4.2.1 Biodiversity Flashcards
(87 cards)
1
Q
what is a species?
A
a group of similar organisms capable of interbreeding to produce fertile offspring
2
Q
what is a population?
A
all the members of one particular species living in a given area at one time
3
Q
what is a Community?
A
all the members of all the species living in a given area at one time
4
Q
what is a Habitat?
A
the place where a species lives
5
Q
what is a Ecosystem?
A
a dynamic system consisting of living organisms, the physical environment and the interactions between all of these
6
Q
what is a Niche?
A
the role of an organism in its ecosystem (including what it requires from the ecosystem and what it contributes to the ecosystem
7
Q
what is Biodiversity?
A
the variety and complexity of life in a given area; this includes the variety of habitats, the number of different species present, how even their population sizes are and the genetic diversity (both within and between species). When biodiversity is quantified, it has two components: species richness and species evenness
8
Q
what is Species richness?
A
the number of different species present in an area, quoted as a single number; the higher the species richness, the higher the biodiversity is likely to be
9
Q
what is Species evenness?
A
the extent of similarity (evenness) in the population sizes of each species in an area, or the relative abundance of each species; high species evenness is a component of high biodiversity, as it means that all population sizes are similar (such that the ecosystem is balanced); low species evenness generally corresponds to lower biodiversity, as it suggests that one or two species may be dominant, having much greater population sizes than other species (such that the ecosystem is unbalanced).
10
Q
what is a Keystone species?
A
a species which has a significant effect on the habitat, despite its own relatively low abundance or total biomass; many other species depend upon the keystone species, which in many cases is the top carnivore in a food chain (e.g. grey wolf) or a species which modifies the habitat substantially (e.g. beaver).
11
Q
what are the three types of biodiversity?
A
Habitat biodiversity
Species biodiversity
Genetic biodiversity
12
Q
what is Habitat biodiversity?
A
the variety of habitats within an ecosystem (e.g. the presence of sand dunes, woodland, meadows and streams)
13
Q
what is Species biodiversity?
A
species richness (how many different species are present in the area) and species evenness (how similar their population sizes are)
14
Q
what is Genetic biodiversity?
A
within and between species (e.g. the occurrence of genetically distinct different breeds/varieties within a species and the size the gene pool, which relates to the number of different alleles of genes present).
15
Q
what is simpsons index, and what does each letter represent?
A
16
Q
read this and understand how simpsons index works
A
17
Q
what does a high simpsons index value show?
A
High biodiversity - high species richness and everness
ecosystem is well-balanced and stable
resilient to minor environmental changes or loss of species
18
Q
what does a low simpsons index value mean?
A
low biodiversity - low species richness and everness
ecosystem is unbalanced and unstable
it may not be resilient to minor changes in the environment or loss of species - further species loss may occur
19
Q
what are the three main factors affecting biodiversity?
A
Human population growth
Agriculture
Climate change
20
Q
how does Human population growth affect biodiversity?
A
the human population has risen exponentially since the Industrial Revolution in the nineteen century; humans increasing require land for the building of homes, industrial sites, roads, airports, mines etc. Most of this land obtained for such purposes was previously a natural habitat; species which thrived in that habitat are unlikely to survive in an urban environment.
21
Q
how does agriculture affect biodiversity?
A
as the human population grows, we need to use an increasing area of land for food production; typically, the biodiversity of the agricultural land will be hugely reduced compared to the natural habitat that is replaced. An extreme example is monoculture, where one specific genetic variety of one crop species is grown over a large area of land.
22
Q
how does climate chagne affect biodiversity?
A
not all climate change is due to human activities, but increased emissions of carbon dioxide and other greenhouse gases are likely to be causing an increase in global temperatures; such changes are likely to cause the modification of the conditions in many habitats and loss of biodiversity is expected.
23
Q
what are the main three reasons for maintaining biodiversity?
A
Ecological reasons
Economic reasons
Aesthetic reasons
24
Q
what are the ecological reasons for maintaining biodiversity?
