Lecture 21: Evolution

Question 1

What are the effects that Darwin observed in slight variations among individuals?

Answer 1

-the chance that a given individual will survive
-the number of offspring it will produce

Question 2

What did Darwin call the differential reproductive success of individuals?

Answer 2

Natural selection.

Question 3

What did Darwin referrer the breeding of domesticated animals as?

Answer 3

Artificial selection.

Question 4

What does natural selection act on?

Answer 4

It acts on the phenotypic variation of the individuals within a population.

Question 5

What does evolution act on?

Answer 5

It acts on the genetic variation of the population.

Question 6

What do we call the many alleys in a population?

Answer 6

A gene pool.

Question 7

What does the gene pool contain?

Answer 7

The variation that produces the differing phenotypes on which agents of evolution act.

Question 8

What is a locally interbreeding group within a geographic population called?

Answer 8

A (Mendelian) population.

Question 9

True or false. The relative proportions or frequencies of all alleles in a population are a measure of that population’s genetic variation.

Answer 9

True.

Question 10

What is the Hardy-Weinberg equilibrium?

Answer 10

A population of sexually reproducing organisms in which allele and genotype frequencies do not change from generation to generation.

Question 11

What are the five exceptions of the Hardy-Weinberg equilibrium?

Answer 11

1) Mating is random.
2) Population size is very large or infinite.
3) There is no migration between populations.
4) There is no mutation.
5) Natural selection does not affect the alleles under consideration.

Question 12

When can we see that a population has had no evolution aka is in Hardy-Weinberg equilibrium?

Answer 12

If after one generation of random mating, the genotype frequencies do not change.

Question 13

What is the most important message of the Hardy Weinberg equilibrium?

Answer 13

That allele frequencies remain the same from generation to generation, unless some agents change them.

Question 14

What does the Hardy Weinberg equilibrium also show?

Answer 14

The distribution of genotypes that would be expected for a population of genetic equilibrium.

Question 15

What does the Hardy-Weinberg equilibrium allow scientist to determine?

Answer 15

Whether evolutionary agents are operating under their identity (as evidenced by the pattern of deviation from the equilibrium).

Question 16

What are evolutionary agents?

Answer 16

The causes that can change the allele and genotype frequencies of a population.

Question 17

What are the five known evolutionary agents?

Answer 17

-mutation
-Gene flow
-Genetic drift
-non-random mating
-natural selection

Question 18

What is mutation?

Answer 18

Any change in an organism’s DNA.

Question 19

True or false. Most mutations appear to be random and are harmful or nutrients with their bearers.

Answer 19

True.

Question 20

True or false. Most mutations can be advantageous.

Answer 20

False. Only some can be advantageous.

Question 21

What is one condition of the Hardy-Weinberg equilibrium?

Answer 21

There are no mutations.

Question 22

What is gene flow?

Answer 22

When individuals migrate to another population and breed in their new location.

Question 23

How does gene flow work?

Answer 23

The immigrants will add new alleles to the gene pool of a population, or will change the frequency of the alleles.

Question 24

What is genetic drift?

Answer 24

The random loss of individuals and the alleles they possess.

Question 25

How can genetic drift affect a very small population?

Answer 25

It can be strong enough to influence the direction of change of audio frequencies.

Question 26

How does genetic drift affect a large population?

Answer 26

it can lead them to pass through occasional periods when only a small number of individuals survive.

Question 27

What is a bottleneck effect and what are some of its causes?

Answer 27

It is a population that goes through occasional period for only a few individuals to survive. Some of his causes are: -predation -habitat destruction -disease

Question 28

What is the founder effect?

Answer 28

A few pioneering individuals that leave their original population and then colonize a new region, creating a new smaller population.

Question 29

What is non-random mating?

Answer 29

Individuals that meet either more often with individuals of the same genotype or individuals of different genotypes.

Question 30

What will happen if individuals mate preferentially with other individuals of the same genotype?

Answer 30

Homozygous genotypes will be overrepresented, and the heterozygous genotypes will be underrepresented in the next generation.

Question 31

True or false. Individuals will not meet preferentially with individuals of a different genotype.

Answer 31

False. Individuals will not meet preferentially with individuals of a different genotype.

Question 32

What is the result of natural selection?

Answer 32

Adaptation.

Question 33

For adaptation to occur, what are the conditions?

Answer 33

Individuals that different heritable traits must survive and reproduce with different degrees of success.

Question 34

What will happen if some individuals contribute more offspring to the next generation than others?

Answer 34

Allele frequencies in the population, will change in a way that adapts.

Question 35

What is a fitness of a phenotype?

Answer 35

The reproductive contribution of a phenotype to subsequent generations relative to the contributions of other phenotypes.

Question 36

What is the fitness of a phenotype determined by?

Answer 36

The average rate of survival and reproduction of individuals with that phenotype.

Question 37

True or false. Most characters are influenced by all had more than one locus and are more likely to show qualitative rather than quantitive variation.

Answer 37

False. Most characters are influenced by all had more than one locus and are more likely to show quantitive rather than qualitative variation.

Question 38

What are the three ways that natural selection connect on the characters with quantitive variation?

Answer 38

1) stabilizing selection 2) directional selection 3) disruptive selection

Question 39

What is stabilizing selection?

Answer 39

The preservation of characteristics of a population by favouring average individuals.

Question 40

What does stabilizing selection occur?

Answer 40

When the extremes of the population contribute relatively fewer offspring than the average members to the next generation.

Question 41

What is directional selection?

Answer 41

The changes of characteristics of a population by favourite individuals that vary in one direction from the mean of the population, reducing the genetic variation.

Question 42

When does directional selection occur?

Answer 42

When one extreme of a population contributes more offspring to the next generation.

Question 43

What is disruptive selection?

Answer 43

Changes of the characteristics of a population, by favourite individuals that vary in both directions from the mean of the population which will maintain the overall variation in a population.

Question 44

When does disruptive selection occur?

Answer 44

When individuals at both extremes of a population are simultaneously favoured.