Section A: Short answer questions (55 marks total).
There are 15 questions in this section. Answer all 15 questions. Within several questions there is choice. Answers will only require a few sentences or bullet points. Do not write excessive text. Not all questions are equally weighted.
1) Answer two of the following three questions (a b, c).
a) consider the following graph which tells me about genotypes AA, Aa and aa
What can you tell me about the fitness of the genotypes – how do you know? (2 marks)
Explain whether selection is occurring (1 mark)
Explain whether evolution is occurring (1 mark)
Explain whether the a allele could become fixed in this system (1 mark)
b) Consider the following two graphs which show isolated populations
Graph D Graph E
What can you tell me about the relative size of the populations and how do you know? (2 marks)
Which allele is probably dominant in each case? (1 mark)
Is the mutation rate greater than zero in each graph and how do you know? (1 mark)
Will the a allele ever be permanently lost in each graph, why? (1 mark)
c) Consider the following graph which shows a simulation of 10 populations with gene flow. The fitness of all three genotypes is the same in this simulation.
Can alleles lost from one of these populations be recovered? If so, how? (2 marks)
Why are the allele frequencies between populations similar? (1 mark)
Is there evidence of drift in these populations? (1 mark)
Does gene flow cause the frequency of A to be high a time zero? (1 mark)
2) Below are a series of statements. You must decide if you agree or disagree with each statement. (2.5 marks)
If you agree simply write “agree” on the answer sheet.
If you disagree rewrite the sentence to be correct on the answer sheet.
Note: the statements are not related to each other (1/2 mark each)
If two populations are experiencing migration, we expect their allele frequencies to be more similar than if there were no migration.
If the relative fitness of genotypes in a population are wAA=0.4, wAa = 0.3 waa = 1, the a allele cannot be lost due to drift.
In a population where wAa is greater than wAA or waa, we expect allele frequencies to reach an equilibrium, but we can’t predict the genotype frequency unless we know the relative fitness of heterozygotes.
In a population undergoing frequency dependent selection the favoured genotype is the common one.
Selection is more likely to fix alleles which are recessive.
3) Select one of the following to answer (2.5 marks)
a) Charles Lyell is said to have had a profound influence in Darwin’s thinking about evolution. Explain how the 4 principles of uniformitarianism may have influenced the idea of evolution and natural selection as presented by Darwin. Do we still agree with these? Use examples to explain why?
b) What were Darwin’s main lines of evidence for evolution by natural selection? Give an example of each. What major misconception did he have about inherited traits?
c) Why was it relatively easy for Darwin to explain natural selection, particularly to the upper-class society in the UK? What aspect did Darwin have no concept of? What major misconception did he have about inherited traits because of this?
4) Describe the general action of selection. What does it act on, what level is impacted (individual, population etc.) and what directly changes as a result? (2.5 marks)
5) Hamilton demonstrated that altruism could evolve. What was his explanation? Ensure you describe both the costs and benefits to the individual and potential sources of conflict. Use an example to illustrate this (5 marks)
6) What is a ring species and how do they help us understand speciation? Use an example to illustrate your answer. What factor may contribute to stability of the terminal populations in real systems in nature? (2.5 marks)
7) There are a great many “problem” cases in taxonomy. Pick one problematic group from class and explain it (do not select viruses, prions, satellites or viroids) (2.5 marks)
8) Compare and contrast the modes of speciation. Diagrams may be useful (2.5 marks).
9) Is Genome size related to the amount of protein coding DNA in most of life? (5 marks)
10) Are adaptations perfect? Use examples to explain (2.5 marks)
11) Using diagrams, explain whether recessive or dominant traits are harder to extinguish from a population (5 marks)
12) Answer one of the following two questions (2.5 marks)
a) What is DNA barcoding and how does it work?
b) You want to construct a phylogeny using DNA based data. You are concerned that the rate of evolution may have changed and that your data set is very large. What approach would you use and why? What are the risks or assumptions of this approach?
13) What is the relationship between reproductive investment and sexual selection and what does reverse dimorphism tell us about this? (2.5 marks)
14) Why do females prefer exaggerated male traits? (2.5 marks)
15) Why do most populations have a 1:1 sex ratio, why might they deviate from this ratio? (5 marks)
Section B: Long Answer Questions (45 marks total) 1000 words total.
16) Select one of the following topics to explain fully as an essay. Use proper references to support your answer if you select options a, b or c. Please use referencing in text using the author date format (Clare et al. 2020) where appropriate. Please use primary literature. For option d references are not required but graphs/figures are expected. If you use figures or tables in any answer, captions are expected and should be referenced in your text. Table contents, captions and references do NOT count in your word count total (but tables should not have full sentences and paragraphs). Proper sentences/paragraphs are expected. Please give your word count under your essay.
a) Explain the paradox of speciation and its solution using the BDM model. Use diagrams to explain your answer. Using your own diagrams will be a stronger answer than recreating those from class.
b) What are magic traits and how are they involved in speciation? Use diagrams and at least two examples to explain your answer. Using examples not presented in class will create a stronger answer.
c) We have discussed many species concepts. Compare and contrast at least 4 of them using examples and then clearly explain which one you think has the widest application and should be of the most general acceptance. Use examples of how you can or can’t apply each concept to different taxonomic groups.
d) You are a scientist, and you discover a new bird on campus. It has unusual feather coloration that makes it appear like a predatory cat when at rest on its nest. How would you test the hypothesis that this feature is adaptive? Describe an experiment you could perform and show what sort of data you would expect if the trait was adaptive or was not adaptive (give me at least two graphs). Make sure you include appropriate controls. Then describe what other approaches we might use to determine whether traits are adaptive. What alternative hypothesis might you test to explain this trait?
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