EVOLUTION. B. Comparative cytology looking at the cell organelles of organisms, most are the same or very similar

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1 EVOLUTION I. Definition (1) change over time, (2) descent with modification, (3) change in allele frequency in a population II. Evidence A. Fossils direct & indirect remains of organisms preserved in media such as rock (sedimentary principle of superposition), tar, ice, amber. Dating can be done using C-14 (<100,000 years) as well as K-Ar B. Comparative cytology looking at the cell organelles of organisms, most are the same or very similar C. Comparative biochemistry looking at hormones, enzymes, blood, DNA D. Comparative anatomy 1. Homologous structures same on the inside but usually serve different functions *sign of evolutionary relatedness* Ex forelimbs of humans, cats, whales, bats & birds 2. Vestigial structures still present but no longer of any use *sign of evolutionary relatedness* Ex appendix, coccyx, wisdom teeth 3. Analogous structures same function but different structure

2 E. Comparative embryology looking at early embryological development of different organisms *sign of evolutionary relatedness* III. Theories of evolution A. Jean Baptiste Lamarck ( ) 1. Need individual organisms can develop structures as needed (Ex long neck of giraffe) 2. Acquired characteristics/inheritance traits acquired during a lifetime can be passed on to offspring *DISPROVED BY August Weismann (tails of mice) 3. Use and disuse structures get bigger/stronger the more they are used and get smaller/lost when not used. B. Alfred Russel Wallace ( ) & Charles Darwin ( ) Independently arrived at the idea of NATURAL SELECTION 1. More organisms are born than can survive influenced by Thomas Malthus populations grow faster than food supply. 2. Struggle for existence (competition) 3. Variation 4. Differential reproductive success

3 C. Theories on Time For Evolution Gradualism Punctuated Equilibrium D. Causes of Evolution 1. Geographic Isolation 2. Reproductive Isolation E. Terms of Evolution 1. Coevolution 2. Convergent evolution 3. Genetic drift 4. Bottleneck effect 5. Adaptive Radiation 6. Types of Natural Selection IV. Hardy-Weinberg Population Genetics A. Evolution will not occur if following 5 conditions are met 1. Large population (N) 2. Random mating 3. No mutations 4. No migration in or out of population 5. Natural selection is not taking place B. Hardy-Weinberg symbols p + q = 1 p = q = 1 =

4 C. Hardy-Weinberg equation p 2 + 2pq + q 2 = 1 Comes from crossing 2 heterozygotes pq x pq p q p pp pq q pq qq p2 = freq of homozygous dominant INDIVIDUALS pq = freq of heterozygous INDIVIDUALS q2 = freq of homozygous recessive INDIVIDUALS H-W Practice Problem 1: You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following: A. The frequency of the "aa" genotype. B. The frequency of the "a" allele. C. The frequency of the "A" allele. D. The frequencies of the genotypes "AA" and "Aa." E. The frequencies of the two possible phenotypes if "A" is completely dominant over "a." H-W Practice Problem 2: If 9% of the population shows the recessive trait, what is the % of the dominant allele in the population AND what is the % of heterozygous individuals? H-W Practice Problem 2 Answer Step 1 aa = q 2 Step 2 If aa = 0.09 Step 3 q = 0.09 = 0.3 p + q = 1 Step 4 therefore p = 0.7 p 2 + 2pq + q 2 = 1 Step (0.7)(0.3) = 1 Step = 1 H-W Practice Problem 1 Answer Step 1 aa = q 2 Step 2 If aa = 0.36 Step 3 q = 0.36 = 0.6 p + q = 1 Step 4 therefore p = 0.4 p 2 + 2pq + q 2 = 1 Step (0.4)(0.6) = 1 Step = 1

5 V. Oparin's Heterotroph Hypothesis theory of origin of life (Old Idea) A. Primitive Conditions of Early Earth 1. High Temperature/heat 2. Gases Present: CH4, H2O, NH3, H2 Not present: O2, CO2 or N2 gases H2 can combine (reduce) CO2 CH4, N NH3, SO4 HS 3. Under conditions of high temp, radioactivity and/or lightning small org cpds formed such as amino acids, sugars and nucleic acids. Over long periods aggregates (coacervates) formed and took in smaller molecules as nutrition 4. Miller-Urey Tube Simulated conditions of primitive earth in a lab setting and were able to produce organic molecules from the "prebiotic soup" VI. Heterotroph Hypothesis updated (Prevailing Idea) 1. Water gets into rock and reacts chemically. Gets subducted along with rock then heated which releases energy (very important) and H (also important). H can combine (reduce) CO2 CH4, N NH3, SO4 HS 2. Basic (high ph) rather than acidic (low ph) like black smokers 3. Warm rather than hot (300 C) 4. Intricate hives (mimics cells) rather than chimneys 5. Iron-sulphur minerals have catalytic properties i.e. fool's gold 6. All ingredients needed for organic cpds are present 7. Natural gradient found between acidic ocean water (dissolved CO2) and alkaline vents (WITSO?) VII. First organisms were anaerobic heterotrophs Anaerobic heterotrophs CO2 autotrophs O2 aerobic heterotrophs VIII. Vertebrate life originated in oceans Fish Amphibians Reptiles Birds Mammals