A
Given the interdependence of organisms in a food web, the keystone species (whose presence significantly affects all others in the ecosystem, e.g. via its role as top predator or via the modification of the habitat) should be identified and conserved as a priority.
25
what are the economic reasons for maintaining biodiversity?
Maintaining high biodiversity in agriculture can avoid problems relating to soil mineral depletion (which is associated with continuous monoculture)
It is important to avoid large‐scale deforestation as this leads to soil loss via erosion by wind/water; soil is an important resource in the context of large scale food production and its sustainability into the future
Ecosystems with high biodiversity are appealing to tourists and many countries derive significant economic benefits from ecotourism; also, conservation projects may themselves provide employment
It is desirable to maintain a genetic resource for future selective breeding or genetic engineering projects that may improve domestic animals and crop plants (particularly important in the context of a change climate and the evolution of new pathogens)
Organisms that have not yet been discovered or studied may provide us with important resources in the future, e.g. new materials for manufacturing or new medicines.
26
what are the aesthetic reasons for maintaining biodiversity?
It is important to protect natural landscapes and their biodiversity as these are considered beautiful and many people experience a better sense of wellbeing (e.g. reduced stress) by spending time in such places.
27
what does the genetic biodiversity of a population relate to?
how many different alleles of genes are present.
28
what is an allele?
Alleles are the different versions of a particular gene that arise via random mutation
29
what is a population with many alleles of their genes mean?
They are genetically biodiverse
They have a great deal of genetic variation
large gene pool
30
what are the advantages of a population with a large gene pool and biodiversity?
the large amount of genetic variation enables the population to evolve by natural selection should conditions change: the population will be able to adapt, e.g. to new diseases or climate change, rather than become extinct (die out)
31
what factors increase genetic biodiversity (increase in the
numbers of alleles of genes in the population’s gene pool)?
High rate of random mutation: environmental factors can influence this, e.g. UV light exposure.
Interbreeding between different population groups: this transfers alleles from one population’s gene pool into the other population’s gene pool, via the production of hybrid offspring; this is referred to as gene flow. Reproduction between genetically very different individuals is called outbreeding.
32
what factors can decrease genetic biodiversity (leads to a decrease in the
numbers of alleles of genes in the population’s gene pool)?
Asexual reproduction - either as a naturally occurring reproductive strategy or via artificial cloning techniques: all offspring produced are genetically identical, so have the same alleles of all genes; a population made up of such individuals has little/no genetic biodiversity.
Natural selection - particularly if selection pressures are strong: alleles corresponding to disadvantageous characteristics are not passed on to offspring and may eventually be lost from the population’s gene pool entirely.
Genetic drift: this is a random change to allele frequencies, that is particularly significant in small, isolated, inbred populations; genetic drift can result in the loss of some alleles from the gene pool, if the few individuals that possessed those alleles did not (by chance) reproduce to pass them on.
Genetic bottleneck: this occurs when a major catastrophe (e.g. a natural disaster,
extensive habitat loss or new disease) wipes out most of a population, leaving a small
number of individuals whose genetic diversity is inevitably much lower than the original
population (since a few individuals can only have a small number of different alleles of
genes in their much reduced gene pool). Even if the population size increases again, the
genetic diversity does not recover.
The founder effect: this occurs when a small number of individuals become separated from the main population, and go on to form a new population elsewhere; these individuals only contain a small selection of alleles from the main population, so the genetic diversity of this group and their future descendants is low.
Artificial selection and selective breeding: humans can direct the evolution of a plant/animal species that we use for food/pets etc, choosing certain individuals from a genetically varied population (based on specific desirable characteristics) and then only allowing these individuals to breed. Alleles that correspond to undesirable traits will not be passed on and may be lost from the gene pool entirely. This phenomenon is seen in pedigree animal breeds and in food crops.
Captive breeding programmes, e.g. in a zoo: only a small number of animals (possessing a limited variety of alleles) are available to breed; if these are closely related individuals and hence genetically similar to one another (i.e. if inbreeding occurs) the loss of genetic diversity may be considerable. A similar phenomenon occurs in rare breeds of domestic animal, where very few individuals remain and so inbreeding is inevitable.
