Lecture 15 - Population Genetics Flashcards
What are the 2 types of genetic traits?
Discontinuous (not effected by environment eg tongue roll) and qualitative (continuous, strongly affected by environment eg height/weight)
What are the 3 types of polygenic trait?
Metric: continuous scale (have a mean)
Meristic: discrete scale
Threshold: present or absent (multifactoral)
Why is quantitative genetics important to medicine?
Prevention, genetic counselling, genetically tailored treatments
Why is genetics important to agriculture?
Economically important traits, selective breeding, directional selection
Why is quantitative genetics important to conservation?
For endangered species and captive breeding programmes, consequences of inbreeding and outcrossing
What is the equation for phenotypic variance?
Phenotypic variance = genetic variance + environmental variance + genetic x environment interaction
What 3 components make up genetic variance?
Alleles present, dominance interactions and epistatic interactions
What does heritability describe?
How much variation is genetic and it known as the h^2 value
What is broad sense heritability?
Measures the genetic variation relative to total variation = how much is genetics and how much is environmental
What is narrow sense heritability?
Importance of additive genetic variation relative to total variation = how much is additive and how much is environmental
What is the infinitesimal model?
Assumes that an infinite number of unlinked loci each with infinite effect will lead to an infinite number of of genes controlling a phenotypic trait with small effect
What 8 factors must be true for Hardy-Weinberg to be correct?
- Organisms are diploid, sexual and have discrete generations
- Allele frequencies are the same for each sex
- Mendelian segregation occurs
- Mating occurs at random
- Large population size
- No immigration/emigration
- No mutations
- No selection
What is linkage disequilibrium?
A non random association between 2 polymorphic loci for example shape and colour
