12.3 Random Change. evolution defined in genetic terms as any change in gene (and allele) frequencies within a population or species
|
|
- Jade Rhoda Harmon
- 5 years ago
- Views:
Transcription
1 evolution defined in genetic terms as any change in gene (and allele) frequencies within a population or species 12.3 Random Change The Hardy Weinberg principle demonstrates that, under a set of specific conditions, a given gene pool remains unchanged from generation to generation. The underlying conditions are critically important. By providing the set of conditions under which genetic change would not occur, the Hardy Weinberg principle helps identify key factors that can cause evolution, a change to the gene pool of a population or a species. The following are the key factors: When a population is small, chance fluctuations can cause changes in allele frequencies. When mating opportunities are nonrandom, individuals that are preferred as mates will pass on their alleles in greater numbers than less preferred mates. When genetic mutations occur, new alleles may be created or one allele may be changed into another, thereby changing the frequencies of both new and original alleles. When individuals migrate, they remove alleles from one population and add them to another. When natural selection occurs, individuals with certain alleles have greater reproductive success than others do, thereby increasing the relative frequency of their alleles in the next generation. Real populations can be affected by any of these situations, resulting in changes to allele frequencies. genetic drift changes to allele frequency as a result of chance; such changes are much more pronounced in small populations Genetic Drift When populations are small, chance can play a significant role in altering allele frequencies. For example, assume only 1 in 50 cricket frogs carries a particular allele, C 1 (Figure 1). In a large population of individuals, you would expect 200 to carry the allele. If severe weather conditions led to the random deaths of half the population, you would expect about 100 of the 5000 survivors to be carrying the C 1 allele; therefore, the allele frequency would not be expected to change. However, if the initial frog population were endangered, with only 100 individuals, you would expect only two to possess the C 1 allele. If half the members of this population died, there would be a good chance that either both the C 1 carriers would die thereby eliminating the C 1 allele entirely or both would survive, thereby instantly doubling the allele frequency of C 1. This pattern, while an extreme example, demonstrates genetic drift, a change in the genetic makeup of a population resulting from chance. Figure 1 The remaining populations of the endangered Blanchard s cricket frog, Acris crepitans blanchardi, once found on Pelee Island in Lake Erie, are very vulnerable to the effects of genetic drift. 550 Chapter 12 NEL
2 Section 12.3 (a) 1.0 AA in five populations (b) 1.0 Frequency of Allele A 0.5 allele A lost from four populations Generation (25 stoneflies at the start of each generation) Figure 2 In small populations (a), genetic drift can result in dramatic changes in allele frequencies, while in larger populations (b), genetic drift is not usually significant. Frequency of Allele A 0.5 allele A neither lost nor fixed Generation (500 stoneflies at the start of each generation) Figure 2(a) illustrates genetic drift in a population of 25 stoneflies. The frequency of allele A fluctuates wildly from generation to generation. In five trials, the A allele became fixed at 100% in 22 generations or fewer, while in the other four trials, the A allele was lost entirely, being reduced to 0 in 36 generations or fewer. In a larger population of 500 stoneflies, as shown in Figure 2(b), the allele frequency remained relatively stable even after 50 generations had passed; there was no trend toward fixing of the allele. Significantly, in small populations, genetic drift can lead to fixation of alleles, thereby increasing the incidence of homozygous individuals within a population and reducing its genetic diversity. When a severe event results in a drastic reduction in numbers, a population may experience a bottleneck effect (Figure 3). When this form of genetic drift occurs, a very small sample of alleles survives to establish a new population. Their relative frequencies may differ from those of the original population and additional genetic drift may result in further deviations in the gene pool. This is known to have occurred with the northern elephant seal (Figure 4). bottleneck effect a dramatic, often temporary, reduction in population size usually resulting in significant genetic drift parent population NEL bottleneck (drastic reduction in population) surviving individuals next generation Figure 3 A dramatic, sometimes temporary, reduction in the size of a population can result in a bottleneck effect. Figure 4 The northern elephant seal population was reduced by overhunting to 20 individuals in the 1890s. Although the population had rebounded to over individuals by 1974, genetic testing of 24 loci exhibited total homozygosity. Mechanisms of Evolution 551
3 TRY THIS activity Demonstrating Chance See for yourself how random chance works in small populations. Model the allele frequency in a new population by tossing a six-sided die 30 times. Record your results. Examine the results of your classmates. (a) How often did you roll a three? Did your response differ from the one sixth you would expect by chance? (b) How many times did you roll a three in your first six tosses? What ratio did this produce? (c) Relate the variations in the frequencies of the number three to variations in allele frequencies that occur when small founder populations form. founder effect genetic drift that results when a small number of individuals separate from their original population and find a new population self-pollinating plants plants that habitually fertilize themselves and produce viable offspring When a few individuals from a large population leave to establish a new population, the resulting genetic drift is a founder effect. The allele frequencies of the new population will not be the same as those of the original population and may deviate further as the new population expands. Founder effects seem to be common in nature, such as when a few seeds carried by a bird or by winds to a distant volcanic island may germinate and rapidly establish a large population. With self-pollinating plants, an entire population can be established from a single fertile seed. Founder effects can also be seen in human populations. Members of the Amish community in Pennsylvania are all descendants of about 30 people who emigrated from Switzerland in One of the founders had a rare recessive allele that causes unusually short limbs. The frequency of this allele in the current Amish population is about 7%, compared to a frequency of 0.1% in most populations. Founder effects have been documented in the