Lecture 2

Lecture 2 - Lecture 2 Special Creation vs Darwin o...

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Lecture 2 Special Creation vs Darwin o Phylogeny (evolutionary history, genus of a species over generations) o Homology Common usage – study of likeness Biological definition – similarity due to inheritance Structural homology: mammalian forelimbs have same basic structure Developmental homology: similarities during development, despite differences in adult Molecular homology: similarities among organisms at the molecular level Genetic code Genetic flaws shared by different species o EVOLUTION AS FACT Pattern Three principles of natural selection o Variation within a trait o Variation is heritable o Some variants are better at reproducing and thus become more common over generations Accepted quickly o Natural selection drives adaptation Process Rejected initially The earth was too young o 1664 archbishop james ussher – earth is 5668 years old. o Lord Kelvin’s Theory Assumed earth began as molten rock = 7000 degrees F Knew size of earth and that temperature increase 1 degrees for every 50 ft of depth Using fourier’s equation of heat loss by conduction, he estimated the age of the earth Earth is 100 million years old Life began 2.7 – 3.7 billion years ago No mechanism for the creation of novel variation o Creationism – god creates variation o Orthogenesis – natural tendency towards complexity and perfection o Transmutationism- macromutations; “hopeful monsters” cats dragons o Lamarckism- acquired characteristics giraffes No mechanism for the inheritance of adaptations o Thomas Morgan and Mutation Worked with fruit flies
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Previously mutations were thought to be large, causing speciation or new morphological features Morgan quantified mutation, its mechanism, and its effect on the body. o Mechanism of inheritance Any beneficial adaptation will be diluted and eventually disappear o Weissman and Lamarckism Infamous mouse tail clipping experiment Debunked “soft inheritance” Inherited characters are from genes of successful parents. o Gregor mendel and inheritance Bread pea plants Discovered the principles of independent assortment and segregation Refuted blending theory and “soft inheritance” Provided evidence for distinct alleles, genotypes, dominance, and the rest of Mendelian genetics o Qualittative traits Can be classified on an either or basis Eye color, blood type, flower color Variation usually due t one or two loci o Quantitative traits
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This note was uploaded on 01/17/2012 for the course HILD 100 taught by Professor Lee during the Spring '11 term at UCLA.

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Lecture 2 - Lecture 2 Special Creation vs Darwin o...

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