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genetic diversity and adaptation Flashcards

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1
Q

why are there 7.3 billion people alive but they all look different

A

genetic diversity

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2
Q

what is the cause of genetic diversity

A

DNA determines the considerable variety of proteins that make up each organism

Therefore genetic similarities and differences between organisms may be defined in terms of variation in DNA
- therefore, DNA leads to genetic diversity

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3
Q

what do members of species have in common

A

a section of DNA that codes for one polypeptide is called a gene

members of the same species have the same genes

e.g. all humans have a gene for blood group and how all snapdragons have a gene for petal colour

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4
Q

how do organisms differ in phenotype -appearance

A

e.g. blood group in humans depends on which two alleles human possess - similar to what colour a snapdragon depends on

Therefore organisms of the same species differ in their combination of alleles, not their genes

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5
Q

what is gene diversity described as

A

it is described as the total number of alleles in a population

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6
Q

what is a population

A

a population is a group of individuals of the same species that live in the same place and can interbreed

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7
Q

how many populations do a species consist of

A

a species consists of one, or more populations

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8
Q

what determines how great the genetic diversity of a species is

A

the greater the number of different alleles that all species possess, the greater the genetic diversity if that species

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9
Q

what reduces genetic diversity

A

genetic diversity can be reduced when a species has fewer different alleles

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10
Q

why is having greater genetic diversity an advantage for a species/population

A

greater GD, the more likely that some individuals in a population will survive and environmental change

this is because of a wider range of alleles and therefore a wider range of characteristics
This gives a greater probability that some individual will possess a characteristic that suits it to the new environmental conditions

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11
Q

what is genetic diversity a factor of

A

natural selection

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12
Q

why do certain alleles get passed on to the next generation

A

not all alleles of a population are equally likely to be passed to the next generation

This is because only certain individuals are reproductively successful and so pass on their alleles

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13
Q

what affects the frequency of different alleles in a population

A

difference between the reproductive success of individuals affects alleles frequency in a population

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14
Q

how do alleles get passed down to the next generation

A
  1. within any population of a species, there will be a gene pool containing a wide variety of alleles
  2. random mutation of alleles within this gene pool may result in a new allele of a gene which in most cases will be harmful
  3. however, in certain environments, the allele of a gene might give its possessor and advantage in their competition with others
  4. these individuals will be better adapted and therefore more likely to survive in their competition with others
  5. These individuals are more likely to obtain the available resources ad so grow more rapidly and live longer. As a result, they will have a better chance of breeding successfully and producing more offspring
  6. only these individuals that produce successfully will pass on their alleles to the next generation
  7. therefore is the new allele that gave the parents an advantage in the completion for survival that is most likely to be passed on to the next generation
  8. as the new individual also have the new “advantageous” allele, they turn are more likely to survive and reproduce successfully
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15
Q

what happens to the less advantageous alleles in the population

A

over many generations, the number of individuals with the new “advantageous” allele will increase at the expense of the individuals with the “less advantageous” alleles

overtime, the frequency of the new alleles in the population will increase and the old alleles decrease

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16
Q

what does it mean when we say advantageous alleles

A

what is “advantageous” depend upon th environment conditions at any one time

e.g. alleles for black body colour may be “advantageous” as camouflage against a smoke-blackened wall but non- advantageous against a snowy landscape

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17
Q

what is selection

A

selection is the process by which organisms that are better adapted to their environment tend to survive and breed while those that are less adapted tend not to

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18
Q

what does selection depend on

A

different environmental conditions favour different characteristics in the population

  • depending on which characteristics are favoured selection will produce a number of different results
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19
Q

what may selection favour

A

selection may favour:

  • individuals that vary in one direction from the mean of the population
    This is called DIRECTIONAL SELCTIONand changes the characteristic of the population

-average individuals.
This is called STABILISING SELECTION and preserved the characteristics of a population

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20
Q

what are characteristics influenced by

A
  • more than one gene (polygenes)

these types of characteristics are influenced by the environment more than one determined by a gene

