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Transcript
Evolution The change in a population’s genetics over time The history of Evolution • People first thought that life originated by spontaneous generation – Nonliving material gives rise to living material – i.e. that maggots and flies spontaneously appear in rotted food web.utk.edu/.../5rubrics/graphics/04_01.gif History continued • Redi- tested the spontaneous generation hypothesis-1668 – Discovered that rotting meat does NOT produce maggots – Thought this only applied to large organisms, not microbes History continued- mid 1800s • Pasteur- demonstrated that microorganisms are not spontaneously generated The Control: The Experiment: Biogenesis • Living organisms can only come from other living organisms http://www.historyoftheuniverse.com/images/cell_division.gif http://www.kingsstilecottage.co.uk/images/lion-with-cubs.jpg So… Where did life begin? • Oparin- hypothesized that life began in the ocean from organic molecules – Inorganic molecules from volcanoes and evaporation were in atmosphere – Lightning storms caused inorganic molecules to fuse – became organic – (C, H, O) – Rain washed organic molecules into ocean – Life began there http://southdakotapolitics.blogs.com/south_dakota_politics/images/2008/04/20/fertilization2.jpg Miller and Urey • Tested Oparin’s hypothesis Lightning Atmosphere Rain Volcanoes Ocean Miller and Urey – Discovered that organic molecules could be made from inorganic – Organic molecules were produced in the closed system Endosymbiosis Theory Possible evolution of mitochondria (aerobic organisms) and chloroplasts (plants) http://faculty.ircc.edu/faculty/tfischer/images/endosymbiosis.jpg Evolution Video How do we know evolution happens? Evidence for evolution It took Charles Darwin 2 decades to develop his theory of evolution What evidences did he look for? • Fossils-earliest record of life – Deep are simple, oldest – Shallow are complex, newest (in undisturbed rock layers) http://www.sculpturegallery.com/three/fossil_fish.jpg Evidence for evolution • Anatomy: – Homologous Structures • Same structure, different function • Ex. Bones of human, whale, crocodile – Analogous Structures http://taggart.glg.msu.edu/isb200/HOMOL.GIF • Same function, different structures • Ex. Bird wings, butterfly wings – Vestigial Structures http://www.citruscollege.edu/pic/46/0345l.jpg • Organ with no function today, but worked in the past • Ex. Pelvic bones in snake, hip bones in whale http://www.answersingenesis.org/assets/images/articles/ee/v2/whale-vestigial-structure.jpg Evidence for Evolution • Embryology – Study of developing fetus/baby – All vertebrates have some common characteristics – Ex. Tail bones, gill slits – Show common origins apps.carleton.edu/.../photostock/193602.jpg Evidence for Evolution • Biochemistry – Compare DNA and proteins – More common points = close relationship Mimio Review Cladogram Shows evolutionary relationships based on similarities: •In characteristics •DNA or amino acids More in common = closer COMMON ANCESTOR Results Copy into lab Notebook: Biochemical Evidence of Evolution Number of Differences in Amino Acid Sequences Human Human Chimpanzee Gorilla Other Chimpanzee Gorilla Other 0 0 0 0 Lab Questions/Analysis • Sketch a cladogram to show the evolutionary relationships • Which organism is most closely related to humans? • Explain how you determined this? • Briefly describe the process of using amino acid sequences or DNA to determine evolutionary relationships among organisms. The Mechanism How Does Evolution Happen? Lamarck- Inheritance of acquired characteristics • Organisms acquire adaptations during lifetime • Adapt because they have to • Use and disuse – Variation gained during lifetime – Giraffe’s neck got longer through use – Trait passed on to offspring Does variation exist in a population or is it acquired through a lifetime? Let’s find out… Problems with Lamarck Expected • Cut off mouse’s tail Actual • Cut off mouse’s tail • Has offspring with no tail • All offspring have tails!!! Charles Darwin ~ 1831 • “Father of Evolution” • Studied in Galapagos Islands • Developed theory of evolution by natural selection – First to propose logical mechanism – Organisms with favorable traits will survive to reproduce and pass on traits to offspring Darwin’s Giraffes • Variation already exists • Favorable adaptations = survival • Avg neck length increases with time 4 aspects of Natural Selection • Overproduction – more offspring are born than can survive, not all survive • Variation – individuals in a population vary in characteristics • Competition – organisms with favorable variations survive and reproduce • Populations change – over time