Chapter 8 Genetic structure in
animal population
第八章 动物群体的遗传结构
? The Hardy-Weinberg equilibrium in
animal populations 动物群体的平衡
? Changes in the genetic structure of
populations 影响平衡和基因频率变化的
因素
? Genetic diversity 遗传多样性
? Species and speciation 物种与物种形成
Population and population genetics
群体与群体遗传学
? Population,entire group of organisms of one kind;
an interbreeding group of plants and animals; the
extensive group from which a sample might be
taken,群体 是由交配和亲子关系相连的个体构成
的集团
? Mendelian population,A natural interbreeding unit
of sexually reproducing plants or animals sharing a
common gene pool.孟德尔群体 是指能相互交配
以有性方式产生个体的集团
? Population genetics,The branch of genetics that
deals with frequencies of alleles and genotypes
in breeding population.研究群体的遗传结构及
其变化规律的遗传学就是 群体遗传学
? Evolution genetics进化遗传学
The Hardy-Weinberg equilibrium in
animal populations 动物群体的平衡
? Allele frequencies and The Hardy-Weinberg
equilibrium 基因频率与 Hardy-Weinberg
平衡
? Calculation of allele frequencies in random-
breeding populations 随机交配群体基因频
率的计算
? The Hardy-Weinberg equilibrium for over
one locus 一个以上座位的平衡
Allele frequencies and The Hardy-
Weinberg equilibrium
基因频率与 Hardy-Weinberg平衡
? Allele frequency,The proportion of one allele
relative to all alleles at a locus in a population
一个群体内某一定等位基因的频率叫做 基因频
率,其中 A1的频率为：
x1 = (2N11+N12)/(2N) = X11+X12/2
A2的频率
x 2 = 1-x1 =X12/2 + X22
Allele frequencies and The Hardy-
Weinberg equilibrium
基因频率与 Hardy-Weinberg平衡
X11 = x12
X12 = 2x1x2
X22 = x22
The Hardy-Weinberg principle of genetic equilibium
describes the relationship between allele frequencies and
genotype frequencies under the assumption of random
mating,This principle applies to loci with alleles,loci
with multiple alleles,and X-linked loci.
Random mating随机交配
这是指在群体中一种性别的任何一个个体
与其相反性别的任一个体交配的机会均等
Allele frequencies in loci with multiple alleles
复等位基因的基因频率
一般情况：
Hardy-Weinberg平衡：
xi = Xii +(1/2) ∑Xiji≠j
Xii = xi2,Xij = 2 xixj
Calculation of allele frequencies in
random-breeding populations
随机交配群体基因频率的计算
? Co-dominant or in-completed dominant alleles
等显性或不完全显性等位基因
xi = (2nii + ∑nij)/(2n)
? Completed dominant alleles 完全显性等位基因
x2 =√ nk/n
? Sex-linked loci 伴性基因频率的计算
For example 例子
Calculate allele frequencies of A,B,C
求出等位基因 A,B,C的频率
Genotype AA BB CC AB AC BC Total
Observed 74 0 26 12 80 8 200
Expected 72 0.5 24.5 12 84 7 200
例 1
一个群体中个体的血型比例是：
血型 A B O AB
比例 0.32 0.15 0.49 0.04
计算各等位基因的频率。
解答
血型 A,B,O分别由基因 IA,IB,i控制，
假定它们的频率为 x1,x2,x3,则
x3 = √0.49 = 0.7
x1 +x2+x3 = 1,(x2 +x3)2 = (1 – x1)2
(x2 +x3)2 =B + O,
x1 =1 –√ B + O = 1 –√0.32+0.49
= 1 – 0.9 = 0.1
x2 = 1 – 0.1 – 0.7 = 0.2
由于
所以
例 2
1998级畜牧专业全体同学的血型比例是：
血型 A B O AB
比例 14(0.259) 10(0.185) 26(0.482) 4(0.074)
计算各等位基因的频率。
Allele frequencies for X-linked loci
伴性基因频率
雌性,x12 + 2x1x2 + x22
A1A1 A1A2 A2A2
雄性,x1 + x2
A1 A2
The Hardy-Weinberg equilibrium
for over one locus
一个以上座位的平衡
Changes in the genetic structure of
populations
影响平衡和基因频率变化的因素
? Mating systems 交配方式
? Selection 选择
? Mutation 突变
? Genetic drift 遗传漂变
? Immigration 迁移
? The founder 创始者效应
Conditions for Hardy-Weinberg equilibium
Hardy-Weinberg 平衡的 5个条件
? Uniform in adaptation 适应性一致
? Big populations 大群体
? Random mating 随机交配
