O1遗传的变异 要点 基因和等位 基因是带有可产生特定蛋白的遗传密码的DNA片段 基因 个基因可有许多等位基因,而个体可有纯合或杂合 的基因型。表达的表现型取决于等位基因是显性的、 隐性的还是共显性的。种群中存在的所有基因组和等 位基因叫做基因库
O1 遗传的变异 要 点 基因和等位 基因 基因是带有可产生特定蛋白的遗传密码的DNA片段。 一个基因可有许多等位基因，而个体可有纯合或杂合 的基因型。表达的表现型取决于等位基因是显性的、 隐性的还是共显性的。种群中存在的所有基因组和等 位基因叫做基因库
O1 GENETIC VARIATION Key Notes Genes are pieces of DNA which contain the genetic code Genes and alleles necessary to produce a specific protein. A gene can have many alleles and individuals can have a homozy gous or heterozygous genotype. The phenotype expressed depends on whether alleles are dominant. recessive or codominant The total set of genes and alleles present in a population known as the gene pool
Genes are pieces of DNA which contain the genetic code necessary to produce a specific protein. A gene can have many alleles and individuals can have a homozygous or heterozygous genotype. The phenotype expressed depends on whether alleles are dominant, recessive or codominant. The total set of genes and alleles present in a population is known as the gene pool. Key Notes Genes and alleles O1 GENETIC VARIATION
多型」 多型指的是种群中等位基因的存在。一个种群或物种 可能颜色是多型的,如蜗牛,或者一些生化特性是多 型的,如植物的毒性。一些多型可能是由自然选择保 持下来的,但其他是由于许多基因控制多型性状的结 果 测定遗传变异种群和物种内的遗传变异可直接由DNA或蛋白(别构 酶)变异来估计。蛋白或DNA片段可通过凝胶电泳分 离,呈现可刻划的带来决定个体的基因型。对个体 DNA的详细调查产生了一种独特的遗传指纹,对建立 父子关系很有用
测定遗传变异 种群和物种内的遗传变异可直接由DNA或蛋白（别构 酶）变异来估计。蛋白或DNA片段可通过凝胶电泳分 离，呈现可刻划的带来决定个体的基因型。对个体 DNA的详细调查产生了一种独特的遗传指纹，对建立 父子关系很有用。 多 型 多型指的是种群中等位基因的存在。一个种群或物种 可能颜色是多型的，如蜗牛，或者一些生化特性是多 型的，如植物的毒性。一些多型可能是由自然选择保 持下来的，但其他是由于许多基因控制多型性状的结 果
polymorphism The term polymorphism refers to the presence of alleles in population. A population or species may be polymorphic for color. as in snails. or for some biochemical function. as in plant toxicity. Some polymorphisms are maintained by natural selection, but others appear to result from the effect of many genes controlling the polymorphic character Measuring genetic Genetic variation within populations and species can be variation estimated directly from the dNa or from protein(allozyme) variation Proteins or DNA fragments are separated by gel electrophoresis to give bands that can be scored to determine the genotype of individuals. Detailed investigation of the DNA of individuals yields a unique genetic fingerprint, useful for establishing paternity
polymorphism The term polymorphism refers to the presence of alleles in a population. A population or species may be polymorphic for color, as in snails, or for some biochemical function, as in plant toxicity. Some polymorphisms are maintained by natural selection, but others appear to result from the effect of many genes controlling the polymorphic character. Genetic variation within populations and species can be estimated directly from the DNA or from protein (allozyme) variation. Proteins or DNA fragments are separated by gel electrophoresis to give bands that can be scored to determine the genotype of individuals. Detailed investigation of the DNA of individuals yields a unique genetic fingerprint, useful for establishing paternity. Measuring genetic variation
遗传漂变 遗传漂变是基因频率的随机变化,仅偶然出现。在小 种群中,遗传漂变更明显。基因频率“漂离”起始值, 增加、减少或上下波动。发生遗传漂变是因为在个体 生后代的合子以及繁殖前死亡的个体中都有偶然要 素。基因频率的随机变化导致来自种群的遗传变异的 固定和逐渐丧失。 遗传瓶颈当种群数量突然减少时,基因频率也会发生变化,总 的遗传变异下降。瓶颈发生的时候,小种群的遗传漂 变导致遗传变异丧失。尽管种群数量可以恢复,遗传 变异在以后许多代仍会保持低水平
遗传漂变 遗传漂变是基因频率的随机变化，仅偶然出现。在小 种群中，遗传漂变更明显。基因频率“漂离”起始值， 增加、减少或上下波动。发生遗传漂变是因为在个体、 产生后代的合子以及繁殖前死亡的个体中都有偶然要 素。基因频率的随机变化导致来自种群的遗传变异的 固定和逐渐丧失。 遗传瓶颈 当种群数量突然减少时，基因频率也会发生变化，总 的遗传变异下降。瓶颈发生的时候，小种群的遗传漂 变导致遗传变异丧失。尽管种群数量可以恢复，遗传 变异在以后许多代仍会保持低水平
Genetic drift is a random change in gene frequency arising Genetic drift through chance alone. It tends to be more apparent in small populations allele frequencies drift away from their starting values, increasing, decreasing or fluctuating up and down. It occurs because there is an element of chance in which individuals and which gametes will produce offspring and which individuals will die before reproducing Random changes in allele frequency can lead to fixation and the progressive loss of genetic variation from the population Genetic When a population undergoes an abrupt contraction in numbers bottleneck this is accompanied by a change in gene frequencies and a decline in the total genetic variation. Genetic drift in the small population during the bottleneck results in the loss of genetic variation. Although population numbers may recover, genetic variation will remain low for many generations
