Module 4 Section 2 - Biodiversity Flashcards
Smithson
What are the three levels at which we can consider biodiversity? Describe them briefly.
- Species - types and abundance of different species
- Habitats - physical factors of living in a certain environment
- Genetics - variations in alleles
species richness
The number of different organisms in an area.
species evenness
The relative abundance of each species in an area.
habitat diversity
The number of different habitats in an area.
How do you calculate the species evenness?
The range in the number of each species there are in the area
taxonomic variety
Essentially the variety of taxonomic groups i.e. classified organisms in an area
I think, don’t quote me
Simpson’s Index of Diversity - what do n and N represent?
n = number of organisms in one specific species
N = total number of all organisms
Simpson’s Index of Diversity is always between ____ and ____.
0 and 1
The higher the Simpson’s Index of Diversity is to 1, the ____ diverse the habitat and the ____ able it is to cope with sudden changes.
more, more
A habitat with a Simpson’s diversity index of 0.2 is/isn’t dominated by one or a few species.
is
How has increasing population sizes affected food sources?
Current sources of food are being exploited faster than they can be replenished e.g. fish stocks
How has increasing population sizes affected waste & pollution? Give an example.
More waste and pollution is released (e.g. oxides of nitrogen from car exhausts) causing acid rain and lowering the pH of soil & water, killing trees and aquatic life
Apart from using more land for farming, how has agriculture increased to feed the growing population? Give two examples.
Land currently used for food is being exploited more intensely.
* Overgrazing by cattle can lead to soil erosion
* Farmers rely on monocultures more. This leads to an increased use of fertilisers (monocultures in particular make soil depletion occur faster)
Why is using lots of fertiliser bad for biodiversity?
Nutrient run-off can cause algal blooms in water, blocking sunlight from reaching the bottom of the bodies of water - aquatic plants die as they can no longer photosynthesise, closely followed by aquatic animals that can no longer respire
aesthetic reason to maintain biodiversity
Tourists may travel to see landscapes with high biodiversity for leisure and personal joy as biodiverse areas are attractive to look at
Why might you want to do non-random sampling? (2)
When you want to get samples from each of the different areas in a habitat, or to sample all the different species.
Three types of non-random sampling techniques
- Systematic sampling
- Opportunistic sampling
- Stratified sampling
When might you do systematic sampling?
Along a transect
How could you investigate crawling insects? (2)
Set up pitfall traps or use a pooter (essentially an insect vacuum)
Why can insects not escape a pitfall trap?
The contained has straight sides so insects can’t escape
What is important about the straws in a pooter?
There are two straws, but one of them is covered so you don’t accidentally suck the insect up
How could you investigate small animals? Explain how this works.
Use a Tullgren funnel (this is a funnel with a mesh, which is covered by soil/leaf litter) and a light is shone on top of it.
The light dries out the soil/leaf litter, drawing out any organisms inside - these then fall into the beaker below.
How could you investigate aquatic life?
Use kick sampling - kick/agitate the sediment in a river for a set amount of time and then use a net to collect any disturbed organisms downstream
How could you investigate organisms living in tall grass?
Use a sweep net - sweep once through the grass and empty the contents into a collection tray
point frame/point quadrat
A standing frame with vertical metal spokes - count an organism that touches these spokes.
What sort of marker must be used when getting a mark-release-recapture sample?
A non-toxic marker so it doesn’t increase the chance of capture by predators
Why must you wait some time to get a valid mark-release-recapture sample?
Time must elapse in order for the organisms to redistribute within the habitat
What two things must you assume when using a mark-release-recapture sample to estimate the population of an organism?
- have to assume no organisms have entered/left the environment
- have to assume enough time has been waited for the captured infividuals to redistribute within the habitat
When you get an estimation of 63.7 organisms in an area using mark-release-recapture, what would you give your answer as?
Truncate it to get 63 - although 64 may or may not be accepted
A question asks you to find the number of individuals to be sampled in each strata.
What do you if the total of the calculated sizes of the samples don’t add up to the specified sample size (i.e. there is an off by one error)?
Starting from the smallest value, find the value which is the highest proportion of the way to the next number and increment it by one.
I think, anyway
bias
A sample that isn’t a representation of the whole population
random sampling
Aa technique where every individual has the same probability of being selected
Give an example of a non-random sampling technique.
Using transects
Throwing a quadrat in a field is random sampling. T/F and why?
False - you are not randomising the direction or power of the throws.
