FA2008 - BILD 3 - Lecture 05 (Population Genetics - 01)

FA2008 - BILD 3 - Lecture 05 (Population Genetics - 01) -...

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10/14/08 1 Lecture 5 The Genetics of Populations Reading Ch 23 Natural selection changes allele frequencies because some ________ survive and reproduce more successfully than others a. Alleles b. Traits c. Gene pools d. Species e. Individuals Evolution occurs in populations but Natural selection acts on individuals Overview I. What is a population II. Probability III. Hardy Weinberg Equilibrium IV. Violations of Hardy Weinberg I. Population – interbreeding individuals Devil’s hole pupfish - entire population (species) lives in one small lake in Death Valley Eel, Anguilla rostrata , lives in rivers throughout eastern N. America, but all migrate to Bermuda to breed, all part of same population II. Probability Probability – formal study of the laws of chance How likely is it that something will happen? Probabilities are always between 0 and 1
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10/14/08 2 1. Chance of two events happening: Chance of getting heads on toss of penny = 1/2 Chance of getting heads on toss of nickel = 1/2 Chance of tossing a penny AND a nickel and getting heads on both = 1/2 * 1/2 = 1/4 Combined chance of 2 independent events - multiplication problem 2. Chance of one OR another event happening: Chance of getting 6 on one roll of die = 1/6 Chance of getting a 5 on one roll of a die = 1/6 Chance of getting a 6 or a 5 on one roll is 1/6 + 1/6 = 2/6 = 1/3 Chance of one OR other independent events - addition problem III. Hardy-Weinberg Equilibrium Principle What would the genetic composition of a population be, if that population were NOT evolving? What would the genetic composition of a population be, if that population were NOT evolving? Why is this an interesting question? Null model – basis for comparison Definitions - review • gene - the functional unit of heredity • allele – alternative forms of a gene • locus – location on a chromosome (pl. loci)
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10/14/08 3 For now, we are concerned with a population: diploid sexually reproducing population 2 possible alleles at a locus (A 1 , A 2 ) Definitions - review • homozygote - same 2 alleles at a locus (AA,
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This note was uploaded on 03/31/2009 for the course BILD 632282 taught by Professor Henter during the Spring '08 term at UCSD.

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FA2008 - BILD 3 - Lecture 05 (Population Genetics - 01) -...

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