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21
Q

what are the effects of the environment on polygenes

A

the effect of the environment on polygenes produces individuals in a population that vary about the mean

when you plot this variation on a graph you get a normal distribution

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22
Q

what is directional selection

A

if environmental conditions change, the phenotypes that are best suited to the new conditions are most likely to survive

some individuals, which fall to either the left or right of the mean will possess a phenotype more suited to the new conditions
- these individuals will be more likely to survive and breed. They will, therefore contribute offspring and pass the alleles they possess to the next generation

over time the mean will then move in the dirc=ection of these individuals

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23
Q

what is an example of directional selection

A

antibiotic resistance in bacteria

e.g.

shortly after the discovery of antibiotics, t became apparent that the effectiveness of some antibiotics at killing bacteria reduced
It was fount that these populations of bacteria had developed resistance to antibiotics such as penicillin

It was found that these populations of bacteria had developed resistance to antibiotics such as penicillin

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24
Q

what was the resistance of the bacteria to antibiotics due too

A

the resistance was not due to the development of tolerance to the antibiotic, but rather a chance mutation within the bacteria

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25
Q

looking at bacterias resistance to antibiotics in more detail

A
  1. SPONTANEOUS mutation occurred in the allele of a gene in a bacterium that enabled it to make a NEW PROTEIN which before it was able to kill the bacteria
  2. the bacterium happened, by chance, to be in a situation where penicillin was being used to treat and individual.
    In these circumstances, the mutation gave the bacterium the advantage of being able to use penicillinase to break down the antibiotic and so survive while the rest of the bacteria population died
  3. bacterium that survived was able to divide by binary fission to build up a small population of penicillin-resistant bacteria
  4. members of this small penicillin-resistant population were more able to survive and therefore multiply, in the presence of penicillin than members of the non - resistant population
    - lead to an increase in the frequency of the allele that enables the production of the penicillinase
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26
Q

what is a common misconception about bacteria resistance

A

bacteria do not mutate because of the presence of antibiotics

  • mutation occurs randomly and are very rare

however as there are so many bacteria around the total number of mutation is large

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27
Q

what is stabilising selection

A

if environmental conditions remain stable itis the individuals with the phenotype closest to the mean that are favoured

individuals are more likely to pass their alleles on to the next generation
These individuals with phenotypes at the extremes are less likely to pass on their alleles
Stabilising selection, therefore, tends to eliminate the phenotype at the extreme

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28
Q

how do you know if a population underwent stabilising selection

A

the population’s characteristics are preserved rather than changed

  • stabilising selection, therefore, results in phenotypes around the mean of the population being selected for and those both extremes being selected against
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29
Q

what does natural selection result in

A

natural selection results in species that are better adapted to the environment that they live in: survive

these adaptions may be:

  1. anotomical
  2. physiological
  3. behavioural
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30
Q

what are anatomical adaptations

A

such as shorter ears and thicker fur in artic foxes compared to foxes in warmer climates

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31
Q

what are physiological adaptions

A

oxidising of fat rather than carbohydrate on kangaroo rats to produce additional water in a dry desert environment

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32
Q

what are behavioural adaptions

A

such as the autumn migration of swallows from the UK to Africa to avoid food shortages in the UK winter

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33
Q

how many living organisms are there

A

around 18 million different living organisms

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34
Q

how many species are there

A

estimates for the total number of species on earth range from 10 million to 100 million

  • this figure is more likely to be 14 million
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35
Q

what is classification

A

classification is the organisation of living organisms into groups

This process is not random but is based on a number of accepted principles

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36
Q

how do scientists distinguish between one type of organism from another

A

at one time, scientists often gave new organism a name that described their features

e.g.
blackbird, rainbow trout e.t.c
This resulted in the same name being used in different parts of the world for very different species

Therefore, it was difficult for scientists to be sure which organisms they were referring to the same organism
Swedish botanist Linnaeus overcame this problem by devising a common system of naming organisms - system is still used today

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37
Q

what was the system that Linnaeus devise

A

it was called the binomial system- this is because it is identified by two names

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38
Q

what are the features of the binomial system

A

it features are as follows:

