BIOEE 2780 Practice Prelim 1 Answer Key (2006)

BIOEE 2780 Practice Prelim 1 Answer Key (2006) - BioEE278...

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Spring 2008 Zamudio Practice Questions, Prelim 1 These are practice questions for Prelim Exam 1 (Feb 28, 2008). These questions are representative of the kind of question you can expect on the exam (the exam will not be this long, however). We will also post a key to these questions, so you can check your answers. However, the best strategy for study is not to just look at the key! Try to complete this practice exam as if it were real. That will help you gauge the areas you need to study more. 1 . Briefly list the attribute(s) of a theoretical population that would have an average inbreeding coefficient of exactly zero (hint: this can best be answered with under 10 words). Infinite population size and random mating. 2. You are studying a toad species that lives only in tiny vernal pools (ponds that fill in the rainy season but dry out in the dry season) at highly scattered locations across the deserts of Arizona. You sample 20 toad tadpoles from each of 10 ponds, and sequence from each a stretch of coding DNA. You discover three alleles that differ only at synonymous nucleotide sites. You then find that the genotype frequencies in the samples from each pond are VERY different from the proportions expected under Hardy-Weinberg equilibrium, but also that these frequencies differ strikingly among the 10 ponds sampled. Start by listing the five HW assumptions below. All five assumptions are likely violated in these toad populations, but of the five possibilities, which in this case are likely to contribute most to your observed deviation from HW equilibrium (and why)? Which are likely to be relatively unimportant (and why)? For each assumption, circle either ‘violation important’ or ‘not important’ and in the space below provide a sentence to justify your rationale. 1. No mutation Not important because mutation by itself is generally not a driver of evolution. Additionally, these populations are small and have probably only been separated for a short period of time, relative to the time necessary for mutations to generate deviation from HW equilibrium. It is true that the three alleles arose from mutations, but this answer does not account for deviation from HW equilibrium, only the origin of variation. 2. No selection Not important because the alleles differ only in synonymous substitutions, so there is no phenotypic difference between individuals at these sites. 3. No migration Not important because migration is a homogenizing force, which would lead to similar allele frequencies among populations. 4. Infinite population size/No genetic drift Important because of small, fragmented populations where sampling error (*not* sample size) would result in random differences between populations. 4.
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This note was uploaded on 10/26/2008 for the course BIOEE 2780 taught by Professor Geber during the Fall '07 term at Cornell University (Engineering School).

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BIOEE 2780 Practice Prelim 1 Answer Key (2006) - BioEE278...

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