Unit 8: Evolution!!!

1. Unit 8: Evolution!!! The Origins of Life (Notes #1)

2. History… • History of Evolution – • Evolution = species change over time • Biogenesis = Life from Life • Scientific experiments disproved spontaneous generation • Earth’s History – • Earth = 4.6 Billion years old • Radioactive dating = radioactive isotopes are used to date fossils • Isotopes decay at constant known rate • Rate it takes for one half of radioactive material to decay = half-life

3. Hypothesis • Oparin/Haldane Hypothesis – • Scientists Oparin & Haldane in 1923 • Hypothesis = volcanic energy, lightning & UV radiation could create amino acids • 1st Life = • Proposed by Thomas Cech • Created ribozymes – can act like enzymes & self-replicate • RNA = first genetic material • Anaerobic prokaryotes appear ~ 4 billion years ago • Photosynthetic prokaryotes appear ~ 3.5 billion years ago • Oxygen levels increase • Ozone begins to form – protects life from UV radiation • Eukaryotes appear ~ 2 billion years ago • Evolve by Endosymbiosis = mutualism between small aerobic prokaryotes & larger anaerobic prokaryotes • Gave rise to mitochondria & chloroplasts

4. Evolutionary Scientists • Evolutionary Scientists – • Aristotle: • Believed species were fixed creations arranged by their complexity – belief lasted 2,000 years • George Cuvier: • Studied sedimentary rocks & found some species completely disappeared in recent layers • Catostrophism: • Stated species disappear due to catastrophic event of Earth’s crust (volcano, earthquake…)

5. Evolutionary Scientists cont. • Evolutionary Scientists: • James Hutton – • 1726-1797 Scottish Geologist • Studied invertebrate fossils in Paris Museum • Proposed: • Layers of rock form very slowly – forces beneath Earth’s surface move rocks up, then bury them, then push them up from sea floor to form Mountain ranges • Gradualism: • Large changes are the accumulation of slow, continuous processes

6. Evolutionary Scientists cont. • Evolutionary Scientists: • Charles Lyell: • 1797-1875 • Proposed: • Theory of Uniformintarianism • Processes that occur today have always occurred; Geological processes occur at uniform rates; building & wearing down of Earth’s crust • Lyell’s Principles of Geology: • Past events must be explained using observable processes since processes that shaped Earth millions of years earlier continue in the present • Examples: • 1) Volcanoes: release hot lava & gasses now just like they did in the past • 2) Erosion: Continues to carve out canyons

7. Evolutionary Scientists cont. • Evolutionary Scientists: • Jean Baptiste Lamarck: • 1744-1829 – a Naturalist • One of the first scientists to understand that change occurs over time • Stated that: • Changes are adaptations to the environment that an organism acquires over a lifetime • Acquired changes are passed to offspring

8. Evolutionary Scientists cont. • Evolutionary Scientists: • Jean Baptiste Lamarck: • Theory of Evolution: • 1. Tendency toward perfection: • Organisms have a tendency toward complexity & perfection so they can continue to change & acquire features that help them live more successfully in their environment • Ex: Birds – over generations birds kept trying to fly & their wings increased in size & became suitable for flying

9. Evolutionary Scientists cont. • Evolutionary Scientists: • Jean Baptiste Lamarck: • Theory of Evolution: • 2. Use & disuse: • Organism could change the size or shape of organs by using them or not using them • Ex: Birds – use their front limbs for flying & eventually those limbs would evolve into wings • Ex: Birds – if they did not use their wings (disuse), wings would decrease in size & eventually disappear

10. Evolutionary Scientists cont. • Evolutionary Scientists: • Jean Baptiste Lamarck: • Theory of Evolution: • 3. Inheritance of acquired traits: • The selective use or disuse of organs or characteristics during an organisms lifetime • These traits could then be passed on to their offspring & overtime could lead to new species • Ex: if you spent more time lifting weights to build big muscles, your children would inherit big muscles

11. Evolutionary Scientists cont. • Evolutionary Scientists: • Jean Baptiste Lamarck: • Errors in his theory: • He didn’t understand how traits are inherited (traits are passed through genes) • Genes are not changed by activities in life – an organisms behavior has no effect on its inheritable characteristics • He did develop a scientific theory of evolution & realized that organisms are adapted to their environment

12. Evolutionary Scientists cont. • Evolutionary Scientists: • Thomas Malthus • 1766-1834 • Published essay on human population • Amount of resources control the size of the population • Influenced Darwin on his ideas about an organism’s struggle for existence • Proposed: • If human population continued to grow unchecked, sooner or later there would be insufficient living space & food • The only circumstances that affected growth were: • War, famine & disease

13. Evolutionary Scientists cont. • Evolutionary Scientists: • Charles Darwin • 1809-1882 – Naturalist • Joined crew of HMS Beagle (1831) – 5 year (1831-1836) voyage around the world • Avid collector • Main observations occurred on the Galapagos Islands – volcanic islands off the coast of the cost of South America • Mainly observed: Finches (Darwin's Finches) & Tortoises

14. Evolutionary Scientists cont. • Evolutionary Scientists: • Darwin's Observations: • Patterns of diversity between species were shown • Unique adaptations in organisms was observed • Species were not evenly distributed across regions (ex: Australia = kangaroos, but no rabbits) • Formed idea: all living organisms share common ancestor • Argued – new organisms come from pre-existing organisms & each new species comes from another species = Descent with Modification

15. Evolutionary Scientists cont. • Evolutionary Scientists: • Darwin's Observations cont: • Evolution = • Slow, gradual change in a population of organisms over time • Fitness = • Ability of an organism to survive & reproduce • Increased fitness arises from adaptations – certain adaptations allow organisms to become better suited to their environment (and survive & reproduce) • Natural Selection: • Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than a less fit individual • The process whereby organisms better adapt to their environment – and reproduce and survive – drives evolution • In 1844 began writing The Origin of Species – not published until 1859