Investigating Populations Flashcards
What is ecology?
The study of organisms and their interactions with each other and their environment and biotic/abiotic factors
What is a species?
A group of closely related individuals with similar characteristics that are able to reproduce together to produce fertile offspring
What is a population?
All the individuals of a given species living together in the same area at the same time
What is a community?
All the individuals of all species in a community living together in the same area at the same time and the ways in which they interact with each other, their environment and abiotic and biotic factors.
What is a habitat?
The place in which an organism lives within an ecosystem, characterised by abiotic and biotic factors
What is a niche?
Describes an organisms role within a community. It is what it feeds on and the way in which it interacts with its environment, other organisms and abiotic/biotic factors
What is carrying capacity?
- The maximum equilibrium number of organisms of a particular species that can be supported indefinitely by a given stable environment
- Can change in response to changes in abiotic or biotic factors
Explain the competitive exclusion principle
No 2 species can occupy the exact same niche for a long period of time.
The better adapted species will always displace the lesser adapted species causing them to become extinct
Reduces interspecific competition so both survive
What is an ecosystem?
A community made of living organisms and their interactions with each other and abiotic components such as air, water, mineral salts.
What is the difference between interspecific and intraspecific competition?
Interspecific: Occurs between different species within the same/similar niche
Intraspecific: Occurs between organisms of the same species in the same niche
What are biotic factors?
Living factors that affect the distribution of an organism
- Competition for food or living space
- Disease
- Parasites
- Predation
What are abiotic factors?
Non-living factors that affect the distribution of an organism
- Temperature
- Light Intensity
- Wind speed
- Salinity
- Water
- pH
Why do no two species have the exact same niche
It would cause interspecific competition, which can’t occur due to the competitive exclusion principle as the better adapted species would displace the lesser adapted species causing it to become extinct
What happens when niches overlap?
Competitive exclusion principle
Why is it incorrect to say that no two species share the same niche?
Different organisms occupy the same ecological niche whilst competing until one species displaces the other e.g extinction of migrants
Explain the 3R’s for a sample?
Random: To ensure the data collected is not biased
Reliable: If it can be repeated to get the same or similar results
Representative: Must be large enough sample and be able to have statistical tests carried out on it or have a running mean
How many quadrats
Running mean Enough when little change/levels off Enough for stats test Large so reliable (20+) Not too large so that it can be carried out in time available
Sytematic sampling
Investigating the effector an environmental gradient (named abiotic factor) on biodiversity
Transect
Belt transect
Interupted belt transet
Belt transect
2 parallel lines a meter apart
Record species found between lines
Interupted belt transect
Use one line and place quadrat down equally spaced points and record abundance in transect
How do you investigate the distribution of marram grass across a dune
Transect from one side to the other
Place quadrats at regular intervals along line
Count plants/percentage cover
Record where they touch transect
Mark recapture release
Moving species
Collect ethically Mark in non harmful way Released and left to redistribute After time recapture Count number caught and how many marked
Population size mark recapture release
N1×N2/Nm
N1: number caught the first time
N2 : number caught second time
Nm : number caught second time marked
Considerations for M.R.R
No change in population size (death rate birth rate constant, no migration)
Shouldn’t make more susceptible to predators
Shouldn’t be lost or rub off
Sufficient time to redistribute byt not long that births or deaths occur
Wind speed device
Anemometer
Soil pH device
pH probe
Light intensity device
Lux meter
Sere
Complete succession from pioneer community to climax community
Seral stage
Particular stage in succession with its own distinctive community of organisms
Climax community
Final stage in ecological succession
Stable and changes very little
Hostility
Abiotic factors unfavourable
Few species adapted to survive in these conditions
Primary succession
Pioneer colonises Changes environment Less harsh Others can survive and colonise Changes biodiversity (more) Increased stability/less hostile Climax community
Secondary succession
After forest fire
Spores, seeds remain viable in so
Influx of animals and plants through dispersal and migration from surrounding area
Begins with intermediate species
Deflected succession
Climax community prevented from establishing
E.g human practices
Community maintained is called a plagioclimax
