Population and Quantitative Genetics

What’s the difference between a quantitative trait and a qualitative trait?

Quantative is non numerical (hair color), qualitative is numerical (number of kids)

What does heritability truly mean?

How much of the differences you see in a trait between people are due to genetic differences (not environment).

How do we determine the genetic component of a disease/trait?

• Twin studies where Concordance rate = how often both twins have the trait

• Genome-Wide Association Studies (GWAS)

  • Finds genetic variants linked to diseases/traits

• Heritability estimates where statistical models are used to calculate how much variation is genetic

Fixed Alleles

only allele in the population

Lost Alleles

no longer found in the population

Founder Effect

A small group of individuals migrates away from a larger population and
establishes a new colony/population

Bottleneck effect

Dramatic, random population reduction

Coefficient of selection

the proportion of mutant
alleles that are not passed on and are lost because of
selection

effective population size equation

Ne​=4Nm​Nf​​/Nm​+Nf​

Hardy-Weinberg equilibrium equation

Used to estimate allele frequencies in a population, p2+2pq+q2=1

Probability Equation

p+q=1

chi-square equation

used test if observed genotype frequencies deviate from expected

• 𝝌𝟐=∑(𝑶−𝑬)𝟐𝑬/E

Fitness

a measure of the number of offspring of affected persons who survive to reproductive age