Evolution of Populations - Microevolution Flashcards
Which is the more likely to evolve, populations or individuals?
Populations. Alone, individuals cannot and do not evolve on their own.
How do we know if evolution has occured?
We look for changes in real allele frequency.
What is a population?
It refers to all the individuals of a species, but we will use it to talk about the local populatoin.
What is a gene pool?
It refers to all the possible alleles in a population. All the alleles at all loci.
What are population genetics?
They are the study of allele frequencies in populations.
Can evolution tell us about the origin of life?
No. It is only a theory about how life has changed, but it cannot teach us about how it all started.
What is the first step in determining real genotype/allele frequencies?
Counting the individuals in a sample or in the whole population if possible.
How do we compute the real genotype frequencies?
Number of a given genotype counted / Total number of genotypes (i.e. # of individuals)
How do we compute the real allele frequencies?
Number of alleles (homozygous gen. *2 and het. 1) / Total number of alleles (2#individuals if diploid)
What should be used to determine if a population is in genetic equilibrium?
The Hardy-Weinberg equations
In H-W eq, what is p?
The expected frequency of the dominant allele.
In H-W eq, what is q?
The frequency of the recessive allele.
In H-W eq, what is q^2?
The expected frequency of the homo. recessive genotype and the recessive phenotype.
In H-W eq, what is 2pq+p^2?
The expected frequency of the dominant phenotype (assume complete dominance).
In H-W eq, what is p^2?
The expected frequency of the dominant phenotype.
What is a population that is in equilibrium?
A population that is not evolving at the moment.
How do you find out if a population is in equilibrium?
Equilibrium: H-W eq work. p+q=1 and p^2+2pq+q^2=1. If not equal to 1, no equilibrium.
Real alleles frequencies match the expected values .
Same allele real allele frequencies in both generations.
If not, then there is no equilibrium.
Do H-W give real frequencies?
No. They give expected values. We need to count the individuals to get real values.
What are the Hardy-Weinberg conditions?
Random mating, no migration (gene flow), large population, no selection, no mutations
Why is the distinction between real and expected frequencies important?
We need to use real frequencies to compute expected ones and we need to use the expected frequencies ot compute the real ones. Do not try to find the expected frequencies using the expected ones. You can compare the real genotypic frequencies with the ones that were expected to speculate on what mechanism of evolution is present.
What is non-random mating?
It is a type of mating in which the choice of mating is not random. We purposely mate two individuals of a given phenotype. This will affect the genotypic and phenotypic frequencies, but not the allele frequencies
What is positive assortative mating?
A kind of non-random mating in which we mate individuals that are physically similar.
What is negative assortative mating?
A kind of non-random mating in which we mate individuals that are not physically similar.
What is inbreeding?
A kind of non-random mating in which individuals that are genetically related (cousins, parents, etc.) are mated.
What is the effect of inbreeding?
It increases the number of homozygous loci.
Why is inbreeding dangerous?
It can lead to many genetic disorders because it can bring about deleterious recessive phenotypes more easily because it increases homozygosity. The more dangerous phenotypes are thus exhibited more likely instead of being hidden by a dominant allele.