? No immigration 无迁入与迁出
? Mutation in balance 突变处于平衡状态
Mating systems 交配方式
? Mating system,inbreeding and
outbreeding 交配方式：近交与杂交
? Effects of mating systems on the Hardy-
Weinberg equilibium 交配方式的作用：
改变基因型频率，不改变基因频率
各种近交类型 Various types of consanguineous mating
近交效应
? Inbreeding,or consanguieous mating,
occurs where mates are genetically
related
? Inbreeding allows rare alleles to become
homozygous,and it greatly increases the
likelihood that rare recessive disorders will
appear in the offspring of related parents
Selection 选择
Selection,Differential survival
and reproduction among genotypes;
the most important of the factors that
change allele frequencies in large
populations选择 是基因型的非随机差异繁殖
Melanic form of moth biston betularia resting on an unpollutted,
lichen-covered tree trunk (a), A typical form of the moth resting
on a polluted,soot-covered tree trunk (b)
Three basic modes of selection and their effects
Mutation突变
A1 A2uv
x2 = uu +v平衡：
Mutation,A change in the DNA at a particular locus
in an organism,The term is used loosely to include point
mutations involving a single gene change as well as a
chromosomal change,
Effects of mutations on populations
? Mutations are a source of new variation
? Some mutations are harmful,some are
beneficial,and some are neutral or nearly so
? Experiments have shown that most,if not all
mutations are preadaptive,not postadaptive
A male lion with
a cub he sired
Genetic drift 遗传漂变
Genetic drift are changes in small
populations
等位基因的随机变动叫做 遗传漂变
Genetic drift operating in a small population,The a allele frequency
changes from 0.5 to 0.3 as a consequence of sampling errors,There
is a chance that the a allele could become extinct.
Migration迁移
Δqi = qi’ – qi = m(qc – qi)
A model of migration between a large continental population and small island
Founder principle
创始者效应
A balance between
selection and mutation
Mutation-selection
balance for a
recessive allele
Genetic diversity
遗传多样性
遗传多态现象 (genetic polymorphism)
是指同一交配繁殖群体中存在两种或两种
以上遗传变异的类型,其中频率最低的类型
并不依靠重复突变维持。
Genetic polymorphism遗传多态现象
? 染色体多态现象 chromosomal polymorphism
? DNA多态现象 DNA polymorphism
? 蛋白质多态现象 protein polymorphism
chromosomal polymorphism
染色体多态现象
? 牛 Y染色体的多态性
? 猪银染核仁组织区多态性
? 结构异染色质多态性
DNA多态现象产生的原因
? 单个核苷酸的点突变即核苷酸的替换
? 单一 DNA序列的插入或缺失
? 整串 DNA序列的插入或缺失
? 基因转换
DNA多态现象检测的原理 -RFLPs
1)
2)
电泳图谱 1) 2)
DNA多态现象的类型
? RFLP(restricted fragment length polymorphism)
? RAPD(random amplified polymorphic DNA)
? 微卫星多态性 (microsatellite polymorphism)
? SSCP(single strand conformation polymorphism)
? DSCP(double strand conformation
polymorphism)
? DNA芯片 (DNA chips)
Protein polymorphism
蛋白质多态现象
蛋白质多态现象 是在蛋白质水平上
存在的遗传变异
蛋白质多态现象是由于构成蛋白质
的多肽链上的氨基酸出现变化引起的
Genetic variation at the Pgm-1 locus of fruit fly
分子水平下多态现象的维持机制
? 选择学说 (selection theory)--认为杂合
子优势维持分子水平下的多态现象
? 中性学说 (neutral theory)--认为分子水
平下的多态现象与选择无关，是一种随
机的固定
群体遗传变异的度量
--群体的杂合性 (H)
Genetic diversity遗传多样性
Species and speciation 物种与物种形成
The species concept
?Phenotypic or phenetic species concept
?Biological species concept
Modes of speciation
? The allopatric mode of speciation
? Sympatric speciation,A controversial mode
? Parapatric speciation
