Genetic Drift exam Flashcards
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Genetic Drift
A random change in allele frequency due to chance, particularly pronounced in small populations.
What is the founder effect?
A phenomenon where a small group establishes a new population, leading to allele frequencies that match the founders.
Population Bottleneck
A sudden environmental change drastically reduces population size, accelerating genetic drift.
How does genetic drift affect genetic variation?
It can lead to the loss of genetic variation as alleles are lost from the population.
Neutral Alleles
Alleles that do not affect the fitness of an organism.
What happens to allele frequencies in small populations due to genetic drift?
Allele frequencies change unpredictably and can lead to fixation or loss of alleles.
Fitness
The likelihood that an allele improves the survival or reproduction of an organism.
How does population size affect genetic drift?
Genetic drift has a greater effect in small populations and a lesser effect in large populations.
Fixation
When an allele frequency reaches 1, meaning it is the only allele present in the population.
What is the effect of genetic drift on deleterious alleles in small populations?
It can increase the frequency of deleterious alleles due to random changes.
What is the main way allele frequencies change for neutral alleles?
Genetic drift, as there is no fitness difference between the alleles.
Probability
The likelihood or chance that a particular event will occur.
How does genetic drift differ from natural selection?
Genetic drift is random and unpredictable, while natural selection is predictable based on fitness.
What can cause a population bottleneck?
A sudden environmental change, such as a natural disaster, that drastically reduces population size.
Generation Time
The time it takes for a new generation to be born and grow to reproductive age.
What is the effect of genetic drift on large populations?
A large population has many individuals, where genetic drift has a lesser effect each generation.
Founder Effect
A type of genetic drift where a new population is established by a small number of individuals.
How does genetic drift affect alleles with fitness differences?
It can still affect them, potentially increasing deleterious alleles or decreasing beneficial alleles.
Random Change
Unpredictable fluctuations in allele frequencies due to chance events.
What happens to genetic variation in a population bottleneck?
Genetic variation is reduced as the population size decreases and then rebounds.
Small Population
A population with a limited number of individuals, where genetic drift has a pronounced effect.
What is the relationship between population size and the predictability of allele frequency changes?
Smaller populations have less predictable allele frequency changes due to greater genetic drift.
Large Population
A population with many individuals, where genetic drift has a lesser effect each generation.
How does the founder effect impact genetic variation?
It reduces genetic variation as the new population's allele frequencies match the small founding group.
Deleterious Alleles
Alleles that negatively affect the fitness of an organism.
What is the main cause of genetic drift?
Random chance events that change allele frequencies, especially in small populations.
Rebound
The recovery of population size after a bottleneck event.