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More on microevolution • Movie (Simpsons) Evolution Evidence • Fossil: Remnant or impression of organism that lived in the past • Mostly in sedimentary rocks Grand Canyon Evolution Evidence • Fossil types: – Organic: coal (reduced carbon: burns!). Evolution Evidence • Fossil types: – Source energy Coal seam Evolution Evidence • Fossil types: – Thank “Lumpy Coal”. Evolution Evidence • Fossil types: – Amber: fossil resin (conifer trees) Evolution Evidence • Fossil types: – Jurassic Park! Mosquitoes in amber to get dinosaur DNA Evolution Evidence • Fossil types: – Mineralize hard parts: “petrification” replaces organic molecules with rock Evolution Evidence – Ex, Petrified Forest National Park, Arizona. Evolution Evidence • Fossil types: – Cast: Original structure dissolves but sediments retain shape Casts of squid-like animal called an ammonite Evolution Evidence • Fossil types: – Casts: footprints!. Dinosaur footprints from Montana Evolution Evidence • Principle of superposition: Old rocks lower, young rocks higher. Evolution Evidence • Principle of superposition: Old rocks lower, young rocks higher. • “Relative dating”: age fossils relative to each other. Evolution Evidence • Fossils show how life evolved Cool fossils • Dinosaurs! • Reptiles dominated Mesozoic Era. Cool fossils • Dinosaurs! • Movie stars today!. T. rex skull Cool fossils • What killed them off? Asteroid impact. Cool fossils • Crater image (buried under ocean sediment) • (Earth owee!). Evolution Evidence • Radioactive dating: Decay radioactive isotopes determines time since formation Evolution Evidence • Radioactive dating: Decay radioactive isotopes determines time since formation Start 1 isotope, which gives off radioactivity and becomes another isotope (predictable rate) Evolution Evidence • Radioactive dating: Decay radioactive isotopes determines time since formation Rate measured by “halflife”: time for half original material to decay. Evolution Evidence • Radiocarbon dating: Radioactive Carbon-14 – Half-life (5370 years): good 4 fossils < 60,000 yr old Shroud of Turin (1988) 1260-1390? Evolution Evidence • Potassium-Argon dating: Radioactive Potassium forms Argon (volcanic rocks) • Half-life 1.3 billion years: good 4 fossils millions years old. • Relative ages converted to absolute ages (years) – Humans only in last 2 million years. Evolution Evidence • “Vestigial structures”: Nonfunctional remnants of useful structures. Evolution Evidence • Ex, some snakes: pelvis/leg bones • Human coccyx (“tailbone”). pelvic girdle coccyx (bones where many other mammals have a tail) small bone attached to pelvic girdle thighbone attached to pelvic girdle Evolution Evidence • Blind cave organisms. Vestigial (nonfunctional) eyes. Blind crayfish Evolution Evidence • Blind cave organisms. Vestigial (nonfunctional) eyes. Blind cave salamander Blind cave fish Evolution Evidence • Comparative anatomy: Same structures, modified to current use • Ex, vertebrate forelimbs Evolution Evidence • Comparative embryology (embryology: study of early stages of development): Embryos related organisms go through similar stages Evolution Evidence • Comparative embryology (embryology: study of early stages of development): Embryos related organisms go through similar stages fish reptile bird (chicken) mammal (human) Evolution Evidence • Molecular biology: compare DNA (nucleotide sequence) or proteins (amino acid sequence) Evolution Evidence • Molecular biology: compare DNA (nucleotide sequence) or proteins (amino acid sequence) • Similarity reflects relatedness. Evolution Evidence • Ex use: What is a quagga? • Native South Africa • Extinct by 1880s (hunting) One of 23 skins in museums Quagga stallion (drawing) Only quagga photographed alive (in London Zoo, 1870) Evolution Evidence • Horse or zebra? Plains zebras from South Africa Przewalski’s horse from Mongolia Evolution Evidence • DNA from museum skin: quagga type of zebra Evolution Evidence • Experimental evidence – Natural selection: peppered moths (England) – Dark and light forms (1 gene) Dark moth Light moth Evolution Evidence • Experimental evidence – Final twist: Pollution controls changing balance again!. Evolution Evidence • Experimental evidence – Natural selection: Galapagos Islands Evolution Evidence • Experimental evidence – Natural selection: Galapagos islands – Finch species eats seeds. Galapagos Islands : telephoto view from the space shuttle! Evolution Evidence • Experimental evidence – Bill size changes: food supply changes with climate. Evolution Evidence • Experimental evidence – Guppy experiment: guppies native to Trinidad Evolution Evidence • Experimental evidence – Guppy experiment – Involves sexual selection: males colorful. Attractive to females but helps predators find males! Evolution Evidence • Experimental evidence – Experiment: Move guppies to low predator site. Male tails became larger/more colorful Evolution Evidence • Artificial selection: Humans cause evolution by our activities – Intentional: Control breeding to change traits Evolution Evidence • Intentional: Control breeding to change traits • Ex: dog breeds. Evolution Evidence • Natural selection also caused evolution of dog-like species Evolution Evidence • Intentional artificial selection – Ex, wild mustard now cabbage, broccoli, kohlrabi, brussel sprouts, cabbage, cauliflower, etc. Wild mustard Foods you should eat more of! Evolution Evidence • Artificial selection: Humans cause evolution by our activities – Unintentional: Usually species we try to kill! – “Antibiotic resistance”: bacteria evolve to be unaffected by antibiotics Evolution Evidence • Ex, bacterium causes tuberculosis (TB) – Some strains now resistant to most antibiotics. Chest x-ray of TB patient TB bacteria Evolution Evidence • Antibiotic resistance solutions: – Use antibiotics only when needed – Develop new antibiotics! Evolution Evidence • Unintentional artificial selection: • Insecticide resistance Evolution Evidence • Solutions: • Look for new chemicals • Use “biocontrol”: natural enemies fight pest species. Biocontrol • Biocontrol ex: Cassava mealybug control • Cassava important crop in Africa. Biocontrol • Cassava attacked by pest (mealybug) • Caused large losses. Biocontrol • Parasite wasp found (attacks mealybug) • Now mealybug under control. Final Point • Humans: our gene pool is changing (we are evolving) Final Point • Human evolution • Ex: medical advances allow us to keep people with genetic disorders alive • But pass defective genes to offspring…….