Evolution: Requirements for Evolution—A change in the allele frequency of a population over time. Requirements: 1. Genetic Variability—may come from mutations and immigration. 2. More offspring are produced than can survive (due to limited resources, predation, etc…) 3. Some organisms must be better adapted than others. 4. There must be differential reproduction rates due to the adaptive characteristics of some members. Fitness Fecundity

Hardy-Weinberg Equilibrium Genetic Equilibrium Hardy-Weinberg Law Defined evolution by describing when it would not happen. There are 5 requirements that must be met for genetic equilibrium to occur. Requirements 1. No mutations. Germ cell mutations bring about evolution. Somatic cell mutations are not passed on to offspring. 2. No immigration or emigration. (No gene flow) 3. There must be a very large population in order to avoid genetic drift. Genetic Drift—unpredicted changes in allele frequencies due to chance. Usually occurs in small, isolated populations. 4. There must be no natural selection. 5. There must be no sexual selection. Mating must be random.

Hardy Weinberg Problem Set 1 In humans, brown eyes are dominant over blue eyes. In a population of 1000 individuals, 750 have brown eyes. Assume the population is in Hardy Weinberg Equilibrium. A. What are the frequencies of the dominant and recessive alleles? B. How many individuals would you expect to be heterozygous (from #1)? C. What is the expected frequency of each possible genotype?

Hardy Weinberg Problem Set 2 Out of a population of 60 people in a small town in Kentucky, 1 person has blue skin (an autosomal recessive trait). Three people in the population are carriers for the trait. Assume the population is in Hardy Weinberg Equilibrium. A. How many total alleles (blue and normal) are in the gene pool for this trait? B. What are the allelic frequencies for this trait? C. What are the genotypic frequencies for the trait? D. If the population is in genetic equilibrium and the original population produces 140 children, how many of these children will be carriers for blue skin?

Hardy Weinberg Problem Set 3 In a given population of mice, brown hair (B) is dominant to blond hair (b). Within the population of mice, there are 125 brown haired mice out of a total population of 300 mice. Assume the population is in Hardy Weinberg Equilibrium. A. What are the frequencies of the dominant (p) and recessive alleles (q)? B. What is the predicted frequency of heterozygous mice? C. What is the predicted frequency of homozygous brown mice? D. How many mice are heterozygous?

Hardy Weinberg Problem Set 4 In a given population of 200 insects, there exist 121 alleles for the recessive trait of purple exoskeleton color. Assume the population is in Hardy Weinberg Equilibrium. A. What are the frequencies of the dominant (p) and recessive alleles (q)? B. What is the expected number of insects with purple exoskeletons? C. Give the three genotypic frequencies for this population.

Hardy Weinberg Problem Set 5 After graduation, you and 19 of your closest friends (lets say 10 males and 10 females) charter a plane to go on a round-the-world tour. Unfortunately, you all crash land (safely) on a deserted island. No one finds you and you start a new population totally isolated from the rest of the world. Two of your friends carry (i.e. are heterozygous for) the recessive cystic fibrosis allele (c). Assume that the frequency of this allele does not change as the population grows (the population is in Hardy Weinberg Equilibrium). A. What is the frequency of the recessive cystic fibrosis allele? B. What is the frequency of the dominant allele? C. In future generations, what is the expected frequency of individuals affected with cystic fibrosis?

Hardy Weinberg Problem Set 6 In a population of frogs, the allele for brown skin is dominant to the allele for green skin. A. A drought leads to selection against green-skinned frogs. When the drought ends, 33 percent of the remaining frogs have green skin. If the population enters and remains in Hardy Weinberg equilibrium immediately upon the end of the drought, what will the frequency of the green skin allele be after three additional generations? B. What is the frequency of the brown skin allele after three additional generations? C. If there are 350 frogs in the population, how many of them are expected to be heterozygous? D. How many of the 350 frogs are expected to be homozygous dominant?