Ecology Flashcards
What is a population?
Group of organisms of same species in the same habitat
What is a habitat?
Part of ecosystem in which specific organism lives in
What is a community?
All the populations of different species in same area + same time
What is an ecosystem?
The community + all the non-living parts of the environment
What is a niche?
An organisms role in an ecosystem e.g. position in food web
What is the carrying capacity?
The maximum population size an ecosystem can support
What would occur if 2 species shared a niche?
They will go into competition and 1 will outcompete the other until there is only 1 in that niche
What will occur if the population goes over the carrying capacity?
The population will have an increased death rate because there not enough food to support or not enough space to support
What are abiotic factors
Non- living e.g. light intensity, temperature, soil pH, O2 concentration
What are biotic factors?
Living e.g. number of plants, predators
How do abiotic factors affect population size?
The less harsh the factors e.g. enough light/water/right temperature = more range of species + larger population size
How does temperature affect population?
Each species optimum temperature for survival and if temperature is different= enzymes work less= less metabolic rate/denatured enzymes or energy used to maintain temperature = less growth= carrying capacity reduced
How does light affect population?
Increased intensity = rate of photosynthesis increased= more seeds produced= carrying capacity increased
How does pH affect population?
Each organism’s enzymes have an optimum pH so where pH is appropriate = larger population but different pH= smaller population
How does water and humidity affect population?
Scarce water= only organisms that are adapted
Humidity affects transpiration rate= only plants with adaptations survive in low humidity
How do biotic factors affect population size?
Competition and predation affect population size
Describe interspecific competition
- Different species
- Compete for space or food
- Species better adapted to environment is more likely to succeed
Describe intraspecific competition
- Same species
- Compete for resources and mate
- Individual which is fitter and better courtship ritual + better fur/ feathers = more likely to get mate
Describe the pattern between the predators and prey relationship
-Increase prey= more food for predators= more predators reproduction
-More predators = less prey as they get eaten= not enough food for predators = less predators
- will always be more prey > predators
- lag time from prey - predator population change
Why do we sample?
As it is more time efficient and more accurate than counting individuals over a large area
How can we ensure sample accurately represent the population?
- Random sampling to eliminate bias
- Large sample 30+ to make sure you accurately represent
Describe sampling for slow or non-motile organisms
Using a quadrat
- UNIFORM DISTRIBUTION: Random sampling
UNEVEN DISTRIBUTION: Line transects
Describe sampling of motile organisms
Using mark-release-recapture
Explain the random sampling method
- Line 2 tape measures at a right angle to create a gridded area
- Use random number generator to generate 2 coordinates
- 2 people will walk along coordinates and where they meet place quadrat
- Collect percentage cover/frequency
- Repeat (1-3) 30 times and calculate average
What are the 2 types of line transect method
- Usually rocky shores + along river path
- BELT TRANSECT: quadrat along tape over every position
- INTERRUPTED BELT TRANSECT: quadrat placed at equal intervals ( every 3m) along tape
Explain the line transect method
- Put tape measure at right angle to shore line
- Place quadrat every 5m
- Collect % cover/ frequency
- Repeat by placing another 30 along area at right angles to the shore
How do you work out local frequency?
Count how many squares out of 100 have part of species present
How do you work out density?
Count how many organisms there are
Total area/area of quadrat * number of organisms
How do you work out percentage cover
Figure out what proportion of the ground is occupied by species = how many FULL squares filled out of 100
Advantages and disadvantage of local frequency
Advantages:
- Quick method for large area
- Good if individuals are hard to identify/ too many to count e.g. moss+grass
Disadvantages:
- Poor accuracy without considering overlap or large size of 1
Advantages and disadvantages of calculating density of species
Advantages:
- More accurate if the individuals are easy to identify and not many to count e.g. flowers
- Used to estimate species richness
Disadvantages:
- Time consuming
Advantages and disadvantages of percentage cover
Advantages:
- Quicker than calculating density
- Useful for individuals that are hard to identify/ too many to count e.g. moss/grass
Disadvantages:
- Subjective to your estimates = limits accuracy
Describe sampling method for motile organisms
- Initial sample of population from an area
- The individuals are marked and released for a period of time that will allow random dispersing
- A second sample is captured
- Record the total and how many are a recapture from the 1st sample
- Repeat more times for a more reliable estimation
How do you calculate the estimated population from mark-release-recapture?
organisms in 1st sample * # organisms in 2nd sample/ # of recaptured organisms
What considerations should you take when using a marker?
- Weather resistant e.g. wash of with rain
- Wear resistant e.g. rub off
- Non-toxic
- Must not cause effect to predation e.g. attract attention
- Must not cause effect to repoduction
What are some assumptions made when calculating using the M-R-R model?
- No immigration/emigration
- No births/deaths
- Even distribution of animals
What is succession?
The change in ecological community over time
What are the steps for succession?
1) Bare rock
2) Pioneer species e.g. lichen
3) Secondary colonizers: Mosses and small plants
4) Tertiary colonizers: Flowering plants and small tress
5) Scrubland: Larger shrubs and trees
6) Climax community
Describe primary succession
-Pioneer species that can adapt in severe abiotic climate colonize bare rock = decomposition = form of humus = less harsh area = mosses and seeds can grow
- Erosion of bare rock and decomposition of moss = thick soil forms = less hostile environment = more small plants can grow
- Causes a more complex food web to grow = more stable community = increased biodiversity
- Pattern continues to form less harsher conditions for next organisms and less suitable for previous = outcompete each other
- Dominating species = climax community
Describe secondary succession
When a climax community is burnt down/ deforested/ succession disrupted = succession started again but NOT from bare rock = start from stage of soil
How can we conserve using succession?
By maintaining early stages of succession and not allowing climax community to be reached = greater variety of habitats conserved = more biodiversity
What is conservation?
Management of earths resources by humans by maintaining ecosystems and biodiversity so that maximum use can be made in the future
