Week 5 Lab Alternate - Mechanism of Evolution W23_V2-1

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University of California, Los Angeles *

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Electrical Engineering

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Dec 6, 2023

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Week 5 Lab Mechanisms of Evolution Learning Goal: Evaluate the effects that violations of Hardy-Weinberg principle may have on allele or genotype frequency Activity 1: Migration Koi fish color is determined by two co-dominant alleles ( R1 and R2 ): homozygous R1 individuals have a solid white scale color, homozygous R2 individuals - a solid orange scale color, and heterozygous individuals ( R1R2 ) - a white scale color with orange spots. Your city has decided to create a canal that connects multiple previously isolated Koi ponds in your city’s botanical garden. You survey a population of isolated Koi fish in one of their ponds before the canal is built and then survey the same pond after the canal is built to determine the effect of migration on allele frequency. Use the information above and your survey data to answer the following questions. Population Size Frequency of R1 Allele Frequency of R2 Allele Frequency of R1R1 Genotype Frequency of R1R2 Genotype Frequency of R2R2 Genotype Initial Survey (Before canal project) 194 0.47 0.53 0.27 0.4 0.32 Migration Survey (After canal project) 203 0.81 0.19 0.69 0.25 0.05 1. When looking at only the initial survey data, is there evidence the population is evolving for the scale color gene? 2. When looking at only the migration survey data, is there evidence the population is evolving scale color gene? 3. When comparing your initial and migration survey data, is there evidence that this population is in Hardy-Weinberg Equilibrium? 4. What is a plausible explanation for the change in genotype frequencies observed between the Initial and Migration Surveys?
Activity 2: Founder effect For your undergraduate research project, you are able to do summer fieldwork surveying four isolated populations of Tasmanian devils on the Australian mainland as well as four Australian islands that were recently (initial) colonized. During your pre-fieldwork research you learn that Tasmanian devil coat pattern is determined by three alleles: W , G , and B . In your graduate program you continue summer fieldwork surveying the same four (final) island populations from your undergraduate fieldwork. You are interested in examining the effect of the founding population size on allele frequencies. Use your undergraduate and graduate survey data below to answer the following questions. Note that each island has nearly the same environments including food availability and predators. Source Population (Mainland) Allele Frequencies (Undergraduate Fieldwork) Initial Colonized Island 1 Allele Frequencies (Undergraduate Fieldwork) Final Island 1 Allele Frequencies After 100 Generations on the Colonized Island (Graduate Fieldwork) Population # Founding Pop Size W G B W G B W G B 1 25 0.104 0.445 0.451 0.074 0.389 0.445 0.02 0.469 0.395 2 20 0.114 0.465 0.421 0.182 0.386 0.432 0.135 0.275 0.59 3 10 0.099 0.455 0.447 0.083 0.5 0.417 0.2 0.185 0.615 4 5 0.107 0.435 0.459 0.083 0.667 0.25 0.405 0.564 0.03 1. How does the founding population size influence the initial colonized and final colonized allele frequencies? Provide a plausible explanation for your description. 2. Do any of the island populations exhibit evidence of evolution for the coat pattern gene? Why or why not? 3. What are the similarities and differences between the founder effect and bottleneck events? 4. Now imagine after 100 generations some individuals from one Island colonize a completely separate island. Assuming that both island populations are only affected by random effects and there is no gene flow after the initial colonization, would you expect allele frequencies between the source island and the colonized island to be different or similar after 1000 subsequent generations? Explain your answer. 5. Knowing about the colonization event described in question 4, imagine a population of individuals from the second island colonize a third island. Biologists sample the Mainland as well as the second and third Island populations fifty years after the colonization events. They determine that allele frequencies on both islands are similar to one another, but they are significantly different than the frequencies of the mainland population. Which of the evolutionary mechanisms could be used to explain these observations?
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