Midterm 2 Study Guide Biology 1101
Midterm 2 Study Guide Biology 1101 BIOLOGY 1101 (Evan Waletzko)
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Biology 1101 (15989) Introduction to Biology Dr. Evan J. Waletzko The Ohio State University Notes by Sophie Chang Midterm 2 Study Guide for Biology 1101 (20 pages) What’s included in this document: • Carmen quizzes pre-2/16, 2/23, and 3/1 –pages 2-9 • In-class activities and answers—pages 10-11 • TopHat questions –answered during class—pages 12-15 • Take-Home Messages for required readings derived from required textbook (What Is Life?)—pages 16-20 1 Carmen Quizzes Carmen Quiz 4 (Pre-2/16) Earned 5/5 points. 1. Peas were well-suited for Mendel's breeding experiments for all of the following reasons except: a. Peas have a particularly long time between generations. b. Many of the characteristics that vary in pea plants are controlled by single genes. c. It is easy to obtain large numbers of offspring from any given cross. d. Peas exhibit variations in a number of observable characteristics, such as flower color and seed shape. e. Mendel and his staff could control the pollination between different pea plants. 2. In pea plants, purple flower color is dominant to white flower color. If two pea plants that are true-breeding for white flowers are crossed, then the offspring will be the following: a. Half of the flowers will be purple and half will be white. b. One-quarter of the flowers will be purple and three-quarters will be white. c. All of the flowers will be purple. d. Three-quarters of the flowers will be purple and one-quarter will be white. e. All of the flowers will be white. 3. In snapdragons, flower color is inherited as a trait with incomplete dominance. There is an allele, Cw, that produces no pigment (white), and an allele, CR, that produces red pigment. A plant with the CWCR genotype will produce ____ flowers. a. Red b. White c. No d. Pink e. Two kinds of 4. In the case of Mendel's peas, a single gene determined the height of the plant; however, in humans, adult height is influenced by many genes. A trait such as human height is said to be: a. Multi-allelic. b. Incompletely dominant. c. Polygenic. d. Codominant. e. Pleiotropic. 5. Genes that are ______ do not assort independently, but they may recombine by crossing over. a. Polygenic b. Pleiotropic c. Linked d. Continuously variable e. Epistatic 6. Most genes come in alternative forms called: a. Chromosomes b. Alleles 2 c. Gametes d. Recessives e. Dominants 7. Capital letters represent a dominant allele, and lower case for a recessive allele. At locus a (position along the gene), the individual bearing these two chromosomes is: a. Heterozygous for the recessive allele b. Heterozygous for the dominant phenotype c. Homozygous for the dominant phenotype d. Homozygous for the dominant allele e. Homozygous for the recessive allele 8. The law of segregation states that: a. An allele on one chromosome will always segregate from an allele on a different chromosome. b. The number of chromosomes in a cell is always divisible by 2. c. Gametes cannot be separate and equal. d. The transmission of genetic diseases within families is always recessive. e. Each of two alleles for a given trait segregate into different gametes. 9. Which term refers to the genetic control of continuously varying traits such as height? a. Incomplete dominance b. Pleiotropic c. Multi-allelic d. Polygenic e. Codominant 10. Linked genes: a. Never have multiple alleles b. Never show crossing over c. Are on the same chromosome d. Have alleles that assort independently of each other e. Must be immediately adjacent to each other on the same chromosome 11. Which of the following did Gregor Mendel never see? a. An F2 generation b. A hybrid c. A pea d. A chromosome e. A stamen 12. A cross between homozygous red-eyed flies and homozygous white-eyed flies results in baby flies that all have red eyes. This result demonstrates: a. A dihybrid cross b. Dominance of genes c. The blending model of genetics d. The norm of reaction e. The law of independent assortment 13. The offspring from each cross done in Mendel's pea experiments always looked like one of the two parental varieties because: 3 a. Each allele affected phenotypic expression. b. Many different genes interacted to produce the F1 phenotype. c. One allele showed complete dominance over the other. d. The traits blended together because of crossing-over in meiosis. e. Many different genes interacted to produce the parental phenotype. 14. Which of the following is NOT a continuously varying trait? a. Skin color b. Weight c. Eye color d. Sickle-cell disease e. Height 15. We say that genes are linked when they: a. Are responsible for producing the same protein. b. Contain multiple alleles. c. Assort independently. d. Are located near each other on a single chromosome. e. Produce a balanced polymorphism. Carmen Quiz 5 (Pre-2/23) Earned 5/5 points. 