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CHAPTER 22 DESCENT WITH MODIFICATION: A DARWINIAN VIEW OF LIFE State the two major points Darwin made in The Origin of Species concerning the Earth's biota. The two major points Darwin made in The origin of species was: the occurrence of evolution and natural selection as its mechanism. Describe Carolus Linnaeus' contribution to Darwin's theory of evolution. Carlus Linnaeus’ contribution to Darwin’s theory of evolution was that Linnaeus provided Darwin with a connection to evolution by recognizing that the great diversity of organisms could be ordered into “groups subordinate to groups” or major taxonomy categories. Describe Jean Baptiste Lamarck's model for how adaptations evolve. Jean Baptiste Lamarck’s model for how adaptations evolve incorporates two ideas that were popular during Lamarck’s era. The first was use and disuse, the idea that those parts of the body used extensively to cope with the environment become larger and stronger, while those that are not used deteriorate. The second idea Lamarck adopted was called the inheritance of acquired characteristics. In this concept of heredity, the modification of an organism acquires during its lifetime can be passed along to its offspring. Explain what evidence convinced Darwin that species change over time. The evidence that convinced Darwin that species change over time was the finches he saw while in the Galapagos. Darwin collected 13 species of closely related finches, some found in only one island. Thus, the most striking difference among species is in their beaks, which adapted for specific diets. Explain why variation was so important to Darwin's theory. Variation was so important to Darwin’s theory because a new species would arise from an ancestral form by gradual accumulation of adaptations to a different environment. Populations would diverge more and more in appearance as ach adapted to local conditions. Thus, Darwin anticipated that explaining how such adaptations arise was essential to understanding evolution. Define and state the basic principles in natural selection. Natural selection is the mechanism for evolution or differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. Evolution occurs when natural selection causes changes in relative frequencies of alleles in the gene pool. According to Darwin’s concept of natural selection, a population of organisms can change over time as a result of individuals with certain heritable traits leaving more offspring than other individuals. The basic principles are 1. Populations produce more individuals that can possibly survive. 2. Population sizes remain stable. 3. Resources are limited 4. “Heritable” variation exists among organisms 5. “Survival of the fittest.” Using some contemporary examples, explain how natural selection results in evolutionary change. Natural selection results in evolutionary change by natural selection is this differential success in reproduction, and its adaptation of organisms to their environment. An example is Camouflage on plants. Describe how molecular biology can be used to study the evolutionary relationships among organisms. An organism’s hereditary background is reflected in its genes and their protein products. Thus, two species considered to be closely related by other criteria should have a greater proportion of their DNA and proteins in common than more distantly related species. Explain the problem with the statement that Darwinism is "just a theory". Darwinism is no longer a theory because it has been proven countless times by fossil records and fields of biology such as biogeography, comparative anatomy and molecular biology. CHAPTER 23 THE EVOLUTION OF POPULATIONS Explain what is meant by the "modern synthesis". Modern synthesis is the focus on populations as units of evolution Explain how microevolutionary change can affect a gene pool. Modern synthesis is the focus on populations as units of evolution In their own words, state the Hardy-Weinberg theorem. The Hardy Weinberg theorem basically states that if a population is large, shows no random mating, is totally isolated, shows no net mutations, and has reproductive success for all individuals then no evolution will occur. Describe the usefulness of the Hardy-Weinberg model to population geneticists. This model would help these geneticists realize the gradual change of a certain population over time because of little or no change in allele and genotype frequencies. Explain how genetic drift, gene flow, mutation, nonrandom mating and natural selection can cause microevolution. Each of these examples causes microevolution because they all affect the allele frequencies of a population. They introduce a change in alleles or genotypes. Distinguish between the bottleneck effect and the founder effect. The bottleneck effect describes a population that undergoes a dramatic decrease in size. The founder effect describes allele frequencies in a migrating group differ, by chance, from their population of origin. Explain why mutation has little quantitative effect on a large population. Mutation is not harmful and has no effect in most cases, it is also adaptive. Mutation is always on a small scale so it could never have a lasting effect on a large population. Give the cause of nearly all genetic variation in a population. Genetic variation is caused by genetic drift, non random mating, natural selection, mutation and gene flow. Explain how genetic variation may be preserved in a natural population. Genetic variation is preserved through diploidy (presence of two copies of each chromosome) and polymorphism (heterozygous advantage and frequency dependent selection). Describe what selection acts on and what factors contribute to the overall fitness of a genotype. Genetic variation is preserved through diploidy (presence of two copies of each chromosome) and polymorphism (heterozygous advantage and frequency dependent selection). Give examples of how an organism's phenotype may be influenced by the environment. Distinguish among stabilizing selection, directional selection and diversifying selection. Stabilizing selection acts against extreme phenotypes and favors the more common intermediate variants. Directional selection shifts the frequency curve for variations in some phenotypic character in one direction or the other by favoring what are initially relatively rare individual the deviate from the