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Evolution is change over time Proof of evolution ◦ ◦ ◦ ◦ ◦ Fossils Comparative anatomy Embryology Cytology Biochemistry The sequence of amino acids in the cytochrome c molecule, an enzyme found in mitochondria, is identical in humans and chimpanzees fossils Composition: molten body solid crust surface (hot) Atmosphere – probably gases from volcanic eruptions ◦ Oxygen-poor Eventual cooling, formation of oceans life on Earth (~3.5 billion yrs ago) Heterotrophic Hypothesis: organic chemistry may spontaneously form from inorganic chemistry autotrophs developed after the evolution of heterotrophs partly because the primitive environment of the Earth lacked carbon dioxide Miller-Urey Experiment First cells: prokaryotic Prokaryotes have no nucleus and no membrane environmentsbound (like organelles ◦ Small ◦ Capable of living in extreme deep sea vents) ◦ Then the appearance of photosynthesizing prokaryotes (cyanobacteria) Production of oxygen ozone layer appearance of eukaryotes ~1.8 billion years ago Endosymbiont Theory: eukaryotic cell ancestors living in association with prokaryotic cells Evidence for the endosymbiont theory ◦ mtDNA & cpDNA, and its circular arrangement ◦ Prokaryotic ribosomes ◦ Mitochondria and chloroplast reproduction by fission Eukaroytes have a nucleus and membrane bound organelles Lamarck- use and disuse ◦ When environments changed, organisms had to change their behavior to survive. ◦ If they began to use an organ more than they had in the past, it would increase in its lifetime. ◦ If a giraffe stretched its neck for leaves, for example, a "nervous fluid" would flow into its neck and make it longer. ◦ Its offspring would inherit the longer neck, and continued stretching would make it longer still over several generations. ◦ Meanwhile organs that organisms stopped using would shrink. Darwin- natural selection Finches Peppered moth game peppered moth simulation Ant simulation Conditions vital to this process are ◦ Overproduction ◦ Finite resources ◦ Genetic variation (mutation and sexual reproduction including crossing over) Adaptive value ◦ Selection by the environment of those better able to survive and reproduce “survival of fittest” ◦ Stabilizing selection: favors a mean, eliminates extremes (ex: birth weight) ◦ Directional selection: favors one extreme (ex: peppered moth) ◦ Disruptive selection: favors two extremes, eliminates the mean (ex: Northern water snakes color patterns) Camouflage: Cuttlefish, Leafy Sea Dragon Mimicry: evolving to resemble another species (drone fly, ash borer) • Gradualism: selection and variation that happens more gradually Over a short period of time it is hard to notice Punctuated equilibrium: change comes in spurts ◦ There is a period of very little change, and then one or a few huge changes occur