Evolutionary Thought: Ancient Philosophers to Modern Discoveries, Study notes of Biology

Download Evolutionary Thought: Ancient Philosophers to Modern Discoveries and more Study notes Biology in PDF only on Docsity! 1 Principles of Evolution • Has become a unifying principle in Biology • For >150 years, stimulated controversy – mostly nonscientists • Initial theory sparked controversy within science and biology The History of Evolutionary Thought Early History • Preceded Darwin • Ancient philosophers explained nature in terms of – What they imagined to be true – Not based on observation • In 1500s, European philosophers began to exhibit discontent 1. 427–347 B.C.—Plato 2. 384–322 B.C.—Aristotle - Scala Naturae The History of Evolutionary Thought 3. Until 1700's—Creationism • James Ussher (17th century, “Biblical”) Sunday, October 23, 4004 BC a. Each species was created individually by God b. Earth was the center of the universe c. Man stood atop creation The History of Evolutionary Thought 2 4. 1707–1788—G.L. Buffon—creation provided a relatively small number of founding species that evolved through natural processes 5. 1769–1832—G. Cuvier—theory of catastrophism The History of Evolutionary Thought The History of Evolutionary Thought 6. 1807–1873—L. Agassiz— new creation after each catastrophe: proposed at least 50 separate catastrophes and creations 7. 1726–1797—J. Hutton— developed uniformitarianism 8. 1797–1875—C. Lyell— supported Hutton 9. 1744–1829—Lamarck—inheritance of acquired characteristics The History of Evolutionary Thought Where Idea Came From? • Darwin’s Voyage on “Beagle” shaped many ideas of Biology • Purpose of voyage – Sail around world & survey little known coastal areas Darwin’s Finches • Galapagos formed from volcanoes • Finch ancestors came from South America – Different islands, different environments – Today – each island has own species 5 Evidence of Evolution Fossils 1. Transitional forms are evidence of evolutionary change 2. Controversies over the interpretation of fossil data a. Dating of fossils b. Do fossils really show transitional forms? Stages of Fossilization (a) (b) (c) Teeth became larger and harder, reflecting a change in diet from soft leaves and buds to more abrasive grasses. Selection for fast running on the open plains favored the evolution of stout, strong legs and large, hard hooves. If a modern horse had small teeth like these, the teeth would be ground away while it was still very young. Body size increased, perhaps in response to selection by predators. Merychippus Hyracotherium forefoot tooth Paleotheres Archaeohippus Anchitherium Pliohippus Mesohippus Hipparion Equus br ow si ng gr az in g Evidence of evolution • Comparative anatomy Homologous structures Evidence of evolution • Comparative anatomy All mammals evolved from common ancestor 6 Evidence of evolution Comparative anatomy Analogous structures have similar form & function, but are structurally quite different Evidence of evolution Convergent evolution Unrelated organisms evolve similar adaptive characteristics Evidence of evolution Comparative anatomy: Vestigial structures These vestigial bones are similar in structure to those of the salamander but serve no function. All three animals inherited the bones from a common ancestor. salamander whale snake Evidence of Evolution Comparative embryology All vertebrate embryos look similar to one another in early development, with the development of a tail and gill arches Fish Snake Chicken Mouse Human Evidence of Evolution Comparative biochemistry and molecular biology All cells have DNA, RNA, ribosomes, the same 20 amino acids, and use ATP as an energy carrier Evidence of Evolution Comparative biochemistry and molecular biology DNA similarities 7 Evidence of Evolution • Artificial selection Is Evolution Happening Today? Recent examples 1. Antibiotic resistance in bacteria 2. Pesticide resistance in insects Patterns in Evolution? • Different from original Darwin model – Gradualism – Darwin described evolution as a slow & gradual process – Evolution may occur more rapid than earlier thought • “Punctuated equilibrium” – Evolution does not always occur Patterns in Evolution? Present-day Evolution Key concepts 1. The variations upon which natural selection works are produced by chance mutations 2. Selection produces organisms that are well adapted to a particular environment