Genetics Flashcards
What is the definition of an evolutionary force?
Any factor that brings about changes in allele frequencies over time in a population and is thus capable of causing evolutionary change
What are the 4 evolutionary forces?
- natural selection
- mutation
- random genetic drift
- gene flow
What is a population?
A groups of organisms of the same species living in the same georgraphical area at the same time who have the capacity of interbreeding
What is Hardy-Weinberg principle?
The principle states that in the absence of evolutionary forces allele frequencies in a population will remain constant from one generation to the next
What is the Hardy-Weinberg equation?
P^2 +2pq + q^2 =1
What are the differences between migration and gene flow?
- migration is more or less a permanent move of individuals which doesn’t always involve interbreeding between immigrant and host
- gene flow always involves interbreeding but ,ah not involve a permanent migration
What is random genetic drift?
A mechanism for evolutionary change resulting from random fluctuations in allele frequencies from one generation to the next
What is founder effect?
Genetic differences between a newly founded population and its parent population due to the small size of the founding group
What is population bottleneck?
A bottle neck occurs when many members of a population die and only a few are left to reproduce. The new population has a restricted gene pool with different allele frequencies
What is a key factor that determines the rate of evolution due to RGD?
Population size - inverse relationship
What is a genetic polymorphism?
The occurrence of two or more commonly occurring alleles at a locus in a population, frequency of the most common allele less than 0.99
What is an example of a polymorphism?
Sickle cell in Africa
When is a locus monomorphic?
When the most common allele has a frequency of greater than 0.99
What is an example of a monomorphism?
ABO in South American natives - all group O
What is a gene pool?
The sum of all the genetic material in a population
How can a population that was monomorphic become polymorphic?
- mutation followed by drift or selection to increase frequency
- gene flow
Is RGD increasing or decreasing?
Decreasing
Is gene flow increasing or decreasing?
Increasing - because migration is increasing
How does gene flow interact with RGD?
Gene flow counteracts with RGD because it means populations act as a single unit with a larger N than two separate populations
What are the assumptions of Hardy-Weinberg?
- no mutation
- large population (no RGD)
- no selection
- random mating
- no gene flow
From an evolutionary perspective, what does a change in allele frequencies mean?
Evolution has occurred
What are the consequences of inbreeding?
- increase in frequency of homozygotes
- increases frequency of rare deleterious recessive conditions
What is the coefficient of inbreeding?
F
0.5 x r (of parents)
Hardy-Weinberg equation considering interbreeding
Q and p: +Fpq
Heterozygote= -WpqF
What are similarities between simple and complex traits?
- genetic
- May have an environmental influence
Differences between simple and complex traits
Number of loci: one vs many
Usual environment impact: small vs small or large
Nature of trait: discrete vs discrete or continuous
What does heritability capture?
Captures how much variation of a trait within a population is due to genetics
What are concordance rates used for?
Discrete diseases
How is heritability measured?
Value between zero and 1
Closer to 1: higher the genetic influence
What are some limitations of heritability?
- H is not constant
- assortative mating overestimates H
- shared environments overestimate H