1. Evolution occurs: a. Only when the environment is changing. b. By altering physical traits but not behavioral traits. c. Only through natural selection. d. Only via natural selection, genetic drift, migration, or mutation. e. Almost entirely because of directional selection. 2. Evolution is defined as: a. A change in the frequency of a physical trait in a population over time. b. A change in a physical trait of an individual during its lifetime. c. A progressive "ladder" of changes from the most primitive organisms to the most advanced organisms. d. Survival of the fittest e. A change in the frequency of alleles in a population over time. 3. During gene flow, where do the genes flow to? a. The genes flow into and out of the population due to migration of individuals from one population to another. b. The genes flow from a locus on one chromosome to a locus on another chromosome. c. The genes flow from a locus on one chromosome to another locus on the same chromosome. d. The genes do now flow at all; flow is a mathematical metaphor for mean gene frequencies being unstable and drifting from one number to another. 4. Natural selection results from interactions between: a. Individual organisms and their genes. 4 b. Species and their populations. c. Genes and ecosystems. d. Species and their environment. e. Individual organisms and their environment. 5. Which of the following is a statement that describes the concept of convergent evolution? a. Closely related organisms develop similar traits b. Organisms that are not directly related develop similar traits. c. Similar traits evolve at the same time in different organisms. d. Different organisms merge to become one species. e. Closely related organisms adapt to a wide range of different traits. 6. A gene pool consists of: a. Alleles for a gene that all confer the same fitness b. The total of all alleles present in a population c. The entire genome of an individual of reproductive age d. All of the gametes in a population e. All of the above choices are correct 7. A mutation is: a. Never adaptive b. Always dominant c. Can be heritable d. Usually lethal e. Always recessive 8. Gene flow means most nearly the same as: a. Genetic drift b. Founder effect c. Natural selection d. Meiotic drive e. Migration 9. What is the difference between artificial selection and natural selection? a. Artificial selection requires human intervention, whereas natural selection does not require human intervention. b. Artificial selection leads to temporary changes, whereas natural selection leads to permanent changes. c. Artificial selection acts on morphological characteristics, whereas natural selection acts on life history traits. d. Artificial selection operates at the genetic level, whereas natural selection operates on the entire organism. e. Artificial selection is directional, whereas natural selection is stabilizing. 10. Convergent evolution can occur only when two species: a. Are separated by a barrier such as a new river b. Live in the same geographic area c. Are both inedible to predators d. Evolve under similar selective forces e. Have a recent common ancestor 5 11. A population consists of a group of organisms: a. Of the same species living in a specific geographic area that have the potential to interbreed. b. Living in a specific geographic locale. c. Of the same species. d. Consisting of 5,000 or more individuals. e. Residing in a geographic area that measures one square mile or greater. 12. All of the following statements are true about mutation EXCEPT: a. Mutations are almost always random with respect to the needs of the organism. b. The mutation rate can be affected by natural selection. c. The origin of genetic variation is mutation. d. A mutation is any change in an organism's DNA. e. Most mutations are harmful or neutral to the organism in which they occur. 13. When a sudden change in the environment, such as a flood or fire, reduces the size of a population, the survivors' collective gene pool will only be a limited representation of what was present before the disaster. This phenomenon is called the: a. Genetic load b. Culling effect c. Hardy-Weinberg effect d. Founder effect e. Bottleneck effect 14. In humans, random mating is most likely to occur for which of the following characteristics? a. Physical appearance b. Blood type c. Meow d. Meow e. Meow 15. Human birth weight is a classic example of the results of: a. Stabilizing selection b. Genotype by environment interaction c. Directional selection d. Genetic drift e. Disruptive selection Carmen Quiz 6 (Pre-3/1) Earned 5/5 points. 