EvolutionarySynthesis

EvolutionarySynthesis - The Evolutionary Synthesis Nothing...

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1 The Evolutionary Synthesis l Nothing in biology makes sense except in the light of evolution. z Dobzhansky, 1973, American Biology Teacher The Seeming Impotence of Natural Selection Selection can only eliminate variants—it cannot produce anything. Variants must arise from somewhere else—mutation, etc. The source of variation is the true cause of evolution l We are now standing at the deathbed of Darwinism, making ready to send the friends of the patient a little money to insure a decent burial. . . z (E. Dennert, At the Deathbed of Darwinism, 1904) Mathematics meets Mendelism: Hardy-Weinberg Equilibrium Punnett felt unhappy with his attempt to explain why recessive phenotypes still exist, and asked his cricket partner and Cambridge mathematician Godfrey Harold Hardy (1877-1947) Question: what happens to a Mendelian mutation? Hardy ` s approach: Assumed a 2-allele case: A and a, with starting ƒ = AA = 0.49, Aa = 0.42 and aa = 0.09 This gives an allele frequency of A = 0.7, a = 0.3 He demonstrated that this ratio would remain constant from generation to generation provided: – Population is large – Mating is random – No selection: All offspring combinations are equally successful – No migration in or out of the population – Mutation rate has reached equilibrium The same result was independently derived by Wilhelm Weinberg (1867-1937), pediatrician in Stuttgart
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2 Pearson and Fisher No love lost between them: l Fisher received an offer from Professor Pearson at the Galton Laboratory. Fisher ` s interests had always been in the very subjects that were of interest at the Galton Laboratory, and for five years he had been in communication with Pearson, yet during those years he had been rather consistently snubbed. Now Pearson made him an offer on terms which would constrain him to teach and to publish only what Pearson approved. It seems that the lover had at last been admitted to his lady ` s court—on condition that he first submit to castration. Fisher rejected the security and prestige of a post at the Galton Laboratory and took up the temporary job as sole statistician in a small agricultural research station [viz., Rothamsted Experimental Station] in the country. z (Box, 1978, p. 61) Ronald Aylmer Fisher and Population Genetics • Strategy of merging Mendelism and Darwinism through statistical analysis 1918: 1st paper, on l The Correlation between Relatives on the Supposition of Mendelian Inheritance. z – Argued that discrete Mendelian gene was the focus of selection – That from many independent Mendelian factors one could account for the continuous variation the Biometricians observed – Opposed Darwin ` s and Pearson ` s view of blending inheritance, and Galton ` s l Laws z Major contributions to the development of statistics, including the analysis of variance (ANOVA) Genetical Theory of Natural Selection (1930) • First half of book involved developing Fisher ` s concepts of genetics at the population level:
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This note was uploaded on 12/12/2011 for the course PHIL 147 taught by Professor Bechtel,w during the Fall '08 term at UCSD.

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EvolutionarySynthesis - The Evolutionary Synthesis Nothing...

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