First name
- which is the generic name, it denoted the genes to which the organism belongs
This is equivalent to the surname used o identify people and shared by their close relatives

Second name
- specific name, denotes the species to which the organism belongs
Equivalent to the first name/ given name used to identify people -
However, its name is never shared by other species within the genus

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39
Q

what are the rules required for the binomial system

A
  • names are printed in italic/ if handwritten, they are underlined to indicate that they are scientific names

the first letter of the generic name is in UPPER CASE but the specific name is in lower case

If a specific name is not known, it can be written as “sp”

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40
Q

are the names of organisms constant

A

naming organisms are in a constant state of change
current names reflect the present state of scientific knowledge and understanding

-classification of species is regularly changing as our knowledge of their evolution, physical features biochemistry and behaviour increases

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41
Q

how do members of their own species distinguish themselves

A

members of the same species have similar/ similar same genes and therefore resembles one another physically and biochemically

  • same is true for behaviour

this helps them to distinguish members of their own species from those of other species

Therefore individuals can recognise members of species by the way they look and behave

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42
Q

what is courtship behaviour

A

the ability to display a behaviour is genetically determined

It too has evolved and it influences the chances of survival

courtship behaviour has therefore evolved to allow species to mate and reproduce

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43
Q

why is reproduction important

A

no individuals live forever

so reproduction is therefore the means by which a species can survive over time
Each individual has adaptions that help to ensure that their DNA is passed on, through the reproductive process, to the next generation

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44
Q

why is it important for mating to be successful

A

females of species only produce eggs of specific time (often as little as once a year)

Therefore it is important to ensure that mating is successful and that offspring have the maximal chance of survival

45
Q

what does courtship behaviour do in order to make sure mating is successful

A

courtship helps to achieve this by enabling individuals to:

  1. recognise members of their own species to ensure that mating only takes place between members of the same species because only members of the same species can produce fertile offspring
  2. identify a mate capable of breeding because both partners need to be sexually mature, fertile and receptive to mating
  3. form a pair bond that will lead to successful mating and raising offspring
  4. synchronising mating and raising of offspring
  5. synchronising mating so that it takes place when there is the maximum probability of the sperm and egg meeting
46
Q

why are females of many species receptive to mating for a period of time

A

females of many species undergo a cycle of sexual activity in which they can only conceive during a very short time

therefore they are receptive to mating for a period around the time they produce eggs

Therefore courtship behaviour is used by males to determine whether the female is at this receptive stage

47
Q

what happens when the females of a species respond to courtship behaviour

A

if she responds with the appropriate behavioural response, courtship continues

  • the likely result is the production of offspring
48
Q

what happens if the females of a species do not respond to the courtship behaviour

A

if the behaviour is not receptive and the females exhibit a different pattern of behaviour, the males cease to court her and urns there attention elsewhere

49
Q

how do individuals know they are the same species

A

during courtship, animals use signals to communicate with potential a potential mate and with numbers of their own sex

typically there is a chain of actions between a male and female
- this chain of behaviour is the same for all members of a species but differs for members of other species

In this way, both the individuals recognise their partner of the same species and they may be prepared to mate

50
Q

why is it important to group species

A

with so many species past and present, it makes sense to organise them into manageable groups

51
Q

what is classification

A

the grouping of organisms is known as classification

52
Q

what is taxonomy

A

the theory and practice of biological classification is called taxonomy

53
Q

what are the 2 main biological classification

A

artificial classification divides organisms according to differences that are useful at the time

e. g.
1. colour
2. size
3. number of legs

these are described as analogous characteristics where they have the same function but do not have the same evolutionary origins
e.g.the way of butterflies and birds are both used for flight however they originated in very different ways

phylogentic classification

54
Q

what is phylogenetic classification

A

a) it is based upon the evolutionary relationships between organisms and their ancestors
b) classifies species into groups using features derived from their ancestors
c) arranges the groups into a hierarchy in which groups are contained within larger composite groups with no overlap

55
Q

what are the relationships in a phylogenetic classification partly based on

A

relationships in a phylogenetic classification are partly based on homologous characteristics

