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Genetics and Evolution Ch. 5 • Selection Natural vs. artificial Fitness Galapagos Finch Directional, Stabilizing, Disruptive Selection Polymorphism = several forms of a species in same habitat • Microevolution vs. Macroevolution Microevolution: change in allele frequency Macroevolution: formation of new species Field Assistants Chesapeake Bay Retrievers= + Newfoundland Water Spaniel English Peppered Moth Example English Peppered Moth Example Before industrial revolution After industrial revolution Darwin’s 2 Major Ideas • Variation within an species (organisms of the same species do not look exactly alike) • Not all the offspring produced survive (there is a struggle for existence) Genetics • Chromosomes are made of DNA • DNA holds genes • Different forms of a gene = allele i.e. brown vs. blue eyes • Dominant = alleles that cover other alleles i.e. brown eye allele = B • Recessive = alleles covered up by other alleles i.e. blue eye allele = b • How many alleles for each trait??? 2 alleles for each trait! • Homozygous = your 2 alleles are the same i.e. BB (what color eyes?) bb (what color eyes?) • Heterozygous = your 2 alleles are different i.e. Bb (what color eyes?) • Genotype = genetic make-up, what alleles you have • Phenotype = appearance, what it looks like Macroevolution: formation of new species • Allopatric Speciation: formation of new species due to geographic (physical) barrier • Sympatric Speciation: formation of new species due to genetic mutation or reproductive isolation (although they occur together) • Adaptive Radiation: formation of new species due to new opportunities (niches) i.e. islands Origin of Life • Big Bang Theory: formation of the universe (20 billion years ago=bya) • Earth formed 4.5 bya Crust • First atmosphere: Core hydrogen, water vapor, carbon monoxide, carbon dioxide,nitrogen, methane, ammonia • What is missing?? FREE OXYGEN Miller Experiment Inorganic Molecules Organic Molecules Electricity (carbohydrates=sugars, Lipids=fats, proteins, DNA) (hydrogen, water vapor, CO2, CO, nitrogen, ammonia) No electricity 3.5 bya, so what could cause a spark? First life on earth 3.5 bya, prokaryotic cells Prokaryotic cells Eukaryotic cells (1.5 bya) Miller Experiment: the origin of life Plate Tectonics Plate Tectonics • What is it called, when plates move against each other? • An earthquake! • What is it called where the plates meet? • Earthquake fault • What earthquake fault do we live near? • San Andreas Fault • Earthquake Kit?? Continental Drift Continental Drift Pangaea: continents in one land mass Laurasia: Gondwana: N. America Europe Asia Africa, S. America Australia, Antarctica, India Cenozoic Mesozoic Paleozoic •Quaternary: modern man •Tertiary: radiation of mammals __________________________________ •Cretaceous: mass extinction of dinosaurs •Jurassic: dinosaurs dominant •Triassic: first dinosaurs __________________________________ •Permian: mass extinction of marine life •Carboniferous: first reptiles •Devonian: first amphibians •Ordovician: first fishes •Cambrian: marine life abundant •Precambrian: first life on earth Past vs. Current Extinction Past Current •Slow •Natural Causes •Extinction with replacement •Fast •Human Causes •Extinction without replacement
