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1 Lecture # - Evolution part #1 Lecture Prep: review Chapter 27, and complete the graphing exercise below The common female house flies lays approximately 100 eggs in her one- month life (column E below). How many of those 100 eggs do you think will live long enough to reproduce? Convert this number of surviving flies into a percent (divide by 100), and place it in column G below. Use the starting data for month 0 and your estimate of fly survival rate (column G) to complete the table. Graph the total number of flies in each generation on the graph below (month on the X- axis, total # of flies from each generation, column B, on the Y- axis make sure you label the numbers on the Y- axis) A. month B. Total # of flies (males + females) alive in each generation C. # of male flies D. # of female flies E. how many eggs does each female lay? F. total number of eggs that are laid this generation G. percentage of those eggs that live long enough to reproduce. H. total number of adult flies reproducing in next round (column H from preceding generation) (C = 1/2 of column B) (D = 1/2 of column B) (F = D x E) (your own estimate, use the same % for all rows) (H = F x G) month 54

2 9 Continue the line below to show what you predict the human population will be in 100 years. What factors will affect the overall size of the human population in 100 years? year 55

3 Lecture Review: While watching the movie The Evidence for Evolution, answer the questions below. The Record in the Rocks 1. Name three things that can fossilize. 2. Look at the horse- like skeletons. How are they changing? (i.e., size, number of toes, way of walking, presence of hooves) 3. Scientific evidence suggests that the continents looked very different 350 million years ago (mya). Briefly describe in what ways. Evidence from Living Things 4. Define what homologous structures are. Give three examples. 5. What is divergent evolution? 6. Define what analogous structures are. 7. Give one example of a vestigial structure. 8. According to the video, how can we explain the fact that there are large flightless birds only in the southern hemisphere? 56

4 The Theory of Evolution 9. What did the theory of acquired characteristics stated? Who formulated this incorrect theory? 10. Who formulated the theory of evolution by natural selection? 11. When individuals reproduce, they generate many more offspring than needed to replace the parents. What are some of the reasons why earth is not overrun with the resultant progeny? 12. If characteristics are inherited, those individuals who reproduce are able to pass on their traits to the next generation. This is referred to as 13. What did Darwin mean when he said that there is a struggle for existence? How can this influence which traits accumulate in any given population? 14. What is defined as natural selection? 15. Define convergent evolution and give at least two examples. 16. Why is the number of light and dark peppered moths changing in a population? Is the color characteristic genetically determined? Variation and Evolution 17. What is the definition of a species? 18. When can we say we have a new species (speciation has occurred)? 19. How can you tell when some organisms are a new species, versus variants from the same species? 20. What is artificial selection? Name some species that may change (or have been produced) due to artificial selection? 21. How can new traits appear in a population? Give an explanation at the molecular level. 22. Is it possible to induce mutations in order to create new traits? Which example is shown in the video? 57

5 Lecture # - Evolution part #2 - Microevolution Lecture Prep: read of your textbook, and complete the Mechanisms of Microevolution exercise on next two pages. 58

6 Mechanisms of Microevolution. Review pages of your book for this exercise. The purpose of this activity is to analyze a hypothetical situation and determine the mechanism of microevolution involved. In each of the following scenarios, there is at least one mechanism of microevolution occurring, but possibly more. How many can you identify? Word bank: mutation nonrandom mating directional selection sympatric speciation genetic drift natural selection disruptive selection allopatric speciation gene flow artificial selection stabilizing selection 1. A type of short ground clover grows in a remote meadow near the top of a mountain. The meadow is small, with only enough space for about 100 clover plants to grow. A DNA replication error occurs during oogenesis in one of these clovers. This error changes the DNA sequence of a plant growth gene (g), thereby producing an egg with a new allele (G). This egg is successfully fertilized by a wildtype (g) pollen, giving rise to a heterozygote clover (Gg). Because of the G allele, the Gg heterozygote initiates germination faster than the gg clovers. Which evolutionary processes are involved in this scenario? 2. Because the heterozygote (Gg) clover germinates faster than its neighboring clovers, it is taller and gets more sunlight than its shaded neighboring clovers. The additional sunlight enables the Gg clover to produce more pollen than its neighbors, and over the course of a few growing seasons, the G allele becomes more common. Which evolutionary processes are involved in this scenario? 3. A few years pass, and as the G allele becomes increasingly common, a few GG genotypes are produced. As it turns out, the G allele exhibits incomplete dominance, so the GG genotype grows even faster (and therefore taller) than the Gg genotype. Over the next few growing seasons, the GG genotype becomes even more common than the Gg genotype. Which evolutionary processes are involved in this scenario? Use the space below to make a bar graph that illustrates the initial genotype frequency of the population after scenario #1. Use the space below to make a bar graph that illustrates the new genotype frequency of the population after scenario #3. 59

