Investigating Populations And Succession Flashcards
Species definition
Group of similar organisms with the same genes that interbreed to produce fertile offspring
Population definition
Individuals of the same species living together in the same area at the same time that interbreed to produce fertile offspring
Carrying Capacity definition
Maximum equilibrium number of organisms of a particular species that can be supported indefinitely in each stable environment
Community definition
All the individuals of the the same species living in the same area at the same time
Habitat definition
A place where an organism lives within the ecosystem
Interspecific competition
Competition between two different species
Intraspecific competition
Competition between the same species
Three types of sampling
- Random quadrat.
2.Systematic sampling - Mark release capture
Why is random sampling used?
To find out what species and present and compare abundance of species used in two different areas
Describe random sampling?
- Mark the area using measuring tapes arranged at right angles to form an axis of a grid.
- Use a random number generator to obtain a series of random coordinates so not biased
- Place a number of quadrants at the intersection of these random coordinates so representative
- Calculate abundance
Why is systematic sampling used?
To determine species abundance cross an area
Three types of systematic sampling?
- Transact.= recording what species are touching the line
- Belt transact=placing two parallel lines across each other 1 m apart and recording what species are found in between the two lines
- Interrupted belt transact=using one line and placing quadrants are equal points as seeing what species are in the transit
Calculate abundance
Why is Mark released capture used?
To determine the population of mobile moving organisms
Describe mark release recapture?
- organisms of specific species are ethically collected.
- Organisms are marked in someway that does not affect their feeding or increased chance of presentation and is not rubbed off
- Animals are released and left to distribute in a population for some time but not long enough for immigration or emigration
- After some time a second capture is carried out and total number is recorded as well as previously marked
- Calculate population size using equation
Equation for population size
P = N1 x N2 / NM
N1= Number caught first time
N2= Number caught second time
Nm= Number called second time which are marked
Important consideration for Mark release and recapture method
- Population size should not change between two time captures e.g. there should be no increase birth rate, death rate and immigration.
- Markings should not make them more visible to predators and harm the animal
- Marking should not be rubbed off or be lost.
- Sufficient time should be left for the release, marked individuals to fully dispersed equally the rest of the population but not so long so birthd or death can occur.
Three ways to measure abundance-dpf
- Density= counting actual number of individuals present.= most accurate but most time-consuming
- Percentage cover= calculate the number of species in one quadratic area which is normally 0.25mm2 as 0.5 x 0.5 over total area as a percentage
- Frequency= proportion of quadrants that contain a particular species= very difficult
Reliability
Data must be random to remove bias.
2. Data must be representative so use a larger enough sample e.g. 20 which enables statistical analysis.
3. Repeatable means reliable.
4. Running mean shows little change.
5. Use appropriate method for that species.
How many quadrants is enough?
- Calculate a ruining mean.
- Enough to carry out a statistical test
- Large number to make sure reliability and representative
Succession definition
Change in the structure and composition of species within a community overtime
Two types of succession
- Primary.= introduction of a new planter species that has not been previously supported by community. That was no sale. a pioneers species such as lichens breakdown a rock and provide nutrients to support a community or small plants
- Secondary succession= occurs after a forest fire or clearance of agricultural land where there is visible soil means introduce of organisms and that’s time for succession to go back to it climax community
Describe succession ?
- Colonised by named species
- Form a soil layer and allow other species to colonise. Change in abiotic abiotic factors
- Change in biodiversity as allows more different species to become established as habitats are formed
- Increase stability as less hostile environment
- Climax community represented by named species
Features of Pioneer species
- Asexual reproduction.
- Able to fix nitrogen
- Photosynthesis
- Tolerance to extreme conditions
- Produced vast quantities of wind dispersed seeds
Features of climax community
- Same species present over a long period of time.
- Abiotic factors constant all the time
- Population stable at carrying capacity
