Genetic drift Flashcards
What is genetic drift?
Non-adaptive, random genetic changes between generations
What are the assumptions of the Hardy-Weinberg theory?
- Either no selection or that selection is constant
- No immigration/emigration
- Negligible effect of mutations
- Population size is large
What is the problem with deterministic models of evolution?
- Real world is stochastic
- Chance always intervenes
How could non-selective forces lead to the loss of a gene?
Random sampling, especially if sampling is small, can induce variation in gene frequencies between generations
Can loose genes due to a lack of gamete success
What conclusions can we draw from genetic simulations?
- Genetic drift happens more quickly at smaller populations
- Even in large populations fixation is inevitable but happens over more generations
- Allele that goes to fixation depends on the initial concentrations in the population
- Near-neutral genes always become fixed, only mutation/migration causes counter-fixation
Why is N not equal to Ne?
Population size not equal to effective population size
- Territorial/sexual selection
- Sex ratio biases towards rarer sex
- Variable fertility
- Negative effect between N & Ne
What is the most common way to estimate Ne?
Inferring the number of breeding adults from hypervariable genetic markers
When does selection win out over drift?
When 4Ne.S»_space; 1
What is the effect of inbreeding?
Causes increase in the frequency of deleterious recessives
