Microevolution I

Question 1

What is microevolution?

Answer 1

The evolutionary processes that occur rapidly within populations and change their genetic makeup from one generation to the next.

Question 2

What is macroevolution?

Answer 2

The evolutionary processes that occur slowly, where the history of life is written both in the fossil record and in the relationship of living species.

Question 3

What are jumping genes (transposable elements)?

Answer 3

They are a mobile segment of DNA that can change their position within the genome and alter the expression of those genes.

Question 4

How were the jumping genes responsible for the dark coloration in moths studied?

Answer 4

Using fine scale linkage association mapping combined with DNA sequencing. And using statistical modeling, this mutation was dated to around 1819.

Question 5

How were jumping genes responsible for the change in coloration in moths?

Answer 5

These genes were inserted within the moth cortex gene and were responsible for that color change.

Question 6

How did the frequency of dark-colored moths change as natural selection acted upon them?

Answer 6

Initially, the pepper-colored moths were more prevalent because they blended in to the tree bark, but with the Industrial Revolution and large amount of pollutants on the trees, the dark variant was selected for and increased in frequency.

Question 7

At the gene level, how is genetic variation quantified?

Answer 7

By the percentage of heterozygous loci in the population.

Question 8

At the molecular level, how is genetic variation quantified?

Answer 8

By comparing nucleotide sequences of two or more individuals.

Question 9

How does genetic variation originate?

Answer 9

When new genes or alleles arise by mutation, gene duplication, sexual reproduction, or other processes.

Question 10

Why is there a disparity in evolution between viruses and mammals?

Answer 10

Viruses’ mutation rate is higher and their generation time is shorter.

Question 11

What is a population?

Answer 11

A population is a group of organisms within the same species that live in the same area and interbreed with each other.

Question 12

What does a gene pool consist of?

Answer 12

All the copies of every allele at every locus of all members of the population.

Question 13

What does it mean to say a locus is fixed?

Answer 13

A locus is fixed if all individuals in that population are homozygous for the same allele. There will be no variation in that population unless there is a mutation or outside organism that brings with it variation.

Question 14

What does p + q equal?

Answer 14

1

Question 15

What do p^2, 2pq, and q^2 represent?

Answer 15

Genotype frequencies.

Question 16

How do p, q, p^2, 2pq, and q^2 change throughout subsequent generations?

Answer 16

They don’t change; p^2 + 2pq + q^2 always equals 1.

Question 17

What is the Hardy-Weinberg Principle?

Answer 17

Whatever the initial genotype frequencies for two alleles may be, after one generation of random mating, the genotype frequencies will be p^2 : 2pq : q^2

Question 18

What does it mean for a locus to be in Hardy-Weinberg equilibrium?

Answer 18

The genotypes at the locus have the frequencies predicted by the Hardy-Weinberg principle.

Question 19

What are the five assumptions of the Hardy-Weinberg principle?

Answer 19

1. There is no mutation.
2. The population is infinitely large (if not, random genetic drift)
3. Mating among individuals is random (if not, assortative mating, inbreeding, etc)
4. Individuals are not moved into or out of the population (if not, gene flow or migration)
5. All individuals have equal probabilities of survival and reproduction (if not, natural selection)

Question 20

What does it mean if any of the assumptions of the Hardy-Weinberg principle are violated?

Answer 20

It means that evolution is occurring and the null hypothesis of the H-W principle is overturned.

Question 21

What happens in the absence of any evolutionary force?

Answer 21

Nothing. The population’s genotype and allele frequencies do not change.

Question 22

What two reasons make the HW equation useful?

Answer 22

1. It allows us to test whether evolution is occurring in a population.
2. By assuming HWE, it allows us to estimate the percentage of a population carrying a disease allele.

Question 23

Of the genotype numbers, what does D represent?

Answer 23

number of AA

Question 24

Of the genotype numbers, what does H represent?

Answer 24

number of Aa

Question 25

Of the genotype numbers, what does R represent?

Answer 25

number of aa

Question 26

Of the genotype numbers, what does D + H + R represent?

Answer 26

The total number of individuals (N).

Question 27

What does d represent?

Answer 27

d = D/N (genotype frequency)

Question 28

What does h represent?

Answer 28

h = H/N (genotype frequency)

Question 29

What does r represent?

Answer 29

r = R/N (genotype frequency)

Question 30

What does d + h + r equal?

Answer 30

1

Question 31

How is the allele frequency of p calculated?

Answer 31

p = (2D + H)/2N, or p = d +h/2

Question 32

How is the allele frequency of q calculated?

Answer 32

q = (2R + H)/2N, or q = r + h/2

Question 33

How is the genotype frequency in the next generation as a function of allele frequencies calculated for d?

Answer 33

d’ = p^2

Question 34

How is the genotype frequency in the next generation as a function of allele frequencies calculated for h?

Answer 34

h’ = pq + pq = 2pq

Question 35

How is the genotype frequency in the next generation as a function of allele frequencies calculated for r?

Answer 35

r’ = q^2

Question 36

How can the HW equation be expanded to more than two alleles?

Answer 36

Since we know that for two alleles (p+q)^2 = 1, we can then say that for 3 alleles with frequencies of p, q, and r: (p + q + r)^2 = 1

Question 37

What is the effect of having sex-linked genes on the HW theorem?

Answer 37

There is a higher frequency of various recessive sex-linked diseases because a male’s frequency is represented by q, not q^2 (as it is for females)