Evolution I. The Origin Of Life A. Evolution = Species change over time B. Biogenesis = Life from life 1. Experiments disprove spontaneous generation a) Francisco Redi (1668)- Flies only come from egg’s of other flies I. The Origin Of Life b) Lazzaro Spallanzani (1700’s) 1) Air doesn’t form microorganisms 2) Boiled broth did not grow microorganisms 3) Opponents said boiling destroyed the “vital force” in air I. The Origin Of Life c) Louis Pasteur (1800’s) 1) Boiled broth in curved-neck flask (allows air in) 2) No microorganisms form till curved neck is removed I. The Origin Of Life C. Earth’s History 1. Earth is 4.6 billion years old 2. Radioactive Dating a) Radioactive isotopes are used to date fossils. b) The isotopes decay at a constant known rate. c) The time it takes for one half of the radioactive material to decay is called the half-life. I. The Origin Of Life 3. Organic Compounds a) Oparin /Haldane (1923) 1) Early earth contained ammonia, hydrogen, water vapor, and methane 2) No Oxygen 3) Volcanic energy, lightning, and UV radiation could create amino acids. Haldane Oparin I. The Origin Of Life b) Stanley Miller & Harold Urey (1953) 1) Experimented with Oparin’s hypothesis 2) Created all 20 amino acids, nitrogen bases, and ATP c) Sidney Fox 1) Produced proteinoids (abiotic polypeptides) 2) Dripped organic monomers on hot sand, clay or rock Urey Miller I. The Origin Of Life 4. First Life-Forms a) Thomas Cech 1) Ribozymes can act as enzymes and self-replicate 2) RNA appears to be the first genetic material b) Anaerobic prokaryotes appear about 4 billion years ago c) Photosynthetic prokaryotes appear 3.5 billion years ago d) Oxygen levels increase I. The Origin Of Life e) Ozone protects life from UV radiation f) Eukaryotes appear 2 billion years ago 1) Evolve by Endosymbiosis 2) Mutualism between small aerobic prokaryotes and larger anaerobic prokaryotes 3) Gave rise to mitochondria and chloroplasts Autotrophic bacteria became mitochondria and chloroplasts Anaerobic heterotrophic bacteria What is endosymbiosis? Explain natural selection in your own words. Use the following words: genetic variation, adaptation, overpopulation, struggle for existence. (minimum of 5 sentences; use text) II. Theories of Evolution A. James Hutton (1726-1797) 1. Geologist 2. Gradualism (1795) a) Processes today are the same as in the past b) Large changes are the accumulation of slow, continuous processes. II. Theories of Evolution B. Thomas Malthus (1766-1834) 1. Published essay on human population (1798) 2. Resources control populations 3. Influences Darwin on his ideas about organism’s struggle for existence II. Theories of Evolution C. Jean Baptiste Lamarck (1744-1829) 1. Naturalist 2. Inheritance of acquired characteristics (1809) a) Organisms change in response to the environment. b) Structures that are used become stronger, and structures that are not used become weaker. c) Pass new trait to kids II. Theories of Evolution D. Charles Lyell (1797-1875) 1. Geologist 2. Proposed Uniformitarianism (1830) 3. Processes that occur today have always occurred II. Theories of Evolution E. Charles Darwin (1809-1882) 1. Naturalist 2. HMS Beagle (1831) a) Made observations in the Galapagos b) Noted differences in finches on each island 3. 1844- begins writing The Origin of Species II. Theories of Evolution 4. Alfred Wallace (1823-1913) a) Sends manuscript on natural selection to Darwin (1858) b) Published that year 5. Darwin publishes The Origin of Species (1859) a) Descent with Modification b) Natural Selection is mechanism 6. Adaptive advantages are determined by nature 7. Fitness is an individual’s gene contribution to the next generation III. Evidence of Evolution A. Evidence from Fossils 1. Types: Imprints, molds (impressions), casts (filled impression), tracks, hard parts, actual remains. 2. Dating Fossils a) Absolute Dating- Radioactive isotopes b) Relative Dating 1) Sediments are layed down in strata 2) Lowest layers are oldest 3) A fossil's position in undisturbed rock gives its age relative to other fossils. III. Evidence of Evolution 3. The Fossil Record a) Creates the Geologic Time Scale b) Oldest fossils found are 3.5 billion years old and are prokaryotic cells (bacteria). c) Fossils show earth's changes (Organisms, Climate, Environment) 4. Biogeography- geographical distribution of species. 