6 EVOLUTION QUIZ 1. According to the heterotroph hypothesis, a) Anaerobic and aerobic organisms evolved simultaneously b) Photosynthetic autotrophs evolved first, since they required only energy from the sun and simple inorganic molecules from the environment c) Autotrophs evolved before a carbon source was made available d) Anaerobic heterotrophs evolved first 2. Which of the following characterizes Lamarckian evolution? a) Evolutionary change happens instantaneously b) An animal that uses a particular trait often pass that trait on in a reduced form because of overuse c) The function of a body part plays no role in evolution d) Acquired traits can be passed on from parent to offspring e) Selection pressures evolutionary change 3. The hypothesis that chloroplasts and mitochondria were originally prokaryotic organisms living with eukaryotic hosts is supported by the fact that mitochondria and chloroplasts possess a) Protein synthesizing ability b) Genetic material c) A plasma membrane d) Ribosome e) All of the above 4. All of the following are homologous structures except a) Horse forelimb b) Whale flipper c) Human arm d) Lobster claw e) Dog front paw 5. Recent studies of the fossil record indicate that evolution may occur in short "spurts" followed by long periods of little or no activity. This concept of evolution is known as a) Gradualism b) Darwinism c) Founder effect d) Lamarckism e) Punctuated equilibrium 6. When two groups of unrelated organisms come to resemble each other and develop similar adaptations, they have undergone a) Divergent evolution b) Parallel evolution c) Adaptive radiation d) Convergent evolution e) Coevolution

7 # of individuals # of individuals 7. Which of the following is not a characteristic of Darwin's theory of evolution? a) Survival of the fittest by natural selection b) Variation among members of a population c) Populations tend to produce more offspring than can survive d) Acquired characteristics are inherited e) There is competition among members of a population 8. The emergence of 13 species of Darwin's finches on the Galapagos Islands is due to: a) Convergent evolution b) Adaptive radiation c) Coevolution d) Artificial selection e) Parallel evolution 9. A species of finch was under observation on a small, isolated island in the South Pacific. Scientists measure the beak width of a wide selection of individuals. Forty years later, a second team returned to the island and found a new distribution (indicated below). Graph 1 Graph 2 Beak Width Beak Width According to graph 2, what happened to the finch population over time? a) Coevolution b) Directional selection c) Speciation d) Disruptive selection e) Founder effect 10. A strong beak is needed to open a big seed. What would happen to the beak width of the original population if seeds on the island grew progressively larger for 40 years and no other changes in the environment occurred? (a) (b) (c) (d)

8 Data on five species of finches (1-5) were collected from a large population of sexually mature individuals on the Galapagos Islands. The full range of values obtained for each species is presented in the table above. The skull of species 5, shown holding a cactus spine, belongs to a species of tool-using finch. These so-called woodpecker finches use their tools primarily in food gathering. Species Number Head Brain Volume (ml) Beak Length (cm) Eye Socket Volume (ml) Beak Thickness (mm) Diet Omnivorous, opportunistic Small seeds & small fleshy fruit Insects Large seed and large fleshy fruit Boring insects and ants ???? 11. Considering the diets of species 2 and 4, the beak shapes may be useful in which of the following actions I. Crushing II. Cracking III. Probing a) II only b) III only c) I and II only d) II and III only e) I, II and III 12. Features of species 4 that allow it to consume large seeds include which of the following? I Smaller eye sockets II Thicker beak III Heavier teeth a) I only b) II only c) I and II only d) II and III only e) I, II and III 13. Finches of species 5 use the cactus spine as a tool for a function analogous to that of a) Human molars b) Dogs' incisors c) Porcupines' quills d) Turkeys' gizzards e) Anteaters' tongues 14. Based on the data, the most likely diet of species 6 is primarily a) Flower nectar b) Small seeds and small fleshy fruit c) Insects d) Large seeds e) Large fleshy fruit 15. In constructing a key to identify these finches, which of the following would be the LEAST useful characteristic? a) Shape of skull and beak b) Brain volume c) Eye-socket volume d) Beak length e) Beak thickness 1)d 2)d 3)e 4)d 5)e 6)d 7)d 8)b 9)d 10)b 11)c 12)b 13)e 14)b 15)b