Name: genetic drift simulation and hardy-weinberg lab prep
Uploaded: 2019-01-31T09:26:08.000Z
Duration: 1 min 53 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Biology

Evolution

Mechanisms

Hardy-Weinberg and Genetic Drift

<ul><li><a href="#" data-time="7">数学建模
</a></li><li><a href="#" data-time="21">哈迪-温伯格平衡与遗传漂变的模拟
</a></li></ul>

<ul class="lab-items"><li data-lab-item="1">
								<div class="ingredient" data-value="彩色珠子（每种颜色，10 种不同颜色）">彩色珠子（每种颜色，10 种不同颜色）</div>
								<div class="成分量">
									<span class="amount" data-value="500">500</span>
									<span class="unit" data-value=""></span>
								</div>
							</li><li data-lab-item="1">
								<div class="ingredient" data-value="具有电子表格功能的笔记本电脑">具有电子表格功能的笔记本电脑</div>
								<div class="成分量">
									<span class="amount" data-value="5">5</span>
									<span class="unit" data-value=""></span>
								</div>
							</li><li data-lab-item="1">
								<div class="ingredient" data-value="纸袋">纸袋</div>
								<div class="成分量">
									<span class="amount" data-value="5">5</span>
									<span class="unit" data-value=""></span>
								</div>
							</li><li data-lab-item="1">
								<div class="ingredient" data-value="珠子的额外塑料容器">珠子的额外塑料容器</div>
								<div class="成分量">
									<span class="amount" data-value="5">5</span>
									<span class="unit" data-value=""></span>
								</div>
							</li><li data-lab-item="1">
								<div class="ingredient" data-value="纸盘">纸盘</div>
								<div class="成分量">
									<span class="amount" data-value="5">5</span>
									<span class="unit" data-value=""></span>
								</div>
							</li></ul>

哈迪-温伯格平衡与遗传漂变

<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">数学建模<button class="expand">展开</button>
	<ul class="lab-items">
		<li data-sub-note-item="1-1">
		<div class="lab-step">在开始数学建模练习之前，请确保每台计算机均可访问在线或离线的电子表格软件程序。</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">哈迪-温伯格平衡与遗传漂变模拟<button class="expand">展开</button>
	<ul class="lab-items">
		<li data-sub-note-item="2-1">
		<div class="lab-step">为每对学生准备一组珠子：分别清点出50颗一种颜色的珠子和50颗另一种颜色的珠子，共计100颗珠子。</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">然后将这些珠子放入一个纸袋中。</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">学生还需要额外的珠子来调整种群组成，这些珠子可提供在一个全班共用的容器中，或由教师为每对学生额外准备若干组。</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">接下来，制作若干纸条，并在上面写下不同的实验情景，用于检验哈迪-温伯格平衡的破坏条件。</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">然后，再制作第二组纸条，用于确定学生将测试的遗传漂变情景。</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">最后，准备好纸条上所列实验情景所需的额外珠子。</div>
		</li>
		<li data-sub-note-item="2-7">
		<div class="lab-step">注意：突变破坏情景需要额外50颗第三种颜色的珠子，基因流动情景则需要额外100颗前两种颜色的珠子。在模拟奠基者效应（10个等位基因）和自然灾害（10个等位基因）情景时，需从10种不同颜色中随机选取共100颗珠子。</div>
		</li>
	</ul>
	</li>
</ol>

<div class="section-question"><h4 class="question-sect">哈迪-温伯格定律是什么？为什么它有用？</h4><p>哈迪-温伯格定律指出，在没有进化发生的情况下，一个群体的等位基因频率在世代之间将保持不变。该定律被用作群体遗传学中的零模型，使科学家能够理解进化机制。</p></div><div class="section-question"><h4 class="question-sect">如何计算哈迪-温伯格平衡？</h4><p>哈迪-温伯格平衡通过将每个等位基因的频率（p 和 q）相乘，以计算特定基因型在平衡状态下的基因型频率。  
<em>p</em><sup>2</sup> + 2<em>pq</em> + <em>q</em><sup>2</sup> = 1；<em>p</em> + <em>q</em> = 1
</p></div><div class="section-question"><h4 class="question-sect">哈迪-温伯格定律的五个假设是什么？</h4><p>种群数量无限大、个体随机交配、无基因突变、无自然选择、无基因流动。</p></div><div class="section-qu...

