2.2 Evolution

Question 1

what is evoluiton

Answer 1

the change, over successive generations, in the proportion of individuals in a population differing in one or more inherited traits

Question 2

what is natural selection

Answer 2

non-random process whereby certain alleles occur more frequently within a population because they confer a selective advantage

Question 3

what is sexual selection

Answer 3

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

Question 4

what is genetic drift

Answer 4

the random change in how frequent a particular allele occurs within a small population

Question 5

which evolutionary changes are random and which are non-random

Answer 5

natural selection - non-random
sexual selection - non-random
genetic drift - random

Question 6

what is a mutation

Answer 6

rare, random changes to genetic sequences which can be harmful, neutral or, in rare cases, beneficial to the fitness of an individual
mutations are the original source of new sequences of DNA
variation in traits arise as a result of mutation

Question 7

how do selection pressures arise

Answer 7

populations produce more offspring than the environment can support, resulting in selection pressures

Question 8

individuals with variations that are better suited to the environment tend to:

Answer 8

survive longer and produce more offspring, breeding to pass on those alleles that conferred an advantage to the next generation

Question 9

what does selection result in

Answer 9

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

Question 10

what can sexual selection lead to

Answer 10

sexual dimorphism

Question 11

what is sexual dimorphism

Answer 11

physical difference between males and females of a species

Question 12

sexual selection can be due to:

Answer 12

male-male rivalry

female choice

Question 13

what is male-male rivalry

Answer 13

large size or weaponry increases access to females through conflict

Question 14

what is female choice

Answer 14

involves females assessing the fitness of males

Question 15

why is genetic drift more important in small populations

Answer 15

alleles are more likely to be lost from the gene pool

Question 16

genetic drift occurs because of:

Answer 16

the bottleneck effect

the founder effect

Question 17

what is the bottleneck effect

Answer 17

occurs when there is a disaster of some sort that reduced a population to a small handful, which rarely represents the actual genetic makeup of the initial population. this leaves smaller variation among the surviving individuals

Question 18

what is the founder effect

Answer 18

the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. the gene pool of the new population is not representative of that in the original gene pool

Question 19

how is a gene pool altered by genetic drift

Answer 19

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

Question 20

when selection pressures are strong, the rate of evolution can be

Answer 20

rapid

Question 21

what are selection pressures

Answer 21

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

Question 22

selection pressures can be:

Answer 22

biotic or abiotic factors

Question 23

examples of biotic factors

Answer 23

competition
predation
disease
parasistism

Question 24

examples of abiotic factors

Answer 24

temperature 
light 
humidity
pH
salinity

Question 25

what is the Hardy-Weinberg (HW) principle

Answer 25

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

Question 26

conditions for maintaining the HW equilibrium are:

Answer 26

``` no natural selection random mating no mutation large population size no gene flow (through migration, in or out) ```

Question 27

what can the HW principle determine

Answer 27

whether a change in allele frequency is occurring in a population over time

Question 28

what does changes in the allele frequency suggest

Answer 28

evolution is occurring

Question 29

what is the HW principle formula

Answer 29

p² + 2pq + q² = 1

Question 30

what does p represent in the HW principle

Answer 30

frequency of dominant allele

Question 31

what does q represent in the HW principle

Answer 31

frequency of recessive allele

Question 32

what does p² represent in the HW principle

Answer 32

frequency of homozygous dominant genotype

Question 33

what does 2pq represent in the HW principle

Answer 33

frequency of heterozygous genotype

Question 34

what does q² represent in the HW principle

Answer 34

frequency of homozygous recessive genotyope

Question 35

what is fitness

Answer 35

the indication of an individual's ability to be successful at surviving and reproducing

Question 36

what is fitness a measure of

Answer 36

tendency of some organisms to produce more surviving offspring that competing members of the same species

Question 37

what does fitness refer to

Answer 37

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

Question 38

what are the types of fitness

Answer 38

absolute | relative

Question 39

what is absolute fitness

Answer 39

the ratio of frequencies of a particular genotype from one generation to the next

Question 40

what is the formula for absolute fitness

Answer 40

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

Question 41

what does it mean if absolute fitness is 1

Answer 41

the frequency of that genotype is stable

Question 42

what does it mean if absolute fitness is a value greater than 1

Answer 42

an increase in the genotype

Question 43

what does it mean if absolute fitness is a value less than 1

Answer 43

a decrease in the genotype

Question 44

what is relative fitness

Answer 44

the ration of surviving offspring of one genotype compared with other genotypes 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 45

what is the formula for relative fitness

Answer 45

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

Question 46

what is co-evolution

Answer 46

where a change in the traits of one species acts as a selection pressure on another species with which it frequently interacts

Question 47

co-evolution is frequently seen in

Answer 47

pairs of species that have symbiotic interactions

Question 48

what is symbiosis

Answer 48

an interrelationship between members of two different species, whereby at least one species benefits

Question 49

the impact of symbiotic relationships can be ... for the individuals involved

Answer 49

positive (+) negative (-) neutral (0)

Question 50

name the symbiotic interactions

Answer 50

mutualism commensalism parasitism

Question 51

what is mutualism

Answer 51

both organisms in the interaction are interdependent on each other for resources or other services as both organisms benefit from each other (+/+)

Question 52

what is commensalism

Answer 52

an interrelationship between organisms of two different species in which one species benefits and the other neither benefits nor suffers (+/0)

Question 53

what is parasitism

Answer 53

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

Question 54

what is the red queen hypothesis

Answer 54

in a co-evolutionary relationship, change in the traits of one species can act as a selection pressure on the other species this means that species in theses relationships must adapt to avoid extinction