1. Before exposure to the fear of snakes, a captive monkey will: a. Express a fear of a plastic snake b. Not reach over a plastic snake for food c. Reach over a plastic snake for food i. https://quizlet.com/1949302/test-2-flash-cards/ d. Reach over a real snake for food e. Eat a plastic snake as food 6 2. In Belding's ground squirrels, why are females much more likely than males to engage in altruistic behavior by sounding alarm calls? a. Belding's ground squirrels have a sex ratio that is biased toward males. b. Belding's ground squirrels have a sex ratio that is biased toward females. c. Females invest more in foraging and food storage, so they are more likely to lose their lives or their food if a predator attacks. d. Females tend to remain in the area in which they were born, so the females that call are warning their own kin. i. https://quizlet.com/31400582/chapter-9-prepu-flash-cards/ e. Males have smaller vocal chords, which are unable to make sounds that can be heard from a distance. 3. When one monkey grooms another, the monkey being groomed has its fitness improved because: a. As a result of the grooming, the percentage of grooming alleles has increased in the population. b. The groomed monkey looks better afterward and is more likely to find mates. c. The groomer is avoiding an antagonistic encounter. d. The groomer is removing parasites. i. https://quizlet.com/5448377/final-review-multiple-choice-flash-cards/ e. It now owes an obligation to the groomer. 4. The energy that a parent puts into the growth, feeding, and care of offspring is called: a. Reproductive success b. Kin selection c. Total reproductive output d. Reproductive investment e. The mating system 5. Which of the following is true about the sexual behavior of males and females? a. The sex of any species with the greater energetic investment in reproduction will be more discriminating about mating. i. https://books.google.com/books?id=F4okAxTXPtIC&pg=PA351&lpg=PA351&dq =male+bush+crickets+spend+a+great+deal+of+effort+courting+females,+while +females+are+much+choosier&source=bl&ots=BSNc_jZT- N&sig=EQNLg0wYT6Q1x22tTe9PzWc6pKM&hl=en&sa=X&ved=0ahUKEwiZo_Ti 1prLAhXim4MKHbbdCR4Q6AEIHDAA#v=onepage&q=male%20bush%20crickets %20spend%20a%20great%20deal%20of%20effort%20courting%20females%2C %20while%20females%20are%20much%20choosier&f=false b. Females are generally more willing to take a mating opportunity; males are generally more hesitant. i. Opposite c. Nearly all mammals are characterized by a greater initial reproductive investment by males. d. Male bush crickets spend a great deal of effort courting females, while females are much choosier when picking a mate. i. Opposite 7 e. The sex of any species with the higher energetic investment in reproduction will compete for access to the sex with lower energetic investment. 6. Although most children don't talk until they are a year old, by the age of three they understand most rules of sentence construction, and the average of 6-year-old native English speaker already has a vocabulary of about 13,000 words. Language acquisition is: a. Highly variable across cultures b. Prepared learning c. A fixed action pattern d. An example of supernormal stimulus e. All of the above choices are correct 7. Altruistic behavior in animals may be a result of kin selection, a theory maintaining that: a. Genes are more likely to persist within a population when they cause behaviors that assist other animals that share those genes. b. Aggression between sexes increases the survival and reproduction of the fittest individuals. c. Companionship is advantageous to animals because in the future they can recognize those that helped them in the past and request help once again. d. Companionship is advantageous to animals because in the future they can recognize those that helped them in the past and provide help to those individuals. e. Aggression within sexes increases the survival and reproduction of the fittest individuals. 8. In a random study of 1000 wills, it was shown that ______ received the smallest share of a deceased's estate. a. Non-relatives b. Spouses c. Grandchildren d. Siblings e. Children 9. Which of the following is the best way to distinguish male from female? a. Males are larger. b. Males are more brightly colored. c. Males are more aggressive. d. Males produce motile gametes. e. All of the above choices are correct. 10. Usually, the female is more discriminating than the male when it comes to mating; however, in bush crickets, the opposite is the case. Why is this? a. The male contributes a massive amount of energy to the female during mating--his ejaculate makes up about one-fourth of his body weight. b. Male bush crickets are prettier than female bush crickets. c. Male bush crickets accept the newly fertilized zygotes from the female and incubate them. d. A male bush crickets must bring the female a large offering of food in order for the female to accept him as a mate. e. Male bush crickets have tremendous variation in the desirability of their territories. 