wild. In 1982, Peter Grant and Rosemary Grant from Queen s University witnessed the establishment of a new population of large ground finches (Geospiza magnirostris) in the Galapagos Islands. The Grants had been studying Darwin s finches on one island, Daphne Major, and had observed juvenile large ground finches visiting the island every year for 10 years. In 1982, however, three males and two females remained on the island to breed. In early 1983, they produced 17 young birds, which became the founders of a new population. The population that they established has remained ever since. Careful measurements of inheritable traits by the Grants indicated that the founding population has a different genetic composition from that of the original large population of Geospiza magnirostris from which the founders came. gene flow the movement of alleles from one population to another through the movement of individuals or gametes neutral mutation has no immediate effect on an individual s fitness; most neutral mutations are silent or occur in noncoding DNA Gene Flow When organisms migrate, leaving one population and joining another, they alter the allele frequencies of both. Such gene flow occurs frequently in most wild populations. For example, prairie dogs live in dense colonies consisting of a few dozen members. For much of the year they prevent other prairie dogs from joining their colony. In late summer, however, mature male pups are permitted to enter new colonies, thereby affecting both gene pools. Gene flow can also occur when individuals of adjacent populations mate without moving permanently. In these ways, genetic information is shared between populations. Unlike genetic drift, gene flow tends to reduce differences between populations. Mutation Mutations are the only source of additional genetic material and new alleles. Mutations may arise as a result of unrepaired changes in DNA sequences or chromosome breakage and rejoining. Although most mutations occur in somatic (body) cells, these mutations cannot be inherited and, therefore, do not play a role in evolution. However, any mutation that occurs in a gamete has the potential to be passed on to later generations, thereby entering the gene pool. These mutant alleles and any new phenotypes they produce become the source of new raw material for natural selection. What effects can mutations have and how frequently do they occur? Inheritable mutations can be neutral, harmful, or beneficial. Because mutations are random changes to the genetic code, they are much more likely to be neutral or harmful than they are to be beneficial. A neutral mutation is one that has no immediate effect on 552 Chapter 12 NEL
4 Section 12.3 an individual s fitness, or reproductive success. A harmful mutation reduces an individual s fitness and usually occurs when a cell loses the ability to produce a properly functioning protein or when major chromosomal changes adversely affect meiosis and mitosis. A beneficial mutation, which occurs when a cell gains the ability to produce a new or improved protein, gives an individual a selective advantage: increased reproductive success. Types of Mutations Different types of mutations vary in their ability to affect the phenotypes of individuals and their impact on the evolution of populations. Point mutations are changes in single base-pairs along the DNA molecule. When a point mutation occurs in a eukaryotic organism s genome where DNA is noncoding, it will be neutral. When a point mutation causes an amino acid substitution in a coding region of the DNA, a new gene product and, therefore, a new phenotype is produced. The change might be deleterious (or lethal), hindering the proper functioning of the final protein product. In other cases, the change may have no significant effect on the protein s function. Rarely, a point mutation could result in a protein with an improved or new function that benefits the individual. Small insertions and deletions that occur within functioning genes almost always produce a nonfunctioning gene; such mutations are usually harmful. Because they are rarely beneficial, these mutations do not play a major role in evolution. While large-scale inversions are often neutral mutations, they are a useful tool for evolutionary biologists as their presence can be inferred by examining chromosome banding patterns (Figure 5). Gene duplication occurs when unequal crossing over during meiosis results in an additional copy of one or more genes being inserted into a chromosome. This kind of mutation is important because it is a source of new genes. At first, these duplicated genes are just extra copies and add redundancy to the genome, providing no advantage to the individual. However, the new DNA is then free to mutate and, potentially, gain a new function. Such duplication events can ultimately produce entire gene families with very similar structures but altered functions. For example, many species have a family of genes called histones. These gene copies, numbering in the hundreds, are all very similar in structure and located very close together on the same chromosome. The small differences in their DNA sequences are thought to result from point mutations that take place after duplication events. In addition, nonfunctioning pseudogenes genes that are duplicated and later lose their ability to be transcribed provide very strong evidence for evolution. How common are mutations? The best experimental evidence suggests that point mutation rates range from about 1 in cell divisions in species with a very small genome (e.g., bacteria) to one or more in each gamete in species with a large genome. Because they rarely result in obvious changes to an individual organism s phenotype, they are not readily observable. Many harmful mutations result in the death of the gamete or individual before birth. Despite these difficulties, researchers sequencing an entire genome are finding evidence of frequent gene duplication. In humans, a gene coding for one enzyme glyceraldehyde-3-phosphate dehydrogenase used in glycolysis occurs in a single functioning copy and 20 nonfunctioning pseudocopies. The 300-base-pair sequence called Alu, which appears to have originated as a copy of a gene coding for ribosomal RNA, serves no function but is present in copies and constitutes about 5% of the entire genome. (a) fitness general term referring to lifetime reproductive success of an individual harmful mutation an inheritable change in a cell s DNA that impairs the proper operation of a gene product or regulatory function or adversely affects mitosis or meiosis beneficial mutation an inheritable change in a cell s DNA that results in an additional or enhanced gene product or regulatory function gene duplication a mutation leading to the production of an extra copy of a gene locus, usually resulting from unequal crossing over pseudogenes DNA sequences that are homologous to functioning genes but are not transcribed (b) Figure 5 A chromosome before (a) and after (b) a mutation. Large inversions can result in the reversal of banding patterns along chromosomes. NEL Mechanisms of Evolution 553