Homologous characteristic have similar evolutionary origins regardless of their functions in the adult of a species

e.g. the wing of a bird, the arm of a human and front legs of a horse all have the same basic structure and evolutionary orgins and therefore homologous

56
Q

what are taxons

A

each group within a phylogenetic biological classification is called taxon (plural taxa)

taxonomy is the study of these groups

57
Q

what is the study of these groups

A

taxonomy is the study of these groups and their positions in a hierarchal order, where they are now as taxonomic ranks

58
Q

what are the taxonomic ranks based on

A

taxonomic ranks are based upon the evolutionary line of descent of the group members

59
Q

what is the highest taxonomic rank

A

the highest taxonomic rank is the DOMAIN

60
Q

what are the three different domains identified

A

bacteria

eukarya

archae ) a group of prokaryotes)

61
Q

what are bacteria

A

are a group of single - celled prokaryotes with the following features

  • absence of membrane -bounded organelles such as nuclei or mitochondria
  • unicellular, although cells may occur in chains or clusters
  • ribosomes are smaller (70s) than in eukaryotic cells
  • cell walls are present and made of murein (but never chitin/ cellulose)
  • single loop of naked DNA made up of nucleic acids but no histones
62
Q

what are archaea

A

group of single - celled organisms originally classified as bacteria which they resemble in appearance

they differ from bacteria:

  • their genes and protein synthesis are more similar to eukaryotes
  • their membranes contain fatty acid chains attached to glycerol by ester linkages
  • there is no murein in their cell walls
  • they have a more complex form of RNA polymerase
63
Q

what are eukarya

A

are a group of organisms made up of one or more eukaryotic cells

features are:
- their cells possess membrane-bounded organelles such as mitochondria

  • they have membranes containing fatty acid chain attached to glycerol by ester linkages
  • not al possess cells with a cell wall, but where they do it contains no murein
  • ribosomes are larger (80s) than in bacteria and Archaea
64
Q

what are the four kingdoms that eukarya is split into

A
  1. fungi
  2. plantae
  3. animalia
65
Q

what is the largest group known as in each kingdom

A

within each kingdom the largest groups known as phyla

66
Q

what is the diversity within the phylum divided into

A

diversity within each phylum allows it to be divided

67
Q

what is each class divided into

A

each class is divided into families and at this level, the differences are less obvious

68
Q

what is each family divided into

A

it is divided into genera

69
Q

what is each genus divided into

A

species

KINGDOM
PHYLUM
CLASS
ORDER
FAMILY
GENUS
SPECIES
70
Q

what is the hierarchical order of taxonomic ranks based upon

A

the supposed evolutionary line of descent of the group members

71
Q

what is phylogeny

A

the evolutionary relationship between organisms is known as phylongeny

It is derived from the word “phylum”, which in classification, is a group of related or similar organisms

72
Q

what does phylogeny of an organism reflect

A

the phylogeny of an organism reflects the evolutionary branch that led up to it

The phylogenetic relationships of different species are usually represented by a tree-like diagram called a phylogenetic tree

73
Q

what are the three components of biodiversity

A

species diversity - refers to the number of different species and the number of individuals of each species within any one community

genetic diversity - refers to the variety of genes possessed by individuals that make up a population of a species

ecosystem diversity - refers to the range of different habitats, from a small local habitat to the whole of the earth

74
Q

how do we measure species diversity

A

one measure of species diversity is species richness

This is the number of different species in a particular area at a given time (community)

e.g. two communities may have the same number of species by the proportions of the community made up of each species may differ markedly

75
Q

how else can we measure species diversity

A

by calculating the index of diversity

76
Q

how do we calculate the index diversity

A

d= N(N-1) /Σn(n-1)

d=index of diversity

N= total number of organisms of all species

n =total number of organisms of each species

Σ = the sum of

77
Q

a worked example of using the index of diversity

A

use the index to calculate the species diversity of the habitats

You must first calculate n(n-1) for each species in each habitat

You can then calculate the sum of n(n-1) for each species

You can now calculate the species diversity index for each habitat

78
Q

what does a higher value of d mean

A

the higher the value of d, the greater is the species diversity

so, even though the total number of species and the total number of individuals are the same in both habitats, thee species diversity of habitats X is much greater

