Mechanisms Of Evolution

Question 1

What can break the Hardy-Weinberg equilibrium and cause evolution?

Answer 1

Mutations
Non-random mating
Natural selection
Genetic drift
Gene flow

Question 2

What is significant about mutations?

Answer 2

They are completely random

Question 3

What are mutations?

Answer 3

Changes in the DNA sequence of an organism (insertion, deletions, substitution at one or more sites)

Question 4

Mutation contributes to…

Answer 4

Genetic variation

Question 5

Mutation can…

Answer 5

Modify allele frequencies
Be good, bad or neutral

Question 6

What is non-random mating?

Answer 6

It occurs when probability that two individuals in a population will mate is not the same for all possible pairs

Question 7

What does non-random mating affect?

Answer 7

It affects the frequencies of homozygous and heterozygous genotypes

Question 8

Natural selection is the only mechanism that…

Answer 8

Consistently leads to adaptive change

Question 9

Natural selection is NOT…

Answer 9

Random
Predictive

Question 10

Natural selection consistently…

Answer 10

Increases frequency of alleles that provide fitness benefits which leads to adaptive evolution

Question 11

What are the types of natural selection.

Answer 11

Directional
Stabilizing
Disruptive
Balancing
Sexual selection

Question 12

When does directional selection occur?

Answer 12

When conditions favor individuals with on extreme of a phenotypic range

Question 13

How does directional selection shift?

Answer 13

Shifts the frequency curve in one direction (left or right)

Question 14

Directional selection tends to…

Answer 14

Reduce genetic variation

Question 15

Stability selection acts against…

Answer 15

Both extreme phenotypes and favors intermediate variants (mean trait value)

Question 16

Stabilizing selection reduces…

Answer 16

Variation

Question 17

Stabilizing selection maintains…

Answer 17

Status quo for a particular phenotypic trait

Question 18

Stabilizing Selection there is no change in…

Answer 18

Average trait value over time

Question 19

Disruptive selection occurs…

Answer 19

When conditions favor individuals at both extreme of a phenotypic range over individuals with intermediate phenotypes

Question 20

Disruptive Selection tends to…

Answer 20

Increase genetic variation

Question 21

Disruptive Selection can lead to…

Answer 21

Speciation (two different species)

Question 22

How does stabilizing selection look on a graph?

Answer 22

Culls extreme variations
Narrows width of distribution

Question 23

How does directional selection look on a graph?

Answer 23

Favors one extreme
Shifts distribution left/right

Question 24

How does disruptive selection look on a graph?

Answer 24

Favors both extremes
Creates bio dual distribution

Question 25

What is balancing selection?

Answer 25

Selection may preserve variation at some loci, thus maintaining two or more phenotypic forms

Question 26

What are the two types of balancing selection?

Answer 26

Frequency dependent selection and heterozygote advantage

Question 27

What is frequency dependent selection?

Answer 27

Fitness of a phenotype depends on how common it is in the population

Question 28

What is a heterozygote advantage?

Answer 28

When individuals are heterozygous at a particular locus have greater fitness than both kinds of homozygotes , fitness is relative to others in the population and in the environment

Question 29

What is sexual selection?

Answer 29

Process where individuals with certain inherited characteristics are mo re likely than other individuals of the same sex to obtain mates

Question 30

What is sexual dimorphism?

Answer 30

Difference in the secondary sexual characteristics between males and females of same species

Question 31

What is intersexual selection?

Answer 31

Selection within the same sex

Question 32

What is intersexual selection?

Answer 32

Individuals of one sex are choosy when selecting mates from the other sex; also called mate choice

Question 33

Why doesn’t natural selection create perfect organisms?

Answer 33

Selection can only act on existing variation Evolution is not forward looking Limited by historical constraints Adaptations often compromises Interactions with other evolutionary processes and chance events

Question 34

What is genetic drift?

Answer 34

Chance events that cause allele frequencies to change unpredictability from one generation to the next, especially in small populations

Question 35

Genetic drift is significant in…

Answer 35

Small populations

Question 36

Genetic drift causes…

Answer 36

allele frequencies to change at random

Question 37

Genetic drift leads to…

Answer 37

A loss of genetic variation in a population

Question 38

Genetic drift can cause…

Answer 38

Harmful alleles to be fixed

Question 39

What are the two types of genetic drift?

Answer 39

Founder effect and bottleneck effect

Question 40

What is the founder affect?

Answer 40

When a few individuals become isolated from a larger population and go on to establish a new population whose gene pool differs from the source population

Question 41

What is the bottleneck effect?

Answer 41

A drastic reduction in the size of a population by chance alone that leads to certain alleles that are over represented/underrepresented among the survivors

Question 42

What is gene flow? Yeah

Answer 42

Aka migration, transfer of alleles in or out of a populations due to the movement of fertile individuals or their gametes

Question 43

Gene flow can help or hinder natural selection forces by…

Answer 43

Affecting how well populations are adapted to local environmental conditions