Genetic Drift and Evolution

These flashcards cover key concepts of genetic drift, evolutionary mechanisms, and population dynamics based on the provided lecture notes.

What is genetic drift?

Genetic drift is a random fluctuation in allele frequencies due to chance events in small populations.

What happens to genetic variation in small populations over time due to genetic drift?

Genetic variation decreases as alleles may become fixed or go extinct.

What is the difference between genetic drift and natural selection?

Genetic drift is a random process that does not favor alleles based on fitness, whereas natural selection favors alleles that confer a survival or reproductive advantage.

What is a bottleneck effect?

A bottleneck effect occurs when a population's size is sharply reduced, leading to a loss of genetic diversity.

How does population size influence the impact of genetic drift?

Smaller populations are more affected by genetic drift because random changes in allele frequencies have a greater impact.

What is the founder effect in genetics?

The founder effect occurs when a small group of individuals establishes a new population, leading to reduced genetic variation compared to the source population.

What is the probability of fixation for an allele in a population?

The probability of fixation for an allele is equal to its frequency in the population.

How does drift affect advantageous alleles in small populations?

Drift can lead to the loss of low frequency advantageous alleles and fixation of disadvantageous alleles in small populations.

What is linkage disequilibrium?

Linkage disequilibrium refers to the non-random association of alleles at different loci, which can develop through genetic drift.

How does the effective population size (Ne) relate to genetic drift?

Effective population size (Ne) estimates how many individuals are needed in an ideal population to experience the same level of genetic drift as a real population.

What does the Hardy-Weinberg equation help estimate in the context of genetic drift?

The Hardy-Weinberg equation helps estimate expected heterozygosity (H) based on allele frequencies.

What are deleterious alleles and how do they become fixed in populations?

Deleterious alleles are harmful mutations that can become fixed in small populations due to genetic drift.

What conclusion can be drawn about the long-term effects of genetic drift in terms of heterozygosity?

Over time, genetic drift tends to reduce heterozygosity in populations.

What role does stochastic environmental events play in genetic drift?

Stochastic environmental events can randomly affect which individuals survive and reproduce, influencing allele frequencies.