7 4. A wandering herd of goat pass through the meadow. The goats like eating the clover flowers, but tend to eat the tallest flowers in the patch. In the few days the goats are in this meadow, they eat almost all the tall flowers. Which evolutionary processes are involved in this scenario? Predict what clover genotype would be most fit if the goats returned to this meadow regularly: Use the graph to the right to make a bar graph that illustrates what you expect genotype frequency would look like if scenario #3 and #4 persisted for many generations. 5. The short ground clover is normally pollinated by a beetle that lives on the ground. This beetle does not often crawl up to the tallest flowers (perhaps because it would be more easily eaten by birds). However, as the tall GG plants become more common, butterflies begin to pollinate the GG plants (the butterflies rarely pollinate the short gg plants, perhaps because the flowers on the short plants are more difficult for the butterflies to reach). Fortunately for the clovers, there is enough pollen and pollinators to ensure that nearly every egg is successfully fertilized, regardless of the plants height and pollinator. Which evolutionary processes are involved in this scenario? Suggest a possible explanation for why birds might eat the beetles but not the butterflies. Use the graph to the right to make a bar graph that illustrates what you expect the genotype frequency would look like if scenario #5 persisted for many generations. (assume the herd of wandering goats does not return to this meadow). 6. It turns out that some of the taller plants eaten by goats in scenario 4 had already been pollinated and produced seeds with a protective outer coating. Therefore, the goats ate these seeds along with the flowers, and then wandered many miles away, depositing seeds as they went. Because the goats ate almost only the tall flowers, most of the seeds in their poop was the GG genotype. Some seeds were deposited in a remote meadow where only short (gg) clovers were growing while other seeds were deposited in a windy, rocky mountain pass where no clovers had previously existed. The butterflies and beetles that pollinate this clover don t usually visit rocky, windy areas, so the clover growing in the rocky areas became dependent on the wind to pollinate its flowers. Various alleles of another gene (H or h) affect the size and weight of the pollen, which then affects how easily the pollen is spread by the wind. Which evolutionary processes are involved in this scenario? 7. Within a few years, the clovers on the mountain pass grew into a lush clover patch; but in one particularly hard winter, 99% of the clovers froze and died. It turns out that one clover (and its few descendants) had a mutation that shifted energy storage from predominantly starch to a related a polysaccharide called inulin, and the inulin prevented these plants from freezing. Which evolutionary processes are involved? 60

8 Lecture # - Evolution part #2 Microevolution Lecture Review: Ch 27 Evolution Classify the following scenarios as examples of either artificial or natural selection by placing the letter for each scenario into the appropriate box below. Scenarios A. Rattlesnakes blend in with their wooded surroundings. B. Desert plants, such as cacti, are adapted to store water during dry conditions. C. A variation that increases the speed of a rodent increases its chances of escaping predators and reproducing. D. A dog breeder wants the agility of a border collie and the coloring of an Australian shepherd, so he breeds the two. E. A gardener choses the seeds from a rose that produces larger flowers to plant. F. Brussel sprouts, kohlrabi, and Chinese cabbage are domesticated plants that all descended from the same ancestor. Artificial Selection Natural Selection Use the terms on the right to complete the sentences below. Each term is used only once. All living organisms use similar biomolecules, suchas, RNA, ATP and proteins. This leads scientists to conclude that all life descended from a common ancestor that also used these. Organisms also use the same genetic code (Universal Codon Chart) to specify which is encoded by a particular 3- nucleic acid codon when building proteins. Thus, differences between species exist mainly due to small difference between the each one produces and uses. A. RNA B. DNA C. proteins D. amino acid E. biomolecules 61

9 Use the terms on the right to complete the sentences below. Some terms may be used more than once. Structures that are anatomicallly similar because they were inherited from a common ancestor are called structures. For example, the forearms of a bat, bird, whale and cat all contain the same of bones, but each serves a different. Some inherited structures are no longer necessary and lose their original function, in which case they are considered structures. The presence of these non- functional structures implies descent from an ancestor that once had a functional form. Oppositely, structures are those that serve the same function in two organisms, but are anatomically different and don t share a common ancestry. A. analagous B. function C. homologous D. arrangement E. vestigial The presence of structures, not analogous structures, is evidence that organisms are related. Scientists conclude that all life descended from a common ancestor because they share biomolecules such as DNA, RNA and proteins. Classify the following examples as either homologous or analogous structures by placing the letter for each example into the appropriate box below. examples A. Cactuses and spurges have convergent (similar but independent) adaptations to hot climates. B. Forearms of chickens, whales, and humans. C. Insect wings and bat wings. D. Structures that are related to each other because of descent from a common ancestor. E. Toe of a horse and wing of a bat. F. Arise because of adaptations to the same type of environment. G. Structures with the same function but different evolutionary ancestry. Homologous Structures Analogous structures Explain how vestigial traits and homologous traits (including both anatomical and biochemical features) support the theory of evolution. 62

