Unit 2 - Evolution

Question 1

What is evolution?

Answer 1

The change over time in the proportion of individuals in a population differing on one or more inherited trait

Question 2

What is essential for remaining part of a species?

Answer 2

Gene flow

Question 3

What happens if there is a larger gene flow?

Answer 3

Then the gene pool is similar to the allele frequencies

Question 4

What happens when a population becomes isolated?

Answer 4

The gene frequencies will become less similar due to selection and inbreeding and eventually lead to speciation

Question 6

What causes allele frequencies to change during evolution?

Answer 6

-Non random processes of natural selection and sexual selection
-Random process of genetic drift

Question 7

What does natural selection act on?

Answer 7

Genetic variation in population

Question 8

How does variation in traits arise?

Answer 8

Mutation

Question 9

Why do mutations cause variation?

Answer 9

Mutations are the original source of new sequences of DNA

Question 10

Mutations can be harmful, neutral or beneficial to the _________ of the individual

Answer 10

Fitness

Question 11

Populations produce more offspring than…

Answer 11

The environment can support

Question 12

What does this lead to when popualtions produce too much offspring?

Answer 12

Struggle for survival, many offspring die before they reproduce due to competition, lack of food and inability to escape predators

Question 13

What happens to those individuals who are better adapted to their environemtn?

Answer 13

They survive longer and produce more offspring which means they pass on those “better suited” alleles to the next generation

Question 14

What does natural selection result in?

Answer 14

The non random increase in the frequency of advantageous alleles and the non random decrease in the frequency of deleterious alleles

Question 15

What is sexual selection?

Answer 15

The non random process involving the selection of alleles that increase the individual’s chances of mating and producing offspring.

Question 16

What can sexual selection lead to?

Answer 16

Sexual dimorphism

Question 17

What is sexual dimorphism?

Answer 17

The difference in appearance between males and females of the same species

Question 18

How is sexual dimorphism caused?

Answer 18

By the inheritance of one sexual pattern in the genetic material

Question 19

Sexual selection can be due to…

Answer 19

-Male-male rivalry
-Female choice

Question 20

What males tend to have a greater reproductive success?

Answer 20

Males who have a larger body size or greater weaponry

Question 21

If a male is not large or does not have great weaponry, how can they increase chance of mating?

Answer 21

By acting as a sneaker

Question 22

What does female choice involve?

Answer 22

Females assessing the fitness of males

Question 23

Signals that influence the definition of fitness

Answer 23

• Physical appearance
• Display
• Chemical signals
• Presence or absence of parasites

Question 24

When does genetic drift occur?

Answer 24

When chance events cause unpredictable fluctuations of allele frequencies from one generation to the next

Question 25

Why does genetic drift have a bigger impact on small populations?

Answer 25

As alleles are more likely to be lost from the gene pool

Question 26

What are the two types of genetic drift?

Answer 26

- Bottleneck effect - Founder effect

Question 27

When do bottlenecks occur?

Answer 27

When a population size is reduced for at least one generation, by natural disaster, hunting or habitat destruction.

Question 28

What does the bottle neck effect lead to?

Answer 28

Leaves a small group of organisms possessing a limited range of alleles

Question 29

When does the founder effect occur?

Answer 29

When a few members of a population are isolated from a larger population

Question 30

What does the founder effect lead to?

Answer 30

The gene pool of the new population is not representative of that the original gene pool

Question 31

Why is a gene pool altered by genetic drift?

Answer 31

Certain alleles may be under-represented or over-represented and allele frequencies change

Question 32

What are selection pressures?

Answer 32

The environmental factors that influence which individuals in a population pass on their alleles

Question 33

Selection pressures can be…

Answer 33

Abiotic or biotic

Question 34

Examples of biotic selection pressures?

Answer 34

- Competition -Predation -Disease -Parasitism

Question 35

Examples of abiotic selection pressure

Answer 35

-Change in temperature -Change in light -Change in humidity -Change in pH

Question 36

What happens when selection pressures are strong

Answer 36

The rate of evolution can be rapid

Question 37

What does the Hardy-Weinberg principle state?

Answer 37

In the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over generation.

Question 38

What are the conditions for maintaining the Hardy-Weinberg equilibrium?

Answer 38

-No natural selection -Random mating -No mutation -Large population size -No gene flow

Question 39

What is fitness?

Answer 39

Fitness is a measure of the tendency of some organisms to produce more offspring than competing members of the same organisms

Question 40

What is fitness an indication of?

Answer 40

An individual’s ability to be successful at surviving and reproducing

Question 41

What is Darwin’s definition of fitness?

Answer 41

Fitness is the contribution made to the gene pool of the next generation by individual genotypes

Question 42

What is absolute fitness?

Answer 42

The ratio between the number of individuals of a particular genotype after selection to those before selection

Question 43

What does it mean if the absolute fitness is 1?

Answer 43

The frequency of that genotype is stable

Question 44

What does it mean if the absolute fitness is greater than 1?

Answer 44

There is an increase in the genotype

Question 45

What does it mean if absolute fitness is less than 1?

Answer 45

There is a decrease in the genotype

Question 46

What is relative fitness?

Answer 46

The ratio of the number of surviving offspring per individual of a particular genotype to the number of surviving offspring per individual of the most successful genotype

Question 47

What is seen in species that live in a close interaction with each other?

Answer 47

They can be seen to have traits that are closely matched to each other

Question 48

If one of these closely interacted species has a change in traits, what does this mean for the other species?

Answer 48

Its acts as a selection pressure

Question 49

What is co-evolution?

Answer 49

The process by which two or more species evolve in response to selection pressures imposed by each other

Question 50

What type of species is c-evolution usually seen in?

Answer 50

Species that have symbiotic relationships

Question 51

What are symbiotic interactions?

Answer 51

Co-evolved, intimate relationships between members of two different species

Question 52

What is mutualism?

Answer 52

When both of the organisms in the interaction are interdependent on each other for resources and other services.

Question 53

What is the impact of mutualism and why?

Answer 53

The interaction is +/+ as both organisms gain from the relationship

Question 54

What is commensalism?

Answer 54

A relationship where one species benefits from the interaction whilst the other species is unharmed and does not gain any benefit

Question 55

What impact does commensalism have and why?

Answer 55

The interaction is +/o since only one of the organisms benefits

Question 56

What is parasitism?

Answer 56

When the parasite benefits in terms of energy or nutrients and the host is harmed.

Question 57

What impact does parasitism have and why?

Answer 57

The interaction is +/- as the host loses resources

Question 58

What does the red queen hypothesis state?

Answer 58

In a co-evolutionary relationship, change in the traits of one species can act as a selection pressure on the other species

Question 59

How do species keep up with the competition (according to red queen hypothesis)?

Answer 59

Species continually need to change

Question 60

Species in co-evolutionary relationships must adapt to…

Answer 60

Avoid extinction

Question 61

What would happen if a species stopped changing?

Answer 61

The species would lose competition with the other species that are continuing to change