Population Genetics And Natural Selection Flashcards
What is a population
Localised group of individuals of the same species
What is a gene pool
Total aggregate of genes (and their alleles) in the population at one time
Why might we need to estimate frequencies of genotypes in a population
To predict how many individuals will inherit a genetic disease
To estimate what proportion of individuals who are carriers of a genetic disease
What is the P + Q = 1 equation
P = dominant allele frequency
Q = recessive allele frequency
P does not have to equal Q
P does not have to be larger than Q
Is used for allele frequencies
What is the P^2 + 2PQ + Q^2 = 1 equation
P^2 is the homozygous dominant frequency
2PQ is the heterozygous frequency
Q^2 is the homozygous recessive frequency
What can cause a change in allele frequency’s
Non - random mating
Random genetic drift
Bottleneck effect
Founder effect
Natural selection
Gene flow of migration
Mutation
What is Random genetic drift
A random change in allele frequencies due to sampling error over generations
What is the bottle neck effect
A extreme example of genetic drift where the size of the population is severely reduced
What is the founder effect
The reduced genetic diversity which results when a population is descended for a small number of colonising ancestors
What is stabilising selection
Reduces variation but does not change the mean
What is directional selection
Changes the mean value towards one extreme
What is disruptive selection
Favours the two extremes producing two peaks
What is mutation role in genetic diversity
Very slow to act on large scale, usually disadvantageous, role is usually in macro evolutionary proportions
What is migration role in genetic diversity
Individual from another population successfully mates to the gene pool
Brings new alleles
Changes proportions of existing alleles
Changes population size
Makes two populations more similar