5 INVESTIGATION Agents of Change (p. 577) Population size, genetic drift, and natural selection all affect allele frequencies. How can their influence be predicted? SAMPLE problem Polyploidy, a mutation that results in three or more sets of chromosomes, occurs when unreduced (diploid) gametes join to form a cell containing one or more entire extra sets of chromosomes. Instead of being diploid (2n), some organisms are tetraploid (4n) or even octoploid (8n) or more. The fern, Ophioglossum reticulatum, contains an astonishing 1260 chromosome pairs (630n). Polyploidy, the most dramatic form of mutation, provides an organism with an immediate doubling of genetic material. This type of mutation has played a major role in the evolution of plants; the majority of ferns and almost half of all flowering plants are polyploids. Animals are rarely polyploids. E. coli Mutation Rate The population of the microorganism E. coli living in your large intestine could be conservatively estimated at 10 billion bacteria. Experimental evidence suggests that these bacteria undergo cell division at a rate of once every hour and experience a mutation rate of 1 per 5000 divisions. How many mutations can this population of bacteria expect to experience in one year? Solution divisions d 36 5d y 1 mutation (17 billion) mutations divisions Note: It is assumed that the population does not increase in size and that the number of surviving bacteria remains constant. Therefore, the number of cell divisions in each generation remains the same. Answer million Practice 1. A population of 10 million free-tailed bats lives in a large cave. Assume that each year 5 million baby bats are born but the population remains the same. If the mutation rate averages 0.4 mutations per gamete, how many mutations would likely occur in 200 years? DID YOU KNOW? Miracle Grain Triticale is a grain of hybrid origin produced by crossing rye and wheat. The hybrid lacked homologous pairs of chromosomes and was infertile. Researchers treated the hybrid with the drug colchicine, which prevented the first meiotic cell division and resulted in the production of diploid (2n) gametes. When these gametes fertilized each other, they produced synthetic tetraploids (4n). These tetraploids contain a diploid set of homologous chromosomes for both rye and wheat within the same individuals. The hybrids are fertile and yield a high-quality grain. SUMMARY Random Change Evolution occurs when the allele frequencies of a population change over time. Genetic drift and gene flow produce changes in allele frequencies and affect genetic diversity. The source of all new genetic information is mutation. Gene duplications are the main source of new genetic material. As extra copies, they are free to mutate without the likelihood of causing harm. Although rare in individual cells, mutations are numerous in large populations over many generations. 554 Chapter 12 NEL
6 Section 12.3 Section Questions Understanding Concepts 1. Use the term allele frequency to explain how biologists define and quantify evolution within a population. 2. Relate two ways in which alleles can become fixed in a population. 3. Define genetic drift and genetic flow, offering two examples to illustrate each definition. 4. Suggest three types of organisms that might produce founder populations. Explain the process that results in this effect. 5. Explain why harmful mutations play virtually no role in the evolution of populations. 6. When a mutation causes gene duplication, it often has little or no immediate effect. How do such mutations play a role in evolution over longer periods of time? 7. For each of the following situations, explain whether the Hardy Weinberg equilibrium would be maintained generation after generation: (a) a population of African violets maintained by a plant breeder (b) the population of the black fly, Simulium venustum, in northern Ontario (c) a racoon population living in the Humber Valley in west Toronto (d) a newly discovered bird population on a remote island off the coast of British Columbia 8. How do pseudogenes offer compelling evidence in support of evolution? 9. Consider the Practice Question about mutation in bats on the previous page. If beneficial mutations are very rare, accounting for only one in every 3 million, how many beneficial mutations are likely to occur in the bat population for the same 200-year period? 10. The world s population of cheetahs is almost identical genetically (Figure 6). Male cheetahs are known to have low sperm counts and the species in general has a low resistance to many infectious diseases. All cheetahs are thought to be homozygous at over 99.9% of their gene loci. Explain how a severe genetic bottleneck effect in the past could account for these observations. Applying Inquiry Skills 11. During the fall migration, several Canada geese stop at a river near a good food source and then nest there the following spring. Because of the abundance of food, this population of geese stops migrating. What effects, both immediate and long-term, might this situation have on the gene pools of the original and founder populations? 12. If variation in species were solely a result of genetic recombination during sexual reproduction, how would that limit the evolution of species? 13. It is thought that a billion prairie dogs once populated an area of more than 100 million ha. Their current territory has been reduced and fragmented to less than 1% of this original space. Predict the impact of these changes in habitat on the prairie dog gene pool, as well as on the evolution and survival of the species. Making Connections 14. Find and describe an example that does not appear in this text in which the founder effect has altered the allele frequency of a human population. 15. Why might evolutionary biologists be more concerned with the study of population genetics than the study of the simple inheritance of alleles by offspring from their parents? 16. Wildlife biologists in British Columbia estimate that fewer than 100 Vancouver Island marmots, Marmota vancouverensis, were alive in (a) Research this endangered species using print and electronic sources to determine the cause(s) of the severe bottleneck effect in their population. (b) What efforts, if any, are being made to maintain the genetic diversity of this species? GO Figure 6 All cheetahs today are virtually identical genetically. NEL Mechanisms of Evolution 555
CHAPTER 12 MECHANISMS OF EVOLUTION
CHAPTER 12 MECHANISMS OF EVOLUTION 12.1 Genetic Variation DNA biological code for inheritable traits GENES units of DNA molecule in a chromosome LOCI location of specific gene on DNA molecules DIPLOID
More informationZoology Evolution and Gene Frequencies
Zoology Evolution and Gene Frequencies I. any change in the frequency of alleles (and resulting phenotypes) in a population. A. Individuals show genetic variation, but express the genes they have inherited.
