Coyne Book

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University of Toronto St. George
Jean Jiang Nash

Why Evolution Is True Chapter 1: What Is Evolution Life on earth evolved gradually beginning with one primitive species that then branched out over time, throwing off many new and diverse species. The mechanism for most but not all of evolutionary change is natural selection. 6 parts to this: 1) Evolution species undergoes genetic change over time. Differences based on change in DNA. 2) Gradualism takes many generations to make a substantial change 3) Common Ancestry recent ancestorsimilar trait, which creates natural classification this is strong proof for evolution. If we were created = no natural agreed upon classification 4) Speciation (splitting) ---starts with 2 populations of the same species that cannot interbreedexponential rise on the number of possible future species 5) Natural Selection requires individuals of species to vary genetically in ability to survive and reproduce causes species to look specifically designed for environment not perfect a. Mutations MOSTLY change in pre-existing trait. Rarely creates new ones. Descendants entirely dependent on ancestors pre-existing design. b. Natural selection produces the fitter species--- not the fittest 6) Non-selective mechanisms of evolutionary change simple random change in proportion of genetics caused by the fact that families have different numbers of offspring (not adaptive) Theory of Evolution ---documented set of principles that explains how and why evolution happens. Testable and can make verifiable predictions. Tests: fossil evidence of lineage; species show genetic variation, which accounts for speciation. Also, retrodictions: fact and data not necessarily predicted by evolution, but only make sense in the light of evolution. Chapter 2: Written In the Rocks Making the Record www.notesolution.comProcess: reach bottom of water; get covered by sediments (thus, rare fossils of dead plants and land animals); soft parts arent preserved causing a bias (explains lack of worms and jellyfish fossils); many are too buried in the earths surface to reach and many lost to natural forces like weather. Thus, fossil records severely incomplete. Relative age Layers dictate age, but not all layers laid down in one place. Must therefore cross-reference. (Same type of rock with same type of fossil= same age) Actual ageradioactivity. Different isotopes decay at different rates. (Radiometric dating) The Facts: Evidence of Evolution in Fossils 1) Early life simpler than complex modern life 2) Visible connected changes in lineage; most modern fossils have similar traits to living organisms 3) Transitional species in fossils (Darwin did not have this) transition ancestor differs in some respect to all descendants (not an intermediate mix of the two)i.e. birds and reptilesreptiles older so ancestor must have looked like a reptile- wings and other bird traits evolve so much later on in the lineage fossils need not be one single species but rather fossils that show linking traits (dating most important) 4) BacteriaSimple eukaryotes multicellular organisms (worms, jellyfish, sponges)terrestrial plants and tetrapodsamphibiansreptilesmammals and birds 5) Mosses and algaefernsconifersdeciduous treesflowering plants 6) Pace of evolution need not be evendue to fluctuating environment (strength of natural selection varies) 7) Not all species must evolve 8) On to Land: Fish to AmphibiansShubinCanadian Artic: Ellesmere Island: TIKTAALIKdirect link to lobe-finned fish and amphibians: had gills, scales, fins, flat head like salamander, eyes and nostrils on top of head and not on the sides, robust fins, had neck (fishes have no necks), STURDY RIBS THAT ALLOWED IT TO BREATH BOTH WAYS, STURDY LIMB BONES 9) Origin of Birds half a wing argument probably started with gliding:: ARCHAEOPTERYXmore reptile than bird, jaw with teeth, long bony tail,
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