数学建模

开始数学建模练习之前，请确保每台计算机均可访问在线或离线的……

Education

教育

JoVE Lab Manual

生物学

进化

Hardy-Weinberg 和遗传漂变

Lab Manual Sub Articles

实验室手册子条目

genetic drift simulation and hardy-weinberg lab prep

<p class="jove_content">Genetic drift simulation and Hardy-Weinberg lab prep use beads and spreadsheet software to model changes in allele frequencies. Before starting the mathematical modeling exercise, make sure each computer has access to either online or offline spreadsheet software.</p>

<p class="jove_content">For the simulation, prepare one set of beads for each pair of students. Count out 50 beads of one color and 50 beads of a second color for a total of 100 beads, and place them in a paper bag. Students will also need extra beads to adjust the population makeup, and those can be kept in a shared class container or set up as additional bead sets for each pair.</p>

<p class="jove_content">Next, create paper slips that list the experimental scenarios used to test violations of Hardy-Weinberg equilibrium. Make a second set of slips to choose which genetic drift scenario the students will test. Set out any extra beads needed for those scenarios. A mutation violation needs 50 additional beads in a third color, and a gene flow scenario needs an extra set of 100 beads in the first two colors.</p>

<p class="jove_content">For the founder effect with 10 alleles and the natural disaster with 10 alleles, randomly select 100 beads from 10 different colors. This setup lets students compare how different population changes affect the model during the Hardy-Weinberg and genetic drift activity.</p>

Genetic Drift Simulation and Hardy-Weinberg Lab Prep

genetic-drift-simulation-and-hardy-weinberg-lab-prep

hardy-weinberg and genetic drift

Allele Frequency Shifts in Small Populations

Allele frequency shifts in small populations can be explored with the Hardy-Weinberg equation and genetic drift. In this activity, students model how dominant and recessive alleles change from one generation to the next. They use both a spreadsheet simulation and a bead-based lab to track those changes over time.<br /><br />The spreadsheet model begins with p, the frequency of allele A, and q, the frequency of allele B. Students enter starting values, then use random formulas and a concatenate function...

Genetic drift simulation and Hardy-Weinberg lab prep use beads and spreadsheet software to model changes in allele frequencies. Before starting the mathematical modeling exercise, make sure each computer has access to either online or offline spreadsheet software.<br /><br />For the simulation, prepare one set of beads for each pair of students. Count out 50 beads of one color and 50 beads of a second color for a total of 100 beads, and place them in a paper bag. Students will also need extra beads to...

lab manual sub articles

Set up a Hardy-Weinberg and genetic drift simulation with beads, paper slips, and spreadsheet software. Includes mutation, gene flow, founder effect, and natural disaster scenarios.

Genetic Drift Simulation and Hardy-Weinberg Lab Prep | JoVE K12

Next Generation Science Standards

High School

Life Science

heredity-inheritance-and-variation-of-traits

Heredity: Inheritance and Variation of Traits

HS-LS3-3

Florida Department of Education

SC.912.L.15

SC.912.L.15.12

SC.912.L.15.14

new-york-state-science-learning-standards

New York State Science Learning Standards

Inheritance and Variation of Traits

HS-LS3-3.

Natural Selection and Evolution

HS-LS4-1.

HS-LS4-3.

