UNIT 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 does natural selection act on?

Answer 2

natural selection acts on genetic variation in different populations

Question 3

what is variation caused by?

Answer 3

mutations

Question 4

what is the source of new DNA sequences?

Answer 4

mutation is the original source of new sequences of DNA, these sequences can be novel alleles

Question 5

what is natural selection?

Answer 5

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

Question 6

what processes cause changes in alleles?

Answer 6

the non-random processes of natural selection, sexual selection and the random process of genetic drift

Question 7

are mutations beneficial?

Answer 7

most mutations are deleterious or neutral but in rare cases they may be advantageous to the fitness of an individual

Question 8

what is the issue with current populations?

Answer 8

populations produce more offspring than the environment can handle

Question 9

what does selection result in?

Answer 9

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

Question 10

what is sexual selection?

Answer 10

the non-random process involving the selection of alleles that increase the individuals chance of mating and producing offspring

Question 11

what can sexual selection lead to?

Answer 11

sexual dimorphism - sexual selection may lead to differences in form between male and female individuals

Question 12

what is sexual selection due to?

Answer 12

male-male rivalry and female choice

Question 13

what is female choice?

Answer 13

females assessing the fitness of males

Question 14

how does genetic drift occur?

Answer 14

genetic drift occurs when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next

Question 15

when is genetic drift most important?

Answer 15

genetic drift is most important in smaller populations as alleles are more likely to be lost from the gene pool

Question 16

what is the bottleneck effect?

Answer 16

the bottleneck is a genetic rift that can occur when a population size is reduced for generation

Question 17

what is a founder effect?

Answer 17

founder effects are examples of genetic rift that can occur through the isolation of a few members from the larger population and the gene pool of the new population is not representative of the larger population

Question 18

how is a gene pool altered by genetic drift?

Answer 18

a gene pool is altered by genetic drift because certain alleles may be under represented or over represented and so allele frequencies change

Question 19

what are selection pressures?

Answer 19

they are the environmental factors that influence which individuals in a population pass on their allele

Question 20

what is meant by abiotic selection?

Answer 20

temperature, light, humidity, pH, salinity

Question 21

what is meant by biotic selection?

Answer 21

competition, predation, disease, parasitism

Question 22

what happens when selection pressures are strong?

Answer 22

the rate of evolution can be rapid

Question 23

what does the Hardy Weinberg principle state?

Answer 23

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

Question 24

what are the conditions of maintaining the Hardy Weinberg principle?

Answer 24

random mating, no natural selection, no mutation, large population size and no gene flow due to migration

Question 25

what is the Hardy Weinberg equation used to determine?

Answer 25

it is used to determine whether a change in allele frequency is occurring in a population over time, if it is then this would suggest that evolutionary processes are occurring

Question 26

what is the Hardy Weinberg equation?

Answer 26

p^2+2pq+q^2=1 ``` p^2 = frequency of dominant homozygous genotype q^2 = frequency of recessive homozygous genotype 2pq = frequency of heterozygous genotyppe ```

Question 27

what is fitness an indication of?

Answer 27

fitness is the indication of an individuals ability to be successful at survival and reproducing

Question 28

what is fitness a measure of?

Answer 28

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

Question 29

what is absolute fitness?

Answer 29

it is the ratio between the frequency of a genotype in individuals after selection, to those before selection

Question 30

what does it mean if absolute fitness is 1?

Answer 30

this means that the frequency of that genotype is stable. a value greater than 1 means an increase in the genotype and less means a decrease

Question 31

what is relative offspring?

Answer 31

this is the ratio of surviving offspring per individual with the most successful genotype

Question 32

what does co-evolution mean?

Answer 32

this is the process by which two or more species evolve in response to selection pressures imposed by each other.

Question 33

what can a change in traits act as?

Answer 33

a change in traits of one species acts as a selection pressure on the other

Question 34

where is coevolution usually seen?

Answer 34

in pairs of species that have symbiotic interactions

Question 35

symbiosis meaning?

Answer 35

a coevolved intimate relationship between members of two different species

Question 36

what type of effect does a symbiotic relationship have?

Answer 36

the effects of this can be both negative and positive or neutral for the species involved

Question 37

what is mutualism?

Answer 37

mutualism is a symbiosis where species in the interaction rely on each other for resources or other services and since both species gain the interaction is positive for both parties

Question 38

what is commensalism?

Answer 38

is a symbiosis in which only one of the species substantially benefits from and for the other species the relationship is usually neutral

Question 39

what is parasitism?

Answer 39

is a sybiosis in which the parasite species benefits in terms of energy or nutrients while the host is harmed by the loss of nutrients

Question 40

what is the the red queen hypothesis?

Answer 40

states that in a coevolutionary relationship, change in the traits of one species can act as selection pressure on the other species which must adapt to avoid extinction

Question 41

what is sexual dimorphism?

Answer 41

females are generally inconspicuous; males usually have more conspicuous markings, structures and behaviours

Question 42

what factors can cause a genetic drift?

Answer 42

disease abiotic factors isolation natural disasters

Question 43

what is intrasexual?

Answer 43

selection within the same sex

Question 44

what is intersexual?

Answer 44

selection between individuals of different sexes

Question 45

what are the stages of coevolution?

Answer 45

1) individuals of species A has a trait that gives them an advantage over species b 2) proportion of individuals with the treat in species A increases 3) some individuals within species B now have a trait that gives them an advantage 4) proportion of individuals with said trait in population b increases

Question 46

steps of natural selection?

Answer 46

1) too much offspring for the environment to sustain 2) individuals struggle for survival until reproductive age 3) better-adapted individuals survive, reproduce and pass on their favoured alleles 4) less well adapted individuals die and dont pass on their genes

Question 47

what is relative fitness?

Answer 47

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 48

what are the equations for absolute and relative fitness?

Answer 48

AF - (New generation/Previous generation) Frequency of a particular genotype after selection/Frequency of a particular genotype before selection RF - (AF of the genotype/AF of most successful genotype) The frequency of surviving offspring per individual of a particular genotype/The frequency of surviving offspring per individual of the most successful genotype