Population and Quantitative Genetics Flashcards
(20 cards)
The proportion of a population with a specific genotype
genotype frequency
individuals with genotype/total population =
genotype frequency
the proportion of a population with a specific allele
allele frequency
individuals with allele/total population =
allele frequency
p^2 + 2pq + q^2 = 1
Hardy-Weinberg Equilibrium
A population that meets assumptions:
1. Mating is random with respect to the gene under study
2. Genotypes do not reduce viability or fertility
3. Population does not contain genetically isolated subpopulations
4. Population is infinitely large (no sampling error)
will not see changes in allele and genotype frequencies across generations and is in
Hardy-Weinberg Equilibrium
Similar types mate
positive assortative mating
unlike individuals mate
negative assortative mating
new alleles enter populations through
mutation and migration
alleles can be lost or fixed in populations through
genetic drift and natural selection
traits that have continuous variation and are influenced by multiple genes and the environment
quantitative traits
influenced by multiple genes
polygenic
multiple genes that contribute to a single phenotype are called polygenes or
quantitative trait loci (QTL)
determines the contribution of alleles to a complex trait:
1. Cross two true-breeding lines of different sizes, then backcross the F1 with a parental strain
2. Backcross progeny show range of phenotype variation
3. Performing a backcross allows allele segregation following recombination to be observed
4. For any locus, the mean trait value will be different between the homozygous P1 and heterozygous individuals
quantitative trait loci (QTL) Mapping
Identifying genotypes with different trait distributions is statistically analyzed using a
Lod score
linked combinations of alleles
haplotypes
new haplotypes can be introduced through migration or mutation and are initially in
linkage disequilibrium (nonrandomly associated)
over time, recombination between individuals with new haplotypes and original haplotypes will result in
linkage equilibrium (random association)
Human QTLs can be studied through _______. They identify loci associated with complex traits
Genome-Wide Association Studies (GWAS)
Data from GWAS are often presented as a scatter plot indicating statistical association of a variant with a phenotype
Manhattan plot