Georgia Standards of Excellence

SB6.d

<p>科学家曾一度困惑，为何像黄褐色长颈鹿斑点这样的显性性状并不会随着每一代的延续而变得更加普遍，从而取代深褐色斑点等隐性性状。在思考这一难题时，1908年，戈弗雷·H·哈代（Godfrey H. Hardy）与威廉·温伯格（Wilhelm Weinberg）在互不知情的情况下各自独立提出了一种理论，即如今所称的哈代-温伯格定律，并由以下方程表示。</p>
<p>该原理指出，在没有进化的条件下，即处于平衡状态时，一个群体的等位基因频率和基因型频率将从一代到下一代保持不变。为了理解这个方程，让我们回到长颈鹿的例子。大写字母 A 代表显性的褐色等位基因，小写字母 a 代表隐性的棕色等位基因。这两个等位基因在群体中的频率分别用 p 和 q 表示。那么我们如何确定等位基因频率呢？每个个体都有两个等位基因。在这个例子中，基因库中 40% 的等位基因是褐色的。因此，褐色等位基因的频率 p 为 0.4，棕色等位基因的频率 q 为 0.6。请注意，p 加 q 始终等于 1。</p>
<p>现在让我们回到哈迪-温伯格方程。方程中的每一项代表一种基因型的频率。纯合显性基因型的频率为 p²，纯合隐性基因型由 q² 表示。杂合基因型为 2pq。此处乘以 2 的原因是产生杂合基因型有两种不同的方式。这些频率加在一起代表了全部基因型，即总频率为 1（100%）。利用之前长颈鹿例子中计算出的 p 和 q 值，我们可以确定该长颈鹿群体中颜色基因等位基因的基因型分布。因此，根据哈迪-温伯格平衡定律，在达到平衡状态时，16% 的长颈鹿为纯合显性，48% 为杂合子，36% 为纯合隐性。</p>
<p>为了维持这种平衡，哈迪-温伯格平衡定律指出，一个群体应满足五个主要假设：随机交配、群体规模足够大、无突变、对所研究的基因无自然选择作用，以及无基因流进入或离开该群体。大多数自然群体至少违反了其中一项假设，因此平衡状态较为罕见……但尽管如此，该定律仍被用作群体遗传学中的零模型。通过将这些预期值与群体中实际的基因型频率进行比较，可以判断该群体是否处于哈迪-温伯格平衡状态。如果不符合，则意味着该群体正在发生某种形式的进化或等位基因频率的改变。</p>
<p>关于进化的一个普遍误解是，认为进化必须通过自然选择才能发生。然而，情况并非总是如此。遗传漂变就是一种无需自然选择也可导致进化的机制。它被定义为由于随机因素导致种群中等位基因频率发生变化。为了理解这一点，让我们回到长颈鹿种群的例子，并设想它们的浅褐色和棕色等位基因由两种不同颜色的弹珠来代表。我们假设每种颜色最初数量相等。如果我们从该种群中繁衍新一代，则需要将个体成对交配，从而每对组合中选出四个等位基因。如果我们随机选择一对进行繁殖，可能会得到每种颜色各两个弹珠。然而，仅凭偶然性，某些配对可能只包含一种颜色的弹珠，或三种一种颜色、一种另一种颜色。在多次配对产生新一代的过程中，这些偏离50-50比例的随机偏差可能导致下一代不再具有相等的等位基因混合比例。</p>
<p>正是等位基因频率随时间发生的变化定义了遗传漂变。因此，与适应性进化不同——在适应性进化中，等位基因频率的改变是为了筛选出更适应环境的性状，例如在寒冷气候中，因含有较多黑色素而具有更强吸热能力、从而生存能力更强的瓢虫——遗传漂变代表了一种完全由随机性变化驱动的进化类型。例如，由于灾难性事件导致种群中某一部分个体被随机移除。</p>
<p>在本实验中，您将通过计算机模拟和彩色珠子模拟来研究群体中哈迪-温伯格平衡和遗传漂变，并测试当平衡假设条件被打破时会发生什么情况。</p>

hardy-weinberg tests for population change

<p class="jove_content">Hardy-Weinberg tests help scientists check whether a population is changing over time. Because evolution happens slowly and over large areas, researchers often use mathematical models to study it. These models use measurable data and computer simulations to predict how allele frequencies may shift across many generations.</p>

<p class="jove_content">The Hardy-Weinberg equilibrium equation is one common model. It was developed independently in 1908 by G. H. Hardy and Wilhelm Weinberg. The equation gives the expected allele frequency for a population that is not evolving, so it serves as a useful null hypothesis. If measured allele frequencies do not match the prediction, the gene may be undergoing evolutionary change.</p>

<p class="jove_content">The model is written as p2 + 2pq + q2 = 1. In this equation, p is the frequency of the dominant allele and q is the frequency of the recessive allele. The three terms represent the expected frequencies of the three diploid genotypes: homozygous dominant, heterozygous, and homozygous recessive. The allele version of the model is p + q = 1, since the two allele frequencies must total 1 in the population.</p>

