Transcript Evolution
• Evolution Evolution Definition • Evolution – Change over time – Individuals Do Not evolve, only populations evolve – Change in the frequency of alleles in a population of time Evidence 1. Geologic Record • • Radioactive dating puts Earth at 4.5-5 Billion years old Fossils show evidence of change over time (oldest fossil is of bacteria dated 3.5 BYA) Types of Fossils Casts or Molds in Rock Sedimentary Rock best rock for fossils! Petrification Resin fossils Frozen Organisms Fossilization Relative Dating of Fossils • Look at Strata • Oldest is deepest unless an earth quake moved strata Further Evidence 2. Comparative Anatomy – Homologous vs. Analogous Structures Evidence 3. Comparative Embryology Evidence 4. Comparative Cytology – All living things made of cells – Most organelle similar structurally and functionally – Note: Prokaryotes=Unique cell wall, unique ribosomes, no membrane bound organelles Evidence 5. Comparative Biochemistry – Compare proteins, DNA etc… – Humans and Chimps have over 99% DNA similarity Wrong! Evidence 6. Vestigial Structures – Appendix – Tail bone – Hair on make chest? – Wisdom teeth? Theory of Evolution • Lamarck – Use and Disuse – Inheritance of acquired characteristics Theory of evolution • Lamarck disproven by Weismann Theory of Evolution • Charles Darwin 1. 2. 3. 4. 5. 6. Overpopulation Competition Survival of fittest Natural Selection Reproduction Speciation Did NOT explain how variations arise! Types of Natural Selection No Selecting Pressure Stabilizing Selection •Very short plants and very tall pants selected out •Too short-not enough sun exposure •Too tall-hit down by wind Types of Natural Selection Directional Selection •Ex. Giraffe neck length favored long and not short Disruptive Selection •Favor extremes •Ex. Blk, Wht, Grey rabbits with only blk and white rocks to hide Darwin • Galapagos Islands Adaptive Radiation •Migrate •Adapt (Natural Selection, Survival of Fittest) •Speciation Adaptive Radiation 1. Species A migrates from the mainland to the first island. 2. Isolated from the mainland, species A evolves to species B. 3. Species B migrates to the second island. 4. Species B evolves in species C. 5. Species C recolonizes the first islands, but is now unable to reproduce with species B. 6. Species C migrates to the third island. 7. Species C evolves into species D. 8. Species D migrates to the first and second island. 9. Species D evolves to species E. Modern Theory of Evolution • Darwin’s Variation and Natural Selection • Genetic basis to variations for mutation work done by DeVries What can cause for changes? Geographic Isolation What can cause for changes? Reproduction/Genetic Isolation Time frame for Evolution • Gradualism vs. Punctuated Equilibrium Time frame for Evolution Types of Evolution • Convergent – Similar adaptations based on similar needs – They are not evolving into 1 species Types of Evolution • Divergent • Coevolution • Parallel Hardy-Weinberg Principle • A population will NOT evolve if: – Population is large – There is no mutation in population – There is no migration – There is random mating p+q=1 p2+2pq+q2=1 • They studied the frequency of alleles in a population’s gene pool (genome=all genes in a organism) Origin of Life • Spontaneous Generation – Living things come from nonliving things Francesco Redi disproves Spontaneous Generation of Life Heterotroph Hypothesis • Primitive Earth Atmosphere – Water vapor – Hydrogen gas – Ammonia (NH3) – Methane (CH4) No Oxygen Gas (O2) Primitive Atmosphere • Evidence that volcanic eruptions release – CO2 – N2 – H2S – SO2 Heterotroph Hypothesis • World filled with energy – Lightning – UV Radiation – X-rays – Heat from lava Heterotroph Hypothesis • Oceans were hot and a perfect site to cook up things – Enough energy for form monomers of organic compound • Ex. Glucose, nucleotides, amino acids, glycerol, fatty acids Proof of this step • Stanley Miller Alternative theory of monomers… • Meteorites have been found containing water, pyrimidines, purines, sugars, amino acids Next Step of Heterotroph Hypothesis • Monomers fused to form Organic Polymers • Proof came from Sidney Fox experiment Monomers to Polymers • Hydrothermal vents rich in Iron Nickel • Iron Nickel can act as a catalyst • Hot pools evaporate and concentrate monomers for enhanced collisions Next Step • Coacervation – “Precursor Cells” – Conglomeration of Polymers Next Step • Rise of Anaerobic Heterotrophs (Precursor to Bacteria) – Took in glucose – Performed fermentation – Produced CO2 Next Steps • Evolution of membranes • Evolution of DNA and RNA • Heterotroph population explosion (-Anaerobic Heterotrophs) • CO2 in air • Evolution of Photosynthetic Bacteria (Cyanobacteria) (Anaerobic Autotrophs) • Ozone layer forms filtering harmful UV • O2 now in air • Evolution of Aerobic Autotrophs and Aerobic Heterotrophs