The Molecular Evolution Exam

The students in my Molecular Evolution course have written the final exam. I finished grading the exams yesterday and the final course marks have been submitted. Now I don't have to think about teaching until August.

Just for fun, I'm posting the final exam questions. How do you think you'd do? I gave the students a list of all possible questions on the last day of class. The only one they hadn't seen was question #2. They knew that the first question would definitely be on the exam.

Students had to answer questions 1 & 2 and choose any three of the other questions.

1. Choose a subtopic from your essay and explain it better than you did in your essay and/or rebut the comments and criticisms made by the marker/grader.
2. Imagine that identical female twins were born to a woman in 1000 AD. Imagine that you could find a direct descendant of each twin in 2013. If you sequence the complete genomes of the descendants, approximately how many differences would you expect to find? How do these compare to the differences between any two randomly selected individuals from the same part of the world? Explain your reasoning and describe any assumptions you make. Think carefully before you answer. The second question is the most important one. (Human mutation rate = 130 mutations per generation. Haploid genome size = 3.2 × 10⁹ bp.)
3. There are hardly any pseudogenes in bacterial genomes. Why haven’t pseudogenes been eliminated from our genome?
4. Explain the two-fold cost of sex. Why is this a problem in evolutionary theory?
5. Richard Lenski’s group at Michigan State University has been following the evolution of 12 cultures of E. coli for over 50,000 generations. All 12 cultures are grown under exactly the same experimental conditions and the mutation rate is high enough that every culture has been exposed to multiple mutations at every base pair in the genome. Explain why only one of the cultures has evolved the ability to use citrate as a carbon source.
6. Why is the Three Domain Hypothesis being challenged by some molecular evolutionary biologists? What are the alternatives?
7. What do you think of Kirschner and Gerhart’s “Theory of Facilitated Variation.” Is this something that has to be incorporated into a new extended version of evolutionary theory? What, if any, are the limitations of the theory and what, if any, new insights into evolution does it provide?

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