Evolutionary Genetics

1) List four post-zygotic isolating mechanisms. How can sterility that occurs as a consequence of chromosomal non-homology be overcome? Think of an older topic...

2) Speciation and evolution are different processes. define each and explain the difference.

3) The rate at which a population evolves is dependent upon 4 things, basically similar to the agents of evolutionary change. List these factors that influence the rate at which a population evolves.

4) As a consequence of the sequencing 'boom', an extraordinary amount of variation was revealed at the molecular level. Even if we discount the new alleles produced each generation by mutation, and instead focus on only the alleles that are maintained in a population at a frequency above 1% (very much higher than background mutation rate, alone, can explain), there is STILL alot of variation. How much? On average, what fraction of loci are 'polymorphic', and what is the mean level of heterozygosity at these polymorphic loci?

5) What is one way that selection can maintain multiple alleles in a population (at a single locus)?

6) Why would it be impossible (for all practical purposes) for this type of selection to maintain all the variation we see in the genome, across all loci? What is the cost to a population of this type of selection?

7) Kimura suggested that much of this variation is selectively neutral. List three types of variation that should be selectively neutral.

8) What predictions does the neutral model make with respect to the rates of substitution between functional and non-functional regions of proteins and DNA? Are these predictions supported by the data?

9) The neutral model predicts that substitution rates in proteins should be faster in organisms with short generation times. However, substitution rates are usually constant in all species for a given protein, regardless of generation time. How does Ohta explain this constancy? What is 'slowing down' the rate in populations with short generation times and 'speeding up' the rate in populations with long generation times?

10) If we can measure the rate of substitutional change in a protein, how can we use this 'molecular clock' to determine when the common ancestor between two species lived? Is this phylogeny, constructed with molecular data from species walking around on the planet today, consistent with the phylogeny based on the fossil record?

11) How did Eldridge and Gould use Mayr's model of peripatric speciation to explain why the fossil record appears 'discontinuous' for some lineages.