Investigating Populations + Succession Flashcards
What is a species?
A species is a group of closely related individuals, which are capable of interbreeding and producing fertile offspring.
What is a population?
A population is all the individuals of a given species living together in the same area at the same time.
What is carrying capacity?
Carrying capacity is the maximum, equilibrium number of organisms of a particular species that can be supported indefinitely in each stable environment. Birth rates and death rates are in equilibrium.
What is a community?
A community is all the individuals of all the species living together in the same area at the same time.
What is a habitat?
Habitat is the place where an organism lives within an ecosystem.
What is a niche?
A niche describes where an organism lives and what it does (its role). This includes what it feeds on and how it interacts with other organisms and the environment.
Can several organisms occupy the same habitat?
Yes, several organisms may be found in the same habitat but will occupy a different niche.
Define the competitive exclusion principle
Two species do not have the same niche as different niches reduce competition between them, so ensures both species survive.
What is interspecific competition?
Competition for resources between organisms of different species
What is intraspecific competition?
Competition for resources between individuals of the same species
Estimating population sizes/abundance?
1) Use a grid
2) Use a random number generator to obtain random coordinates and place quadrats on each random coordinate
3) Count number of named species or frequency (% cover) in quadrat
4) Calculate running mean
How many quadrats should be used in a sample?
1) Calculate running mean
2) Stop sampling when there is little change
3) Enough to carry out a statistical test
4) A large number to make sure the mean is reliable
Systematic sampling? Changes across an area.
1) Transect
2) Place quadrats at regular intervals along the line
3) Count species/% cover in quadrats
Equation for calculating estimated population size?
N1 × N2 ÷ Nm
N1 - number caught the first time
N2 - number caught the second time
Nm - number caught the second time, which were marked
Mark-Release-Recapture method?
1) Capture sample, mark and release
2) Ensure method of marking does not harm the organism
3) Allow organism to redistribute back into the population
4) Take second sample and count marked organisms
5) No population = N1 × N2 ÷ Nm
Why should species not be removed from the position they originate?
If they are removed, it will cause distress
Why should the species be returned to the same spot if possible (even if they’re dead)?
Their absence causes distress to their family/friends
Why should there be minimal damage to the organisms habitat?
Could change abiotic/biotic factors and therefore change the ecosystem
Why should sites not be overused and be given time to recover?
Animals become aware of traps, take advantage of them, or avoid them.
Why should marking not be brightly coloured?
Individual is more susceptible to predation.
Biotic factors?
Competition between organisms, disease, predation
Abiotic factors?
Temperature, light intensity, wind speed, water + soil pH, salinity, water level in soil, slope of the land
Describe the process of succession?
1) Colonisation by named pioneer species
2) Pioneers cause change in environmental abiotic / biotic factors e.g soil pH
3) Pioneers make the environment less hostile for new species
4) New species make conditions less suitable for previous species
5) Change in biodiversity
6) Stability increases
7) Climax community
8) Occurs over a long time
What are features of a climax community?
Stable community
Same species present over a long time
