Population Genetics I

1) What were the positions of the mutationist and selectionist schools in the early 20th century?

2) Hardy and Weinberg independently created a mathematical model that showed the conditions necessary for the genetic structure of a population to remain in equilibrium. State these conditions.

3) If no real population meets these conditions exactly, how can the model be useful?

4) Consider this population:

Calculate the genotypic and gene frequencies.

Calculate the expected genotypic frequencies for this population in HWE.

Conduct a chisquared goodness of fit test, comparing the observed genotypic frequencies (60, 20, 20, not 0.6...etc.) with what you would expect if the population was in HWE. (Remember to compute expected number of individuals, not percentages/fractions (not 0.49).

5) The frequency of the CCR-32 allele vairies across human populations, with a higher frequency in populations of northern European ancestry than African or Asian ancestry. Although these differences might arise by chance (like differences in the frequency of A,B, or O alleles in human populations), the fact that this allele confers resistance to HIV and some other viruses suggests that it might be high in some populations because of previous selection. What two pieces of evidence - one experimental and one correlational - suggest that this might be related to smallpox epidemics in Europe?

6) Hemachromatosis is one of the most common hereditary diseases of caucasian populations, causing enriched iron levels in the blood that can result in cirrhosis and diabetes. The frequency of individual afflicted with hemachromatosis in some populations is 1/200. If Hardy-Weinberg is assumed, what is the frequencie of heterozygous carriers?

7) Consider a population with p = 0.7 and q = 0.3. Suppose 'A' mutates to 'a' at a rate of 2 x 10^-5. What will the gene frequencies be in the next generation?

8) Consider two populations, with p = 0.3 and q = 0.7 in pop1 and p= 0.4 and q = 0.6 in pop2. Suppose individual migrate from pop2 to pop1 such that the immigrants comprise 5% of the 'new' pop1 (residents and immigrants). What would you expect the new gene frequencies to be in this new population?

9) Consider a population that exhibits positive assortative mating for the flower color, with red flowering plants (AA), pink flowering plants (Aa), and white flowering plants (aa). If the inital genotypic frequencies are 0.1 (AA), 0.8 (Aa), and 0.1 (aa) what will be the genotypic AND GENE frequencies in the next two generations?

10) How are the effects of inbreeding similar to and different from the effects of positive assortative mating?

11) In a 'genetic bottleneck' the effects of selection AND drift are probably both occurring. Explain with reference to the following example: In 1994, the lion population in Serengeti National Park was decimated by canine distemper virus. Explain how the population changed as a result of selection AND drift.