Lecture 13 Nov.1/2016
Q: Which describes heterozygote advantage?
Heterozygote advantage maintains allele freq in a population.
A: W AAW >WAa aa
Q: wAA=WAa>Waa what type of selection is occurring?
A: Selection against a recessive allele.
If all were equal, then no selection is occuring
How to remove genetic variation from a population?
Population bottleneck is a massive reduction in the population due to natural disaster/ human damage.
It results in a decrease in genetic variation.
What happens when a group of animals moves to a smaller island away from the
Genetic diversity will be lower on the island and allele frequencies will be different on the island. These
are due to the founder effect. The founder effect is the loss of genetic variation following a new
population being established by a small # of individuals from the main population.
What is the genetic effect of inbreeding on a population?
Inbreeding increases the frequency of homozygous genotypes. Inbreeding DOES NOT change allele
Processes that reduce, remove, or maintain heritable variation in populations
Only changes in allele frequency can cause changes in variation.
Reduce: Population bottleneck, genetic drift
Remove: Founder effect, gene flow, heterozygote disadvantage
Maintain: heterozygote advantage
Effect of non-random mating (e.g., inbreeding) on allele frequencies and on genotype
Inbreeding does not affect allele frequencies, however it increases the frequency of the homologous
Effects of genetic drift and gene flow on variation within a population
Genetic drift refers to changes in allele frequency over time and this causes a reduction in variation.
Gene flow, on the other hand, increases genetic variation in a population by introducing new genes. Lecture 13 Nov.1/2016
Relative fitness for each genotype, given a set of absolute fitnesses
Absolute fitness, W, is the avg number of surviving offspring for each genotype.
To be able to interpret fitness, divide by the absolute fitness of most successful genotype to calculate
relative fitness (to compare genotype fitness). Therefore, the most successful genotype has a relative
fitness of w=1.
So, given a set of absolute fitnesses, take each absolute and divide by the most successful genotype
What type of selection is operating, given a set of relative fitnesses
Effect of heterozygote disadvantage on genetic variation
In a situation where hetero are less fit than homo, whichever allele starts of