7.4 Populations in ecosystems Flashcards
(18 cards)
Define Population
All the organisms of one species within a habitat
Define Community
A group of populations of different species interacting with each other in the same area at the same time.
Define Ecosystem
All the biotic organisms living with abiotic features of an organism’s environment
Define Habitat
Part of an ecosystem where organisms live
What is a Niche? + give an example
An Organism’s role in the Ecosystem e.g their position i the food web.
- no two species can share a niche (competitive exclusion will take place)
Give 2 reasons why Population size can vary in ecosystems
1) the effect of Abiotic Factors
2) the interactions between Organisms:Intra and Inter specific competition and predation
What is Carrying capacity?
The maximum Population size an ecosystem can hold
Give 3 examples of Abiotic factors
1)Temperature
2)O2 and CO2 concentrations
3)Light Intensity
4)PH
5)Water and Humidity
How may specific abiotic factors affect population size?
- temperature significantly above or below the optimum causes enzymes to work at a slower rate, decreasing metabolic rate and causing for a smaller carrying capacity
- Higher light intensity = increased rate of photosynthesis = faster growth of plants, so, potentially greater carrying capacity
- In dry air conditions, populations of species adapted to tolerate low humidity will increase
IN general, the less harsh the abiotic factor…….
…..the larger the population size
Outline what us meant by INTRAspecific competition + what is competed over
Competition that occurs when individuas of the SAME species compete with each other for resources: food, water,habitat but also for mates.
Outline what is meant by INTERspecific competition + what is competed over
competition that occurs when individuals of DIFFERENT species compete with each other for resources: food, water, habitat.
What does sampling investigate and what are the two types of sampling?
- Sampling is a method of investigating the abundance and distribution of species and populations
There are two different types of sampling:
Random
Systematic
What makes random sampling advantageous over systematic sampling?
Random sampling = positions of the sampling points are random/due to chance
–> beneficial as it means there will be NO BIAS
Systematic sampling = positions of the sampling points are chosen
–> possibility that the person choosing could show bias towards or against certain areas
–>Individuals may deliberately place the quadrats in areas with the least species as these will be easier and quicker to count
This is unrepresentative of the whole area
What are the 3 main sampling techniques used to estimate population size?
Quadrats (for non-motile or slow-moving species)
Transects (for non-motile or slow-moving species)
Mark-release-recapture (for motile species)
What does it mean when an ecosystem is described as Dynamic
It is constantly changing i.e the process if succession
Give an Overview of Succession
Primary Succession
1. pioneer species such as moss and lichens colonise bare rock after seeds and spored are carried by wind and land on exposed rock.
- As these pioneer species die and decompose, the dead organic matter (humus) forms a basic soil
2. seeds of small plants and grasses, also carried by wind, or sometimes by bird faeces land on this basic soil and begin to grow (these smaller plants are adapted to survive in shallow, relatively nutrient-poor soils)
