1. Mutation & genetic variation

2. Mutations

3. gene – stretch of dna that codes for a distinctive type of rna or protein allele – versions of the same gene that differ in their base sequence mutation – any change in the base sequence of dna Mutations

4. Types of mutations Point mutation Frameshift mutation Gene duplication Chromosome inversion Polyploidy

5. Point mutations are single base substitutions in DNA Point mutation

7. Genetic code

8. Frameshift mutation

10. Gene duplication

11. Duplicated loci can: -retain their original function and provide an additional copy of the parent locus -gain a new function through mutation & selection -become functionless pseudogenes Gene duplication

12. Chromosome inversion

13. Inversions change gene order and decrease the frequency of crossing over As a result, the alleles inside the inversion tend to be inherited as a unit Chromosome inversion

14. Polyploidy

15. Polyploid populations are reproductively isolated from their parental species Polyploidy

16. Fitness effects of mutation

17. Mutation rate SpeciesTaxonmutations/genome/ generation E. colibacteria0.0025 S. acidocaldariusarchaea0.0018 S. cerevisiaefungi0.0027 C. elegansroundworm0.0360 D. melanogasterinsect0.1400 M. musculusmammal0.9000 H. sapiensmammal1.6000

18. Mutation rates vary among species because of differences in the number of cell divisions that take place prior to gamete formation Human400 cell divisions Fruit fly 25 cell divisions Mutation rate

19. If more than one allele exists at a particular locus, a population is said to be polymorphic at that locus Polymorphism

22. One third to one half of all coding loci are polymorphic in a typical population Polymorphism

23. Selectionist theory - genetic diversity maintained by natural selection Neutral theory - genetic diversity maintained because it is not eliminated by selection Why are populations genetically diverse?