Evolution of Populations - Microevolution

Question 1

Which is the more likely to evolve, populations or individuals?

Answer 1

Populations. Alone, individuals cannot and do not evolve on their own.

Question 2

How do we know if evolution has occured?

Answer 2

We look for changes in real allele frequency.

Question 3

What is a population?

Answer 3

It refers to all the individuals of a species, but we will use it to talk about the local populatoin.

Question 4

What is a gene pool?

Answer 4

It refers to all the possible alleles in a population. All the alleles at all loci.

Question 5

What are population genetics?

Answer 5

They are the study of allele frequencies in populations.

Question 6

Can evolution tell us about the origin of life?

Answer 6

No. It is only a theory about how life has changed, but it cannot teach us about how it all started.

Question 7

What is the first step in determining real genotype/allele frequencies?

Answer 7

Counting the individuals in a sample or in the whole population if possible.

Question 8

How do we compute the real genotype frequencies?

Answer 8

Number of a given genotype counted / Total number of genotypes (i.e. # of individuals)

Question 9

How do we compute the real allele frequencies?

Answer 9

Number of alleles (homozygous gen. *2 and het. 1) / Total number of alleles (2#individuals if diploid)

Question 10

What should be used to determine if a population is in genetic equilibrium?

Answer 10

The Hardy-Weinberg equations

Question 11

In H-W eq, what is p?

Answer 11

The expected frequency of the dominant allele.

Question 12

In H-W eq, what is q?

Answer 12

The frequency of the recessive allele.

Question 13

In H-W eq, what is q^2?

Answer 13

The expected frequency of the homo. recessive genotype and the recessive phenotype.

Question 14

In H-W eq, what is 2pq+p^2?

Answer 14

The expected frequency of the dominant phenotype (assume complete dominance).

Question 15

In H-W eq, what is p^2?

Answer 15

The expected frequency of the dominant phenotype.

Question 16

What is a population that is in equilibrium?

Answer 16

A population that is not evolving at the moment.

Question 17

How do you find out if a population is in equilibrium?

Answer 17

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.

Question 18

Do H-W give real frequencies?

Answer 18

No. They give expected values. We need to count the individuals to get real values.

Question 19

What are the Hardy-Weinberg conditions?

Answer 19

Random mating, no migration (gene flow), large population, no selection, no mutations

Question 20

Why is the distinction between real and expected frequencies important?

Answer 20

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.

Question 21

What is non-random mating?

Answer 21

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

Question 22

What is positive assortative mating?

Answer 22

A kind of non-random mating in which we mate individuals that are physically similar.

Question 23

What is negative assortative mating?

Answer 23

A kind of non-random mating in which we mate individuals that are not physically similar.

Question 24

What is inbreeding?

Answer 24

A kind of non-random mating in which individuals that are genetically related (cousins, parents, etc.) are mated.

Question 25

What is the effect of inbreeding?

Answer 25

It increases the number of homozygous loci.

Question 26

Why is inbreeding dangerous?

Answer 26

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.