.实际选择指数可反映群落物种组成对现状生境的选择性,相对环境选择指数可综合反映群落物种组成与环境间的关联性;相对环境选择指数与单独生境因子的相关性不显著,而与表征综合环境特征的Mahalanobis距离显著正相关;随生境异质性增大,群落物种组成的环境专—性更强.此结果为天童常绿阔叶林的群落物种组成与生境关联性提供了新证据,也为如何完善物种与环境之间关系的定量化研究提供了借鉴. 相似文献
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根据系统保种理论有关保种和选择可以相互结合的观点,本文提出了保种-选择指数的概念、导出了适于各种资料条件和各种保种与选择目的的通用保种-选择指数公式、并探讨了该公式在几种特殊情况下的形式,为国内大量地方品种保种选育提供了必要的理论和方法。 相似文献
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为了明确河川沙塘鳢(Odontobutis potamophila Günther)养殖宜投喂饵料生物的种类和规格, 通过室内外试验研究了沙塘鳢对生活习性不同8种饵料生物的种类选择, 对不同规格赤眼鳟(Squaliobarbus curriculus Richardson)的选择, 以及其不同生长阶段对饵料鱼大小的选择。研究结果表明, 沙塘鳢对麦鲮(Cirrhinus mrigala Hamilton)的选择指数显著大于其对剩余7种饵料生物的选择指数; 在无仿真水草条件下, 沙塘鳢对小规格饵料生物的选择指数显著大于对大、中规格饵料生物的选择指数; 在仿真水草条件下, 沙塘鳢对小规格饵料生物的选择指数显著大于其对大规格饵料生物的选择指数。在不同生长阶段中, 沙塘鳢全长与其捕食的饵料鱼全长呈现正相关关系; 沙塘鳢捕食的饵料鱼PPR值为0.23—0.73, 均值为0.49±0.1(均值±标准差); 随沙塘鳢规格的增加其捕食饵料鱼的PPR值降低, 捕食饵料鱼规格分布小于环境中饵料鱼规格分布。综上, 沙塘鳢养殖宜投喂饵料鱼麦鲮, 饵料鱼PPR值宜为0.38—0.6。 相似文献
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Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis
It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis. 相似文献
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RICHARD E. NORRIS 《Botanical journal of the Linnean Society. Linnean Society of London》1991,106(1):1-40
Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera. 相似文献
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JOAN VALUÈS MONTSERRAT TORRELL NÚRIA GARCIA JACAS 《Botanical journal of the Linnean Society. Linnean Society of London》2001,137(4):399-407
Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted. 相似文献
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肝癌中HBV和HCV基因和抗原的分布及意义 总被引:1,自引:0,他引:1
采用原位分子杂交方法检测HCV
RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV
RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV
RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV
X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV
C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细 相似文献
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H.-R. GREGORIUS 《Biological journal of the Linnean Society. Linnean Society of London》1984,23(2-3):157-165
For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment. 相似文献
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment. 相似文献