BIO1011 Lecture Notes - Lecture 12: Genotype Frequency, Allele Frequency, Panmixia
16 Jun 2018
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Lecture 12 - Population and Evolutionary Genetics
Definitions
● Population and evolutionary genetics is the study of genetic variation in
populations and evolution
○ It studies: how genetic variation arises, varies, and is maintained
● Population is a localised group of interbreeding individuals of the same
species.
○ All alleles of a gene in a population make up the gene pool
● Polymorphism is when many traits show variation in a population
Polymorphic traits and genes
Variation/polymorphism levels:
1. Morphological
2. Physiological
3. Biochemical
Most genes are polymorphic (more than one allele in population)
If there’s only one allele and it is called monomorphic (this means that the allele is
fixed in the population)
Biochemical
● Allozymes (different forms of enzymes)
● Migration in gel electrophoresis (fast and slow forms) was studied before
other DNA methods were used for studies
Genotype and allele frequencies
● Genetic structure of a pop is defined by frequencies of different genotypes or
frequency of alleles
○ Eg. one gene, two alleles that show incomplete dominance for flower
colour
● Frequency of alleles denoted by: p, q, r, s
○ Remember to calculate the heterozygote
● Frequencies should always sum to 1
Hardy-Weinberg Principle
● A population that is not evolving
○ The allele and genotype frequencies remain constant from gen to gn
○ Also called the H-W Equilibrium
● If mating is random, every male gamete unites at random (has same
probability as each other) with every female gamete, and frequencies or
pairings depend on the allele frequencies
○ If gametes unite randomly, you can calculate the genotype frequencies
in the next generation
■ Use a probability table to calculate the genotype frequencies in
the population
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Population and evolutionary genetics is the study of genetic variation in populations and evolution. It studies: how genetic variation arises, varies, and is maintained. Population is a localised group of interbreeding individuals of the same species. All alleles of a gene in a population make up the gene pool. Polymorphism is when many traits show variation in a population. Most genes are polymorphic (more than one allele in population) If there"s only one allele and it is called monomorphic (this means that the allele is fixed in the population) Migration in gel electrophoresis (fast and slow forms) was studied before other dna methods were used for studies. Genetic structure of a pop is defined by frequencies of different genotypes or. Eg. one gene, two alleles that show incomplete dominance for flower frequency of alleles colour. Frequency of alleles denoted by: p, q, r, s. The allele and genotype frequencies remain constant from gen to gn.
