7_Macroevolution 9_10_2009

7_Macroevolution 9_10_2009 - Macroevolution(Ch 24.3 and...

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1 Macroevolution* (Ch. 24.3 and parts of other sections) *evolutionary change at or above the species level Many can accept microevolution but not macroevolution (e.g. Michael Behe, The Edge of Evolution, 2007) 2 From Speciation to Macroevolution Macroevolution is the cumulative effect of many speciation and extinction events 3 The Modern Synthesis Established in the 1930s and 1940s Connected the units of evolution (genes) with the mechanism of evolution (selection on populations) Integrated Darwinian evolution with Mendelian genetics + 4 Architects of the modern synthesis JBS Haldane G Ledyard Stebbins Theodosius Dobzhansky Sewall Wright (no need to memorize these guys)
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5 Natural selection is the primary mechanism of adaptive evolution Natural selection accumulates and maintains favorable genotypes in a population Depends on existence of heritable, genetic variation 6 Populations evolve, individuals do not In case you didn’t get that Populations evolve, individuals do not 7 Evolutionary Processes Mutation and sexual recombination produce new variation Selection, drift and gene flow alter a population’s genetic composition 8 Mutations The raw material of evolution A “two edged sword” - most mutations are deleterious but a few are beneficial and these provide the basis for evolutionary change A partial list of kinds of mutations Point mutations Insertions / Deletions Gene duplications Chromosome inversions Polyploidization
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