79
Q

what has happened to classification systems as science has developed

A

as science has developed it has become possible too use a wider range of evidence to determine relationships between organisms

80
Q

what are the changes that happens to organisms when they evolve

A

when organisms evolve not only their internal and external features that change, but also the molecules of which they are made

81
Q

what determines the changes in the organisms when they evolve

A

DNA determines the proteins of an organism

It follows that changes in the features of a species are due to changes in its DNA
Comparing the genetic diversity within, and between species helps scientists to determine the evolutionary relationship

82
Q

what are the different ways that scientists can use genetic info to compare evolutionary relationships between organisms

A

comparison of DNA base sequences

comparison of the base sequence of mRNA

comparisons of amino acid sequences in proteins

comparison of observable characteristics

83
Q

what is the traditional way of measuring genetic diversity

A

by observing the characteristics of organisms

This method is based on the fact that each observable characteristics is determined by a gene or genes (with environmental influences)

84
Q

what are the limitations of using observable characteristics as a measure of genetic diversity

A

using observable characteristics has its limitation because a large number of them are coded for by more than one gene

They are polygenetic. This means thy are not discrete from one another but rather vary continuously
It is often difficult to distinguish one from another

Characteristics can also be modified by the environmental Differences may therefore be a result in the different environmental conditions rather than different alleles

e.g. height in humans is determined by a number of genes. However, environmental factors like diet can influence the actual height of an individual

85
Q

how do we compare DNA base sequences

A

with the advent of gene technology, we can now read the base sequence of the DNA of any organism

e.g. we can now determine the exact order of nucleotides on DNA
DNA sequencing is now routinely done by automatic machines and the data produced is anlaysed by computers

86
Q

how do we use a computer to analyse the sequence of DNA

A

In these computerised systems, each nucleotide base can be tagged with a different coloured fluorescent dye

adenine=green, thymine=red, cytosine=blue,
guanine=yellow

This produces a series of coloured bands, each of which represents one of the four nuclotide bases

87
Q

how do we use the sequence of base pairings to measure base sequences

A

we can measure the genetic diversity of a species by sampling hr DNA of its members and sequencing it to produce a pattern of coloured bands

Analysis of these coloured bands.
Analysis of these patterns allows us to compare one species with another or one individual with another of the same species to determine how diverse they are

88
Q

the process of reading DNA sequences with the human eye is slow - what do scientists do instead

A

the process would be slow with the human eye and so the patterns are scanned by lasers and interpreted by computer software to give the DNA nucleotide base sequence in a fraction of the time

89
Q

other than measuring the genetic diversity what else can we use base sequences to determine

A

we can also use this technique to determine the evolutionary relationships between species

90
Q

how can the base sequences determine the evolutionary relationships between species

A

when one species gives rise to another species during evolution, the DNA of the new species will initially be very similar to that of the species that gave rise from it

due to mutations, the sequences of nucleotide bases in the DNA of the new species will change
-consequently, over time, the new species will accumulate more and more differences in its DNA

As a result, we would expect species that are more closely related to show more similarly in their DNA base sequences than species that are more distantly related to show more similarity in their DNA base sequence a than species that are more distantly related
As there are millions of base sequences in every organism, DNA contains a vast amount of information about the genetic diversity and evolutionary history of all organisms

91
Q

how can comparing the base sequence of mRNA measure genetic diversity

A

mRNA is coded by DNA
The base sequences on mRNA are complementary to those of the strand of DNA from which they were made

It allows that we can measure DNA diversity, and therefore genetic diversity, by comparing the base sequence of mRNA

92
Q

how does comparing the amino acids sequences of proteins

A

the sequence of amino acids in proteins are determined by mRNA which is determined by DNA

Genetic diversity between and within species can therefore be measured by comparing the amino acid sequences of proteins

93
Q

what does the degree of similarity between the base sequences in species show/mean

