Population in ecosystems Flashcards
Define species
Group of similar organisms that reproduce to produce fertile offspring
Define population
All of the individuals of a species in a specific place at the same time
Define community
All of the populations of different species in a particular place at the same time
Why can two species not occupy the same niche?
Competitive exclusion principle
What is the name given to the maximum size a population can become?
Carrying capacity
What is a limiting factor in terms of population?
A factor which would limit the growth of a population
Example of a limiting factor of a population
Nutrients
Mineral ions
Light
Temperature
Predators
Disease
What are abiotic limiting factors
Non-living factors
What are biotic limiting factors?
Living factors
Why might temperature limit a population?
Every organism has a optimum temperature. Too cold, enzymes work slowly, too hot enzymes denature
Why might light limit a population?
Ultimate energy source. Allows photosynthesis. More photosynthesis= more plants and therefore more organisms which follow in the food chain
Why is pH a limiting factor of population?
pH affects the activity of enzymes
Why might water and humidity limit a population?
Humidity affects transpiration. Few organisms survive when water is scarce
What are two types of competition?
Interspecific and intraspecific
Describe interspecific competition
When individuals of different species compete for resources
Describe intraspecific competition
Individuals of the same species compete for resources
If there is intraspecific competition and the environment stays constant, what will happen?
Competitive exclusion. One organism will be better suited to the environment so its population will increase, its competitors will decrease until extinction
What does the competitive exclusion principle mean for niches?
No two organisms occupy the same niche
What is a predator?
An organism which hunts and feeds on other animals
What is prey?
An animal which is hunted and eaten by a predator
Why do changes in conditions and number of predators affect evolution|?
Create a selection pressure so those best suited survive.
Two types of sampling
Random and systematic
What is used to sample systematically?
Belt transect
What are three factors too assess when using quadrats?
- Size of quadrat
- Number of quadrat
- Position of quadrat
What are the two methods of measuring abundance?
Frequency and percentage cover
How do you carry out the mark-release recapture technique?
Capture animals, mark and release them and wait for distribution. Capture again over same time period.
Estimate population size by
number in same 1 X number in sample 2/ marked in sample 2
What assumptions does the mark-release recapture technique have?
- Mark does not affect survival chances
- Mark doesn’t wear off
- No births or deaths
- No migration
- Distribute themselves evenly
- Ratio of marked to unmarked in sample 2 is equal to marked to unmarked in whole population
What is succession?
How an ecosystem changes overtime. Each organism makes an environment less hostile and is then outcompeted by better species
What is the first stage in succession?
Pioneer species settle (first)
What characteristics does a pioneer species have?
- Asexual
- Vast number of wind dispersed seeds
- Photosynthetic
- Nitrogen fixing
- Withstand extreme coonditions
What are the two types of succession?
Primary and secondary
What is the final stage of succession?
Climax community
What is the climax community in the UK?
Deciduous oak woodland
What changes occur through succession?
Increased biodiversity
More complex food webs
Increased biomass
What is conservation?
Management of the earths resources by humans so they can be used in the future
What conditions does conservation maintains?
Ecosystems and biodiversity
Why does conservation take place?
Personal, ethical, economic, cultural and aesthetic
How can managing succession aid habitats?
Preventing the successional change, habitats will not disappear and species will not be out competed.