8 11. Behaviors that are learned easily and by all (or nearly all) individuals in a species are called: a. Instincts b. Fixed action patterns c. Prepared learning d. Innate behaviors e. Reciprocal altruism 12. In amphibians, it is generally the case that: a. The male invests more energy in the care of offspring than does the female b. Neither the female nor the male invest much energy in the care of offspring c. Both males and females invest significant energy in the care of offspring, but the female invests more d. Both males and females invest significant and equal energy in the care of offspring e. The female invests more energy in the care of offspring than does the male 13. Mate guarding is a reproductive tactic that functions to: a. Reduce paternity uncertainty b. Increase the female's investment in the offspring c. Reduce the male's reproductive investment d. Reduce the female's fitness e. Increase the number of mates to which a male has access 9 In-Class Activities & Answers In-Class Activity: 2/23/16 Observation Side-blotched lizards (Uta stansburiana) are a small lizard species found in many states in the American West and Mexico. Males come in three varieties, each with a different throat color: orange, yellow, or blue. Those throat colors announce to the lizard world what mating strategy a male will use. Orange-throated males are bigger and more aggressive, and they have large territories with several females. Blue-throated males have smaller territories with only one female, and they cooperate with other blues for defense. Yellow-throated males, whose markings and behaviors mimic those of females, are known as "sneakers"; they don't keep a territory but instead cluster around and sneak into the territories of other males to mate with their females. http://www.smithsonianmag.com/ist/?next=/science-nature/the-lizards-that-live-rock-paper- scissors-118219795/#v3GzlL0rHpeo79CU.99 Hypothesis Certain morphs (yellow, orange, blue) will have greater fitness depending on the environment (competition) they find themselves in. Predictions • Orange will have a higher reproductive success when competing mainly against the color BLUE. • Blue will have a higher reproductive success when competing mainly against the color YELLOW. • Yellow will have a higher reproductive success when competing mainly across the color ORANGE. ***Each member of the group must pick a color and enter it into TopHat*** A. At this point you have already chosen your color and they are all displayed. B. Examine the results and determine which color type is the most prominent. C. Depending on your birth date (odd/even) you will be able to choose a new color for the next generation. Choose the color type that would do best in the current distribution of color types. D. I will open TopHat back up to do the next round. E. Go back to B. This will be done for 9 rounds. ***Graph the results of each round on one large graph*** 1. Use the terms "allele" and "population" in your description of what happened over the several generations we ran the simulation. a. The blue, orange, and yellow lizards represented different alleles present in the lizard population. 10 2. Only half of the students were allowed to change their colors in between rounds based on their birthdates. What was that simulating? a. The lizards that reproduced in each generation. The changed colors represent the lizards in the next generation. 3. Over the course of the simulation was there a color type (morph) that was more successful (biological fitness) than all the others? Explain your reasoning. a. Yes. Orange. I added up the total of each color lizard and orange had 100 over the 6 generations, compared to 82 for blue and 62 for yellow. Clearly, orange had a higher biological fitness than all the others. LOL JK BC EVAN SAID NO THERE WASN'T ONE THAT WAS MORE SUCCESSFUL AHH. 4. Look at the graph you made for the 6 years. Was there a pattern to the change of color prominence over the several generations we ran the simulation? a. Yes. Each generation, the majority of the morph types were the morph types that won out over the majority in the last generation. For example, if blue was the majority in the previous generation, orange tended to be the majority in the next generation, because orange has a higher reproductive success over blue. 5. Do you think you can generally predict the color type that will be most prominent the next generation? If so, what will the color be? a. Yes. Yellow, because yellow has a higher reproductive success over the orange, which was the most prominent morph in the last in-class simulation. 6. Why is it important to do this several times? a. To observe trends and track overall biological fitness of the different lizard morphs. In-Class Activity: The Mating Game (3/1/16) 1. Which sex was more cautious about choosing a mate? FEMALES. a. Why was this? THEY HAD LESS GAMETES TO TRADE. 