4. Biogeography- geographical distribution of species. III. Evidence of Evolution B. Evidence from Living Organisms 1. Homologous Structures a) Similar features that originate in a shared ancestor b) Structures may have different uses in adult, but come from same tissue in embryo. c) Analogous Structures 1) Identical functions 2) No embryo tissue in common 3) Not closely related III. Evidence of Evolution 2. Vestigial Organs a) Structures that serve no useful purpose. b) Shows relationship to organisms in which the structure is functional. 3. Embryology a) Similarities of embryos b) Embryo development repeats evolutionary history III. Evidence of Evolution 4. Biochemistry a) Enzymes and structures for important biological pathways are universal (respiration, photosynthesis) b) The more similar the amino acid sequences, the more closely related the species. c) Universal genetic code IV. Evolution of Populations A. Populations are the smallest unit that can evolve (adapt) B. Variation exists in a population 1. Due to resources- food, soil 2. Due to heredity- genotype C. Cause of variation in Genotypes 1. Mutation 2. Recombination (independent assortment, crossing-over) 3. Random fusion of gametes IV. Evolution of Populations D. Gene Pool 1. All genetic information in a population 2. Frequency of a certain allele in a population will determine the phenotype frequency E. Hardy-Weinberg Equilibrium 1. Allele frequencies stay the same in an undisturbed population (genetic equilibrium) 2. Allows scientists to measure changes in a gene pool A. V. Disruption of Genetic Equilibrium Mutation 1. Caused by mutagens 2. Change DNA producing totally new alleles 3. Most are harmful B. Migration 1. Immigration and emigration of individuals 2. Ensures gene flow V. Disruption of Genetic Equilibrium C. Genetic Drift 1. Change of allele frequencies due to random events 2. Small populations are highly affected D. Nonrandom Mating 1. Geographic proximity 2. Assortive matinglike to like V. Disruption of Genetic Equilibrium E. Natural Selection 1. Most significant factor in evolution of populations 2. Nature selects against non-fit individuals 3. Reduces harmful alleles 4. V. Disruption of Genetic Equilibrium Types a) b) c) d) Stabilizing Selection- towards the average Directional Selection- towards one extreme Disruptive Selection- away from the average Sexual Selection- females tend to choose VI. Speciation= 1 species becomes 2 A. When populations become significantly different B. Morphological Species Concept 1. Physically different 2. Problem- individual variation C. Biological Species Concept 1. Proposed by Ernst Mayr 2. A population that can interbreed 3. Problem- Extinct species? D. Modern Species Concept 1. Morphologically similar 2. Can interbreed to produce fertile offspring 3. Biochemistry –DNA, Proteins VI. Speciation E. Extinction can be a natural process 1. When conditions change too rapidly 2. When a species is out competed 3. When specialization restricts a lifestyle and conditions change VII. Human Evolution A. Hominids are extinct humans and immediate ancestors B. All hominids are primates 1. Moveable fingers and toes 2. Nails instead of claws 3. Color vision (unusual for mammals) 4. Binocular Vision VII. Human Evolution C. The First Hominids 1. Australopithecus a) A. afarensis (3 to 3.9 mya) 1) Lucy 2) Walked upright b) A. africanus (2.3 to 3 mya) 1) Taller and heavier than Lucy 2) Slightly larger brain 3) Probably not our direct ancestor VII. Human Evolution 2. Genus Homo a) H. habilis (1.6 to 2.5 mya) 1) “handy human” 2) Stone tools b) H. erectus (1.8 mya to 500,000 ya) 1) “upright human” 2) Hunted and used fire 3) Typical “cave-man” VII. Human Evolution c) H. sapiens (800,000 ya) 1) Neanderthals (230,000 to 300,000 ya) 2) Cro-Magnons (100,000 ya) a. Modern humans b. Out competed H. erectus and Neanderthals VII. Human Evolution D. African-origin Hypothesis 1. Based on similarities in mitochondrial DNA 2. Modern humans came from Africa 100000 to 200000 years ago.