More informationEvolution of Populations (Ch. 17)
Evolution of Populations (Ch. 17) Doonesbury - Sunday February 8, 2004 Beak depth of Beak depth Where does Variation come from? Mutation Wet year random changes to DNA errors in gamete production Dry year
More informationChapter 14: Genes in Action
Chapter 14: Genes in Action Section 1: Mutation and Genetic Change Mutation: Nondisjuction: a failure of homologous chromosomes to separate during meiosis I or the failure of sister chromatids to separate
More informationBIOLOGY 3201 UNIT 4 EVOLUTION CH MECHANISMS OF EVOLUTION
BIOLOGY 3201 UNIT 4 EVOLUTION CH. 20 - MECHANISMS OF EVOLUTION POPULATION GENETICS AND HARDY WEINBERG PRINCIPLE Population genetics: this is a study of the genes in a population and how they may or may
More information-Is change in the allele frequencies of a population over generations -This is evolution on its smallest scale
Remember: -Evolution is a change in species over time -Heritable variations exist within a population -These variations can result in differential reproductive success -Over generations this can result
More information11.1 Genetic Variation Within Population. KEY CONCEPT A population shares a common gene pool.
11.1 Genetic Variation Within Population KEY CONCEPT A population shares a common gene pool. 11.1 Genetic Variation Within Population Genetic variation in a population increases the chance that some individuals
More informationSection KEY CONCEPT A population shares a common gene pool.
Section 11.1 KEY CONCEPT A population shares a common gene pool. Genetic variation in a population increases the chance that some individuals will survive. Why it s beneficial: Genetic variation leads
More informationHow Populations Evolve. Chapter 15
How Populations Evolve Chapter 15 Populations Evolve Biological evolution does not change individuals It changes a population Traits in a population vary among individuals Evolution is change in frequency
More informationDistinguishing Among Sources of Phenotypic Variation in Populations
Population Genetics Distinguishing Among Sources of Phenotypic Variation in Populations Discrete vs. continuous Genotype or environment (nature vs. nurture) Phenotypic variation - Discrete vs. Continuous
More information11.1 Genetic Variation Within Population. KEY CONCEPT A population shares a common gene pool.
11.1 Genetic Variation Within Population KEY CONCEPT A population shares a common gene pool. 11.1 Genetic Variation Within Population! Genetic variation in a population increases the chance that some individuals
More informationAll the, including all the different alleles, that are present in a
Evolution as Genetic Change: chapter 16 Date name A group of individuals of the same species that interbreed. All the, including all the different alleles, that are present in a Relative Allele frequency
More informationREVIEW 5: EVOLUTION UNIT. A. Top 10 If you learned anything from this unit, you should have learned:
Period Date REVIEW 5: EVOLUTION UNIT A. Top 10 If you learned anything from this unit, you should have learned: 1. Darwin s Principle of Natural Selection a. Variation individuals within a population possess
More informationPopulation- group of individuals of the SAME species that live in the same area Species- a group of similar organisms that can breed and produce
Dr. Bertolotti Essential Question: Population- group of individuals of the SAME species that live in the same area Species- a group of similar organisms that can breed and produce FERTILE offspring Allele-
More informationPopulation Genetics (Learning Objectives)
Population Genetics (Learning Objectives) Recognize the quantitative nature of the study of population genetics and its connection to the study of genetics and its applications. Define the terms population,
More informationPopulation Genetics (Learning Objectives)
Population Genetics (Learning Objectives) Recognize the quantitative nature of the study of population genetics and its connection to the study of genetics and its applications. Define the terms population,
More informationThe Modern Synthesis. Terms and Concepts. Evolutionary Processes. I. Introduction: Where do we go from here? What do these things have in common?
Evolutionary Processes I. Introduction - The modern synthesis Reading: Chap. 25 II. No evolution: Hardy-Weinberg equilibrium A. Population genetics B. Assumptions of H-W III. Causes of microevolution (forces
More informationChapter 23: The Evolution of Populations. 1. Populations & Gene Pools. Populations & Gene Pools 12/2/ Populations and Gene Pools
Chapter 23: The Evolution of Populations 1. Populations and Gene Pools 2. Hardy-Weinberg Equilibrium 3. A Closer Look at Natural Selection 1. Populations & Gene Pools Chapter Reading pp. 481-484, 488-491
More informationChapter 25 Population Genetics
Chapter 25 Population Genetics Population Genetics -- the discipline within evolutionary biology that studies changes in allele frequencies. Population -- a group of individuals from the same species that
More informationLAB. POPULATION GENETICS. 1. Explain what is meant by a population being in Hardy-Weinberg equilibrium.
