Evolution The Tree of Life A Summary of the Development of the Theory of Evolution over Time
Pre Darwin 320 B.C. Aristotle-Metaphysical Classification System Linnaeus-Morphological Taxonomic System Hutton-Gradualism Malthus-4 Horsemen of the Apocalypse Lamarck-Adaptation Cuvier-Catastrophism Lyell-Uniformitarianism. 1858Wallace-Natural Selection.
Darwin HMS Beagle On the Origin of Species 1859 Big Ideas: Natural Selection or “Survival of the Fittest” & Descent with Modification. Variation + Overproduction = Natural Selection Evolution. Evidence: Fossil Record, Artificial Selection, Geographic Distribution, Embryology, Homology & Vestigial Structures.
Neo-Darwinism ’s Microevolution: Evolution of Populations Mendelian Genetics rediscovered Hardy-Weinberg allele frequencies & equilibrium Wegener Biogeography-Pangaea, Continental Drift & Plate Tectonics. Big Ideas: Genetic Drift, Gene Flow, Founder Effect, Bottleneck Effect & Heterozygous Advantage. Types of Selection: Directional, Disruptive, Stabilizing & Sexual.
Modernism 1950’s-1990’s Speciation: Darwin’s “Mystery of Mysteries”. “The bridge between Microevolution and Macroevolution.” What is a species? New definitions had to be developed. Reproductive Isolation & Hybrid zones. Prezygotic & Postzygotic Barriers. Allopatric Barriers-Geographic.
Modernism 1950’s-1990’s (continued) Sympatric Barriers-Behavioral, Temporal & Polyploidy (Plants). Speciation Rates, Mass Extinctions & Punctuated Equilibrium ’s Biotechnology, Genetic Engineering, DNA analysis, HOX genes & Phylogenetic Trees Human Genome Project & Gene Mapping.
Post Modernism Evolutionary Development or “Evo-Devo” 1980’s- Today Type of DNA Amount Research Type of Evolution Homeobox (HOX) Found on every chromosome Somewhat Understood Macroevolution Regulatory Sequences At least 5% of DNA Poorly Understood Both Genes Only 1.5% of DNA Very Well Understood Microevolution FunctionBasic body plan design. Where and when body parts develop. Activate Regulatory Sequences. Series of specific directions (switches) on how, when and how much genes are expressed. Code for proteins. Humans have about 23,000 genes. Same as most animals. SignificanceMostly the same for Families of organisms. Small mutations cause major changes in structure. Can cause rapid and extreme evolution such as loss of legs. Very complex specific steps on how to assemble body structure. Mutations cause structural changes and complex diseases. Building blocks of bodies (structural). Control chemical reactions (enzymes). Immune system (antibodies). ExamplesHead goes here, nervous system develops first, eye goes there, etc. Same within a species. Ex. All the steps and materials to make an eye. Epigenetics: cancer, MS, diabetes etc. Small variations among individuals. Ex. Eye color. Cause genetic diseases. Ex. Sickle Cell Anemia.