? Quantum speciation
animal population
第八章 动物群体的遗传结构
? The Hardy-Weinberg equilibrium in
animal populations 动物群体的平衡
? Changes in the genetic structure of
populations 影响平衡和基因频率变化的
因素
? Genetic diversity 遗传多样性
? Species and speciation 物种与物种形成
Population and population genetics
群体与群体遗传学
? Population,entire group of organisms of one kind;
an interbreeding group of plants and animals; the
extensive group from which a sample might be
taken,群体 是由交配和亲子关系相连的个体构成
的集团
? Mendelian population,A natural interbreeding unit
of sexually reproducing plants or animals sharing a
common gene pool.孟德尔群体 是指能相互交配
以有性方式产生个体的集团
? Population genetics,The branch of genetics that
deals with frequencies of alleles and genotypes
in breeding population.研究群体的遗传结构及
其变化规律的遗传学就是 群体遗传学
? Evolution genetics进化遗传学
The Hardy-Weinberg equilibrium in
animal populations 动物群体的平衡
? Allele frequencies and The Hardy-Weinberg
equilibrium 基因频率与 Hardy-Weinberg
平衡
? Calculation of allele frequencies in random-
breeding populations 随机交配群体基因频
率的计算
? The Hardy-Weinberg equilibrium for over
one locus 一个以上座位的平衡
Allele frequencies and The Hardy-
Weinberg equilibrium
基因频率与 Hardy-Weinberg平衡
? Allele frequency,The proportion of one allele
relative to all alleles at a locus in a population
一个群体内某一定等位基因的频率叫做 基因频
率,其中 A1的频率为：
x1 = (2N11+N12)/(2N) = X11+X12/2
A2的频率
x 2 = 1-x1 =X12/2 + X22
Allele frequencies and The Hardy-
Weinberg equilibrium
基因频率与 Hardy-Weinberg平衡
X11 = x12
X12 = 2x1x2
X22 = x22
The Hardy-Weinberg principle of genetic equilibium
describes the relationship between allele frequencies and
genotype frequencies under the assumption of random
mating,This principle applies to loci with alleles,loci
with multiple alleles,and X-linked loci.
Random mating随机交配
这是指在群体中一种性别的任何一个个体
与其相反性别的任一个体交配的机会均等
Allele frequencies in loci with multiple alleles
复等位基因的基因频率
一般情况：
Hardy-Weinberg平衡：
xi = Xii +(1/2) ∑Xiji≠j
Xii = xi2,Xij = 2 xixj
Calculation of allele frequencies in
random-breeding populations
随机交配群体基因频率的计算
? Co-dominant or in-completed dominant alleles
等显性或不完全显性等位基因
xi = (2nii + ∑nij)/(2n)
? Completed dominant alleles 完全显性等位基因
x2 =√ nk/n
? Sex-linked loci 伴性基因频率的计算
For example 例子
Calculate allele frequencies of A,B,C
求出等位基因 A,B,C的频率
Genotype AA BB CC AB AC BC Total
Observed 74 0 26 12 80 8 200
Expected 72 0.5 24.5 12 84 7 200
例 1
一个群体中个体的血型比例是：
血型 A B O AB
比例 0.32 0.15 0.49 0.04
计算各等位基因的频率。
解答
血型 A,B,O分别由基因 IA,IB,i控制，
假定它们的频率为 x1,x2,x3,则
x3 = √0.49 = 0.7
x1 +x2+x3 = 1,(x2 +x3)2 = (1 – x1)2
(x2 +x3)2 =B + O,
x1 =1 –√ B + O = 1 –√0.32+0.49
= 1 – 0.9 = 0.1
x2 = 1 – 0.1 – 0.7 = 0.2
由于
所以
例 2
1998级畜牧专业全体同学的血型比例是：
血型 A B O AB
比例 14(0.259) 10(0.185) 26(0.482) 4(0.074)
计算各等位基因的频率。
Allele frequencies for X-linked loci
伴性基因频率
雌性,x12 + 2x1x2 + x22
A1A1 A1A2 A2A2
雄性,x1 + x2
A1 A2
The Hardy-Weinberg equilibrium
for over one locus
一个以上座位的平衡
Changes in the genetic structure of
populations
影响平衡和基因频率变化的因素
? Mating systems 交配方式
? Selection 选择
? Mutation 突变
? Genetic drift 遗传漂变
? Immigration 迁移
? The founder 创始者效应
Conditions for Hardy-Weinberg equilibium
Hardy-Weinberg 平衡的 5个条件
? Uniform in adaptation 适应性一致
? Big populations 大群体
? Random mating 随机交配
? No immigration 无迁入与迁出
