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">Modelagem Matemática
</a></li><li><a href="#" data-time="21">Simulação para Hardy-Weinberg e Deriva Genética
</a></li></ul>

<ul class="lab-items"><li data-lab-item="1">
								<div class="ingrediente" data-value="Miçangas coloridas (cada cor, 10 cores diferentes)">Miçangas coloridas (cada cor, 10 cores diferentes)</div>
								<div class="ingrediente-quantidade">
									<span class="amount" data-value="500">500</span>
									<span class="unit" data-value=""></span>
								</div>
							</li><li data-lab-item="1">
								<div class="ingrediente" data-value="Laptop com capacidade de planilha">Laptop com capacidade de planilha</div>
								<div class="ingrediente-quantidade">
									<span class="amount" data-value="5">5</span>
									<span class="unit" data-value=""></span>
								</div>
							</li><li data-lab-item="1">
								<div class="ingrediente" data-value="Saco de papel">Saco de papel</div>
								<div class="ingrediente-quantidade">
									<span class="amount" data-value="5">5</span>
									<span class="unit" data-value=""></span>
								</div>
							</li><li data-lab-item="1">
								<div class="ingrediente" data-value="Recipientes de plástico extra para miçangas">Recipientes de plástico extra para miçangas</div>
								<div class="ingrediente-quantidade">
									<span class="amount" data-value="5">5</span>
									<span class="unit" data-value=""></span>
								</div>
							</li><li data-lab-item="1">
								<div class="ingrediente" data-value="Prato de papel">Prato de papel</div>
								<div class="ingrediente-quantidade">
									<span class="amount" data-value="5">5</span>
									<span class="unit" data-value=""></span>
								</div>
							</li></ul>

hardy-weinberg e a deriva genética

<ol class="note-items">
	<li data-note-item="1" data-parent-collapse="">Modelagem Matemática<button class="expandir">Expandir</button>
	<ul class="itens-de-laboratório">
		<li data-sub-note-item="1-1">
		<div class="lab-step">Antes de iniciar o exercício de modelagem matemática, certifique-se de que cada computador tenha acesso a um programa de software de planilha on-line ou off-line.</div>
		</li>
	</ul>
	</li>
	<li data-note-item="2" data-parent-collapse="">Simulação para Hardy-Weinberg e Deriva Genética<button class="expandir">Expandir</button>
	<ul class="itens-de-laboratório">
		<li data-sub-note-item="2-1">
		<div class="lab-step">Prepare um conjunto de contas para cada par de alunos contando 50 de uma cor e depois 50 de uma segunda cor, para um total de 100 contas.</div>
		</li>
		<li data-sub-note-item="2-2">
		<div class="lab-step">Em seguida, coloque as contas em um saco de papel.</div>
		</li>
		<li data-sub-note-item="2-3">
		<div class="lab-step">Os alunos também precisarão de contas extras para ajustar a composição da população e estas podem ser fornecidas em um recipiente conjunto para toda a turma ou os instrutores podem fazer conjuntos adicionais para cada par de alunos.</div>
		</li>
		<li data-sub-note-item="2-4">
		<div class="lab-step">Em seguida, crie tiras de papel e escreva nelas os diferentes cenários experimentais que testarão as violações do Equilíbrio de Hardy-Weinberg.</div>
		</li>
		<li data-sub-note-item="2-5">
		<div class="lab-step">Em seguida, crie um segundo conjunto de tiras de papel para determinar qual cenário de deriva genética os alunos testarão.</div>
		</li>
		<li data-sub-note-item="2-6">
		<div class="lab-step">Finalmente, defina quaisquer contas adicionais necessárias para os cenários experimentais listados nas tiras.</div>
		</li>
		<li data-sub-note-item="2-7">
		<div class="lab-step">NOTA: Serão necessários 50 grânulos adicionais em uma terceira cor para a violação da mutação e um conjunto extra de 100 grânulos nas duas primeiras cores para o cenário de fluxo gênico. Para simular o efeito fundador com 10 alelos e desastre natural com 10 cenários de alelos, selecione aleatoriamente 100 contas de 10 cores diferentes.</div>
		</li>
	</ul>
	</li>
</ol>

<div class="section-question"><h4 class="question-sect">O que é o princípio de Hardy-Weinberg e por que ele é útil?</h4><p>O princípio de Hardy-Weinberg afirma que, na ausência de evolução, as frequências alélicas de uma população permanecerão as mesmas ao longo das gerações. Este princípio é usado como um modelo nulo para genética populacional e permite que os cientistas entendam os mecanismos evolutivos.
</p></div><div class="section-question"><h4 class="question-sect">Como é calculado o equilíbrio de Hardy-Weinberg?</h4><p>O equilíbrio de Ha...

Hardy-Weinberg e a deriva genética


Modelagem MatemáticaExpandir
	
Antes de iniciar o exercício de modelagem matemática, certifique-se de que cada computador tenha acesso a um ...