<p class="jove_content">Hardy-Weinberg also depends on a set of assumptions. The population must be very large and closed, which means no individuals move in or out. There must be no mutations in the gene being studied. Individuals must mate at random, and natural selection must not be acting. When real data breaks one or more of these assumptions, the model can help point to what may be happening.</p>

<p class="jove_content">Genetic drift is one reason a small population can change by chance alone. This violates the large-population assumption of Hardy-Weinberg. One form of genetic drift is the founder effect. It happens when a small group leaves and starts a new isolated population. The genes carried by those founders shape future generations. In an extreme case, if the founders are all homozygous recessive, the dominant allele can disappear and the recessive allele can reach 100%.</p>

<p class="jove_content">A similar pattern is called the bottleneck effect. It can occur after a natural disaster, human intervention, or disease causes a major drop in population size. Genetic drift is not necessarily adaptive, because it does not specifically favor traits that fit the environment. Even so, it is an important evolutionary force in small populations and can create differences from Hardy-Weinberg predictions. In larger populations, those differences are more likely to suggest natural selection.</p>

<p class="jove_content">Scientists also use Hardy-Weinberg testing in modern studies of human and animal populations. One focus is how immune system genes relate to susceptibility to infectious disease. Researchers study genes such as CCR5 and the major histocompatibility complex, or MHC, called HLA in humans. By comparing genetic data with disease data, they can find patterns showing that some individuals are more resistant to certain infections while others are more likely to become ill. These studies have helped explain how infections have influenced evolution.</p>

Hardy-Weinberg Tests for Population Change

进化变化的研究既有趣又重要，但种群的变化发生在漫长的时间尺度和广阔的物理空间中，并且是……

hardy-weinberg-tests-for-population-change

使用 JoVE Lab Manual 上的这个Biology评估测验来测试你对Hardy-Weinberg 和遗传漂变的理解。通过视频问题涵盖关键概念，旨在评估学生的学习情况。

Hardy-Weinberg 和遗传漂变（Biology）- 评估测验 | JoVE Lab Manual

在这段 16 分钟的学生实验流程视频中，逐步学习 哈迪-温伯格平衡与遗传漂变 的操作步骤。属于 JoVE Lab Manual 上的 Biology 系列。

Biology 中的 哈迪-温伯格平衡与遗传漂变 学生实验流程 - 8.6K+ 观看次数 | JoVE Lab Manual

What is Natural Selection?

Natural selection is an evolutionary process in which individuals with survival-promoting traits reproduce at higher rates. These favorable traits become ...

Types of Selection

Natural selection influences the frequencies of particular alleles and phenotypes within populations in several different ways. Primarily, natural ...

Frequency-dependent Selection

When the fitness of a trait is influenced by how common it is (i.e., its frequency) relative to different traits within a population, this is referred to ...

Limits to Natural Selection

Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly ...

Natural Selection

Fitness
Widespread variation of phenotypes in natural populations provides the raw material for evolution, which is the change in the inherited traits of ...

Simulating Natural Selection
ExpandTo prepare for the lab, set out workstations for each student pair containing 6 white, 6 black, and 13 gray 12 inch ...

Simulating Natural Selection
ExpandTo begin, cut the white, black, and gray pipe cleaners into quarters, which should produce a total of 100 pieces that ...

Artificial Selection

Natural Selection and Adaptive Evolution
In natural settings, adaptive evolution takes place by natural selection, a process in which differences in ...

Observing Artificial Selection in Plants
ExpandTwo weeks before beginning the pollination experiments, collect a sufficient amount of small pots with a ...

Observing Artificial Selection in Plants 
ExpandTo begin the experiment, collect five two-week old grown plants from the generation one population that ...

What is Population Genetics?

A population is composed of members of the same species that simultaneously live and interact in the same area. When individuals in a population breed, ...

Hardy-Weinberg Principle

Diploid organisms have two alleles of each gene, one from each parent, in their somatic cells. Therefore, each individual contributes two alleles to the ...

Mutation, Gene Flow, and Genetic Drift

In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions ...

Genetic Drift

Natural selection&#x2014;probably the most well-known evolutionary mechanism&#x2014;increases the prevalence of traits that enhance survival and ...