33
how do we quantify genetic biodiversity?
by calculating the proportion of genes in the genome which occur as more than one variant (allele), i.e. the proportion of gene loci that are polymorphic
34
what is a locus?
the position of a specific gene on its chromosome
35
what does polymorphic mean?
the gene occurs as two or more versions (alleles) in the population’s gene pool
36
what is monomorphic mean?
when a gene exists as one version only, across the vast majority of the population
37
Are human genes poly or monomorphic?
monomorphic
38
what is the formula for the proportion of polymorphic genes?
39
what does a high Proportion of polymorphic gene loci mean?
The greater the proportion, the greater the genetic biodiversity within a species.
40
what is sampling?
only a selected proportion of the habitat is actually studied in detail, where the data provided is representative of the whole area
41
what is Random sampling
every part of the habitat (and hence every organism in it) has an equal probability/chance of being selected.
large, fairly uniform area
1. Set out x‐ and y‐axes (or a complete grid) across the area to be sampled, using long tape measures at right angles
2. Pick coordinate points at random, e.g. using a random number button on a calculator.
3. Take a sample at each of the points picked, e.g. place a frame quadrat, identify the species present, estimate/count the abundance of each.
4. The more quadrats placed, the better the reliability of the data and the more likely it becomes that the data really is representative of the whole area; this is because chance variation (which can lead to unrepresentative results) has a decreasing effect as sample size increases. The reliability of the study could also be improved by repeating the whole sampling process
42
what are the three main forms of non-random sampling?
Opportunistic
Stratified
Systematic
43
what is oportunistic sampling?
this means that you sample the areas and/or organisms that are most convenient; this approach does not generate data that is representative of the whole area and so is NOT usually used in ecological studies.
This opportunistic approach can lead to a significant amount of sampling bias (i.e. bias in the data arising from a biased sampling technique): the data is not at all representative because each part of the habitat did not have an equal chance of being selected. Forexample, the ecologist may have selected only the parts of the habitat that look most interesting, leading to overestimation of the habitat’s overall biodiversity
44
what is stratified sampling?
the sample area or population is divided into two or more sections/groups (called strata) according to a key characteristic (e.g. males/females, or wet/dry areas of land); a random sample is then carried out within each of these strata, in proportion to the size of that stratum compared to the others.
We want to take 40 samples in an area made up of 40% marshland and 60% dry fields. How many sample sites should be in each area?
MARSHLAND 40% of 40 = 0.4 x 40 = 16
FIELDS 60% of 40 = 0.6 x 40 = 24
45
what is Systematic sampling?
habitat is changing from one side to the other (e.g. going down a hill, up from a beach, towards a river, or across a path); it usually involves setting up a transect across the habitat in order to study how the vegetation changes as the habitat conditions change
1. Lay out a long tape measure across the habitat, in a straight line that follows the direction of change; this is the transect line.
2. To carry out a line transect, walk along the transect line and record all species that touch the line (including the distance at which each is found along the line). This type of transect is quick and easy to carry out but such a narrow area has been sampled that the data may not be representative.
OR
To carry out a belt transect, lay frame quadrats next to the transect line (either end‐to‐end to form a continuous belt transect, or, alternatively, at regular intervals, to form an interrupted belt transect). The species in each quadrat are identified and the abundance of each is estimate/counted. Belt transects sample a wider area than line transects so are considered more reliable and generate data that is more likely to be representative.
3. Measure relevant abiotic factors at each sample point.
4. Present the data in such a way that trends along the transect line and any correlations with the levels of abiotic factor are apparent.
46
what is a pooter?
this is a jar, with two tubes in entering the lid, enabling an individual insect to be sucked into the container
47
what is a pitfall trap?
these are (covered) holes in the ground that small animals fall into, typically left for a 24 hour period before the animals are identified, counted etc
48
what is a sweep nest?
a net is dragged across a specific area of grass or bushes, catching the insects present.