? Mutation in balance 突变处于平衡状态
Mating systems 交配方式
? Mating system,inbreeding and
outbreeding 交配方式：近交与杂交
? Effects of mating systems on the Hardy-
Weinberg equilibium 交配方式的作用：
改变基因型频率，不改变基因频率
各种近交类型 Various types of consanguineous mating
近交效应
? Inbreeding,or consanguieous mating,
occurs where mates are genetically
related
? Inbreeding allows rare alleles to become
homozygous,and it greatly increases the
likelihood that rare recessive disorders will
appear in the offspring of related parents
Selection 选择
Selection,Differential survival
and reproduction among genotypes;
the most important of the factors that
change allele frequencies in large
populations选择 是基因型的非随机差异繁殖
Melanic form of moth biston betularia resting on an unpollutted,
lichen-covered tree trunk (a), A typical form of the moth resting
on a polluted,soot-covered tree trunk (b)
Three basic modes of selection and their effects
Mutation突变
A1 A2uv
x2 = uu +v平衡：
Mutation,A change in the DNA at a particular locus
in an organism,The term is used loosely to include point
mutations involving a single gene change as well as a
chromosomal change,
Effects of mutations on populations
? Mutations are a source of new variation
? Some mutations are harmful,some are
beneficial,and some are neutral or nearly so
? Experiments have shown that most,if not all
mutations are preadaptive,not postadaptive
A male lion with
a cub he sired
Genetic drift 遗传漂变
Genetic drift are changes in small
populations
等位基因的随机变动叫做 遗传漂变
Genetic drift operating in a small population,The a allele frequency
changes from 0.5 to 0.3 as a consequence of sampling errors,There
is a chance that the a allele could become extinct.
Migration迁移
Δqi = qi’ – qi = m(qc – qi)
A model of migration between a large continental population and small island
Founder principle
创始者效应
A balance between
selection and mutation
Mutation-selection
balance for a
recessive allele
Genetic diversity
遗传多样性
遗传多态现象 (genetic polymorphism)
是指同一交配繁殖群体中存在两种或两种
以上遗传变异的类型,其中频率最低的类型
并不依靠重复突变维持。
Genetic polymorphism遗传多态现象
? 染色体多态现象 chromosomal polymorphism
? DNA多态现象 DNA polymorphism
? 蛋白质多态现象 protein polymorphism
chromosomal polymorphism
染色体多态现象
? 牛 Y染色体的多态性
? 猪银染核仁组织区多态性
? 结构异染色质多态性
DNA多态现象产生的原因
? 单个核苷酸的点突变即核苷酸的替换
? 单一 DNA序列的插入或缺失
? 整串 DNA序列的插入或缺失
? 基因转换
DNA多态现象检测的原理 -RFLPs
1)
2)
电泳图谱 1) 2)
DNA多态现象的类型
? RFLP(restricted fragment length polymorphism)
? RAPD(random amplified polymorphic DNA)
? 微卫星多态性 (microsatellite polymorphism)
? SSCP(single strand conformation polymorphism)
? DSCP(double strand conformation
polymorphism)
? DNA芯片 (DNA chips)
Protein polymorphism
蛋白质多态现象
蛋白质多态现象 是在蛋白质水平上
存在的遗传变异
蛋白质多态现象是由于构成蛋白质
的多肽链上的氨基酸出现变化引起的
Genetic variation at the Pgm-1 locus of fruit fly
分子水平下多态现象的维持机制
? 选择学说 (selection theory)--认为杂合
子优势维持分子水平下的多态现象
? 中性学说 (neutral theory)--认为分子水
平下的多态现象与选择无关，是一种随
机的固定
群体遗传变异的度量
--群体的杂合性 (H)
Genetic diversity遗传多样性
Species and speciation 物种与物种形成
The species concept
?Phenotypic or phenetic species concept
?Biological species concept
Modes of speciation
? The allopatric mode of speciation
? Sympatric speciation,A controversial mode
? Parapatric speciation
? Quantum speciation
