Population Genetics
Exam #3
19 November 2002
Section I. Briefly define or identify the following words and terms. (4 pts each)
1. altruism
2. Nathan Mantel
3. correlogram
4. Hamilton’s Rule
5. Kin selection
6. isolation by distance
7. inclusive fitness
8. relative fitness
9. partial fitness
10. source and sink populations
Section II. Resolve and briefly discuss the following.
II/1. The average coancestry between pairs of individuals within social groups (packs) of wolves is 0.05, whereas that between brothers and/or sisters born within the groups is 0.25. The average inbreeding coefficient is approximately zero. If a younger brother stays to help his older brother become the pack alpha male the cost to him is two fewer offspring in his lifetime (on the average). However, the average gain in his brother’s lifetime reproductive success is 5 additional offspring. Is it in the younger brother’s advantage to assist his brother in this instance? Show your work. (10 pts)
II/2. In a population of macaques the FST = 0.08, FfT=0.33, FfS=0.26, and FIT=0.03. If Hamilton’s rule is applied to potential competitive interactions between individuals within families (f) relative to the subgroup (S) what would be the maximum ratio of cost to benefit (c/b) in order for the behavior to be of genetic advantage? What if the competitive interaction was between individuals within the subgroup relative to the total population? (5 pts)
II/3. An experiment was performed on Drosophila melanogaster. It was found that the heterozygotes for alcohol dehydrogenase were more fit than either homozygote (overdominance). The fitnesses were: AA =0.8, Aa=1.0, aa=0.7. What is the expected equilibrium frequency of alleles A and a? (note: you could assign s=0.2 and t=0.3 because the fitness of Aa =1.0. It is not necessary, however.) (10 pts)
II/4. An analysis on the genetics of snails in Florida showed a significant correlation between matrices for genetic distance between populations and geographic distance separating the populations. What is this called? What kind of analysis would have been performed to assess this? The investigators also derived the following graph. What is it? What does it mean? (interpret the results) Does this result support the previous result of a significant correlation between matrices? (15 pts)
Section III. Discuss the following in detail.
III. A student wishes to conduct a study on the population genetics of earthworms in a landfill contaminated with a pesticide. The student hypothesizes that the earthworms will not travel through soil contaminated with the pesticide, but will move around it instead. She decides to investigate 5 populations (areas) of earthworms in the landfill to determine if the genetic distances are related to straight geographic distances or by avoiding the contaminated earth. The map of pesticide (red) and population locations are mapped below. What kind of data should she generate (vector, matrix, other) and what will they depict? What type(s) of analysis should she perform? Each grid is 20 meters on each side. (20 pts). (Earthworms don’t swim).
Pair-wise Geographic Distances
1 2 3 4 5
1 0 40 100 126 205
2 40 0 60 89 146
3 100 60 0 41 72
4 126 89 41 0 40
5 205 146 72 40 0