1. Constant Allele Frequencies Hardy-Weinberg Equilibrium

2. Population  An interbreeding group of the same species within a given geographical area  Gene pool the collection of all alleles in the members of the population  Population genetics the study of the genetics of a population and how the alleles vary with time  Gene Flow alleles can move between populations when individuals migrate and mate

3. Allele Frequencies Allelic # of particular allele Frequency total # of alleles in the population  Count both chromosomes of each individual  Allele frequencies affect the genotype frequencies The frequency of each type of homozygote and heterozygote in the population

4. Phenotype Frequencies  Frequency of a trait varies in different populations Table 14.1

5. Microevolution and Macroevolution  Microevolution Genetic change due to changing allelic frequencies in populations  Macroevolution The formation of new species

6. Allelic frequencies can change when there is:  Nonrandom mating Individuals of one genotype are more likely to produce offspring with each other than with those of other genotypes  Gene flow e.g. migration  Genetic drift Reproductively isolated groups form within or separate from a larger population  Mutation Introduces new alleles into the population  Natural selection Individuals with a particular genotype are more likely to produce viable offspring

7. Hardy-Weinberg Equilibrium  Developed by mathematicians  A condition in which allele frequencies remain constant  Used algebra to explain how allele frequencies predicts genotype and phenotype frequencies in equilibrium

8. Hardy-Weinberg Equilibrium p + q = 1 All of the allele frequencies together equals 1 or the whole collection of alleles p = allele frequency of one allele (e.g. dominant) q = allele frequency of a second allele (e.g. recessive) p 2 + 2pq + q 2 = 1 All of the genotype frequencies together equals 1 p 2 and q 2 =genotype frequencies for each homozygote 2pq = genotype frequency for heterozygotes 2 possible combinations (p egg + q sperm or vice versa)

9. Figure 14.3

11. Table 14.2

12. Applying Hardy-Weinberg Equilibrium  Used to determine carrier probability  Homozygous recessive used to determine frequency of allele in population (phenotype is genotype)

13. Applying Hardy-Weinberg Equilibrium: Cystic Fibrosis

14. Calculating Carrier Frequency for X-linked Traits Figure 14.6

15. DNA Profiling (a.k.a. DNA Fingerprinting  Hardy-Weinberg equilibrium applies to portions of the genome that do not affect phenotype They are not subject to natural selection Short repeated segments that are not protein encoding, distributed all over the genome  Detects differences in repeat copy number  Calculates probability that certain combinations can occur in two sources of DNA  Requires molecular techniques and population studies

16. Preparing DNA for Profiling – Restriction Enzymes  Chop up the DNA at specific sequences using “restriction enzymes”  Creates RFLPs Restriction fragment length polymorphisms

17. Preparing DNA for Profiling –Running a Gel  Run samples on an agarose or polyacrylamide gel DNA has a negative charge so it will travel toward a positive charge Larger fragments will not move as far through the gel

18. DNA Profiling  Developed in 1980s  Identifies individuals  Used in forensics, agriculture, paternity testing, and historical investigations  DNA can be obtained from many sources

19. DNA Profiles Figure 14.9

20. DNA Profiling  Types of repeats Variable number tandem repeats (VNTRs) Short tandem repeats (STRs)  Shorter than VNTRs  Useful if DNA from sample is fragmented or degraded mtDNA  Useful if nuclear DNA is highly damaged

21. A Sneeze Identifies Art Thief Table 14.6

22. Comparing DNA Sequences Figure 14.10