1 Biology Unit 7—Evolutionary Biology 1. 2. 3. 4. 5. Early evolution of life Theory of Evolution Evidence for evolution Genetic Equilibrium Speciation Chapters 15-17 Concepts: 17.2, 17.3 Concepts: 15.1, 15.2, 15.3, 17.4 Concepts: 15.2, 17.1 Concepts: 16.1, 16.2 Concepts: 16.3 Key Terms 1. Evolution 2. Adaptive radiation 3. Divergent evolution 4. Convergent evolution 5. Fossil 6. Gene pool 7. Hardy-Weinberg Law 8. Natural selection 9. Embryology 10. Vestigial structure 11. Biogeography 12. Homologous structures 13. Analogous structures 14. Genetic variability 15. Mutation 16. Directional selection 17. Stabilizing selection 18. Disruptive selection 19. Speciation 20. Allopatric speciation 21. Sympatric speciation 22. Genetic drift Recommended Work For Chapters 15-17 Chapter 15 Section 1 #1-4 Section 2 #1-3 Section 3 #1-3, 5 Chapter Assessment #1-10, 11-25 Chapter 16 Section 1 #1-4 Section 2 #1-5 Section 3 #1-4 Chapter Assessment #1-10, 11-21, 26-32 Chapter 17 Section 1 #1-4 Section 2 #1-4 Section 3 #1-3 Section 4 # 1-3 Chapter Assessment #1-10, 11-15, 21-24, 26-32 1 2 Biology Unit 7—Evolutionary Biology General review Define the following: o Evolution o Microevolution o Macroevolution o Natural selection Evidence for evolution Evidence for evolution is provided by the following five scientific disciplines. Describe and give examples for each of the five disciplines. 1. Paleontology 2. Biogeography 3. Embryology 2 3 AP Biology Unit 7—Evolutionary Biology 4. Comparative anatomy, include homologous structures and analogous structures. 5. Molecular biology Natural Selection Define the following o Natural selection o Adaptations o Fitness Darwin presented his theory for natural selection using the following arguments. Explain each one. 1. Populations posses an enormous reproductive potential. (Overproduction) 2. Genetic Variation 3 4 Biology Unit 7—Evolutionary Biology 3. Resources are limited. (Struggle to Survive) 4. Individuals complete for survival. 5. There is variation among individuals in a population. (Differential Reproduction) 6. Much variation is heritable. (What are the sources of genetic variation?) 7. Only the fit individuals survive. (Survival of the Fittest) 8. Evolution occurs as advantageous traits accumulate. 4 5 Biology Unit 7—Evolutionary Biology Natural selection may act upon a population in a variety of ways. Describe and explain each one, include a graph that represents the type of selection. 1. Stabilizing selection 2. Directional selection 3. Disruptive selection 4. Artificial selection (no graph) Sources of Variation In order for natural selection to operate, there must be variation among individuals in a population. Indeed, considerable variation exists in nearly all populations. The variation arises from or is maintained by the following mechanisms. Describe and explain each of the following. 5 6 Biology Unit 7—Evolutionary Biology 1. Mutations 2. Sexual reproduction a. Include the following i. Genetic recombination/Crossing over ii. Independent assortment of homologues iii. Random joining of gametes 6 7 Biology Unit 7—Evolutionary Biology Causes of Changes in Allele Frequencies Natural selection was the mechanism that Darwin proposed for evolution. With the understanding of genetics, it became evident that factors other than natural selection can change allele frequencies and thus promote evolution. These factors, together with natural selection, are given below. Describe each one and explain how it causes changes in allele frequencies. 1. Natural selection 2. Mutations 3. Gene Flow 4. Genetic drift, include the founder effect and bottleneck 5. Nonrandoming mating 7 8 Biology Unit 7—Evolutionary Biology Genetic Equilibrium When the allele frequencies in a population remain constant from generation to generation, the population is said to be in genetic equilibrium, or Hardy-Weinberg equilibrium. At genetic equilibrium, there is no evolution. In order for equilibrium to occur, the factors that normally change gene frequencies do not occur. List the five conditions required for Hardy-Weinberg equilibrium: 1. 2. 3. 4. 