Unit 2 - KA2.2 Evolution

Question 1

Define evolution

Answer 1

evolution is the change over time in the proportion of individuals in a population differing in one or more inherited traits

Question 2

What are the three type of mutations?

Answer 2

Neutral
Positive
Negative

Question 3

What type of mutations increase the individual’s fitness?

Answer 3

Positive

Question 4

Changes in allele frequency during evolution take place through random and non-random processes. What are these?

Answer 4

Random - Genetic drift
Non-random - natural selection and sexual selection

Question 5

What are the three causes of evolution?

Answer 5

Genetic Drift, Natural Selection, Sexual Selection

Question 6

What is Natural Selection?

Answer 6

Non random process which affects the allele frequency in the population over generations

Question 7

What is Sexual Selection?

Answer 7

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

Question 8

Explain what a sexual dimorphism is?

Answer 8

sexual selection may lead to sexual dimorphism (where the different sexes have different physical characteristics)

Question 9

What two factors cause sexual selection?

Answer 9

male-male rivalry and female choice

Question 10

Define Genetic Drift

Answer 10

Random increase/decrease in the frequency of inherited traits over a number of generations

Question 11

What are the two mechanisms of genetic drift

Answer 11

bottleneck and founder effect

Question 12

What type of populations does genetic drift have the biggest effect?

Answer 12

Small populations

Question 13

When do population bottlenecks occur?

Answer 13

population bottlenecks occur when a population size is reduced for at least one generation, due to disease, human impact, natural disasters etc.

Question 14

When is the rate of evolution fast?

Answer 14

When selection pressures are strong

Question 15

What is a selection pressure?

Answer 15

Selection pressures are the environmental factors that influence which individuals in a population pass on their alleles.

Question 16

Give some examples of selection pressures?

Answer 16

selection pressures can be biotic: competition, predation, disease, parasitism; or abiotic: changes in temperature, light, humidity, pH, salinity.

Question 17

Describe what the Hardy-Weinberg principle states?

Answer 17

Hardy-Weinberg (HW) principle states that, in the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over the generations

Question 18

One of the conditions for maintaining the Hardy-Weinberg principle is that there is no natural selection. What are the other conditions?

Answer 18

the conditions for maintaining the HW equilibrium as: no natural selection, random mating, no mutation, large population size and no gene flow (through migration, in or out)

Question 19

What do the letters in the Hardy-Weinberg principle mean?

Answer 19

“p2 + 2pq + q2 = 1”

p = frequency of dominant allele
q = frequency of recessive allele
p2 = frequency of homozygous dominant genotype
2pq = frequency of heterozygous genotype
q2 = frequency of homozygous recessive genotype

Question 20

What does fitness mean in evolution?

Answer 20

fitness is an indication of an individual’s ability to be successful at surviving and reproducing

Question 21

Define absolute fitness

Answer 21

absolute fitness is the ratio between the frequency of individuals of a particular genotype after selection, to those before selection

Question 22

What is the absolute fitness equation?

Answer 22

(frequency of a particular genotype after selection )/(frequency of a particular genotype before selection )

Question 23

Define relative fitness

Answer 23

relative fitness is 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 24

What is the relative fitness equation?

Answer 24

(number of surviving offspring per individual of a particular genotype)/(number of surviving offspring per individual of the most successful genotype)

Question 25

Co-evolution is the process by which ____________________ evolve in response to __________________ imposed by each other.

Answer 25

co-evolution is the process by which two or more species evolve in response to selection pressures imposed by each other

Question 26

What is symbiosis

Answer 26

symbiosis is a co-evolved intimate relationship between members of two different species.

Question 27

Define mutualism?

Answer 27

mutualism occurs when both organisms in the interaction are interdependent on each other for resources or other services. As both organisms gain from the relationship, the interaction is (+/+).

Question 28

Define commensalism?

Answer 28

commensalism occurs when only one of the organism’s benefits (+/0).

Question 29

Define parasitism?

Answer 29

parasitism takes place when the parasite benefits in terms of energy or nutrients and the host is harmed as the result of the loss of these resources (+/-).

Question 30

Explain what is meant by the red queen hypothesis?

Answer 30

the red queen hypothesis states that in a co-evolutionary relationship a change in the traits of one species can act as a selection pressure on the other species. This means that both species must evolve to survive.