49
what is a tree beating?
a beater/paddle is used to beat (hit) part of a tree, with any insects dislodged falling onto a white sheet
50
what is a kick sampling
(used for sampling invertebrates in a river or stream): the investigator kicks the stones in a given area of the river/stream bed (bottom surface) and a second investigator holds a net downstream to catch the animals dislodged
51
what is a tullgreen funnel?
used to extract small animals from soil): a soil sample is placed on a mesh in a funnel; heat and light source is applied from above to drive animals downwards into a container of alcohol – see diagram
52
what do we use to estimte a population size?
capture‐mark‐release‐recapture
53
Describe capture-mark-recapture
This technique is useful because direct counting of each member of the population may be impossible, as animals move around so much and because it can be difficult to be certain that an individual is not counted twice (or not at all).
The technique involves catching as many individuals as possible (e.g. using pitfall traps), counting them, and then marking them (in such a way that does not affect their chance of survival). These marked individuals are released and left long enough to mix back into the population.
Another sample is then collected later, and the numbers of marked and of unmarked individuals are counted.
Dividing the number of marked individuals in the second sample by the total number in the second sample gives you the proportion of the population that you caught in the first sample; from this you can estimate how big the original population was
54
when should capture-mark-recapture be used?
when a population is large
55
when should'nt capture-mark-recapture be used?
If the sample taken is very small, one less or one extra individual has a massive effect on the population size estimated, meaning the percentage error on the estimate is unacceptably high
56
how do we measure species richness?
The species richness is the number of different species present, e.g. 57 different species
57
how do we meaasure species evenness (the relative abundance of each species) ?
all species must be identified and the population size of each should be determined, and we use the simpsons index formula
58
what is conservation?
Conservation is the active management of a habitat/ecosystem (by humans) with the aim of maintaining or increasing its biodiversity
59
What do extinction mean?
All individuals in a species are dead
60
what are the small aims of conservation?
increase or maintain the diversity of habitats
increase the species diversity the species diversity (species richness and the species evenness)
increase the genetic diversity of one or more species
61
what is the main aim of conservation?
To prevent the extinction of endangered species
62
what are some factors which may cause a species into extinction?
The remaining populations of a species are all small and are isolated from each other, meaning it is difficult for individuals to find a mate (particularly if there is a gender imbalance in each group);
Inbreeding (mating between closely related individuals) is causing low genetic diversity;
The lack of genetic variation means the remaining populations are less able to adapt to environmental change by natural selection;
The lack of genetic variation increases the likelihood that all individuals are wiped out by the same (new) disease;
A small population may be more vulnerable to predators or poachers;
A natural or man‐made disaster could completely wipe out a small population.
63
what are the conservation status' from best to worst
least concern - vulnerable - endangered - extinct in the wild - extinct
64
what does least concern mean?
the species is not considered likely to be endangered in the near future.
65
what does vulnerable mean?
the species is considered likely to be endangered in the near future, e.g. because its population size is declining at a rapid pace
66
what does endangered mean?
the species is considered likely to be extinct in the near future, e.g. because its population size is already very low
67
what does extinct in the wild mean?
no individuals of this species remain alive in any wild habitats, but some exist in zoos or in otherwise in captivity
68
what is in situ conservation?
methods of maintaining biodiversity are those which are carried out within the habitat itself
69
what is in situ conservation succesfull at?
very effective at maintaining species diversity (richness and evenness) and the genetic diversity within those species
good long term survival prospects
cheaper than ex situ
70
what are the two examples of in situ conservation we must know?
Marine conservation zones and wildlife reserves
71
describe marine conservation zones
these are areas of coastline and/or the sea that are protected
no fishing
Such schemes can be effective in **protecting coral reefs**, for example. The presence of the conservation zone **allows fish stocks (populations) to build up**, such that (sustainable levels of) **fishing can be permitted in the surrounding areas**.
