Genetic Drift Flashcards
Genetic drift and allele frequencies
Yes changes allele frequencies and is a random evolutionary force in terms of which allele will fix (not random in knowing one allele with fix and other will not)
Genetic drift
Random changes in allele frequencies within a population caused by chance (can happen at any stage)
Results in non-adaptive evolution (evolution of traits that are not associated with an increase in fitness)
Long term concern
Genetic drift violate the Hardy-Weinberg equilibrium principle?
Yes
Gamete sampling error
Chance that actual frequencies are different than expectation, like percent error
Founder effect
When a small number of individuals move somewhere else and start a new population, allele frequencies are likely to be different, by chance, from the source population, can lose genetic diversity
Population bottleneck
Large initial population with lots of diversity, bottleneck allows only a few to make it out or survive, loss of diversity and survivors are founders of the next generation
Fixation of alleles
An allele becomes fixed when it reaches a fitness of 1 and the other allele is lost over time
Loss of alleles
When an allele loses all fitness and is removed from a population overall, no chance of being brought back unless a mutation occurs
Genetic drift and type of evolution
Random evolution, due to chance
Effect of population size
Strongest in small populations
Allelic diversity and heterozygosity
Results in the random fixation of alleles and thus a loss of heterozygosity, smaller population size means quicker fixation and heterozygosity decrease
Two alleles present, can you predict which will fixate?
Higher frequency more likely to fixate while lower frequency more likely to be lost, not always the case since due to chance, if 50:50 then either may fixate
Effect on allelic diversity
Always decreases allelic diversity
Strong evolutionary force?
In small populations yes, takes longer on larger populations, long term effect mainly