10 Classify the following examples by placing the letter for each example into the appropriate box below. A. British land snails have two very different phenotypes as they are both adapted to different habitats. B. Individual finches within one population occupy different niches and eventually evolve to have different beak sizes. C. Very large and very small newborns are more likely to suffer serious health problems. D. Chloroquine is no longer effective against malaria because it has evolved resistance against it. E. A new flu vaccine is needed every year. F. Bird clutch size consisting of 4-5 eggs are more likely to hatch than larger or smaller clutches. Disruptive selection Stabilizing selection Directional selection Use the space below each graph to illustrate how the initial population distribution that is shown would change after undergoing disruptive, stabilizing, or directional selection. The x- axis represents the phenotype of the population being measured, such as the size of an animal (small animals on the left, medium sized animals in the middle, and larger animals on the right). The y- axis is the frequency of each phenotype in the population (i.e. the number of individuals in the population that are small, medium or large). Initial Population Distributions: small large small large small large size size size New Population Distribution After Selection: Disruptive selection stabilizing selection directional selection small large small large small large size size size 63

11 Use the terms on the right to complete the sentences below. Some terms may be used more than once. Sickle cell is a genetically inherited disorder that affects molecules that carry oxygen in the blood. Individuals that are have the sickle cell disease, while individuals that belong to the other two genotypes do not. Individuals that carry an allele for sickle cell also carry a resistance to malaria, as the sickle shaped lack and malarial parasites die. Therefore, individuals that are carry an advantage, as they are resistant to malaria and do not have sickle cell disease. A. autosomal dominant B. homozygous dominant C. heterozygous D. homozygous recessive E. autosomal recessive F. hemoglobin G. white blood cells H. red blood cells I. calcium J. potassium Use the terms on the right to complete the sentences below. Some terms may be used more than once. A process where small measurable changes occur from generation to generation is called. A process where large changes occur over long periods of time is called. This process requires, or the splitting of one species into two or more new species, to occur. The describes a species as groups of organisms that interbreed, have a shared, and are reproductively isolated from all other species. One limitation of this way of defining species is that it applies only to organisms. A. asexually reproducing B. biological species concept C. extinct D. gene pool E. macroevolution F. microevolution G. natural selection H. sexually reproducing I. speciation 64

12 Classify the following examples by placing the letter for each example into the appropriate box below. Examples of reproductive barriers A. F2 fitness B. habitat isolation C. gamete isolation D. zygote mortality E. hybrid sterility F. behavioral isolation G. temporal isolation H. mechanical isolation Postzygotic isolating mechanisms Prezygotic isolating mechanisms Use the terms on the right to complete the sentences below. Some terms may be used more than once. In order to mate, male blue- footed boobies must display an elaborate courtship dance. This is an example of. Because sugar maples and red maples occupy different habitats, they do not exchange pollen, even though they live in the same locations. This is an example of. Male insects of a species have reproductive genitalia that make it impossible to reproduce with females of other closely related organisms. This is an example of. Two species of termites live in the same location but don t mate because they have different breeding seasons. This is an example of. Pollen of one species of flower is not able to survive the journey to reach the egg produced in embryo sac of a flower of another species, so they cannot reproduce together. This is an example of. A. behavioral isolation B. habitat isolation C. mechanical isolation D. gamete isolation E. hybrid sterility F. temporal isolation 65

13 Classify the following examples by placing the letter for each example into the appropriate box below. Examples A. Speciation that is based on geographic separation. B. Organisms in different locations are subject to different selective pressures and evolve into different species. C. Organisms are reproductively isolated by postzygotic mechanisms and evolve into different species. D. Speciation that does not require geographic isolation. E. Bread wheat evolved from two species of wheat with different numbers of chromosomes. Allopatric speciation Sympatric speciation Use the terms on the right to complete the sentences below. Rapid and dramatic is a significant cause of extinction. The changed global weather patterns and the amount of shoreline and interior land, leading to the Permian mass extinction of and terrestrial organisms 250 million years ago. High levels of iridium and a large crater in the Gulf of Mexico indicate the impact of a giant during the Cretacious period 66 million years ago. This impact would likely have caused large environmental changes including a prolonged global winter, and is believed to have contributed to a mass extinction that killed of the. There appears to be an on- going mass extinction caused by. A. drifting of continents B. environmental change C. dinosaurs D. meteorite E. human- induced environmental changes F. marine 66

14 Lecture # - Evolution part #3 Human evolution Lecture prep: Watch the TED talk: Debunking the Paleo diet by Christina Warinner There is a link under the cool science tab on the course website. Compare this talk to the TED talk we watched earlier (Minding your mitochondria). Is there anything we can conclude from these two talks? Lecture Review: prepare for the unit #2 exam! 67