Exam 4: Intro to Population Genetics Flashcards
Describe how migration and genetic drift impact allele frequencies.
Migration can homogenize allele frequencies between populations. If individuals with different allele frequencies migrate into a population, they can alter the genetic composition of that population. It tends to reduce genetic differences among populations.
Genetic drift is particularly significant in small populations. Due to random sampling in each generation, certain alleles may become more or less common over time, regardless of their fitness. Genetic drift can lead to the fixation (one allele becomes fixed and the other is lost) or loss (loss of an allele) of alleles, especially in small populations. It has a more pronounced effect in populations with lower genetic diversity.
What is a population?
A population is a sexually interbreeding group whose set of genes constitutes the gene pool
What is a gene pool?
A gene pool is the collective set of alleles, described by allelic frequency. Allele frequencies are a reflection of genetic diversity.
What are the assumptions of the Hardy-Weinburg law?
-Large population
-Randomly mating
-No mutations
-No migrations
-No natural selection.
Hardy-Weinburg equation
p^2 +2pq+q^2 = 1
Migration – gene flow
The amount of change in allelic
frequency due to migration between
populations depends on the difference in allelic frequency and the extent of migration.
- prevents genetic distinction between these populations
- increases genetic diversity and variation
Genetic Drift
Genetic drift; random changes in allelic frequency
Causes of genetic drift:
-Founder effect: a population is established by a few individuals
-Genetic bottleneck: a drastic reduction in population numbers
The effects of genetic drift:
–Allele fixation: frequency of 100%
–Allele loss: frequency of 0%
What does Hardy-Weinburg equilibrium imply?
A lack of evolution.