2. Meow a. For the females, was there a clear point along the quality gradient (letters) where their reproductive success started to drop off? i. As letters decreased b. For the males, was there a clear point along the quality gradient (letters) where their reproductive success started to drop off? i. No. more sporadic because males suck. 3. Meow a. For the females did your strategy for selecting a mate change in later rounds? NO LATER ROUNDS. i. If so, how did it change? NO LATER ROUNDS. b. For the males did strategy for selecting a mate change in the later rounds? NO LATER ROUNDS. i. If so, how did it change? NO LATER ROUNDS. 4. In terms of evolution, explain how those strategies/behaviors could have evolved. a. FEMALES WERE PICKY ABOUT BECAUSE THEY WANTED THEIR OFFSPRING TO HAVE THE BEST ADVANTAGES. 11 TopHat Questions 1. What does crossing over do? a. Creates new alleles b. Creates new combinations of alleles c. Creates new chromosomes d. Recombines alleles from non-homologous chromosomes 2. If an organism lives in an environment that is variable what type of reproduction will it likely use? What type of cell division will it use? a. Asexual; meiosis b. Asexual; mitosis c. Sexual; meiosis d. Sexual; mitosis 3. How could two normal parents have a child with fish odor syndrome? a. Both parents each had two normal alleles of FMO3. b. Both parents each had two mutant alleles of FMO3. c. One parent had two normal alleles and one parent had two mutant alleles of FMO3. d. Both parents had one normal and one mutant allele of FMO3. 4. What part to the scientific method did Mendel employ when selecting pea plants for his experiments? a. Observation b. Hypothesis c. Prediction d. Conclusion 5. Only if a person has two defective versions of the FMO3 gene do they have a "fishy" odor. That person is… a. Heterozygous b. Homozygous recessive c. Homozygous dominant d. None of the above 6. The cross between a female white giraffe and a pigmented male resulted in white offspring. What is the genotype of the father? a. MM b. Mm c. mm d. Cannot be determined 7. Which of the following sets of parents could produce a colorblind daughter? TALK TO YOUR NEIGHBOR. a. XR, Y : XR, XR b. Xr, Y : XR, XR c. XR, Y : Xr, XR d. Xr, Y : Xr, XR i. Because rr is a possibility. 8. Look around the classroom. Which trait below is likely polygenic (many genes for one trait)? 12 a. Hair color b. Length of neck c. Skin color d. Facial features e. All of the above 1. Given that beak size in mature adults does not change, what factor is driving the change in average beak size in Galápagos finches over time? a. Seed size b. Rainfall amount c. Seed number -only incorrect answer d. Both A and B 2. Which of the following is an example of migration? a. Your family moves to a new town in a different state b. A foreign male lion becomes the new leader of a pride (group of lions) c. A small group of farmers starts a new settlement on an uninhabited island - Founder's Effect, not migration d. Both 1 and 2 e. All of the above 3. The American Bison was hunted to near extinction by early settlers. Which answer is correct about the current population of American Bison? a. It has experienced a population bottleneck. b. It is more genetically diverse. c. It has experienced the founder effect. d. Both 1 and 2 e. Both 2 and 3 4. You are a breeder who has a variety of flowers that range from red to purple to blue. Purple flowers are the most valuable. If they wanted to make the most money which type of selection will they employ? a. Directional b. Stabilizing c. Disruptive 1. Why do species have taste preferences? a. Feeding choices directly influence fitness b. Natural selection can shape feeding behavior c. Taste is just an opinion and therefore random d. A and B e. All of the above 2. Which example below do you think might be a prepared learning behavior in humans? a. Fear of heights b. Fear of the dark c. Fear of cars d. Fear of horses e. Both 1 and 2 13 3. Why did the fairly old female prairie dog make alarm calls when transplanted into a foreign group? a. She evolved to want to prove herself to her new group b. The behavior has evolved to warn the group, regardless of genetic similarities c. It is a deceptive (false) signal 4. Which choice below illustrates a conflict in kin selection? a. Worker bees in a colony help raise sons and daughters of the queen bee b. Stepparents are more likely to abuse unrelated children c. Gestational diabetes d. Sibling rivalry e. Both 3 and 4 5. Which choice below can be explained by reciprocal altruism that benefits the individual? a. Donating money to help poor children in a developing country i. Child you help might grow up to cure cancer b. Donating money for research of a rare disease c. Donating money for cancer research d. Friends helping each