Transcript Evolution
Evolution • spontaneous generation (abiogenesis) – the idea that life comes from nonliving things Redi – experimented with meat in jars, one covered with cheesecloth; maggots appeared in open jar Redi’s experiment Spallanzani – experimented with broth in flasks,heated both, put a stopper in one; stoppered one stayed clear, open one became cloudy *Pasteur – experimented with 2 flasks with broth heated, bent the neck into S-shape on one; open one became cloudy *finally disproved spontaneous generation Spallanzani’s experiment Pasteur’s experiment biogenesis – the idea that life comes from living things Oparin – hypothesized that organic compounds formed in warm seas and energy from the sun or lightning allowed the compounds to form more complex molecules to form the first organism Miller – tested Oparin’s hypothesis in the lab Earth’s first atmosphere Miller’s experiment 1st organism is thought to be a bacterium – • prokaryotic • asexual • heterotrophic • anaerobic • evolution – a change over time Charles Darwin developed currently accepted theory of evolution of life on Earth from common ancestry (common descent) Evidence for evolution 1) fossil record (Geologic time scale) – collective history of Earth’s climate and organisms fossil – preserved remains of ancient organisms 4.5 billion years – estimated age of Earth paleontologists – scientists who study fossils Fossils Evidence for evolution 2) homologous structures – structures which originate from the same body region ex: human arm and bat’s wing vestigial structures – structures once necessary in ancestral forms, but no longer needed today ex: appendix, coccyx, wisdom teeth Homologous structures Vestigial structures Evidence for evolution analogous structures – structures which perform a similar task ex: fly wing and bird wing 3) comparative embryology – embryos of similar organisms have very similar early development indicating similar DNA at work Analogous structures Embryological similarities Evidence for evolution 4) biochemical similarities – comparing protein structure in all organisms to find similarities & differences Biochemical similarities Natural Selection Darwin – developed the idea of natural selection – organisms with favorable traits are more likely to survive and reproduce; “survival of the fittest” Natural Selection fitness – combination of physical traits and behaviors that allow an organism to be more successful in its environment adaptation – any inherited characteristic that increases an organism’s fitness for survival Natural Selection Darwin – developed the idea of natural selection – organisms with favorable traits are more likely to survive and reproduce; “survival of the fittest” fitness – combination of physical traits and behaviors that allow an organism to be more successful in its environment Natural Selection Lamarck – thought acquired traits could be passed on to future generations ex: giraffe neck length Natural Selection Peppered moth (Biston betularia) In the 1800’s in Manchester, England these moths lived in tree groves. Two varieties were seen: a speckled (peppered) moth due to a dominant allele & a black moth due to a recessive allele. Before Industrial Revolution Natural Selection Before the Industrial Revolution, lichen-covered trees were light in color, dark moths were eaten more. After the Industrial Revolution, lichens absorbed soot & tree bark became dark in color, light moths were eaten more. After Industrial Revolution