How can you reduce bias? (2)
- Use random sampling
- Do repeats
How can you make samples that are more valid? (2)
Repeat at different times of the day and year/season
How do you carry out stratified sampling?
- Split the population into mutually exclusive subgroups
- Sample each of these subgroups in the same proportion as their relative size within the population
polymorphic gene
A gene that has multiple different potential alleles.
polymorphic gene locus
A particular point on a chromosome where multiple different alleles can be found.
What sort of genes are typically not polymorphic?
The ones that are required to synthesise certain proteins necessary to life e.g. lots of digestive enzymes, haemoglobin (if you discount sickle cell anemia)
A scientist finds that 17 out of 24 genes are polymorphic in a species of bumblebee. Another scientist finds that only 10 out of 18 genes of a different bumblebee species are polymorphic. Evaluate the conclusion that the first species is more genetically diverse. [typically 3 marks]
For:
* There does seem to be more polymorphic genes in the first species of bumblebee.
Against:
* No statistical test and analysis done so can’t verify that the results are significant (and so not due to chance).
* Small sample size (only one bee of each species was sampled) -> can’t draw a conclusion.
* We cannot verfiy that the same genes were sampled.
A human is heterozygous for eye colour. What does this mean in terms of the gene?
The gene is polymorphic (there are at least two different alleles).
How does urbanisation affect biodiversity?
City and road developments can isolate species -> populations cannot interbreed -> decreases genetic biodiversity
How can air pollution affect biodiversity?
Gases released from factories -> acid rain -> lowers pH of water and soil -> kills aquatic life and trees
How do pesticides & herbicides affect biodiversity?
Monocultures increases use of pesticides & herbicides -> kills local plants and animals -> reduces species diversity
How do planting monocultures rather than local crops affect biodiversity?
Hertigate (traditional) crops don’t make a lot of money -> they aren’t grown-> decreases species diversity
What happens if a species is critically endangered?
It has a small population size so is likely to die out/become extinct.
How can nature reserves protect species?
They prevent urban, industrial and agricultural development, protecting habitats
How can controlling invasive species conserve biodiversity? Give an example.
Some species can threaten other ones, for example through increased competition for food
e.g. stopping grey squirrels from spreading in the Isle of Wight
Is preventing the introduction of invasive species in situ or ex situ?
In situ
How can you protect woodland habitats?
Coppicing (trimming trees at ground/low level) - organisms can continue living in their natural habitat
How can you protect wetland habitats? How does the conserve biodiversity?
Control water levels - organisms can continue living in their natural habitat
ex situ
Protecting organisms by making them ‘exit’ their original, threatened habitat and moving them to a safer location
two examples of ex situ conservation of organisms in captivity
Breeding programmes for animals and botanic gardens for (usually rare) plants (then releasing them back into suitable habitats)
How can plants be conserved if, for example, a nature reserve has been destroyed?
Freezing then storing seeds in seed banks - these can then be replanted in controlled conditions
Are seed banks in situ or ex situ?
Ex situ
advantages of ex situ conservation (3)
- Organisms grown in captivity, and the conditions, can be closely controlled (e.g. by reducing competition for food or removing predators)
- Organisms made in breeding programmes can be reintroduced into their natural habitat once they are ready
- Breeding can be manipulated (e.g. through reproductive hormones, IVF or preventing in-breeding)
disadvantages of ex situ conservation (3)
- Very few organisms can be looked after in breeding programmes
- Hard and expensive to control conditions
- Animals used to human contact may struggle to adapt to their new habitats when reintroduced
advantages of in situ conservation (4)
- ensures organisms continue to adapt within their environments (preserves genetic diversity)
- conserves the whole ecosystem (not only one species)
- larger populations can be protected
- higher chance of success compared to ex situ conservation
CBD
Rio Convention on Biological Diversity
What two things does CBD do?
- Makes it international law that everyone needs to conserve biodiversity
- Gives governments advice on how to conserve biodiversity
What does CBD aim to do?
To develop international strategies on conserving biodiversity and using animal & plant resources sustainably
CSS
Countryside Stewardship (supervising/taking care of something) Scheme
What is CSS?
A local (UK) agreement to conserve biodiversity by promoting specific land management strategies to landowners
Give three examples of the land management strategies that CSS suggest.
- Reintroducing hedgerows
- Leaving grassy areas between the edges of fields
- Grazing upland areas to keep down bracken (type of fern)
