Time allowed: 2 hours Answer ALL questions in Section A, ALL PARTS of the question in Section B and ONE question from Section C.

Transcription

1 UNIVERSITY OF EAST ANGLIA School of Biological Sciences Main Series UG Examination EVOLUTIONARY BIOLOGY BIO- 5008B / BIO-2B10 Time allowed: 2 hours Answer ALL questions in Section A, ALL PARTS of the question in Section B and ONE question from Section C. Write answers to EACH SECTION in the Answer Grid or SEPARATE booklet. The maximum number of marks available for your answers in SECTION A is 40 marks The maximum number of marks available for your answer in SECTION B is 30 marks The maximum number of marks available for your answer in SECTION C is 30 marks The TOTAL number of marks available for the paper is 100 Numbers in square brackets [ ] indicate the relevant mark applied to each part of the question. Notes are not permitted in this examination. Do not turn over until you are told to do so by the Invigilator. BIO-5008B / BIO-2B10 Module Contact: Prof David S Richardson, BIO Copyright of the University of East Anglia Version 1

2 2 SECTION A: MULTIPLE CHOICE AND SHORT ANSWER QUESTIONS Answer ALL questions. Answer multiple choice questions in the answer grid provided and attach this to your booklet for Section A. 1. Which mechanism is the null hypothesis to explain evolutionary change? [1 mark] a) Natural selection b) Genetic drift c) Sexual conflict d) Sexual selection e) Group selection 2. Variation at a single genetic locus (MC1R) has been found to influence both plumage colouration and levels of immunological response in birds. This is an example of: [1 mark] a) epistasis b) pleiotropy c) linkage d) polymorphism e) dominance 3. The evolution of a new adaptive trait that allows a new niche to be exploited, thus leading to the evolution of new species, is an example of: [1 mark] a) vicariance b) co-evolution c) environmental stability d) micrroevolution e) ecological divergence 4. Which of the following is not evidence that HIV is generating selection on humans in Africa? [2 marks] a) The onset of Aids is delayed in individuals with specific variants of the CCR 5 gene b) Individuals with these variants produce more offspring than those with other variants c) Levels of HIV differ between populations across Africa d) The difference in relative lifetime reproductive success between individuals with different variants of CCR 5 is greater in populations with higher HIV infection e) The beneficial CCR 5 variants are increasing in frequency within African populations infected with HIV Section A continues on next page/...

3 3 Section A continued Which of the following has not been proposed to explain why humans evolved to be bipedal? [1 mark] a) Frees the hands for fine manipulations b) Greater stamina for long distance travel c) More effective hunting d) Faster running speed e) Improved ability to carry food 6. Adult migrants now travel equally between two previously isolated island populations of a species. Which of the following statements is not correct? [2 marks] a) Gene flow will only occur if migrants successfully reproduce b) Gene flow will counteract drift c) High gene flow will homogenise the two populations d) Less than one migrant per generation will cause allele frequencies to reach the same mean in each population e) The rate of gene flow can be estimated by calculating F statistics 7. Which is not a subset or a direct product of a genome? [1 mark] a) Mitogenome b) Exome c) Transcriptome d) Biome e) Metabolome 8. Genetic variation in the activity of the neural enzyme, catechol-o-methyltransferase (COMT), is implicated in what kind of phenotypic variation? [1 mark] a) Variable susceptibility to schizophrenia b) Variation in sensation-seeking behaviour c) Variation in executive control ability d) Variation in ability to benefit from training for stressful situations e) Variation in heritability of IQ Section A continues on next page/... TURN OVER

4 4 Section A continued Why are phylogenetic trees built using shared, derived mutations? [2 marks] a) Because this eliminates the possibility that back mutations will lead to incorrect inference of shared ancestry b) Because phylogenetics attempts to group together organisms that are phenotypically similar to each other c) Because convergent evolution never results in shared mutations d) Because a mutation that arises in an ancestral species is inherited by all descendants e) Because only DNA provides useful information about evolutionary relationships 10. Hawaiian spiders exhibit four different ecomorphs: green, maroon, small brown, and large brown. What does Gillespie s phylogenetic analysis suggest is the most common origin of these different ecomorphs? [2 marks] a) Each ecomorph originated once and spread to all other islands b) A single dispersal event per island radiated into different forms c) Large brown spiders exclusively gave rise to small brown spiders, and green morphs gave rise to maroon morphs d) Multiple ecomorphs originated on each island, and selective extinction led to four surviving morphs e) Stepping-stone dispersal resulted in closely related ecomorphs being found on neighbouring islands 11. What is thought to be the role played by mutualistic microbial symbionts in bobtail squid? [1 mark]. a) Mutualistic protection from parasites b) Mutualistic production of light to counter-illuminate shadows c) Mutualistic digestion of complex carbohydrates d) Mutualistic feeding of the host with photosynthate (products of photosynthesis) e) Mutualistic production of essential nutrients 12. The cichlids inhabiting the Great lakes of Africa are textbook examples of: [1 mark] a) genetic drift b) speciation through polyploidy c) insect speciation d) host race formation e) vertebrate adaptive radiations Section A continues on next page/...

