Evolutionary Biology Spring 2016 Study Questions
Lecture 1 - Jan 19th 2016
1) What type of adaptation would you expect to see in an organism living in an environment with visual predators?
2) What’s one possible explanation for powered flight appearing only once in invertebrates and at least three times in vertebrates?
3) Why would it be advantageous for an organism to resemble something else; i.e. a caterpillar that looks like bird droppings or an orchid that smells like carrion?
4) What’s convergence? Can you think of an example we saw in lecture?
5) Do similar traits always evolve because they solve the same challenges? For instance, are bright colors always favored because of their role in getting a mate?
6) In what ways can humans be a source of selection to other organisms?
7) What’s the difference between evolutionary change and plasticity?
Lecture 2 - Jan 21st 2016
1) What is the difference between genotype and phenotype?
2) How might an organism’s environment influence its phenotype? Think of the examples you saw in lecture and come up with two more.
3) In class, we focused on figuring out how to tell if a phenotypic difference was caused by an evolutionary change. What if there is no phenotypic difference between two populations you observe in the wild? Could there still have been an evolutionary change? Why or why not?
4) In class, we talked about the work of Peter and Rosemary Grant on Galápagos finches. Why were these finches a good system in which to study evolution? Give three reasons.
5) What do you predict would happen to finch bill size after another generation, if the rains return? Explain your answer.
6) Define adaptation/an adaptive trait. What happens to the frequency of adaptive traits over generations?
7) What conditions must be met for evolution by natural selection to take place?
8) Why do we think that the loss of armor in freshwater sticklebacks is adaptive, even though we don’t know how armor loss helps their survival?
9) What is one way that the stickleback and finch examples are similar? What is one way they are different?
Lecture 3 - Jan 26th 2016
1) A trait in certain individuals within a population increases their fitness by 3%, can this trait be considered an adaptation?
2) Why were researchers able to use corn to examine the effects of natural selection? What factors made this a good study system?
3) A scientist is studying mice in meadows and has been able to document fitness levels of different genotypes over many years. If this scientist transplanted these mice to a woodlands environment would you expect to see the same trends in fitness in this new environment? Why or why not?
4) You are studying a rabbit species in which some individuals have brown fur and some have black fur. After performing some crosses you are able to determine that the allele for black fur is dominant. With this information can you conclude then that having black fur makes the rabbits more fit than if they had brown fur?
5) How were researchers able to conclude that apical dominance in corn was not a new mutation caused by domestication?
6) Is there a limit on how many bases must be changed by a mutation before this new mutation can be considered adaptive?
7) What are the different ways in which selection can vary?
8) Are there ways that natural selection could act upon a population without producing an evolutionary response?
Lecture 4 - Jan 28th 2016
1) Why was it important for researchers to understand the life cycle of HIV?
2) What method was used for the first treatment of HIV?
3) How was the virus able to rebound after treatment with AZT?
4) What were some of the factors that we discussed that allows HIV to quickly evolve drug resistance?
5) What do we need to know about a study system in order to conclude whether or not evolution has occurred?
6) Do changes in alleles need to be directional in order to be considered an evolutionary change or can they fluctuate randomly? Explain your answer.
7) When organisms are in a changing environment, what do we need to know in order to conclude that a phenotypic change is a result of evolution rather than plasticity?
8) Explain how treating HIV-infected individuals with multiple drugs slows down the evolution of drug resistance. What else can we attempt to slow down the evolution of resistance?
Lecture 5 - Feb 2nd 2016
1) Explain the differences between Mendelian and quantitative traits, and give an example for each.
2) Why can’t we perfectly predict phenotype from genotype for quantitative traits?
3) Fur color in mice depends primarily on the genetic composition at five different loci (A-E). Suppose that each locus has two alleles, and that one of the alleles (called A1-E1) makes fur lighter while the other allele (called A2-E2) makes fur darker. As a result, mice that possess 10 '2' alleles are jet black while those that possess 10 '1' alleles are white.
- A. How many different fur color phenotypes are there (ignoring environmental effects)?
- B. How many different genotypes are there?
- C. How many different genotypes produce the phenotype that is one shade lighter than jet black? (Hint: think about how many different places a '1' allele could occur)
4) Explain what is wrong with the following statement: “Heritability indicates the degree to which a trait is genetic. Traits with high heritability are genetically determined, while those with low heritability are environmentally determined.” Give an example (real or hypothetical) in which a trait is genetically determined, but the heritability is low (or zero).
5) Provide the name and meaning for each term of the following equation: R = h2 * S.
6) How is heritability defined? How can heritability be measured?
7) The slope of the regression line describing the relationship between the number of abdominal bristles in offspring and the number of abdominal bristles in parents is 0.63 in a laboratory population of Drosophila melanogaster.
- A. What is the heritability of abdominal bristle number in this population?
- B. Suppose that the mean abdominal bristle number in this strain is 237 and suppose that a population geneticist imposes selection on bristle number so that the mean abdominal bristle number among those allowed to reproduce is 196. What will the mean abdominal bristle number among the offspring be?
8) Why is heritability dependent on the environment in which it's measured?
9) How are natural selection and sexual selection similar? How are they different?
Lecture 6 - Feb 4th 2016
1) What is the key difference between the “good genes” hypothesis and the runaway sexual selection model?
2) What does it mean to say that male ornamentation and female choosiness are genetically correlated?
3) In pipefish, females transfer their eggs to males, who then fertilize, carry, and care for them. Which sex would you predict is the choosy sex? Which sex probably participates in intrasexual selection? Why?
4) Why do males typically have more variability in their reproductive success compared to females?
5) Peacocks with a large number of eyespots on their tails attract more mates than those with few eyespots. Design an experiment to test whether the number of eyespots in a male’s tail is a signal of his genetic quality (aka how would you test the “good genes” hypothesis in this system?).
6) Does natural selection always oppose sexual selection? Explain your answer.
7) What is the relationship between population genetics and Mendelian genetics?
8) In a population of 550 plants, a single gene (DFR) controls flower color. There are 222 homozygous dominant (DFR/DFR) individuals, 150 homozygous recessive individuals (dfr/dfr), and 178 heterozygotes (DFR/dfr). What is the frequency of the dfr allele in this population?
Lecture 6 - Feb 4th 2016
1) A population contains the alleles D and d. The frequency of D is 0.6 and the frequency of d is 0.4. If individuals mate at random within the population what is the chance that an offspring will have the genotype Dd?
2) What happens to genotype frequencies in a population under Hardy-Weinberg equilibrium in subsequent generations? What happens to allele frequencies?
3) You observe the genotype frequencies of a cow population for 2 generations. The allele frequencies and genotype frequencies do not change. Is this population in HWE? Why or why not.
4) Today we discussed several factors that could have caused an increase in heterozygote genotype frequencies within sample 2 from our activity. What were some of those factors?
5) If you observe no change in genotype/allele frequencies between two generations can you conclude that nothing is influencing the population?
6) In a population of 100,000 flour beetles there exists a recessive genetic disease that causes antennae to develop in a “Z” shape when in the homozygous condition. You find 10 individuals with Z-shaped antennae. Calculate the genotype and allele frequencies for this population of flour beetles. Assume that the population is in Hardy-Weinberg equilibrium.
7) Explain why there was an increase in the heterozygote genotype frequencies within the older generation sample (sample 2).
8) How many generations does it take for a population to establish genotype frequencies in HWE (Hardy-Weinberg equilibrium) given all the assumptions are met?