A-Level Notes > Swanshurst Sixth Form A-Level Notes > OCR Biology - F212: Biodiversity and Evolution Notes
Biodiversity And Evolution Notes
This is a sample of our (approximately) 16 page long Biodiversity And Evolution notes, which we sell as part of the OCR Biology - F212: Biodiversity and Evolution Notes collection, a 80-90% package written at Swanshurst Sixth Form in 2012 that contains (approximately) 16 pages of notes across 1 different document.
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Biodiversity and Evolution Biodiversity Biodiversity - The number and variety of organisms found within the area being studied. Species - A group of individual organisms that are similar in appearance, anatomy, biochemistry and genetics that can freely interbreed to produce fertile offspring's. Habitat - the area in which the species being studied lives. It includes the physical features of the area such as temperature or soil pH… plus living Biotic Features such as food availability and predators Levels of Biodiversity
Habitat Biodiversity - The number of different habitats in the area of study. For example costal areas may contain beach, dunes, mudflats, salt marshes etc.
Species Diversity: the number of different species and the abundance of each species in the area:
Genetic diversity: the genetic diversity between the animals in the same species (variation in alleles) Do we have note of all species in the world? No. We can only have estimates for the number of known species because:
The earth is large so we cannot be sure all species have been found. There will be places on the earth that we have not investigated
New species are being found all the time
Evolution and speciation are continuing
Many species are endangered or have been extinct
We need to measure the biodiversity of a habitat, identify all species present and count each individual of the species. This is a difficult thing to do so instead we sample a habitat. This means we select a small portion of the habitat and study that area carefully. Then, we multiply up the no. of individuals of the species to estimate the number in the while habitat.
Why is Sampling Important?
Human activities affect the environment. If we study these effects we can understand our impacts and help improve and maintain Random biodiversity. EIA is an important part of the planning process and estimates the effects of plan development in the area. Random Sampling - studying a small part of a habitat and assuming it contains a representative set of species that can be applied to the whole habitat. The sample sites must be chosen at random
3 ways to randomly choose sampling sites:
1. use samples at regular distances across the habitat
2. use random numbers, generated by a computer or random number table, to plot co-ordinates within the habitat
3. Select co-ordinates from a map of the area and use a portable global satellite system to find the exact position inside the habitat. More samples = more accurate measure of the number of species and their abundance. Method 1: Random Quadrates
Quadrates are placed at random in the habitat and the plants within the quadrate are identified.
Abundance is measured in 3 ways:
1. Abundance scale - each species identifies has an abundance score applied to it - ACFOR
2. Percentage cover - of each plant is estimated. Some quadrates have a grid of string that divides the quadrate into smaller squares - helps with estimation
3. Point Frame - a frame holding a number of long needles (usually 10). Any plant touching the needles is recorded as 1% cover. Method 2: Transect
A long rope or tape measure is stretched across the habitat and samples are taken along the lines.
1. Line Transect - used in a large habitat, any plants touching the line at set intervals is recorded.
2. Interrupted Belt Transect - use a quadrat at set intervals.
3. Continuous Belt Transect - a quadrate is used continuously along the line.
Sampling Animals Problems:
Attempt in capturing animals can disturb the environment.
Large animals can detect your presence and hide away
Small flying insects can fly away Overcoming this:
Don't trap large animal just observe them and note their presence by careful observation.
You can try to hide and wait to see if any animals may pass by or come out of hiding, but this could take a long while and can be unsuccessful.
See signs animals have left behind e.g. droppings or deer damage to tree barks in a particular way.
Method 1: Sweep Netting
Used on small animals, such as insects
This technique involves the person walking through the habitat sweeping a net. The insects caught will be put on a white sheet and counted.
Insects can crawl or fly away so a pooter should be used to collect the animals before they fly away.
This method is suitable for low vegetation (plants) that is not too woody. Method 2: Collecting from Trees
Put a white sheet under a branch. Use a stout stick to knock the branch. The vibrations dislodge small animals, which then drop onto the white sheet.
Must count quickly as they will try to escape fast.
Method 3: Pitfall trap
Trap in the soil to capture small animals
A container buried in the soil so that it's rim is just below the surface.
To stop animals escaping there should be a small amount of water or scrunched up paper in the container.
In rainy weathers there should be a shelter so the container doesn't fill up. Method 4: Tullgren Funnel
Collects small animals from leaf litter.
Leaf litter is placed in a funnel with a light above. The light drives the animals downwards as the leaf dries and warms. The animals fall through the mesh screen and collected in a jar underneath the funnel. Method 5: Light Trap
Ultraviolet light attracts the insects, which eventually fall into the alcohol.
Measuring Biodiversity Species SpeciesRichness Richness--the theno. no.ofofspecies speciespresent presentininaahabitat/the habitat/thearea area ofofstudy. study. Species SpeciesEvenness Evenness--the theabundance abundanceofofindividuals individualsinineach eachspecies species ininthe thearea areaofofstudy. study. Simpson's Simpson'sDiversity DiversityIndex Index--aaformula formulaused usedto tomeasure measurethe the diversity ofofaahabitat. diversity habitat. Estimating Species Richness
You can use a qualitative survey to estimate species richness.
Observe the environment and record all the species you have seen
Walk around the environment to make further observations to see if there are any species you have missed from your recording.
The more species found = the richer the habitat Estimating Species Evenness
Surveying the Freq. of Plants
Take samples Then with large plants count the no. of plants of each species per unit area and with small plants measure percentage cover of each species
Measuring the Density of Animals in a Habitat (means calculate no. of animals in each species there are per area of the habitat.)
Large animals (e.g. deer's and badger's) - observe and count individuals present
Smaller animals - sample.
Use the mark and recapture method. The mark and recapture method
1. Capture as many of your chosen species as possible
2. Mark them in a way that is not harmful e.g. will not get them eaten (UV, dye) number captures is C1
3. Let them go and leave enough time for them to get back to normal life
4. Go back and capture the same species again the number you get this time is C2 but you also note how many were marked already this is C3
5. Estimated Population = (C1 X C2)/C3
Sampling water and soil - sift through and sample animals Simpson's Diversity Index
Takes into account species richness and species evenness.
D = 1-[E(n/N)2]
Squared No. of individuals of species divided by total
High Value on SDI = a diverse habitat. So many species and organisms live there. A small change in the environment would affect one species which is a small part of the habitat - therefore the effect on the environment is small and the habitat remains stable and able to withstand the change.
Low Value on SDI = a habitat dominated by only a few species. So a small change in the environment that affects one of those species could damage or destroy the whole habitat.
Classification and Taxonomy
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