A

the degree if similarity in the amino acid sequence of the same protein in two species will also reflect how closely related the two species are

94
Q

why has mankind made a considerable impact on the natural world

A

in our efforts to provide enough food for the human population at a low cost, mankind has had a considerable impact on the natural world

95
Q

what happens when natural ecosystems develop

A

as natural ecosystem develop over time, they become complex communities with many individuals of a large number of different species

in other words these communities have a high index of diversity

96
Q

what are agricultural ecosystems controlled by

A

agricultural ecosystems are controlled by humans and are different

97
Q

how are agricultural ecosystems different from natural ecosystems

A

farmers often select species for particular qualities that make them more productive

As a result of species, and the genetic variety alleles they possess, is reduced to the few that exhibit the desirable features

to be economic the number of these desirable species need to be large

98
Q

why is the index of species diversity low in agricultural ecosystems

A

any particular area can only support a certain amount of biomass

If most of the area is taken up by the one species that the farmer considers desirable it follows that there is a smaller area for all the other species - these other species now have to compete for what little space and resources are available

many will not survive this competition- even if the species evolved to adapt to the changes

In addition pesticide are used to exclude these species because they compete with the light,mineral ions, water and food by farmed species

99
Q

why is food important

A

food is essential for life, and with an ever - expanding human population there is pressure to produce it more and more intensively

100
Q

what has happened to the food production in the UK over the last 40yrs

A

food production has doubled over the past 40 years

101
Q

how has the increased food production in the UK happened

A
  • it has been achieved by the use of improved genetic varieties of plant and animal species
  • greater use of chemical fertilisers and pesticides,
  • greater use of biotechnology and changes in farm practices, leading to larger farms and conversion of land supporting natural communities into farmland

these changes have had many ecological impacts

102
Q

what is the overriding effect of intensive food production

A

the overriding effect of intensive food production has been to diminish the variety of habitats within ecosystems and consequently reduce species diversity

103
Q

what are the certain practices that directly removed habitats and reduced species diversity

A
  1. removal of hedgerows and grubbing out woodland
  2. creating monoclutures, e.g. replacing natural meadows with cereal crops or grass for silage
  3. filling in ponds and draining marsh and other wetland
  4. over - grazing of land, e.g. upland areas by sheep, thereby preventing regeneration of woodland
104
Q

what farming practices have a indirect effect on habitats

A
  1. use of pesticides and inorganic fertillisers
  2. escape of effluent from silage and slurry tanks into water courses
  3. absence of crop rotation and lack of intercropping or undersowing
105
Q

why have we created a number of management techniques

A

despite the obvious conflicts between intensive food production and conservation, there are a number of management techniques that can be applied to increase species and habitat diversity, without unduly raising food costs or lowering yields

106
Q

examples of management techniques

A
  1. maintain existing hedgerows at the most beneficial height and shape
    An A - shape provides better habitats than a rectangular one
  2. Plant hedges rather than erect fences as field boundaries
  3. maintain existing ponds and where possible create new ones
  4. leave wet corners of fields rather than draining them
  5. plant native trees on the land with a low species diversity rather than in species rich ares
  6. reduce the use of pesticides - use biological control where possible or genetically modified organisms resistant to pests
  7. use organic instead of inorganic fertillisers
  8. use crop rotation that includes a nitrogen - fixing crop, rather than fertiliser to improve soil fertility
  9. use intercropping rather than herbicides to control to control weeds and other
  10. create natural meadows and use use hay rather than grasses for stage
  11. introduce conservation headlands - areas at the edges of field where pesticides are used restrictively so that wild flowers and insects can breed
107
Q

what effects does the management techniques on the food

A

these practices will make food slightly more expensive to produce

108
Q

what does the Department for Environment, Food and Rural Affairs (DEFRA) and The European Union

A

they encourage farmers with financial incentives

this is because maintaining biodiversity is very important

109
Q

why is maintaining biodiversity important

A

if biodiversity is reduced the global living system becomes increasingly unstable and we all rely on the global system for food and other resources

biology a levels (9 decks)

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