ANTH-UA 2 Lecture Notes - Lecture 10: Genetic Drift, Mutation
14 Dec 2016
School
Department
Course
Professor
Modern Evolutionary Theory
Thursday, October 6th, 2016
Individuals do not evolve, populations do
Forces of Evolution
● Mutation: DNA Errors in replication process that results in random alterations in
DNA sequence
● Gene Flow: migration and reproduction
○ Not random
● Genetic Drift: random sampling of alleles
○ No new traits
○ Some traits are fixated or lost
● Natural Selection: differential survival and reproduction
● Mutations in...
○ Non -coding regions = neutral
○ Coding regions = neutral or good/bad
○ Gametes can be passed on
● IMPORTANT
○ Individuals do not evolve
○ Populations evolve
○ Individuals can be selected for or against
○ No mutation = No variation = No evolution
● Gene Flow
○ Admixture or the exchange between populations of genetic material
■ Migration with reproduction
■ Increases genetic relatedness between populations
■ Populations are introduced to new genotypes and phenotypes
■ Variation within a population increases
■ Variation between populations decreases
● Genetic Drift: neutral theory or random changes in gene frequencies in a
population due to random sampling
○ Effect inversely proportional to population size: strongest in small
populations (coin flip analogy)
○ Effect often greater over longer time periods
○ Random and there is no directionality
○ Fixation or disappearance of alleles
● Bottleneck: population size reduction
○ Reduced genetic variation
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