One **limitation** of such schemes is that it can be **difficult/impossible in practice to prevent fishing** within the conservation zone, since physical barriers cannot be established and **insufficient numbers of patrol boats/personnel** may be available due to their **high cost**.
72
describe wildlife reserves
* **Specific areas which are actively managed with the aim of conservation**, e.g. by conservation charities, and which have (some) protection from development.
A wide variety of **conservation techniques** may be used in the Reserve, depending on the context and aims, including:
Control of **grazing**;
Restriction of **human access**;
Control of **poaching**;
**Provision of suitable food** for animals;
**Reintroduction of species** that were found in the habitat in the past;
**Culling** of invasive/alien species;
**Halting succession** – preventing the ecosystem undergoing its natural process of change over time, e.g. from grassland to forest: this typically involves **regular removal of young shrubs/trees** (manually or via controlled grazing or burning).
73
what is ex situ conservation?
methods of maintaining biodiversity are those which involve the transfer of organisms from their natural habitat to somewhere else, forexample to a zoo, botanic garden or seed bank
74
when are ex situ methods effective?
Ex situ methods are generally effective only if used in addition to (not instead of) in situ measures
75
when is ex situ conservation used?
when the number of individuals of an endangered species remaining in the wild is critically low, and the only hope for survival is in captivity
76
what are Captive breeding programmes in zoos?
Ex situ conservation
this involves humans (attempting to) provide the ideal conditions for the reproduction of the animals via natural mating, or the use of assisted reproductive strategies including artificial insemination (AI), in vitro fertilisation (IVF), artificial cloning (e.g. via the somatic cell nuclear transfer method) and/or the use of surrogate mothers.
The chance of breeding success may be increased as the animals are given adequate nutrition, protection from predators and the provision of veterinary care if needed. If the breeding programme is successful at producing many healthy offspring, some of these may be reintroduced back into wild habitats.
77
why are Captive breeding programmes in zoos not always successful?
There may be a loss of genetic diversity due to inbreeding (leaving the population with high incidence of genetic disorders and an inability to adapt by natural selection in the case of new diseases and environmental change).
o The captively‐bred animals may (over many generations) become genetically too different to breed with wild animals and produce fertile offspring.
o Furthermore, the animals’ immune systems may not develop appropriately if they are reared in a zoo rather than in their intended habitat (leaving them vulnerable to infectious disease later).
o Animals may not have developed appropriate learned behaviours for feeding or avoidance of danger if reared in captivity, hence they may have low survival chances in the wild.
o Finally, there may not be enough suitable areas of natural habitat available for successful release and survival of (all) the captively‐bred individuals.
78
what are botanic gardens?
ex situ conservation
these are effectively ‘plant zoos,’ in that they play a role in conservation by maintaining a wide range of plant species in a context that enables them to be viewed by the public and studied by scientists.
In each section of the garden, different habitat conditions are provided, so that a specific selection of plants can grow, e.g. the soil type, mineral content, watering regime and pathogen/pest control will be all be carefully controlled to increasing the survival chances and reproductive success of the plant species in that section
79
why are botanic gardens not always succesful?
Some species are too difficult to grow – the specific conditions needed may be impossible to provide;
o Some are too harmful (e.g. toxic) to humans to have in a public garden;
o Some are not considered interesting/decorative or they are apparently too similar to plant species already represented;
o Lack of space or financial resources available to the botanic gardens
80
what are seed banks?
these are essentially gene banks (i.e. genetic resources) storing large numbers of plant seeds from many different species.
The seeds are stored in carefully‐controlled conditions (e.g. low temperature) so that they remain viable (able to germinate into live plants) long term, for decades or even hundreds of years. The seeds are less likely to be lost/destroyed (e.g. by a natural disaster) than the live, whole plants growing in botanic gardens.
The small size of individual seeds means that a huge number can be stored in a small space; seed banks are therefore more able to conserve a good level of genetic diversity that botanic gardens can.
The purpose is to provide a ‘backup’ (allowing reintroduction of members of a species into the wild) in the case that wild plant species suffer loss of genetic diversity or even near‐extinction due to climate change, natural disasters or large‐scale habitat destruction by humans.