Genetic drift Genetic drift is a random change in gene frequency arising through chance alone. It tends to be more apparent in small populations allele frequencies drift away from their starting values, increasing, decreasing or fluctuating up and down. It occurs because there is an element of chance in which individuals and which gametes will produce offspring and which individuals will die before reproducing. Random changes in allele frequency can lead to fixation and the progressive loss of genetic variation from the population. Genetic bottleneck When a population undergoes an abrupt contraction in numbers, this is accompanied by a change in gene frequencies and a decline in the total genetic variation. Genetic drift in the small population during the bottleneck results in the loss of genetic variation. Although population numbers may recover, genetic variation will remain low for many generations
建立者效应 建立者效应描述由一个或几个个体建立新种群,导致 低水平的遗传变异和在亲本种群中稀少的等位基因的 经常不成比例的数量。人类中特定遗传病的高发病率 可归因于建立者效应 相关主题 适应(B1) 稀有物种、生境损失和灭绝(V1)
建立者效应 建立者效应描述由一个或几个个体建立新种群，导致 低水平的遗传变异和在亲本种群中稀少的等位基因的 经常不成比例的数量。人类中特定遗传病的高发病率 可归因于建立者效应。 相关主题 适应（B1） 稀有物种、生境损失和灭绝（V1）
Founder effect This term describes the establishment of a new population by one or a few individual(s), resulting in low levels of genetic variation and often a disproportionate number of alleles that are rate in the parent population. In human populations the high incidence of certain genetic diseases can be traced to founder effects Related topics Adaptation (B1) Rare species, habitat loss and extinction (V1)
Related topics Adaptation (B1) Rare species, habitat loss and extinction (V1) Founder effect This term describes the establishment of a new population by one or a few individual(s), resulting in low levels of genetic variation and often a disproportionate number of alleles that are rate in the parent population. In human populations the high incidence of certain genetic diseases can be traced to founder effects
O2物种形成 要 繁殖种的概念 繁殖种的概念,集中在如下思想:物种延续并保持其 遗传的完整性和独特性是因为不进行异种杂交。生物 种概念和识别种概念都根据相互杂交定义种。本观点 与实际的物种定义不同的是后者以明显的形态学性状 为基础。 基因流 基因流描述的是基因在种群内通过相互杂交、扩散和 迁移进行的运动。高基因流使种群遗传上彼此相似。 受到限制的基因流使种群间发生分化
O2 物种形成 要 点 繁殖种的概念 繁殖种的概念，集中在如下思想：物种延续并保持其 遗传的完整性和独特性是因为不进行异种杂交。生物 种概念和识别种概念都根据相互杂交定义种。本观点 与实际的物种定义不同的是后者以明显的形态学性状 为基础。 基 因 流 基因流描述的是基因在种群内通过相互杂交、扩散和 迁移进行的运动。高基因流使种群遗传上彼此相似。 受到限制的基因流使种群间发生分化
O2 SPECIATION ey Notes Reproductive The reproductive species concept focuses on the idea that species concept species exist and maintain their genetic integrity and distinctness because they do not interbreed. The biological pecies concept and the recognition species concept both define species in terms of interbreeding. His view contrasts with the practical definition of species on the basis of distinguishing morphological characters Gene flow describes he movement of genes among populations Gene fl through interbreeding, dispersal and migration. High gene flow causes populations to become genetically similar to one another Restricted gene flow allows differentiation to occur among populations
The reproductive species concept focuses on the idea that species exist and maintain their genetic integrity and distinctness because they do not interbreed. The biological species concept and the recognition species concept both define species in terms of interbreeding. His view contrasts with the practical definition of species on the basis of distinguishing morphological characters. Key Notes Reproductive species concept O2 SPECIATION Gene flow describes he movement of genes among populations through interbreeding, dispersal and migration. High gene flow causes populations to become genetically similar to one another. Restricted gene flow allows differentiation to occur among populations. Gene flow