BIOL 112 1nd Edition Lecture 6 Outline of Last Lecture I Analogy II Biogeography III Population genetics Outline of Current Lecture I Variation within a population II Variation between a population III Sources of genetic variation a Mutations b Sexual reproduction IV Hardy Weinberg Equation V Application of H W Current Lecture In breeding of remaining animals o Genotypes Bb and Bb or Bb X Bb B b B BB Bb B Bb bb of progeny white Polygenic vary over a continuous range Variation within a population o Discrete traits single locus mendelian No intermediate forms o Quantitative traits have to measure vary over a range polygenic phenotype conferred by multiple loci who products interact Ex Human height Variation between populations o Ex Clinical variation graded change in a character trait along a geographical transient 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 o Ex From text Ch 23 frequency of lactate dehydrogenase enzyme allele B in fish populations from Maine Georgia Main population B 1 Georgia population B 0 o B allele encoded enzyme woks best in cold climates Therefore selected in Maine but not Georgia Sources of genetic variation o 1 Mutation BUT minor Mutation rate for DNA genomes is about 1 100 000 genes genomes But mutations are the ONLY source of new alleles Mutation types Nonsense STOP codon termination of translation translated protein Missense alteration in an amino acid ex SER ACA Deletions Duplications Not all mutations are delirious Ex Gene duplications olfactory receptor genes Each receptor binds different types of molecules they smell The more receptor genes an organism has the more types of molecules they smell o Ex Rodent receptor gene humans o 2 Sexual reproduction Major source of genetic variation Get recombination random mating random association of gametes All result in fresh combinations of alleles and variation in phenotypes Microevolution changes in allele frequencies over generations Hardy Weinberg principle o Mendel s laws if allele frequency in a population don t change just shuffled around then NO EVOLUTION is occurring o Analogy shuffling a deck of cards does NOT change the content of the deck Application of H W o 1 Test whether evolution is occurring Measure allele frequencies at T 1 T stands for time Compare allele frequencies at T 2 If frequencies changed has evolved In reality no such thing as a non evolving population
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