BCOR 12 1st Edition Lecture 3 Outline of Last Lecture I Evidence for Evolution II Evolution Process and a pattern III Darwin s Main Observations and inferences IV Important Points about Natural Selection Outline of Current Lecture I Microevolution mechanisms II Genotypes and allele frequencies III The Hardy Weinberg Principle IV HW assumptions Current Lecture The Evolution of Populations Chapter 23 Natural selection and evolution are NOT synonyms Natural selection directed change works on the INDIVIDUAL level Microevolution a change in allele frequencies in a population over time at the molecular level The mechanisms that cause evolutionary change I II Natural selection directed change Gene flow random change due to migration of new individuals and alleles into the population III Genetic drif random change the random fluctuations from one generation to the next a Founder effect b Bottleneck effect go into more detail in next lecture IV Mutation random change in the nucleotide sequence of an organism s DNA individual level Smallest unit that evolution can occur is population we determine frequency of alleles by taking in consideration of whole population These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Population group of individuals of the same species that can interbreed and produce fertile viable offspring Community populations living among other populations Evolution at the molecular level involves changes in the gene pool of a population Gene pool all of the alleles present in all individuals in a population Allele alternative form of a gene at the same locus location in a DNA sequence Problem What is the allele frequencies of p in a population of 100 flowers with the following genotypes 50 pp 25 Pp 25 PP Alleles of P of p PP 50 50 0 Pp 50 25 25 pp 100 0 100 75 125 Total the number of alleles is double the amount of individuals with the certain genotype for there are two alleles present Frequency of p Total of p alleles in population total alleles in population Frequency of p 125 200 625 or 62 5 Hardy Weinberg Equation can be used to test whether or not a population is evolving P2 pq q2 1 p dominant trait frequency q recessive trait frequency p q 1 Allele frequencies genotype frequencies Hardy Weinberg Equation Five Assumptions I II III NO mutations Random Mating no sexual selection NO natural selection IV Extremely large population size no genetic drif V NO gene flow If any of these assumptions are not followed then the Hardy Weinberg will not apply and the population will be evolving If a population follows all of the assumptions of the Hardy Weinberg then the population is NOT evolving and the allele frequencies will remain constant over time
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