Lectures 8 and 9: Population Genetics Flashcards
What is a population?
A group of interbreeding individuals f the same species that inhabit the same space and time
What is a gene pool?
All of the alleles present and carried by the population
What is population genetics?
Changes in the frequency of the alleles in a gene pool over time
Selection can occur when ___________________________________________.
one genotype is more “fit” than another
What is a heterozygote advantage?
An individual heterozygous at a particular locus exhibits greater biological fitness
What is the Founder Effect?
Disproportionate effect on gene frequencies that can
occur when a new population is founded by a small group of individuals from a larger population
With respect to medical genetics, what is a founder?
Used to describe the first person in a community who displays the symptoms of a particular genetic disorder
What is Genetic Drift?
Random chance fluctuation in the frequency of a gene in the absence of selection. Allele frequency can increase to fixation (100%) or can be lost from the gene pool by random chance.
Random Genetic Drift generally occurs in ________________.
Small Populations
What is the effective population size (Ne)?
The proportion of the population that is capable of reproduction, on average 1/3 of population
What is Endogamy?
A preference for individuals to marry within their
own specific community
What is Consanguinuity?
Marriage between close biological relatives
What is Phenotypic Frequency?
The proportion of individuals within a population that are of a particular phenotype
What is Genotypic Frequency?
The proportion of individuals within a population that are of a particular genotype
What is Allelic Frequency?
The proportion of all copies of a gene in a population that are of a particular allele type
The frequency of the dominant allele is denoted __ and the formula for calculating it is ____________.
p
p = F(AA) + 1/2F(Aa)
The frequency of the recessive allele is denoted __ and the formula for calculating it is ____________.
q
q = F(aa) + 1/2F(Aa)
What is the Hardy-Weinberg Equation?
q^2 + 2pq + p^2 = 1 OR (p + q)^2 = 1
What are the assumptions of the Hardy-Weinberg Equation?
- Mating is random
- Allelic frequencies are the same in males and females
- All genotypes have equivalent viability and fertility
- Mutation does not occur
- Migration into the population is absent
- Population is large so that allelic variations do not occur by chance
What causes a deviation from the Hardy-Weinberg equilibrium?
- Non-random mating (e.g. inbreeding)
- Gene flow (e.g. migration)
- Genetic drift
- Mutation
- Natural Selection
- Genotyping errors
