Tooic 9 Flashcards
What is a population?
What are population genetics?
A group of individuals of the same species
Population genetics analyzed the amount and distribution of genetic variation in populations and the forces that control this variation
Studies genes in groups of individuals and focuses on how alleles flow down generations
Genetic variation: amount and distribution
Forces controlling this variation
What is neutral mutation, deleterious mutation, and advantageous mutation in the population?
Neutral- mutant allele is at stable frequency in the population
Deleterious- mutant allele is extinct in the population
Advantageous- mutant allele fixed in population
Slides 8-10 topic 9
What 3 things does population genetics study?
Temporal changes in the genetic makeup of a population due to systematic and random evolutionary forces
Allelic variation among individuals
Transmission of allelic variants from parents to offspring generation after generation
What is the gene pool concept of population genetics?
Basic tool for thinking about genetic variation in populations
Sum total of all alleles in the breeding members of a population at a given time
Make genotypic and allele frequencies with allele count
Slide 15-17 topic 9
What is the theory of allele frequencies?
Simple formulas to get allele frequencies:
For A: p=2(AA) + Aa / 2N
For a: q=2(aa) + Aa / 2N
p+q=1
The frequency of an allele in the gene pool is equal to the probability that the allele will be chosen to form sperms and eggs
Slides 18-21 topic 9
How can homozygous frequencies be calculated easily with allele frequencies?
How do we get heterozygous?
P(AA)= f(A) x f(A) = p x p = p^2 AA= p^2
P(aa)= f(a) x f(a) = q x q = q^2 aa= q^2
Heterozygous:
P(Aa)= 2pq
Aa= 2pq
p^2 + 2pq + q^2 = 1
Slides 22-23 topic 9
What is the hardy Weinberg principle?
Describes mathematical relationship between allele frequencies and genotype frequencies
Can predict the genotype frequencies in an ideal population based on its allele frequencies
Can also be used to calculate allele frequencies from the genotype frequencies within a single generation
Slides 24-29 topic 9
Slides 2-7 topic 9.5
What is the difference between the hardy Weinberg principle and evolution?
HWP:
Random mating, no genetic drift, no mutation, no natural selection, no migration, population size is constant
If mating is random, and no different risk survival or reproduction exists, the genotype frequencies persist generation after generation (this is the hardy Weinberg equilibrium)
Evolution:
Migration, natural selection, genetic drift, nonrandom mating, mutation
Study hardy Weinberg example slide 25-29 topic 9
Ok
What is the point of the hardy Weinberg equilibrium if populations are rarely ever in equilibrium?
The HWP estimates the allele/genotype frequencies in an ideal state of the population
The real population can be compared against that ideal one
The differences between the expected and observed frequencies reveal the external factors that are influencing allele frequencies in the population
Slide 8 topic 9.5
How does natural selection effect the hardy Weinberg equilibrium?
Allele frequencies change systematically in populations because of differential survival and reproduction among genotypes
Natural selection is selection for survival and reproduction in the face of competition
Natural selection is the mechanism that changes the physical and behavioural characteristics of species
It acts as a negative force that weeds out alleles that express into less competitive phenotypes
Slides 11-14 topic 9.5
How does genetic drift affect the hardy Weinberg equilibrium?
The random change in allele frequencies due to sampling error
In small populations individuals that carry a particular allele may leave more descendants than other individuals do, just by chance
Over time a series of chance occurrences of this type can cause an allele to become common or even fixed in a population
Slides 15-17 topic 9.5
