1102/196.207 ALB Internal Only

MASSEY UNIVERSITY ALBANY CAMPUS

EXAMINATION FOR 196.207 BIOLOGICAL EVOLUTION

Semester 2 - 2011

TIME ALLOWED: THREE (3) HOURS

Answer ALL questions from SECTION A. Answer THREE (3) questions from SECTION B.

Section A consists of 10 short answer questions. Each question is worth 3 marks, 30 marks in total. Allocate 1 hour for Section A.

Section B consists of six long answer questions.

Each question is worth 20 marks, 60 marks in total. Allocate 2 hours for Section B.

TOTAL marks: 90

All answers are to be written in the blue answer book provided.

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SECTION A (Short answer questions) [Answer ALL questions from SECTION A]

1. What is an "outgroup" and why are they so important when building a phylogeny?

2. Briefly describe how the concepts of evolution and phylogeny have helped

us understand AIDS? 3. With respect to proteins, what is meant by the term functional constraint?

How might functional constraints affect the rate of evolution of different proteins within an organism?

5. We discussed Dr. Paul Rainey's pioneering study using Pseudomonas

fluorescens to look at change in populations over time. Adaptive radiation was observed within 10 days. (a) What feature of the environment allowed the radiation to proceed?

(b) Would you expect the same range of mutations to arise amongst bacteria propagated in shaken (homogeneous) microcosms? Why / why not?

(c) Describe the experimental evidence that supports the claim that diversity, once emerged, is stably maintained. [You may illustrate your answer as a diagram if you wish]

The figure to the left shows the frequency of allele A1 (relative to allele A2) over 50 generations for 6 populations ranging in size (N) from 10 - 1000000 individuals. (a) What evolutionary process is most likely responsible for the fluctuations in allele frequencies that we observe? (b) Why do the evolutionary outcomes differ for populations of different size? 0 5 10 15 20 25 30 35 40 45 50

generations

N = 10 N = 100 N = 1000 N = 10000 N = 100000 N = 1000000

4.

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1102/196.207 ALB Internal Only 6. The figures to the right each show a

sample of 4 chromosomes from a population. Four neutral polymorphisms are indicated (variants: diamond, circle, arrow, square, star and pac-man).

In Time Point 1 a new mutation arises on a

single chromosome, indicated by X. Time Points 2A, 2B and 2C represent three

possible samplings of chromosomes long after the observed mutation X in Time Point 1 arose. Assume that the populations being sampled are large and that our samples are representative for the population as a whole. How could the population from Time Point 1 give rise to the population represented in each of Time Points 2A, 2B and 2C? Carefully consider all of the evolutionary concepts that we have developed in this course to describe a scenario for each transition.

(a) Time Point 1 to Time Point 2A: (b) Time Point 1 to Time Point 2B: (c) Time Point 1 to Time Point 2C:

7. What is peripatric speciation? 8. Define and provide an example of complex emergence. 9. What are HOX genes, and what do they control? 10. From an evolutionary biologist’s point of view, use an example to explain what

is meant by ‘conflict between individual and group benefits’.

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SECTION B (Long answer questions) [Answer THREE (3) questions from SECTION B]

1. You have spent years of your life in the dedicated

study of a population of beetles. At left are two sets of data that you have generated that describe the population of interest. Soon after you started examining your beetles you became interested in a trait that appears to be determined by a single locus and has only two possible alleles. The phenotype is wing colour. The genotype and phenotypes map as follows:

A1 A1 = Red wings A1 A2 = Purple wings A2 A2 = Blue wings

Figure A is a representation of the population's mean fitness per observed frequency of the A1 allele. Figure B is a representation of the change in the observed frequency of allele A1 over a period of 50 years.

Answer the following questions based on the data available: (a) At what frequency of the A1 allele does the population of beetles have a

maximum mean fitness? [1 mark]

(b) Estimate the mean fitness of a population of beetles in which the frequency of the A2 (NB: not A1) allele at this location is 0.2.

[1 mark] (c) According to Figure B, over what span of years did the population of

beetles have the highest mean fitness? [1 mark]

(d) Based on the data shown here, what was the least common beetle wing colour in your favourite population in 1981? Show your working.

[2 marks] (e) Something pretty dramatic happened to this population between 1970 and

1980. Describe in your own words what happened in terms of the change in allelic frequencies based on the data above.

[5 marks] (f) Assuming that the environment of the population stayed constant during the

transition from the 70s to the 80s, hypothesize about what might account for the dramatic change in allelic frequencies.

[10 marks]

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1102/196.207 ALB Internal Only

2. Despite its unrealistic simplicity the Hardy-Weinberg Principle is a

fundamental component of evolution. Why does the Hardy-Weinberg Principle occupy such a central role? Please use examples to illustrate your answer.

3. What is the neutral theory of molecular evolution? Describe how variation

at the molecular level can sometimes be selectively neutral. Discuss how the neutral theory may be applied to address various evolutionary questions that you have encountered in this course.

4. Describe and discuss the different barriers to gene flow that might give rise

to speciation. 5. Compare the different explanations for the evolution of cooperation. Please

use examples to illustrate your answer. 6. (a) From an evolutionary perspective clearly explain why the evolution of

sexual reproduction is such a difficult problem.

(b) Outline a logical hypothesis for the function of sexual reproduction and describe some real observational and/or experimental evidence that supports this hypothesis.

END OF PAPER

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