Transcript Darwin
Evolution Evidence and Theory Biology 2009 Charles Darwin Natural Selection Organism best suited to their environment will survive and reproduce Population Interbreeding of a single species HMS Beagle Darwin was a naturalist on the H.M.S. Beagle 5 year mapping and collecting expedition of South America Darwin observed finches of Galapagos Islands 13 species with different beaks but all similar The Origin of Species (1859) Book stating Darwin’s Theory 21 years of refining after trip to Galapagos Descent With Modification Newer forms are modified descendents of older forms because of VARIATION Variation Subtle differences between individuals Modification with Natural Selection Environment limits population growth because of variation Organisms with more favorable traits will survive and pass on traits to offspring. Unfavorable traits will die out thus changing the population Adaptation Adapt To change genetically over generations to be more suited to the environment Adaptive Advantage An organism that adapts will more likely survive and reproduce Ex. giraffes Geographic Isolation Separation of populations as a result of geographic change or dispersal to isolated places Adaptive Radiation Evolution from a common ancestor that results in diverse species adapted to different environments Punctuated Equilibrium Species often diverge in spurts of rapid change followed by periods of stability Evidence of Evolution Fossils Traces of a dead organism often found in layers of sedimentary rock Mold Imprint in rock of shape of organism Cast Rock-like model of organism More Fossil Stuff Law of Superposition Successive layers of rock are deposited on top of one another by wind or water Stratum - Layer of Earth Relative age - Use stratum to say whether fossil was older or younger Absolute age - Age in years depending on layer above it Succession Forms Extinct Disappearance of a species Mass Extinction Brief period when large number of species disappeared Homologous Structures Similar Features that originated from a common ancestor Beaks of finches Forelimb of vertebrate animals Vestigial Structure Structures that were useful to an ancestor but not to modern organism Human tailbone Once a tail Pelvic bones in snakes Previous attachment of legs Similarities in Embryos Vertebrates had common ancestors Ontogeny Recapitulates Phylogeny Embryo - fertilized egg that develops into an individual Develop and look alike Similarities in Biochemistry Many species with common ancestors share similar proteins, DNA, and RNA Human vs Gorilla hemoglobin protein Amino Acid sequence has 1 different Amino Acid Human Vs. Frog 67 differences in hemoglobin protein