5 5 Section A continued The biological species concept can be defined as: [1 mark] a) groups that remain recognizable in sympatry because of the morphological and genotypic gaps between them b) a lineage judged to be evolutionarily independent on the basis of size, shape or other morphological features c) the smallest monophyletic group of common ancestry d) groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups e) a lineage or species that occupies an adaptive zone minimally different from other species or lineages in its range 14. Allopolyploidy is: [1 mark] a) commonly found in humans b) whole genome duplication within a single species c) whole genome duplication driven by vicariance d) whole genome duplication as a result of hybridisation e) the most common form of speciation in reptiles 15. Reinforcement is the term used to describe: [1 mark] a) greater energy allocation to morphological structures involved in mate choice b) hybridisation increasing the evolutionary potential of a lineage c) populations adapting to different niches in allopatry d) genetic drift leading to populations diverging e) selection for prezygotic isolation, arising from reduced fitness in hybrids Section A continues on next page/... TURN OVER

6 6 Section A continued Ecological character displacement is the phenomenon where: [2 marks] a) allopatric populations diverge most in morphological characters that are related to their ecology b) sympatric populations diverging in morphological characters related to ecology c) differences among similar species whose distributions overlap geographically are accentuated in regions where the species cooccur but are minimized or lost where the species distributions do not overlap d) differences among similar species whose distributions do not overlap geographically are accentuated in more extreme habitats e) behaviours relating to ecology change rapidly among diverging populations 17. The goatsbeards (Tragopogon): [1 mark] a) are plants that have evolved new tetraploid species in the last 80 years b) are an example of a vicariant speciation c) are an example of adaptive radiation d) have diverged through sexual selection e) are fishes that have evolved through parapatric speciation For all remaining questions in Section A, please use an answer booklet. Remember to attach your multiple choice answer grid to the booklet. 18. Inbreeding depression can be caused by two genetic mechanisms which reduce survival and reproductive success in the short term. Explain both of them. [6 marks] 19. Briefly explain how lice phylogenies help us date when human behaviours evolved. [6 marks] 20. Briefly explain what punctuated equilibria is and state who the theory was developed by. [6 marks] END OF SECTION A START YOUR ANSWER TO THE NEXT SECTION IN A NEW BOOKLET Section B begins on next page/...

7 7 SECTION B: DATA HANDLING QUESTION Answer ALL PARTS of this question [30 marks] 21. A single species of snake which lives in Madagascar is polymorphic for colour. Individuals are coloured either red, pink, or white. A sample of 2000 snakes is collected. Colour in this species behaves as a single-locus, two-allele system with incomplete dominance. Simple calculators may be used for this question. Type Red (AA) Pink (Aa) White (aa) Total Number Table 1. Sample of 2000 snakes (a) What are the frequencies of each genotype in the sample? [3 marks] (b) Showing your working; calculate the frequencies of the two alleles A and a. [6 marks] (c) What are the expected genotype frequencies under Hardy-Weinberg equilibrium in a sample of the same size? [9 marks] Degrees of Freedom P = 0.05 P = 0.01 P = Table 2. Chi Square table of critical values (d) Using a chi-squared test with the appropriate degrees of freedom, investigate whether the observed genotype frequencies are in Hardy Weinberg equilibrium. A table of chi-square critical values has been provided below in table 2. Chisquare formula: ((OBS-EXP) 2 )/EXP. [7 marks] Section B Q21 continues on next page/... TURN OVER

8 8 Section B Q21 continued... (e) In less than 30 words state what your result tells you about this population. [5 marks] END OF SECTION B START YOUR ANSWER TO THE NEXT SECTION IN A NEW BOOKLET SECTION C: ESSAY QUESTION Answer ONE question [30 marks] 22. Explain how genomics technology is used to study the genetic basis of phenotypic traits. Full marks require a (brief) example of how genomics might be used to study adaptation in a trait not discussed in the genomics lecture. 23. Explain the different types of isolating barriers that could lead to evolutionary divergence among populations or species. 24. Our understanding of evolution is informed by different lines of evidence, including the fossil record, comparisons between extant organisms and experimental evolution. Using examples, compare and contrast what different lines of evidence can (and cannot) tell us and how they allow us to deduce the evolutionary relationships between organisms. END OF PAPER

9 UNIVERSITY OF EAST ANGLIA School of Biological Sciences Main Series UG Examination EVOLUTIONARY BIOLOGY BIO-5008B / BIO-2B10 Registration Number SECTION A: Answer Grid (for Multiple Choice Questions only) Place a single cross in the appropriate box Question No. A B C D E Marks given Marks available

10 10 BIO-5008B / BIO-2B10 EXAMINATION MARKERS [Do not print this when printing to take to Examinations Office! This is for our information only.] Question No. 1 st Marker 2 nd Marker Section A Q1 20 Prof David S Richardson Dr Martin Taylor Section B Q21 Prof David S Richardson Prof Tracey Chapman Section C Q22 Dr Doug Yu Dr Martin Taylor Section C Q23 Dr Martin Taylor Prof David S Richardson Section C Q24 Prof David S Richardson Dr Martin Taylor