other with childcare e. Both 3 and 4 6. Altruism, kin selection, and reciprocal altruism are examples of: a. Direct fitness b. Indirect fitness -more correct than the others c. Inclusive fitness d. Overall fitness 7. Which behavior ultimately can be linked to a selfish gene? a. Helping the homeless b. Treating all patients who enter an emergency room c. Helping to feed hungry people d. Helping out family members in financial need e. All of the above 8. Females' reproductive success generally does not increase by seeking additional mating opportunities, equal to male opportunities. a. Females have increased parental care b. Females produce fewer gametes c. Paternity uncertainty d. Both 1 and 2 e. All of the above 9. According to the graph, when do females and males have equal reproductive success? a. Female has 1 mate, male has 1 mate. 10. Do any of the four factors that influence a female's choice of mate in animals also apply to human courtship? If so, which factors? a. Mate with a male who performs a courtship ritual b. Mate with a male who controls valuable resources c. Mate with a male who contributes a large investment up front d. Mate with a male who has a valuable physical attribute 14 e. All of the above apply to human courtship 15 Take-Home Messages from What Is Life? Chapter 7 MANDELIAN INHERITANCE 7.1-1.5 Why do offspring resemble their parents? 7.1 Family resemblance: your mother and father each contribute to your genetic makeup. Take-Home Message 7.1 Offspring resemble their parents because they inherit genes - instruction sets for biochemical, physical, and behavioral traits, some of which are responsible for diseases -from their parents. 7.2 Some traits are controlled by a single gene. Take-Home Message 7.2 More than 9,000 human traits are determined by the instructions a person carries on a single gene, and the traits exhibit straightforward patterns of inheritance. 7.3 Mendel learned about heredity by conducting experiments. Take-Home Message 7.3 In the mid-1800s, Gregor Mendel conducted studies that helped us understand how traits are inherited. He applied methodical experimentation and rigorous hypothesis testing, focusing on easily observed and categorized traits in garden peas. 7.4 Segregation: you've only got two copies of each gene but put only one copy in each sperm or egg. Take-Home Message 7.4 Each parent puts into every sperm or egg it makes a single set of instructions for building a particular trait. This instruction set is what today we call a gene. The trait observed in an individual depends on the two copies (alleles) of the gene it inherits from its parents. 7.5 Observing an individual's phenotype is not sufficient for determining its genotype. Take-Home Message 7.5 It is not always possible to determine an individual's genetic makeup, known as its genotype, by observation of the organism's outward appearance, known as its phenotype. For a particular trait, an individual may carry a recessive allele whose phenotypic effect is masked by the presence of a dominant allele. Much genetic analysis therefore makes use of clever experiments and careful record-keeping, using Punnett squares, to determine organisms' genotypes. 7.6-7.8 Probability and change play central roles in genetics. 7.6 Chance is important in genetics. Take-Home Message 7.6 Probability plays a central role in genetics. In segregation, each gamete that an individual produces receives only one of the two copies of each gene the individual carries in its other cells, but it is impossible to know which allele goes into the gamete. Chance plays a role in fertilization, too: all of the sperm or eggs produced by an individual are different from one another, and any one of those gametes may be the gamete involved in fertilization. 7.9-7.14 The translation of genotypes into phenotypes is not a black box. 16 7.9 Incomplete dominance and codominance: the effects of both alleles in a genotype can show up in the phenotype. Take-Home Message 7.9 Sometimes the effects of both alleles in a heterozygous genotype are evident in the phenotype. With incomplete dominance, a heterozygote appears to be intermediate between the two homozygotes. With codominance, a heterozygote displays characteristics of both homozygotes. 7.11 Multigene traits: how are continuously varying traits such as height influenced by genes? Take-Home Message 7.11 Many traits, including continuously varying traits such as height, eye color, and skin color, are influenced by multiple genes. 7.12 Sometimes one gene influences multiple traits. Take-Home Message 7.12 In pleiotropy, one gene influences multiple unrelated traits. Most, if not all, genes may be pleiotropic. 