Population Genetics I. What is Population Genetics

3) Genetic Drift
• Genetic Drift
Random fluctuations of allele frequencies
between generations
compounded by small population size
alleles can become fixed
The genetic bottleneck effect
4) Inbreeding (non-random mating)
• Inbreeding = Mating between relatives
•IDB– identical by descent, the two alleles
may be copies of the same gene in an
earlier member of the line
5) Natural selection
• Darwinian fitness – relative probability of
survival and rate of reproduction of a
phenotype or genotype
– Differential rates of survival and
reproduction
• Fitness is a consequence of the relation
between the phenotype of the organism
and the environment in which it lives, so
the same genotype will have different
fitnesses in different environments
consequence of relationship between
phenotype and environment
same genotype may have different fitness in
different environments
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