Period Date LAB. POPULATION GENETICS PRE-LAB 1. Explain what is meant by a population being in Hardy-Weinberg equilibrium. 2. List and briefly explain the 5 conditions that need to be met to maintain a
More information5/2/ Genes and Variation. How Common Is Genetic Variation? Variation and Gene Pools
16-1 Genes 16-1 and Variation Genes and Variation 1 of 24 How Common Is Genetic Variation? How Common Is Genetic Variation? Many genes have at least two forms, or alleles. All organisms have genetic variation
More informationThe Evolution of Populations
LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 23 The Evolution of Populations
More informationThe Evolution of Populations
Chapter 23 The Evolution of Populations PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from
More informationThe Evolution of Populations
The Evolution of Populations What you need to know How and reproduction each produce genetic. The conditions for equilibrium. How to use the Hardy-Weinberg equation to calculate allelic and to test whether
More informationPopulation Genetics. Chapter 16
Population Genetics Chapter 16 Populations and Gene Pools Evolution is the change of genetic composition of populations over time. Microevolution is change within species which can occur over dozens of
More information5/18/2017. Genotypic, phenotypic or allelic frequencies each sum to 1. Changes in allele frequencies determine gene pool composition over generations
Topics How to track evolution allele frequencies Hardy Weinberg principle applications Requirements for genetic equilibrium Types of natural selection Population genetic polymorphism in populations, pp.
More informationTHE EVOLUTION OF DARWIN S THEORY PT 1. Chapter 16-17
THE EVOLUTION OF DARWIN S THEORY PT 1 Chapter 16-17 From Darwin to Today Darwin provided compelling evidence that species and populations change. What he didn t know (and neither did anyone else at the
More information5 FINGERS OF EVOLUTION
MICROEVOLUTION Student Packet SUMMARY EVOLUTION IS A CHANGE IN THE GENETIC MAKEUP OF A POPULATION OVER TIME Microevolution refers to changes in allele frequencies in a population over time. NATURAL SELECTION
More informationHardy Weinberg Equilibrium
Gregor Mendel Hardy Weinberg Equilibrium Lectures 4-11: Mechanisms of Evolution (Microevolution) Hardy Weinberg Principle (Mendelian Inheritance) Genetic Drift Mutation Sex: Recombination and Random Mating
More informationEvolutionary Mechanisms
Evolutionary Mechanisms Tidbits One misconception is that organisms evolve, in the Darwinian sense, during their lifetimes Natural selection acts on individuals, but only populations evolve Genetic variations
More informationGenetic variation and change the short version
Part 1: Biodiversity and variation Genetic variation and change the short version Define biodiversity and describe its advantages. Why is variation important to a species? What is DNA? A chromosome? A
More informationEVOLUTION OF POPULATIONS Genes and Variation
Section Outline Section 16-1 EVOLUTION OF POPULATIONS Genes and Variation When Darwin developed his theory of evolution, he didn t know how HEREDITY worked. http://www.answers.com/topic/gregor-mendel Mendel
More informationEvolution. Population Genetics. Targets: Alleles and Genes 3/30/2014
Targets: Alleles and Genes Evolution Population Genetics 1. I can explain how genetic variation in a species increases chances for survival 2. I can write an example of how lethal alleles are stored in
More informationQuiz will begin at 10:00 am. Please Sign In
Quiz will begin at 10:00 am Please Sign In You have 15 minutes to complete the quiz Put all your belongings away, including phones Put your name and date on the top of the page Circle your answer clearly
More informationSummary Genes and Variation Evolution as Genetic Change. Name Class Date
Chapter 16 Summary Evolution of Populations 16 1 Genes and Variation Darwin s original ideas can now be understood in genetic terms. Beginning with variation, we now know that traits are controlled by
More informationCH. 22/23 WARM-UP. 1. List 5 different pieces of evidence for evolution.
CH. 22/23 WARM-UP 1. List 5 different pieces of evidence for evolution. 2. (Review) What are the 3 ways that sexual reproduction produces genetic diversity? 3. What is 1 thing you are grateful for today?
More informationThe Evolution of Populations
Chapter 23 The Evolution of Populations PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from
More informationHardy-Weinberg Principle 4/5/09. Chapter 20. Godfrey H. Hardy: English mathematician Wilhelm Weinberg: German physician
Chapter 20 1 Godfrey H. Hardy: English mathematician Wilhelm Weinberg: German physician Concluded that: The original proportions of the genotypes in a population will remain constant from generation to
More informationThe Evolution of Populations
The Evolution of Populations Population genetics Population: a localized group of individuals belonging to the same species Species: a group of populations whose individuals have the potential to interbreed
More informationCHAPTER 23 THE EVOLUTIONS OF POPULATIONS. Section A: Population Genetics
CHAPTER 23 THE EVOLUTIONS OF POPULATIONS Section A: Population Genetics 1. The modern evolutionary synthesis integrated Darwinian selection and Mendelian inheritance 2. A population s gene pool is defined
More informationEvolution of Populations
Chapter 23. Evolution of Populations 1 Populations evolve Natural selection acts on individuals differential survival survival of the fittest differential reproductive success bear more offspring Populations
More informationLAB ACTIVITY ONE POPULATION GENETICS AND EVOLUTION 2017
OVERVIEW In this lab you will: 1. learn about the Hardy-Weinberg law of genetic equilibrium, and 2. study the relationship between evolution and changes in allele frequency by using your class to represent
More information16.2 Evolution as Genetic Change
16.2 Evolution as Genetic Change 1 of 40 16-2 Evolution as Genetic Change 16-2 Evolution as Genetic Change If an individual dies without reproducing, it does not contribute to the gene pool. If an individual
More informationIntroduction Chapter 23 - EVOLUTION of
Introduction Chapter 23 - EVOLUTION of POPULATIONS The blue-footed booby has adaptations that make it suited to its environment. These include webbed feet, streamlined shape that minimizes friction when
More informationThis is DUE: Tuesday, March 1, 2011 Come prepared to share your findings with your group.
