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Please fill out the survey on Vista by JAN 16 It will help us make biology courses better at UBC

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Please fill out the survey on Vista by JAN 16 It will help us make biology courses better at UBC

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    3. Inbreeding: mating with a close relative Biparental: two different individuals are involved

    4. Selfing: mating within the same individual ~50% reduction in heterozygosity in one generation Intragametophytic selfing: mating between gametes produced from the same haploid individual -100% homozygosity in one generation! - some ferns and mosses

    5. Selfing P: Aa x Aa F1:

    6. Selfing P: Aa x Aa F1: 1/4 AA 1/2 Aa 1/4 aa

    7. Selfing P: Aa x Aa F1: 1/4 AA 1/2 Aa 1/4 aa

    8. Selfing P: Aa x Aa F1: 1/4 AA 1/2 Aa 1/4 aa

    10. 1. What is genetic drift? 2. How does it work? 3. When and why is it important in plant populations?

    11. 1. What is genetic drift?

    12. 1. What is genetic drift? -random changes in allele frequency due to sampling of gametes

    13. 2. How does it work? Problem: Suppose you have 1000 green jelly beans and 1000 red jelly beans in a pot. What is the probability you will draw one green jelly bean? What is the probability you will draw three red jelly beans in a row? What is the probability you will draw one green bean in three draws?

    14. What is the probability you will draw one green jelly bean? 1/2 What is the probability you will draw three red jelly beans in a row? 1/2*1/2*1/2 What is the probability you will draw one green bean in three draws? 3 (1/2*1/2*1/2)

    15. Random drift works just like the jelly bean problem where we draw from an infinite pool of jelly beans (aka “gametes”) to make our new population. For diploids N individuals have 2N gametes We can use the binomial distribution to figure out the probability of drawing x alleles of type A

    25. Within populations Changes allele frequencies Reduces variance Does not cause deviations from HW expectations Among populations (if there are many) Does NOT change allele frequencies Does NOT degrade diversity Causes a deficiency of heterozygotes compared to Hardy-Weinberg expectations (if the existence of populations is ignored), like inbreeding.

    26. Erodes genetic variation within population Causes population differentiation Strength is dependant on population size The demographic history of populations effects patterns of genetic variation Can oppose selection- conservation implications Provides a “neutral” model for evolutionary change and most molecular changes are effectively neutral

    32. But wait! Populations often fluctuate in allele frequency more than pq/2N (i.e. what we would predict from drift acting on the population size we observe) Why? We made some big assumptions. What are some of the assumptions we made? Diploid, sexually reproducing, non overlapping generations, populations are constant in size, random mating in each population, no migration, no selection, no mutation

    33. How do we solve this dilemma?? Effective population size: is the size of an ideal population having the same magnitude of genetic drift There are different types depending on how we assess the magnitude of genetic drift -fluctuations in populations size (bottlenecks) -skewed sex ratio -variation in family size

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