Education

JoVE Lab Manual

Biologia

Evolução

Lab Manual Sub Articles

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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>Os cientistas já se perguntaram por que características dominantes, como manchas de girafa de cor bronzeada, não se tornam mais frequentes a cada geração e substituem características recessivas, como manchas marrom-escuras. Ao pensar sobre esse enigma, em 1908, independentes um do outro, Godfrey H. Hardy e Wilhelm Weinberg derivaram independentemente uma teoria, hoje conhecida como Princípio de Hardy-Weinberg e representada por essa equação. </p>
<p>O princípio afirma que, na ausência de evolução, ou seja, em equilíbrio, as frequências alélicas e genotípicas de uma população permanecerão constantes de uma geração para a seguinte. Para entender essa equação, vamos voltar ao exemplo da girafa. A maiúscula representa o alelo bronzeado, pois é dominante, e a minúscula é para o alelo marrom porque é recessivo. A frequência desses dois alelos na população é designada como p e q, respectivamente. Então, como sabemos a frequência do alelo? Bem, cada indivíduo tem dois alelos. Neste exemplo, 40% dos alelos no pool genético são bronzeados. Assim, a frequência do alelo tan, p, é 0,4, e a frequência do alelo marrom, q, é 0,6. Observe que p mais q é sempre igual a um. </p>
<p>Agora vamos voltar à equação de Hardy-Weinberg. Cada termo na equação representa uma frequência de genótipo. A frequência do genótipo homozigoto dominante é p ao quadrado, e o homozigoto recessivo é representado por q ao quadrado. O genótipo heterozigoto é de dois pq. A razão pela qual multiplicamos por dois aqui é que existem duas maneiras diferentes de gerar um genótipo heterozigoto. Combinados, todos eles representam 100% dos genótipos. Assim, uma frequência total de um. Usando os valores de p e q do nosso exemplo de girafa, podemos determinar a distribuição genotípica dos alelos do gene da cor em nossa população de girafas. Portanto, de acordo com o Princípio de Hardy-Weinberg, em equilíbrio, 16% da população de girafas será homozigótica dominante, 48% será heterozigótica e 36% será homozigótica recessiva. </p>
<p>Para manter esse equilíbrio, o Princípio do Equilíbrio de Hardy-Weinberg afirma que uma população deve atender a cinco suposições principais. Deve haver acasalamento aleatório, grande tamanho da população, nenhuma mutação, nenhuma seleção no gene em questão e nenhum fluxo gênico dentro ou fora da população. A maioria das populações naturais viola pelo menos uma dessas suposições e, portanto, o equilíbrio é raro ... mas, apesar disso, o princípio é usado como um modelo nulo para a genética populacional. Ao comparar esses valores esperados com a frequência real do genótipo em uma população, pode-se determinar se essa população está no equilíbrio de Hardy-Weinberg. Se não, isso significa que alguma forma de evolução ou mudança na frequência do alelo está ocorrendo. </p>
<p>Um equívoco geral sobre a evolução é que ela requer que a seleção natural ocorra. No entanto, nem sempre é esse o caso. A deriva genética é um mecanismo pelo qual a evolução pode ocorrer sem seleção natural. É definido como uma mudança na frequência alélica de uma população devido ao acaso. Para imaginar isso, vamos voltar ao exemplo de uma população de girafas e imaginar seus alelos de castanho e marrom sendo representados por bolinhas de gude de duas cores diferentes. Vamos supor aqui que cada cor começa igualmente abundante. Se fôssemos começar uma nova geração a partir dessa população, precisaríamos criar pares de indivíduos e, assim, selecionar entre quatro alelos por par. Se selecionarmos um casal reprodutor aleatoriamente, podemos acabar com duas bolinhas de gude de cada cor. No entanto, apenas por acaso, alguns pares terão apenas uma cor de mármore, ou três de uma cor e uma da outra. Esses desvios casuais de 50-50 em vários pares para criar uma nova geração podem significar que a próxima geração não tem mais uma mistura igual de cada alelo. </p>
<p>É essa variação das frequências alélicas relativas ao longo do tempo que define a deriva genética. Portanto, ao contrário da evolução adaptativa, onde a frequência do alelo muda para selecionar características adequadas ao ambiente, como joaninhas com uma quantidade maior de melanina sobrevivendo melhor em climas mais frios devido a uma capacidade aprimorada de absorver calor, a deriva genética representa um tipo de evolução que é puramente devido à mudança estocástica. Por exemplo, a remoção aleatória de uma seção de uma população por meio de um evento catastrófico. </p>
<p>Neste laboratório, você realizará simulações de computador e contas coloridas do equilíbrio de Hardy-Weinberg e da deriva genética em uma população e, em seguida, testará o que acontece quando as suposições do equilíbrio são violadas.</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

A mudança evolutiva é interessante e importante de estudar, mas as mudanças nas populações ocorrem por longos períodos de tempo e em enormes espaços físicos e são ...

hardy-weinberg-tests-for-population-change

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Hardy-Weinberg e a deriva genética - Questionário de Avaliação | JoVE Lab Manual

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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

O que é o princípio de Hardy-Weinberg e por que ele é útil?

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