Genetic Drift Flashcards
What are the 4 major factors that alter allele frequencies in a population?
- Mutation
- Genetic drift
- Gene flow
- Natural selection
What size of population is more prone to genetic drift?
Smaller populations
What is genetic drift?
Random changes in allele or genotype frequencies within a population
What causes genetic drift?
Sampling effects in finite populations or accidents that are completely due to chance and not natural selection
What does genetic drift describe?
How allele frequencies fluctuate unpredictably from one generation to the next
What is the result of genetic drift?
Alleles are fixed or lost in a population not from natural selection, leading to a loss of heterozygotes and genetic diversity
Why are small populations more prone to genetic drift?
It is easier for an allele to become fixed or lost from random chance
What are the fitness differences of alleles subject to genetic drift?
No allele is more fit than any other. Drift is random and the alleles are not being naturally selected
What is a fixed allele?
An allele whose frequency in the populations doesn’t fluctuate
Where do founder effects often happen?
Islands and other isolated habitats like caves, ponds, mountain-top forests
What is a founder effect?
A few individuals become isolated from the main population so only their alleles are present in the new founder population, which is a reduced allele sample of the large population
How does the genetic diversity of founder populations compare to the genetic diversity of the parent population?
Founder populations have low genetic diversity from the reduced sample of the parent population alleles
What is a bottleneck effect?
Sudden reduction in population size due to environmental changes
How does the gene pool of a bottleneck population compare to the original population?
The gene pool has been substantially reduced and may not be a representative sample of the original population’s gene pool
Why do bottleneck effects contribute to low genetic diversity?
The population lost a huge amount of alleles and diversity, and if the population stays small it is prone to genetic drift
