Question: Each olfactory receptor (OR) gene is involved in detecting specific odors. However, humans are losing OR genes: while mice and other mammals have ~1500 such genes, humans have ~900 (the rest received deactivating mutations that turned them into pseudogenes). One such gene is associated with detecting the odor of an asparagus breakdown product in urine; it is active in 25% of humans but has been deactivated in the rest of the human population. Imagine you figured out which OR gene was associated with the trait, and found that individuals with two broken copies (aa) lost the ability to detect asparagus in urine, while those with at least one intact copy (AA or Aa) were able to detect it. In a population analysis, you found 3 AA, 22 Aa, and 75 aa individuals. Test for HW equilibrium and draw conclusions about evolutionary forces acting on the population. Were you able to detect the activity of mutation in the population? Why or why not, do you think? (Hint: At what rate do mutations accumulate in a population?)
