Lab 15: Population Genetics - eScience Labs

Lab 15: Population Genetics
Concepts to explore:
Concepts to explore:
Gene pool
Mutation
Gene frequency
Natural selection
Genetic variation
Genetic drift
Founder effect
Introduction
In the previous lab we looked at how genes are passed on to
offspring. In this lab, the exercises are designed to look at individual
genes (two alleles, one dominant, one recessive). However,
we will be looking at their presence, prevalence and distribution
at the population level.
The gene pool is the sum of all genes and their corresponding
alleles in a given population.
Take a look at the population of 100 brown and white mice in
Figure 1. The color brown (B) is dominant. The standard for
naming alleles is to use the case of the dominant trait, with the
lower case to represent the recessive allele. Their gene pool is
B, b.
Figure 1: Mouse Population
Gene frequency refers to how many times each allele is found
in the population. These 100 mice have 200 genes:
55 heterozygous mice (B, b) have 55 B alleles and
55 b alleles.
27 homozygous recessive mice (b, b) have 54 b alleles (2 x 27 “b”= 54).
18 homozygous dominant mice (B, B) have 36 B alleles (18 x 2 “B” = 36).
The gene frequency of the population is:
B: 91 b: 109
Often this is represented as a percentage of the dominant gene, in this case, the percentage of B is
161