The role of Genetics and DNA in Evolution

The role of Genetics and DNA in Evolution (Ch 16. 1) Dec 2018 Biology 11 1

The Role of Genetics in Evolution § Darwin knew that traits were inherited, but not how they were inherited. § Genes provide the variation necessary for evolution. 2

§ Recall: There are 2 mechanisms of variation: 1. Meiosis. This reshuffles genes creating new combinations of genes. 2. Mutation. This provides new genes. Both result in the variation necessary for evolution to occur. 3

§ Variation is random. Combinations of genes are determined by chance, as are the resulting variations. 4

§ Variation provides the raw material for natural selection. 5

§ Now recall: § Gene l a section of DNA code that determines the traits of an organism § Alleles l Different forms of a gene at a particular point on a chromosome. 6

Genotype vs Phenotype § Genotype = l GENETIC makeup § Phenotype l PHYSICAL make up or characteristics § E. g. You may have brown eyes with BB or Bb 7

Gene pool = l The collection of genes held by all members of a population. 8

§ A population (definition) l l Is a collection of individuals of the same species in a given area whose members can breed with each other. Example: • The wolves of Jasper National Park • Brown bears in Southern BC 9

§ Relative frequency of alleles l The number of times an allele occurs in a gene pool compared with the number of times other alleles of the same gene occur. 10

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