Genetic drift and mutation

Card Set Information

Author:
doncheto
ID:
307807
Filename:
Genetic drift and mutation
Updated:
2015-09-14 13:51:26
Tags:
genetic drift geneticdrift mutation genetics
Folders:
marine pop
Description:
asd
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  1. Drift
    • Random change in allele frequencies from generation to
    • generation due to sampling error
    • Two main consequences:
    • 1. Allele frequencies will change
    • 2. Genetic variation will be lost
    • Stronger in smaller populations
  2. Reproduction as Poisson process
    • • Probability of a given # of events happening in a period
    • of time if each event happens independently and with
    • a fixed probability of occurrence
    • • Probability of k copies in generation 1:
  3. Probability of survival
    • • One allele will eventually drift to fixation...
    • • Assume neutrality
    • • Probability of it being the red one
    • = q0 = 1/2N
  4. Founder Effect
    • • Change in allele frequencies when a new population
    • arises from only a few individuals (the “founders”)
    • • E.g. only a few fish make it to an island
    • • E.g. only a few individuals are introduced to a new
    • habitat
  5. N
    = census population (total)
  6. Ne
    • = breeding population
    • • Factors that affect Ne
    • – Unequal sex ratios
    • – High variance in reproduc+ve success
    • – Changes in population size
    • – Overlapping generations
    • • Long term average number of successfully
    • breeding individuals
    • • Less than the census size
  7. Assumptions
    • • Equal sex ratio
    • • All individuals have an equal chance at
    • reproducing
    • • Constant population size
    • • Non-overlapping (discrete) generations
  8. Effect of variation
    • • High levels of variation =
    • low ratio of Ne / N
  9. Study formation
  10. Effect of population fluctuations
    • • Years with small populations =
    • low ratio of Ne / N
    • • Current population may be large, but
    • effective size could be small
  11. Marine species
  12. Know the three types of survivorship

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