Biology 160 NAME: Reading Guide 12: Population Dynamics, Humans, Part II This is DUE: Tuesday, March 1, 2011 Come prepared to share your findings with your group. *As before, please turn in only the Critical
More informationLecture #3 1/23/02 Dr. Kopeny Model of polygenic inheritance based on three genes
Lecture #3 1/23/02 Dr. Kopeny Model of polygenic inheritance based on three genes Reference; page 230 in textbook 13 Genotype; The genetic constitution governing a heritable trait of an organism Phenotype:
More informationThe Evolution of Populations
Microevolution The Evolution of Populations C H A P T E R 2 3 Change in allele frequencies over generations Three mechanisms cause allele frequency change: Natural selection (leads to adaptation) Genetic
More informationLesson: Measuring Microevolution
Lesson: Measuring Microevolution Recall that a GENE is a unit of inheritance. Different forms of the same gene are called LLELES (uh-leelz ) lleles arise from an original gene via the process of MUTTION.
More informationAP BIOLOGY Population Genetics and Evolution Lab
AP BIOLOGY Population Genetics and Evolution Lab In 1908 G.H. Hardy and W. Weinberg independently suggested a scheme whereby evolution could be viewed as changes in the frequency of alleles in a population
More informationLAB 12 Natural Selection INTRODUCTION
LAB 12 Natural Selection Objectives 1. Model evolution by natural selection. 2. Determine allele frequencies within a population. 3. Use the Hardy-Weinberg equation to calculate probability of each genotype
More informationThe Modern Synthesis. Causes of microevolution. The Modern Synthesis. Microevolution. Genetic Drift. Genetic drift example
The Modern Synthesis Populations are the units of evolution Natural selection plays an important role in evolution, but is not the only factor Speciation is at the boundary between microevolution and macroevolution
More informationModule 20: Population Genetics, Student Learning Guide
Name: Period: Date: Module 20: Population Genetics, Student Learning Guide Instructions: 1. Work in pairs (share a computer). 2. Make sure that you log in for the first quiz so that you get credit. 3.
More informationModule 20: Population Genetics, Student Learning Guide
Name: Period: Date: Module 20: Population Genetics, Student Learning Guide Instructions: 1. Work in pairs (share a computer). 2. Make sure that you log in for the first quiz so that you get credit. 3.
More informationLABORATORY 8. POPULATION GENETICS AND EVOLUTION
STUDENT GUIDE LABORATORY 8. POPULATION GENETICS AND EVOLUTION Objectives In this activity, you will learn about the Hardy-Weinberg law of genetic equilibrium study the relationship between evolution and
More informationAlgorithms for Genetics: Introduction, and sources of variation
Algorithms for Genetics: Introduction, and sources of variation Scribe: David Dean Instructor: Vineet Bafna 1 Terms Genotype: the genetic makeup of an individual. For example, we may refer to an individual
More informationSection A: Population Genetics
CHAPTER 23 THE EVOLUTIONS OF POPULATIONS Section A: Population Genetics 1. The modern evolutionary synthesis integrated Darwinian selection and Mendelian inheritance 2. A population s gene pool is defined
More informationEvolution in a Genetic Context
Evolution in a Genetic Context What is evolution? Evolution is the process of change over time. In terms of genetics and evolution, our knowledge of DNA and phenotypic expression allow us to understand
More informationIntroduction. Let s try this again. Do you change during your lifetime? Do you evolve??
Introduction Let s try this again Do you change during your lifetime? Do you evolve?? What questions couldn t Darwin answer? What if he could have called Mendel as a lifeline? Population genetics was born
More information7-1. Read this exercise before you come to the laboratory. Review the lecture notes from October 15 (Hardy-Weinberg Equilibrium)
7-1 Biology 1001 Lab 7: POPULATION GENETICS PREPARTION Read this exercise before you come to the laboratory. Review the lecture notes from October 15 (Hardy-Weinberg Equilibrium) OBECTIVES At the end of
More informationGENETICS - CLUTCH CH.21 POPULATION GENETICS.
!! www.clutchprep.com CONCEPT: HARDY-WEINBERG Hardy-Weinberg is a formula used to measure the frequencies of and genotypes in a population Allelic frequencies are the frequency of alleles in a population
More informationV SEMESTER ZOOLOGY HARDY-WEINBERG S LAW
V SEMESTER ZOOLOGY HARDY-WEINBERG S LAW The most fundamental idea in a population genetics was proposed by English-man G.H. Hardy and German W. Weinberg simultaneously in the year 1908. At that time it
More informationThe Evolution of Populations
Chapter 23 The Evolution of Populations PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from
More informationPopulation genetics. Population genetics provides a foundation for studying evolution How/Why?