favorable traits (inherited traits) increase in a population Natural selection • Populations evolve through natural selection • 3 main types of natural selection 1. Stabilizing selection 2. Directional selection 3. Disruptive selection Stabilizing selection • Natural selection that favors the average individual Directional selection • Favors one extreme variation of a trait – Ex. the giraffe with the longest neck maybe able to reach more food Disruptive Selection • Both extreme variations are favorable – Ex. light and dark shells blend in, medium are seen and eaten Variation Lab Purpose: Does variation exist in a population? You will be given 10 peanuts. Open the shells and measure each shell. Record the length (in millimeters) of each shell in the data table. We will make a tally sheet from each group for the class data table. Group Data Peanut 1 2 3 4 5 6 7 8 9 Length in mm 10 Length (mm) Class Data Length (mm) 16 - 20 21 - 25 26 - 30 31 – 35 36 – 40 41 – 45 46 – 50 51 – 55 56 - 60 Variation Lab Analysis Due to variation, we need a large sample size (class data). Analysis: 1. What is the largest peanut shell in the sample? 2. What is the smallest shell in the sample? 3. What is the mean value of shell lengths? 4. What is the mode of shell lengths? 5. Draw a bar graph of the results. Dependent variable is # of pods, Independent variable is pod size. 6. What is the shape of the curve over the bars of the graph? 7. What type of selection does this represent? Adaptations the process or structure that enables organisms to become better suited to their environment www.doe.virginia.gov/VDOE/LFB/glossary/index.html http://www.lapshin.org/nikita/cacti/Echinocactus-grusonii2.jpg Adaptations • Camouflage – ability to blend into surrounding environment http://3quarksdaily.blogs.com/3quarksdaily/images/wolfe_seal_1.jpg http://lpmpjogja.diknas.go.id/kc/a/animal/animal-camouflage-1.jpg Adaptations • Mimicry - resembling another species or object to hide, for protection from predators http://abc-rags.tripod.com/Peru/StickInsect.JPG http://mrgrassosclass.com/images/mimicry.gif Competition Activity Purpose: Does variation allow for success in competition for resources? Macaroni Rubber Bands Paper Clips Toothpicks Spoon Scissors Tweezers Clip Make a data table for your group and for the class data. Enter Data Here Competition Activity Analysis 1. What strategy was used to get the most food? 2. What variation was best for each type of food? Use data to support your answer. 3. How does this relate to natural selection? a) Competition b) Variation c) Overproduction – How do new species form? • Speciation- the evolution of new species – Species can only reproduce with the same species to produce fertile offspring • 3 ways for speciation to occur 1. Geographic isolation 2. Reproductive isolation 3. Adaptive radiation www.bio.indiana.edu/.../broodxmovies/index.htm Geographic Isolation • 2 populations separated by geography (river, mountain, etc.) • Cannot cross barrier • Stop reproducing become 2 different species • Ex. mice separated by mountains Rocky Mountains Reproductive Isolation • Can occur 2 different ways 1. populations become different in reproductive (courtship) behavior and stop reproducing 2. Incompatible DNA • Ex. songbirds with different or incomplete songs Adaptive radiation • A common ancestor leads to many variations • Species fill many niches, cause divergent evolution • Ex. Galapagos finches Hawaiian birds Common Ancestor Convergent Evolution • unrelated species have similar adaptations while living in different locations – Ex. Euphorbia and Organ Pipe cactus: cactus like plants share fleshy body types and no leaves (one in deserts of Africa, other in deserts of N. and S. America) http://www.milosh.net/photo/usa99/organ1.jpg http://cactiguide.com/graphics/x_noncacti_euphorbia_600.jpg How fast does speciation occur? • 2 timeframes for speciation 1. Gradualism 2. Punctuated equilibrium • Both result in new species http://stowa.de/shop/pix/a/z/antea365/b1.jpg Gradualism • Species originate gradually through a number of adaptations Punctuated Equilibrium • Quick rapid bursts of change (adaptations) followed by periods of stability Fishy Frequency Lab Purpose: Will gene frequencies change over time? Color # before selection Frequency before selection # after 1st selection Frequency after 1st selection Blue (p) Clear (q) Total p+q=1 # after 2nd selection Frequency after 2nd selection Fishy Frequency Lab Analysis 1. What happened to the frequency of the blue colored fish? Why? 2. What happened to the frequency of the clear colored fish? Why? 3. Which colored fish had the advantage (selected for)? Why? 4. How would Darwin have explained these results?