average for that character. Diversifying selection occurs when environmental conditions are varied in a way that favors individual in both extremes of a phenotypic range over intermediate phenotypes Give at least four reasons why natural selection cannot breed perfect organisms. *Organisms are locked into historical constraints. *Adaptations are often compromises. *Not all evolution is adaptive. *Selection can only edit variations that exist CHAPTER 2 4 THE ORIGIN OF SPECIES Define biological species (E. Mayr). *Organisms are locked into historical constraints. *Adaptations are often compromises. *Not all evolution is adaptive. *Selection can only edit variations that exist Describe some limitations of the biological species concept. Some limitations of the biological species concept are that the criterion of interbreeding is useless for organisms that are completely asexual in their reproduction; it is also inadequate as a criterion for grouping extinct forms of life, and if two populations are geographically segregated from each other, they do not interbreed, although they may be so much alike that they are placed in the same species on morphological grounds. Distinguish between prezygotic and postzygotic isolating mechanisms. Prezygotic barrier is a reproductive barrier that impedes mating between species or hinders fertilization of ova if interspecific mating is a hempted. Postzygotic barrier is any of several species-isolating mechanisms that prevents hybrids produced by two different species from developing into viable, fertile adults. Describe five prezygotic isolating mechanisms and give an example of each. There are five different types of prezygotic isolating mechanisms. Habitat Isolation is when two species that live in different habitats within the same area encounter each other rarely, for example, two species of parasites living on different hosts will not have a chance to mate. Behavioral Isolation is that special signal that attracts mates, as well as elaborate behavior unique to a species like male fireflies of different species signal to females of their kind by blinking their lights in particular patterns. Temporal Isolation is when two species that breed during different times of the day, different seasons, or different years cannot mix their gametes. Mechanical Isolation, is when closely related species may attempt to mate, but fail to consummate the act because they are anatomically incompatible. Gametic Isolation is when even if the gametes of different species meet, they rarely fuse to form a zygote. Gamete recognition may be based on the presence of specific molecules on the coats around the egg, which adhere only to complementary molecules on sperm of the same species. Distinguish between allopatric and sympatric speciation. Allopatric speciation is a mode of speciation induced when a geographical barrier segregates the ancesteral population. Sympatric speciation is a mode of speciation occurring because of a radical change in the genome that produces a reproductively isolated subpopulation in the midst of its parent population. Describe the adaptive radiation model and use it to describe how it might be possible to have many sympatric closely related species even if geographic isolation is necessary for them to evolve. 1. One island in this cluster of three is seeded by a small colony founded by individuals of species A, blown over from a mainland population. 2. Its gene pool isolated from the parent species, the island population evolves into species B as it adapts to its new environment. 3. Storms or other agents of dispersion spread species B to a second island, 4. where the isolated colony evolves into species C. 5. Later, individuals from species C recolonize the first island and cohabit with species B, but reproductive barriers keep the species distinct. 6. A colony of species C may also populate a third island, 7. where it adapts and forms species D. 8. Species D is dispersed to the two islands of its ancestors, 9. forming a new species, E, on one of those islands. The story could go on, with a series of allopatric speciation episodes made possible by the combination of isolation and occasional dispersal. Define sympatric speciation and explain how polyploidy can cause reproductive isolation. 1. One island in this cluster of three is seeded by a small colony founded by individuals of species A, blown over from a mainland population. 2. Its gene pool isolated from the parent species, the island population evolves into species B as it adapts to its new environment. 3. Storms or other agents of dispersion spread species B to a second island, 4. where the isolated colony evolves into species C. 5. Later, individuals from species C recolonize the first island and cohabit with species B, but reproductive barriers keep the species distinct. 6. A colony of species C may also populate a third island, 7. where it adapts and forms species D. 8. Species D is dispersed to the two islands of its ancestors, 9. forming a new species, E, on one of those islands. The story could go on, with a series of allopatric speciation episodes made possible by the combination of isolation and occasional dispersal. List some points of agreement and disagreement between the two schools of thought about the tempo of speciation (gradualism vs. punctuated equilibrium). One view of speciation is that it usually occurs gradually by an accumulation of micro evolutionary changes in gene pools. In contrast, the punctuated equilibrium model views species as changing most when they bud from an ancestral species and then undergoing relatively little change for the rest of their existence. CHAPTER 26 EARLY EARTH AND THE ORIGIN OF LIFE Provide evidence to support the hypothesis that chemical evolution resulting in life's origin occurred in 4 stages: One view of speciation is that it usually occurs gradually by an accumulation of micro evolutionary changes in gene pools. In contrast, the punctuated equilibrium model views species as changing most when they bud from an ancestral species and then undergoing relatively little change for the rest of their existence. a. Abiotic synthesis of organic monomers b. Abiotic synthesis of polymers c. Formation of protobionts d. Origin of genetic information Describe Whittaker's five-kingdom system. Munera, Plantae, Animalia, Protists, Describe three alternatives to the five-kingdom system and explain the rationale for each.