7.13 Why are more men than women color-blind? Sex-linked traits differ in their patterns of expression in males and females. Take-Home Message 7.13 The patterns of inheritance of most traits do not differ between males and females. However, when a trait is coded for by a gene on a sex chromosome, such as color vision on the X chromosome, the pattern of expression differs for males and females. Chapter 8 EVOLUTION AND NATURAL SELECTION 8.1 Evolution is an ongoing process. 8.1 We can see evolution occurring right before our eyes. Take-Home Message 8.1 The characteristics of the individual present in a population can change over time. We can observe such change in nature and can even cause such change to occur. 8.5-8.10 Four mechanisms can give rise to evolution. 8.5 Evolution occurs when the allele frequencies in a population change. Take-Home Message 8.5 Evolution is a change in allele frequencies within a population. It often occurs by four different mechanisms: mutation, genetic drift, migration, and natural selection. 8.6 Mutation—a direct change in the DNA of an individual—is the ultimate source of all genetic variation. Take-Home Message 8.6 Mutation is an alteration of the base-pair sequence in an individual’s DNA. If such an alteration changes an allele in an individual’s gamete-producing cells, the frequency of alleles has changed and this constitutes evolution within the population. Mutations can be caused by high-energy radiation or chemicals in the environment and also can appear spontaneously. Mutation is the only way that new alleles can be created within a population, and thus it generates the variation on which natural selection can act. 17 8.7 Genetic drift is a random change in allele frequencies in a population. Take-Home Message 8.7 Genetic drift is a random change in allele frequencies within a population, unrelated to the alleles’ influence on reproductive success. Genetic drift is a significant mechanism of evolutionary change, primarily in small populations. 8.8 Migration into or out of a population may change allele frequencies. Take-Home Message 8.8 Migration, or gene flow, leads to a change in allele frequencies in a population as individuals move into or out of the population. 8.9 When three simple conditions are satisfied, evolution by natural selection is occurring. Take-Home Message 8.9 Natural selection is a mechanism of evolution that occurs when there is heritable variation for a trait, and individuals with one version of the trait have greater reproductive success than do individuals with a different version of the trait. Natural selection can also be though of as the elimination of alleles that reduce the reproductive rate of individuals carrying those alleles, relative to the reproductive rate of individuals who do not. 8.11-8.17 Through natural selection, populations of organisms can become adapted to their environment. 8.11 Traits causing some individuals to have more offspring than others become more prevalent in the population. Take-Home Message 8.11 Fitness is a measure of the relative amount of reproduction by an individual with a particular phenotype, compared with the reproductive output of individuals with alternative phenotypes. An individual’s fitness can vary, depending on the environment in which it lives. 8.12 Organisms in a population can become better matched to their environment through natural selection. Take-Home Message 8.12 Adaptation, with refers to the process by which organisms become better matched to their environment and to the specific traits that make an organism more fit, occurs as a result of natural selection. 8.13 Natural selection does not lead to perfect organisms. Take-Home Message 8.13 Natural selection does not lead to organisms becoming perfectly adapted to their environment because (1) environments can change more quickly than natural selection can adapt organisms; (2) mutation does not produce all possible alleles; (3) there is not always a single, optimum adaptation for a given environment. 8.14 Artificial selection is a special case of natural selection. Take-Home Message 8.14 Animal breeders and farmers are making use of natural selection when they modify their animals and crops through selective breeding, because the three conditions for natural selection are satisfied. Since the differential reproductive success is determined by humans and not by nature, this type of natural selection is also called artificial selection. 18 8.15 Natural selection can change the traits in a population in several ways. Take-Home Message 8.15 Acting on traits for which populations show a large range of phenotypes, natural selection can change populations in several ways These include directional selection, in which the average value for the trait increases or decreases; stabilizing selection, in which the average value of a trait remains the same while extreme versions are selected against; and disruptive selection, in which individuals with extreme phenotypes have the highest fitness. 