Gene Flow

Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.

This ...

Evolutionary change is interesting and important to study, but changes in populations occur over long periods of time and in huge physical spaces and are ...


	Mathematical ModelingExpand
	
		
		Before beginning the mathematical modeling exercise make sure each computer has access to an either on or offline ...

Class Simulation
ExpandBegin by opening a new spreadsheet file. Following the Hardy-Weinberg equation where p is the frequency of a dominant allele A in a ...

Mechanisms
• Natural selection
• Mutation
• Genetic drift
• Gene flow (immigration, emigration)
• Sexual selection

Content elaboration: Natural selection is used to describe the process by which traits become more or less common in a population due to consistent environmental pressures upon the survival and reproduction of individuals with the trait. Mathematical reasoning is applied to solve problems (e.g., use Hardy-Weinberg principle to explain deviations in observed gene frequency patterns in a population compared to expected patterns based on the assumptions of the principle). Populations evolve over time. Evolution through natural selection is the consequence of the interactions of:
1. The potential for a population to increase its numbers; 
2. The genetic variability of offspring due to mutation and recombination of genes; 
3. A finite supply of the resources required for life; and 
4. The differential survival and reproduction of individuals based on phenotype(s). 
Mutations are described in the content elaboration for Heredity. Apply the knowledge of mutation and genetic drift to real-world examples. Biological evolution explains the natural origins for the diversity of life. Emphasis shifts from thinking in terms of selection of individuals with a particular trait to changing proportions of a trait in populations as a result of the mechanisms of natural selection, genetic drift, movement of genes into and out of populations and sexual selection.

Taxonomy

Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics. It uses a hierarchy of increasingly ...

Phylogeny

Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon ...

evolutionary-relationships-through-genome-comparisons

Evolutionary Relationships through Genome Comparisons

Genome comparison is one of the excellent ways to interpret the evolutionary relationships between organisms. The basic principle of genome comparison is ...

Genome Copying Errors

DNA replication is a well-evolved process that copies millions of base pairs with high fidelity during each cell division. Occasionally a wrong base or a ...

Phylogenetic Trees

Synteny and Evolution

John H. Renwick first coined the term &#8220;synteny&#8221; in 1971, which refers to the genes present on the same chromosomes, even if they are not ...

Multi-species Conserved Sequences

Next-generation sequencing technologies have created large genomic databases of a variety of animals and plants. Ever since the human genome project was ...

Gene Duplication and Divergence

The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of ...

Exon Recombination

The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new ...

comparing-copy-number-variations-and-snps

Comparing Copy Number Variations and SNPs

Sequencing of the human genome has opened up several best-kept secrets of the genome. Scientists have identified thousands of genome variations that exist ...

Speciation
• Biological classification expanded to molecular evidence
• Variation of organisms within a species due to population genetics and gene frequency

Content elaboration: Biological classification expanded to molecular evidence
Classification systems are frameworks, developed by scientists, for describing the diversity of organisms; indicating the degree of relatedness among organisms. Recent molecular sequence data generally support earlier hypotheses regarding lineages of organisms based upon morphological comparisons. Both morphological and molecular comparisons can be used to describe patterns of biodiversity (cladograms present hypotheses to explain descent from a common ancestor with modification). The concept of descent from a common ancestor with modification provides a natural explanation for the diversity of life on Earth as partially represented in the fossil record and in the similarities of existing species. 
Variation of organisms within a species due to population genetics and gene frequency
Different phenotypes result from new combinations of existing genes or from mutations of genes in reproductive cells. At the high school level, the expectation is to combine grade 8 knowledge with an explanation of genes and the function of chromosomes. Natural selection works on the phenotype. Heritable characteristics influence how likely an organism is to survive and reproduce in a particular environment. When an environment changes, the survival value of inherited characteristics may change. This may or may not cause a change in species that inhabit the environment. Use real-world examples to illustrate natural selection, gene flow, sexual selection, and genetic drift.

Speciation

Genetic Drift Simulation and Hardy-Weinberg Lab Prep

Learning Objectives

哈迪-温伯格定律是什么？为什么它有用？

如何计算哈迪-温伯格平衡？

Lab Prep

Transcript

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