5. Speciation A species is usually defined as a group of individuals capable of interbreeding. Speciation, the formation of new species, occurs by the following processes. Describe and explain each process and draw a graph to illustrate it. 1. Allopatric speciation 2. Sympatric speciation 3. Adaptive radiation 8 9 Biology Unit 7—Evolutionary Biology Maintaining Reproductive Isolation If species are not physically separated by a geographic barrier, various mechanisms commonly exist to maintain reproductive isolation and prevent gene flow. These mechanisms may appear randomly (genetic drift) or may be the result of natural selection. There are two categories of isolating mechanisms. The first category, prezygotic isolating mechanisms, consists of mechanisms that prevent fertilization. Describe each of the following: 1. Habitat isolation 2. Temporal isolation 3. Behavioral isolation 4. Mechanical isolation 5. Gametic isolation The second category, postzygotic isolating mechanisms, consists of mechanisms that prevent the formation of fertile progeny. Describe each of the following: 1. Hybrid inviability 2. Hybrid sterility 3. Hybrid breakdown 9 10 Biology Unit 7—Evolutionary Biology Patterns of Evolution The evolution of species is often categorized into the following four patterns. Describe each of the following and draw a graph to illustrate each one. 1. Divergent evolution 2. Convergent evolution 3. Parallel evolution 4. Coevolution 10 11 Biology Unit 7—Evolutionary Biology Macroevolution Define macroevolution: The two distinct macroevolution theories listed below reflect different interpretations of fossil evidence and explanations for the development of evolutionary history. Summarize the two theories and draw a diagram to illustrate each one. 1. Gradualism 2. Punctuated equilibrium 11 12 Biology Unit 7—Evolutionary Biology The Origin of Life The steps hypothesized to have led to the first primitive cell and the subsequent steps that led to more complex living cells are outlined below. Describe each of the following: 1. The earth and its atmosphere formed a. What was Earth’s early atmosphere like? List the possible contents. 2. The primordial seas formed. a. As the earth cooled, gases condensed to produce primordial seas consisting of water and minerals. 3. Complex molecules were synthesized a. Describe Stanley Miller’s experiment, and what is the significance of his experiments? Draw a picture of their apparatus. 12 13 Biology Unit 7—Evolutionary Biology 4. Polymers and self-replicating molecules were synthesized a. Monomers combined to form polymers. Some of these reactions may occurred by dehydration synthesis (condensation) reactions, in which polymers formed from monomers by the removal of water molecules. 5. Organic molecules were concentrated and isolated into protobionts. a. Protobionts were the precursors of cells. They were able to carry out chemical reactions enclosed within a border across which materials can be exchanged, but were unable to reproduce. Borders formed in the same manner as hydrophobic molecules aggregate to form membranes (as phospholipids form plasma membranes). 6. Primitive heterotrophic prokaryotes formed. a. Heterotrophs are living organisms that obtain energy by consuming organic substances. Pathogenic bacteria, for example, are heterotrophic prokaryotes. b. The organic “soup” was a source of organic material for heterotrophic cells. As these cells reproduce, composition for organic material increased. Natural selection would favor those heterotrophs at obtaining food. 7. Primitive autotrophic prokaryotes were formed. a. As a result of mutation, a heterotrophy gained the ability to produce its own food. As an autotroph, this cell would be highly successful. b. Autotrophs manufacture their own organic compounds using light energy or energy from inorganic substances. Cyanobacteria (photosynthetic bacteria), for example, are autotrophic prokaryotes that obtain energy and manufacture organic compounds by photosynthesis. 8. Oxygen and the ozone layer formed and abiotic chemical evolution ended. a. As a by-product of the photosynthetic activity of autotrophs, oxygen was released and accumulated in the atmosphere. The interaction of UV light and oxygen produced the ozone layer. b. As a result of the formation of the ozone layer, incoming UV light was absorbed, preventing it from reaching the surface of the earth. Thus, the major source of energy for the abiotic synthesis of organic molecules and primitive cells was terminated. 13 14 Biology Unit 7—Evolutionary Biology 9. Eukaryotes formed (endosymbiotic theory) Page 427 a. Explain the endosymbiotic theory and cite the evidence for it. 14