8.16 This is how we do it: By picking taller plants, do humans unconsciously drive the evolution of smaller plants? Take-Home Message 8.16 Humans value the Tibetan snow lotus flower for medicinal and other purposes. Because people prefer to harvest the largest snow lotus plants, there has been selection for smaller plants. Data from herbaria collections and from snow lotus populations in protected areas reveal a significant negative trend in height over the past hundred years. 8.17 Natural selection can cause the evolution of complex traits and behaviors. Take-Home Message 8.17 Natural selection can change allele frequencies for genes involved in complex physiological processes and behaviors. Sometimes a trait that has been selected for one function is later modified to serve a completely different function. 8.18-8.22 The evidence for the occurrence of evolution is overwhelming. 8.20 Comparative anatomy and embryology reveal common evolutionary origins. Take-Home Message 8.20 Similarities in the anatomy and development of different groups of organisms and in their physical appearance can reveal common evolutionary origins. Chapter 9 EVOLUTION AND BEHAVIOR 9.1-9.4 Behaviors are traits that can evolve. 9.3 Some behaviors must be learned (and some are learned more easily than others). Take-Home Message 9.3 In contrast to innate behaviors are those behaviors that are influenced more by the individual’s environment, requiring some learning, and are often modified over time in response to past experiences. Organisms are well-prepared to learn behaviors that were important to the reproductive success of their ancestors, and less prepared to learn behaviors irrelevant to their evolutionary success. 9.5-9.9 Cooperation, selfishness, and altruism can be better understood with an evolutionary approach. 9.5 “Kindness” can be explained. Take-Home Message 9.5 Many behaviors in the animal world appear altruistic. In almost all cases, the apparent acts of altruism are not truly altruistic; they have evolved as a consequence of either kin selection or reciprocal altruism and, from an evolutionary perspective, are beneficial to the individual engaging in the behavior. 9.6 Apparent altruism toward relatives can evolve through kin selection. 19 Take-Home Message 9.6 Kin selection is apparently altruistic behavior in which an individual that assists a genetic relative compensates for its own decrease in direct fitness by helping increase the relative’s fitness and, consequently, its own inclusive fitness. 9.8 In an “alien” environment, behaviors produced by natural selection may no longer be adaptive. Take-Home Message 9.8 When there is a mismatch between the environment organisms are in and the environment to which they are adapted, the behaviors they exhibit are not necessarily evolutionarily adaptive. 9.10-9.16 Sexual conflict can result from disparities in reproductive investment by male and females. 9.10 There are big differences in how much males and females must invest in reproduction. Take-Home Message 9.10 In mammals and many other types of animals, there are important physical differences between males and females relating to reproduction. Fertilization usually takes place in the female. Lactation takes place only in the female. And in species where fertilization occurs inside the female, males cannot be certain that offspring are their progeny. These physical differences have led to the evolution of differences in male and female reproductive behavior. 9.11 Males and females are vulnerable at different stages of the reproductive exchange. Take-Home Message 9.11 Differing patterns of investment in reproduction make males and females vulnerable at different stages of the reproductive process. This has contributed to the evolution of differences in their sexual behavior. The sex with greater energetic investment in reproduction is more discriminating about mates, and members of the sex with a lower energetic investment in reproduction compete among themselves for access to the higher- investing sex. 9.12 Tactics for getting a mate: competition and courtship can help males and females secure reproductive success. Take-Home Message 9.12 As a consequence of male-female differences in initial reproductive investment, males tend to increase their reproductive success by mating with many females and have evolved to compete among themselves to get the opportunity to mate. 9.13 Tactics for keeping a mate: mate guarding can protect a male’s reproductive investment. Take-Home Message 9.13 Mate guarding can, in general, increase reproductive success by reducing additional mating opportunities for a partner, and can improve a male’s reproductive success by increasing his paternity certainty and thus reducing his vulnerability when he makes investment in offspring. 20
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