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Advanced Higher Biology > UNIT 2 - Evolution > Flashcards

UNIT 2 - Evolution Flashcards

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1
Q

define evolution

A

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

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2
Q

what does natural selection act on?

A

natural selection acts on genetic variation in different populations

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3
Q

what is variation caused by?

A

mutations

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4
Q

what is the source of new DNA sequences?

A

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

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5
Q

what is natural selection?

A

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

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6
Q

what processes cause changes in alleles?

A

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

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7
Q

are mutations beneficial?

A

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

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8
Q

what is the issue with current populations?

A

populations produce more offspring than the environment can handle

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9
Q

what does selection result in?

A

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

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10
Q

what is sexual selection?

A

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

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11
Q

what can sexual selection lead to?

A

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

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12
Q

what is sexual selection due to?

A

male-male rivalry and female choice

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13
Q

what is female choice?

A

females assessing the fitness of males

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14
Q

how does genetic drift occur?

A

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

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15
Q

when is genetic drift most important?

A

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

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16
Q

what is the bottleneck effect?

A

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

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17
Q

what is a founder effect?

A

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

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18
Q

how is a gene pool altered by genetic drift?

A

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

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19
Q

what are selection pressures?

A

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

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20
Q

what is meant by abiotic selection?

A

temperature, light, humidity, pH, salinity

21
Q

what is meant by biotic selection?

A

competition, predation, disease, parasitism

22
Q

what happens when selection pressures are strong?

A

the rate of evolution can be rapid

23
Q

what does the Hardy Weinberg principle state?

A

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

24
Q

what are the conditions of maintaining the Hardy Weinberg principle?

A

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

25
Q

what is the Hardy Weinberg equation used to determine?

A

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

26
Q

what is the Hardy Weinberg equation?

A

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
27
Q

what is fitness an indication of?

A

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

28
Q

what is fitness a measure of?

A

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

29
Q

what is absolute fitness?

A

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

30
Q

what does it mean if absolute fitness is 1?

A

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

31
Q

what is relative offspring?

A

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

32
Q

what does co-evolution mean?

A

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

33
Q

what can a change in traits act as?

A

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

34
Q

where is coevolution usually seen?

A

in pairs of species that have symbiotic interactions

35
Q

symbiosis meaning?

A

a coevolved intimate relationship between members of two different species

36
Q

what type of effect does a symbiotic relationship have?

A

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

37
Q

what is mutualism?

A

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

38
Q

what is commensalism?

A

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

39
Q

what is parasitism?

A

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

40
Q

what is the the red queen hypothesis?

A

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

41
Q

what is sexual dimorphism?

A

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

42
Q

what factors can cause a genetic drift?

A

disease
abiotic factors
isolation
natural disasters

43
Q

what is intrasexual?

A

selection within the same sex

44
Q

what is intersexual?

A

selection between individuals of different sexes

45
Q

what are the stages of coevolution?

A

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

46
Q

steps of natural selection?

A

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

47
Q

what is relative fitness?

A

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

48
Q

what are the equations for absolute and relative fitness?

A

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

Advanced Higher Biology (11 decks)

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