However, not all species of plant have seeds that remain viable if stored long term in the conditions provided by a seed bank, hence seed banks may never be able to store a complete set of seeds from all the Earth’s plant species.
81
what are the three conservation agreements you must know?
Convention on International Trade in Endangered Species (CITES)
Rio Convention on Biological Diversity (CBD)
Countryside Stewardship Scheme
82
what is the Convention on International Trade in Endangered Species (CITES)?
aims to control/regulate the international trade in wild plants and animals (or parts from them).
makes it illegal to trade in species deemed endangered; other, less threatened species may be traded but with a number of restrictions (e.g. quotas); manyother (‘least concern’) species can be traded without
restriction set up by an organisation called the International Union for the Conservation of Nature (IUCN); this organisation also maintains the lists (updated each year) of which species are endangered and so cannot be legally traded
83
what is Rio Convention on Biological Diversity (CBD)?
172 countries
countries which signed up to the CBD are obliged to develop national strategies for sustainable development, in relation to maintaining biodiversity
[UK] Environmental Impact Assessment (EIA) must be carried out before any major development can be permitted, e.g. a new road or housing estate. The current biodiversity of the habitat is assessed (including the variety of habitats, species richness and species evenness) and a survey is undertaken to determine whether any unusual habitats are present or whether any rare species live there.
Ecologists (scientists who study ecosystems) then consider the likely effects of the proposed development on the biodiversity of the area and on survival of any rare species, conditions may be set which involve the development plans being modified to reduce their impact on biodiversity,
84
What is Countryside Stewardship Scheme (CSS)
government grants (payments) to farmers/landowners for the purposes including the implementation of conservation strategies that would maintain biodiversity
85
what are the two peices of apparatus used to sample plants?
Frame quadrats and Point quadrats
86
how does a point quadrat work?
these are metal/wooden strips with 10 pins, evenly spaced, which can be placed randomly in a uniform habitat or systematically along a transect that crosses a changing habitat.
Once a point quadrat has been placed, the species that each of the ten pins touches is identified, e.g. using a key. The relative abundance of each species is assessed bycalculating the proportion of pins that touch each species. For example, if 4 of the 10 pins touch dandelion leaves, this indicates 40% cover with dandelions.
Point quadrats are often quicker to use in sampling compared to frame quadrats, are regarded as giving more accurate percentage cover estimations, and make it less likely that inconspicuous species are entirely missed.
87
how does a frame quadrat work?
square grids which can be placed randomly in a uniform habitat or systematically along a transect that crosses a changing habitat. Once a frame quadrat has been placed, all the species present should be identified, e.g. using a key (a diagram/chart assisting with species identification). There are then several possible (alternative) approaches to assessing the abundance of each species within that quadrat:
o For some species, it may be straightforward to count the number of individualspresent in the quadrat. From this, the species density can be found, i.e. the number of individuals of this species per m2; this in turn can multiplied up to enable an estimate of the population size for that species, if the total habitat area is known.
o If it is difficult to count the number of individuals, e.g. because they are small and numerous, species frequency may be an appropriate way to quantify the abundance: this is the proportion of quadrats (or proportion of squares in each quadrat) that contains at least one member of this species. For example, a species frequency of 0.05 (or 5%) would mean that 5% of quadrats (or 5% of the squares in one quadrat) contain this species
Percentage cover: this is useful for species where the organisms are difficult to identify individually, e.g. grass plants. Percentage cover is an estimate of the percentage of the quadrat covered by a particular species. The percentages for each species may not always add up to 100, e.g. if there is bare ground or plants with overlapping leaves.
o Use of a subjective scale, e.g. ACFOR: this is a quick method for assessing the relative abundance of each species in the quadrat, in a case where quantitative data is not required. The ecologist assesses the area covered by each species in the quadrat, assigning a letter to each species: A (abundant), C (common), F (frequent), O (occasional) or R (rare).