Population genetics 1.Definition of microevolution 2.Conditions for Hardy-Weinberg equilibrium 3.Hardy-Weinberg equation where it comes from and what it means 4.The five conditions for equilibrium in more
More informationChapter 23: The Evolution of Populations
AP Biology Reading Guide Name Chapter 23: The Evolution of Populations This chapter begins with the idea that we focused on as we closed the last chapter: Individuals do not evolve! Populations evolve.
More informationThe Theory of Evolution
The Theory of Evolution Mechanisms of Evolution Notes Pt. 4 Population Genetics & Evolution IMPORTANT TO REMEMBER: Populations, not individuals, evolve. Population = a group of individuals of the same
More informationChapter 8: Evolution Lesson 8.3: Microevolution and the Genetics of Populations
Chapter 8: Evolution Lesson 8.3: Microevolution and the Genetics of Populations Microevolution refers to varieties within a given type. Change happens within a group, but the descendant is clearly of the
More informationGenes and Variation. Section 16-1 pgs
Genes and Variation Section 16-1 pgs 393-396 Genes and Variation As Darwin developed his theory of evolution, he worked under a serious handicap. He didn t know how heredity worked! Although Mendel s work
More information3. A form of a gene that is only expressed in the absence of a dominant alternative is:
Student Name: Teacher: Date: District: Robeson Assessment: 9_12 Agriculture AU71 - Biotech and Agrisci Rsch I Test 3 Description: Obj 12 - Simple Mendelian Genetics Form: 501 1. The genotype of an organism
More informationCHAPTER 14 Genetics and Propagation
CHAPTER 14 Genetics and Propagation BASIC GENETIC CONCEPTS IN PLANT SCIENCE The plants we cultivate for our survival and pleasure all originated from wild plants. However, most of our domesticated plants
More informationPopulation and Community Dynamics. The Hardy-Weinberg Principle
Population and Community Dynamics The Hardy-Weinberg Principle Key Terms Population: same species, same place, same time Gene: unit of heredity. Controls the expression of a trait. Can be passed to offspring.
More informationThe Evolution of Populations
Chapter 23 The Evolution of Populations PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from
More informationMICROEVOLUTION. On the Origin of Species WHAT IS A SPECIES? WHAT IS A POPULATION? Genetic variation: how do new forms arise?
MICROEVOLUTION On the Origin of Species WHAT IS A SPECIES? Individuals in one or more populations Potential to interbreed Produce fertile offspring WHAT IS A POPULATION? Group of interacting individuals
More informationUnderstanding Sources of Variation. Part 1: Variation Overview (
Name: Per. Date: Understanding Sources of Variation Part 1: Variation Overview (http://learn.genetics.utah.edu/content/variation/sources/) After watching the variation presentation, answer the following
More informationGenetic variation, genetic drift (summary of topics)
Bio 1B Lecture Outline (please print and bring along) Fall, 2007 B.D. Mishler, Dept. of Integrative Biology 2-6810, bmishler@berkeley.edu Evolution lecture #11 -- Hardy Weinberg departures: genetic variation
More informationPopulation Genetics Modern Synthesis Theory The Hardy-Weinberg Theorem Assumptions of the H-W Theorem
Population Genetics A Population is: a group of same species organisms living in an area An allele is: one of a number of alternative forms of the same gene that may occur at a given site on a chromosome.
More informationThis is a classic data set on wing coloration in the scarlet tiger moth (Panaxia dominula). Data for 1612 individuals are given below:
Bellringer This is a classic data set on wing coloration in the scarlet tiger moth (Panaxia dominula). Data for 1612 individuals are given below: White-spotted (AA) =1469 Intermediate (Aa) = 138 Little
More informationGenetic Variation. Genetic Variation within Populations. Population Genetics. Darwin s Observations
Genetic Variation within Populations Population Genetics Darwin s Observations Genetic Variation Underlying phenotypic variation is genetic variation. The potential for genetic variation in individuals
More information12 The Chromosomal Basis of Inheritance
CAMPBELL BIOLOGY IN FOCUS Urry Cain Wasserman Minorsky Jackson Reece 12 The Chromosomal Basis of Inheritance Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge Overview: Locating Genes
More informationBiology Handout "Modern Genetics"
Biology Handout 13-14 "Modern Genetics" Name: 2950-1 - Page 1 1) Which statement best describes human insulin that is produced by genetically engineered bacteria? A) This insulin is produced as a result
More informationBiology Evolution Dr. Kilburn, page 1 Mutation and genetic variation
Biology 203 - Evolution Dr. Kilburn, page 1 In this unit, we will look at the mechanisms of evolution, largely at the population scale. Our primary focus will be on natural selection, but we will also
More informationEXERCISE 1. Testing Hardy-Weinberg Equilibrium. 1a. Fill in Table 1. Calculate the initial genotype and allele frequencies.
