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EVOLUTION 101 Darwin developed his revolutionary proposal over time, influenced by the work of others and by his travels. March 2, 2016 Agenda: - Power Words - Biotechnology FRQ - Darwin’s Ideas Notes Charles Darwin Section 1 and 2 • An English naturalist • 5 year voyage on the HMS Beagle • Galapagos Islands • Journal: Observations, questions, and discoveries • Published “Origin of the Species” 1859 Darwin travels the world Unity and Diversity of Life Darwin’s Ideas 1. Descent with modification: Living and extinct animals descended by reproduction from pre-existing species. 2. Theory of Natural Selection 1. Overproduction: Organisms have more offspring than will survive to adulthood 2. Genetic variation: There are variations among populations 3. Struggle for Survival: Individuals compete for resources; some win, some lose. Some variations (adaptations) improve their chances. 4. Differential reproduction: Well adapted survive, reproduce, & pass on the traits that helped them win (Survival of the fittest) After MUCH time, the population contains mostly favorable traits Galapagos Finches Example of “descent with modification” • • • • 13 Different species on the islands Specific beak shape and size Correlated with food source on island Suspected they diverged from a smaller group of ancestors Overproduction Overproduction and Genetic Variation What determines survival? Adaptations. – Need traits that will help them survive • predators • disease • competition for food • competition for territory – Traits that help individuals reproduce • so they can attract a mate • compete for nesting sites • successfully raise young – New species arise from gradual accummulation of adaptations over long period of time in response to changing environment. Acclimatization (To acclimate) A short-term process in which physiological changes take place in a single being in its own lifetime. Example: An animal adjusting to a new climate by growing thicker fur. Small changes over long periods of time, multiple generations. Adaptation Survival & Reproduction of the Fittest Bug… Why does evolution matter now? 1. Drug Resistant Pathogens 1. HIV: Resistant to Drug 3TC 2. Multi-Drug Resistant TB 3. DDT Resistant Mosquitoes 4. MRSA: Resistant Staph bacteria 2. Natural Selection = Edits and Selects, It does not Create Natural Selection vs. Artificial Selection Artificial Selection Domesticating wolves 15,000 years ago Dog breeders Choose specific animals with specific traits to reproduce. Only heritable traits, not acquired traits are passed to offspring. Key Misconceptions: Individuals do not evolve. The population does. A favorable trait in one environment may be detrimental in another. Evidence of Natural Selection and Evolution Section 3 • Direct Observation • Paleontological – Fossils • Distribution of Fossils • Transitional Species – Biogeography • Anatomical and Embryological • Molecular From fossils we can infer, – Adjacent/Horizontal Layering • Different organisms lived at different times. – Radioactive Dating – Half-lives – Relate Age Dating – When and where an organism existed – Species have existed in gradual sequence over time The Smoking Gun: The Walking Whale • Even though scientists could predict what early whales should look like, they lacked the fossil evidence. • The smoking gun came in 1994, when paleontologists found the fossilized remains of Ambulocetus natans, "swimming-walking whale.“ – Its forelimbs had fingers and small hooves but its hind feet were enormous given its size. • When it swam, it moved like an otter, pushing back with its hind feet and undulating its spine and tail. • Modern whales propel themselves through the water with their tail flukes but Ambulocetus still had a whip-like tail and had to use its legs to provide most of the propulsive force needed to move through water. Livescience.com Fossil skeleton sequence of whales. Horse Fossils Biogeography • Darwin observed animals that seemed closely related yet lived in different environments. • Pangaea/Continental Drift Anatomical Evidence • Homologous • Analogous • Vestigial Anatomy and Embryology • Similar bone structure. – Homologous structures or organs, inherited from common ancestors – look the same but might have different function Homologies: Embryological Evidence Phylogeny or Cladogram: Shows relatedness/ancestry Phylogeny Branch length indicates time/evolutionary change or both Cladogram A difference cause of resemblance • Analogous structures, have related functions but don’t look the same. – Example #1: Birds, bats and moths have wings, but the underlying structure is different. • Convergent Evolution: Independent evolution of similar features with a different lineage – Example #2: Marsupials vs. Eutherians Similar features. Different Lineage. Sometimes different Biogeography. Anatomy • Vestigial Structures: Seem to serve no function but resemble structures with function • Psuedogenes p474 – Human tailbone – Pelvic bone of modern whales – Human Appendix Questions Molecular Evidence: Which is closest to humans? If humans and chimps have similar DNA this must mean… A. Humans and chimps share a common ancestor B. Humans evolved from chimps C. Chimps evolved from humans D. Convergent evolution led to DNA similarities Comparing DNA Sequences – Which two species are the most similar? Homologous, Analogous or Vestigial Structure? Least likely homology… A. B. C. D. E. Wings of bat and arms of human Hemoglobin of baboon and that of gorilla Mitochondria of plant and that of animal Wings of bird and that of insect Brain of cat and that of a dog