Lecture 53. Pop Genetics & Looking Ahead to Year 2 Flashcards
What is a population?
A group of individuals of the same species that are able to interbreed
What are sub-populations?
Where some species occupy a wide geographic range
What is the purpose of population genetics?
To see genetic structure of a population (the number of alleles and frequency of each within a population (gene pool))
To see geographic patterns in distribution of allelic variation within and amongst sub-populations
To see temporal changes in genetic structure of a population
What are the applications of population genetics?
Species conservation and utilisation of biodiversity
Essential for Genome-Wide Association Mapping (GWAM)
What is the Hardy-Weinberg principle?
Method for investigating the movement of alleles in populations
What is the Hardy-Weinberg principle essential for?
Understanding mechanisms of evolutionary change (e.g speciation)
Using the Hardy-Weinberg principle, what are the starting parameters you must assume?
Infinitely large population
Random mating amongst individuals
No new mutations, migration or natural selection
In the Hardy-Weinberg principle, what represent the frequency of the dominant allele?
p
In the Hardy-Weinberg principle, what represent the frequency of the recessive allele?
q = (1-p)
What is the total of genotype frequencies in the Hardy-Weinberg principle?
p² + 2pq + q² = 1
What are the five things that can cause a change in genetic structure?
Mutation
Migration
Natural selection
Genetic drift
Non-random mating
What are the three types of new alleles that mutations create?
Lethal, neutral and beneficial
What is the ultimate source of all genetic variation?
Mutations
How does migration cause a change in genetic structure?
New individuals move into a population, which introduces new alleles “gene flow”
What is natural selection?
Differences in survival or reproduction which leased to adaptation
Differences in “fitness”
What are the four types of natural selection?
Directional selection
Stabilising selection
Disruptive selection
Balancing selection
What does directional selection favour?
Individuals at one extreme of a phenotypic distribution, which have greater reproductive success in a particular environment
What does stabilising selection favour?
Survival of individuals with intermediate phenotypes
Extreme phenotypes are selected against
What is an example of a stabilising selection factor?
Bird clutch size
Too many eggs and offspring die due to lack of care and food
Too few eggs does not contribute enough to next generation
What does disruptive selection favour?
The survival of two or more different genotypes that each produce different phenotypes
Where is disruptive selection likely to occur?
Populations that occupy diverse environments
When does balancing selection occur?
When two or more alleles are kept in balance, and therefore are maintained in a population over many generations
What symbol represents a heterozygote advantage?
Hˢ allele
What is an example of balancing selection?
Sickle cell allele or malaria in Africa