Biology 152/153 Hardy-Weinberg Mating Game EXERCISE 1 Testing Hardy-Weinberg Equilibrium Hypothesis: The Hardy-Weinberg Theorem says that allele frequencies will not change over generations under the following
More informationUNIT 4: EVOLUTION Chapter 11: The Evolution of Populations
CORNELL NOTES Directions: You must create a minimum of 5 questions in this column per page (average). Use these to study your notes and prepare for tests and quizzes. Notes will be stamped after each assigned
More informationCHAPTER 5 Principle of Genetics Review
CHAPTER 5 Principle of Genetics Review I. Mendel s Investigations Gregor Johann Mendel Hybridized peas 1856-1864 Formulated Principles of Heredity published in 1866 II. Chromosomal Basis of Inheritance
More information6E identify and illustrate changes in DNA and evaluate the significance of these changes
6E identify and illustrate changes in DNA and evaluate the significance of these changes 1. This illustration is an example of a normal DNA sequence. Which of the following represents a point mutation
More informationPopulation Genetics (Learning Objectives)
Population Genetics (Learning Objectives) Define the terms population, species, allelic and genotypic frequencies, gene pool, and fixed allele, genetic drift, bottle-neck effect, founder effect. Explain
More informationThe Evolution of Populations
LECTURE PRESENTATIONS For CAMPBELL BIOLOGY, NINTH EDITION Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson Chapter 23 The Evolution of Populations
More informationLABORATORY 8: POPULATION GENETICS AND EVOLUTION
LABORATORY 8: POPULATION GENETICS AND EVOLUTION OVERVIEW In this activity you will learn about the Hardy-Weinberg law of genetic equilibrium and study the relationship between evolution and changes in
More informationThere are a number of evolutionary forces that produce changes in gene frequencies at the population level (microevolution).
1 Quiz I Results 2 3 Mechanisms of Evolution Their Microevolutionary Effect 4 Hardy-Weinberg Equilibrium The Hardy-Weinberg Equilibrium Model maintains that certain conditions exist that contribute to
More informationLab 2: Mathematical Modeling: Hardy-Weinberg 1. Overview. In this lab you will:
AP Biology Name Lab 2: Mathematical Modeling: Hardy-Weinberg 1 Overview In this lab you will: 1. learn about the Hardy-Weinberg law of genetic equilibrium, and 2. study the relationship between evolution
More informationIntroduction to Biological Anthropology: Notes 9 Population genetics and the modern synthesis of evolutionary theory Copyright Bruce Owen 2010 We
Introduction to Biological Anthropology: Notes 9 Population genetics and the modern synthesis of evolutionary theory Copyright Bruce Owen 2010 We have seen that: Mendel s model explains some variations
More informationHow does the human genome stack up? Genomic Size. Genome Size. Number of Genes. Eukaryotic genomes are generally larger.
How does the human genome stack up? Organism Human (Homo sapiens) Laboratory mouse (M. musculus) Mustard weed (A. thaliana) Roundworm (C. elegans) Fruit fly (D. melanogaster) Yeast (S. cerevisiae) Bacterium
More informationMultiple Choice (3.35 each) Total = 100pts. Choice the choice that best answers the question! Good luck!
NAME DATE Multiple Choice (3.35 each) Total = 100pts. Choice the choice that best answers the question! Good luck! 1. Could the characteristic followed in the pedigree be caused by an autosomal dominant
More informationAssumptions of Hardy-Weinberg equilibrium
Migration and Drift Assumptions of Hardy-Weinberg equilibrium 1. Mating is random 2. Population size is infinite (i.e., no genetic drift) 3. No migration 4. No mutation 5. No selection An example of directional
More informationGenetic drift is change in allele frequencies due to chance fluctuations; its strength depends on population size.
Roadmap Genetic drift is change in allele frequencies due to chance fluctuations; its strength depends on population size. Rate of fixation (recap) Proportion of homozygotes in population (genetic diversity)
More informationAnthro 101: Human Biological Evolution. Lecture 3: Genetics & Inheritance. Prof. Kenneth Feldmeier feldmekj.weebly.
Anthro 101: Human Biological Evolution Lecture 3: Genetics & Inheritance Prof. Kenneth Feldmeier feldmekj@lavc.edu feldmekj.weebly.com What is Genetics??? Spend a few minutes discussing Genetics.. Genetics
More informationAverage % If you want to complete quiz corrections for extra credit you must come after school Starting new topic today. Grab your clickers.
Average 50.83% If you want to complete quiz corrections for extra credit you must come after school Starting new topic today. Grab your clickers. Evolution AP BIO Pacing Evolution Today Mutations Gene
More informationMutation and sexual reproduction produce the genetic variation that makes evolution possible. [2]
GUIDED READING - Ch. 23 POPULATION EVOLUTION NAME: Please print out these pages and HANDWRITE the answers directly on the printouts. Typed work or answers on separate sheets of paper will not be accepted.
More informationBio 6 Natural Selection Lab
Bio 6 Natural Selection Lab Overview In this laboratory you will demonstrate the process of evolution by natural selection by carrying out a predator/prey simulation. Through this exercise you will observe
More information1) Genetic Drift. Genetic Drift - population with stable size ~ 10
1) Genetic Drift Flip a coin 1000 times 700 heads and 300 tails very suspicious. Flip a coin 10 times 7 heads and 3 tails well within the bounds of possibility. 700 7 300 3 The smaller the sample, the
More informationPopGen1: Introduction to population genetics
PopGen1: Introduction to population genetics Introduction MICROEVOLUTION is the term used to describe the dynamics of evolutionary change in populations and species over time. The discipline devoted to
More information