Population Genetics Flashcards
Discrete Trait
Trait with a fixed set of possible values (Blood: A, B, AB, or O ONLY)
Continuous Trait
Trait with a range of expression values (human height)
Population Genetics
Investigates how the genotype frequencies in an offspring population are related to the genotypes in a parental population
Null Model
Expected outcome given that no environmental mechanism is acting on a population
Stable Equilibrium
System does not change and returns to original state when disturbed
Unstable Equilibrium
At equilibrium, system does not change, but any disturbance will cause change away from original state
Neutral Equilibrium
At equilibrium, state does not change, but any disturbance will cause system to move to new state and remain at that state
Mixed Equilibrium
At equilibrium, system is stable in response to one type of change, but unstable in response to a different change
Positive Frequency Dependent Selection
Fitness associated with a trait increases as the frequency of the trait increases in the population
-more common a trait is, higher fitness
Negative Frequency Dependent Selection
The fitness of a trait decreases as the frequency increases in the population
Mutation-Selection Balance
Balance between ongoing deleterious mutations and the purging effect by nation selection
-selection takes out BAD mutations
Assortative Mating
Individuals mate with other individuals of the same genotype or phenotype
Disassortative Mating
Individuals mate with other individuals of different genotypes or phenotypes
Self-Fertilization
Fertilization of own gametes (hermaphrodites; plants)
Inbreeding
Mating with a genetic relative
What are the HWE assumptions?
- NO natural selection
- Organisms mate randomly with respect to the locus being investigated
- NO mutation is occurring
- NO migration in or out of the population
- Large population size so genetic drift is negligible
only ONE of these assumptions can be violated
Compare allele frequencies between sink and source populations over time following migration
Allele frequencies of sink population can change over time as a result of migration of individuals from the source population (violates HWE)
How to determine a population is in HWE?
HWE Equations: p+q=1 & p^2+2pq+q^2=1
-Must get genotype frequency, allele frequency, expected genotype, expected/predicted individuals
-Do chi-square analysis (critical value is 3.84; lower than CV means in HWE, above CV means NOT in HWE)
Chi-Square Analysis?
x^2=E[(obs-exp)^2/exp]
Critical value is 3.84 (<3.84 means in HWE, >3.84 means NOT in HWE)
