Populations in Ecosystems Flashcards
Define habitat
Place where an organism lives
Define population
Group of individuals of same species living in particular habitat + able to interbreed
Define community
Populations of diff species in a habitat
Define ecosystems
Self contained area made up of living + all the non-living factors
Define abiotic conditions
Non-living fts of the ecosystem
Eg. temp + water availability
Define biotic conditions
Living fts of the ecosystem
Eg. predators + food
Define niche
Roles of a species w/in its habitat
Why can a niche only be occupied by 1 species?
Bc the 2 species will compete until only 1 is left
Do 2 species ever occupy the same niche?
- No
- Own unique niche
- Look similar but have slight differences eg. what they eat
Define adaptations
Fts that inc chances of survival + reproduction
Adaptations can be:
- Physiological
- Behavioural
- Anatomical
Give eg. of organisms adapting to abiotic conditions
- Otters : webbed feet - can hunt + live on land + water
- Seals : thick layer of blubber - keep warm
- Hedgehogs : hibernate - lower rate of metabolism
Give eg. of organisms adapting to biotic conditions
- Sea otter : use rocks to smash shellfish
- Male frogs : produce mating calls
- Bacteria : produce antibiotics, kills other bacteria
Define population size
Total no. of organisms of 1 species in a habitat
Define carrying capacity
Max stable population size of a species that an ecosystem can support
Varies as result of abiotic + biotic factors
Give examples of abiotic factors that affect the population size
- Amount of light, water + space available
- Temp
- Chemical composition of env
What happens to the population size when the abiotic conditions are ideal?
- Inc
- Eg. ideal temp for metabolic reactions, don’t use up much energy maintaining body temp. More energy for growth + reproduction
Give examples of biotic factors that affect the population size
- Interspecific competition - btw diff species
- Intraspecific competition - w/in species
- Predation
Outline interspecific competition as a factor affecting population size
- Btw diff. species for same resources
- Resources available to both pop is reduced - both pop limited by lower amount of food. Less energy for growth + reproduction so population size dec
- If 1 better adapted, likely to out-compete other species
Outline intraspecific competition as a factor affecting population size
- Same species compete for same resources
- Pop inc when resources is plentiful, as pop inc, more organisms competing for same food + space
- Resources become limiting - not enough so pop dec
- Smaller pop means less comp for food + space, better for growth + reproduction - pop inc
Outline predation as a factor affecting population size
- Pop size of predators + preys are interlinked
- As prey pop inc, more food for predators so pop inc
- As predator pop inc, more prey eaten so prey pop fall
- Less food for predator so pop dec
Outline how to carry out a random sample
- Choose an area to sample - set up tape measure
- Use random no. generator to generate coordinates - avoid bias
- Repeat to reduce likelihood that results are due to chance
- Estimate by multiplying mean by area size
Define non-motile organisms
Organisms that don’t move - plants
What is used to investigate non-motile/slow organisms?
- Quadrats
- Transects
Describe how you would use a quadrat to investigate non-motile organisms
- Set up tape measure
- Using random no. generator, generate co-ordinates
- Place quadrat at co-ordinates
- Species freq: count no. diff species in each quadrat
- Percentage coverage : count how much of quadrat is covered - quicker
When are transects used?
Find how plants are distributed across an area
What are diff types of transects?
- Belt transect: quadrat placed next to each other
- Interrupted belt transect: quadrat placed at regular intervals (cover longer distance)
Describe how you would use a transect to investigate non-motile organisms across an area (4)
- Lay tape
- Take samples at regular intervals
- Using quadrat
- Count no/percentage coverage
- Use several transects
What is used to investigate motile organisms?
Mark-Release-Recapture
Outline how to carry out mark-release-recapture to investigate motile organisms
- Capture sample + count
- Mark them in harmless way
- Release
- Wait until re-intergrate, take 2nd sample from same pop
- Count how many are marked
- Use equation :
Total pop = no. 1st sample x no. 2nd sample / no. marked 2nd sample
Outline the assumptions when carrying out mark-release-recapture
- Marked sample has had enough time to re-intergrate
- Marking hasn’t affected chances of survival
- Marking is visible
- No changes in pop size (births, deaths + migration)
Why are ecosystems described as being dynamic?
They’re constantly changing
Define succession
Change in ecosystem over time due to abiotic + biotic conditions
What are the types of succession?
- Primary succession - land that been newly formed/exposed. No soil/organic material to start w/
- Secondary succession - land thats been cleared of all plants but soil remains
Outline what happens during primary succession
- Pioneer species (seeds + spores) blown by wind + grow
- Abiotic conditions are hostile - pioneer species grow bc adapted to cope
- Change abiotic conditions - die + microorganisms decompose dead organic material (humus). Forms basic soil
- Makes condition less hostile eg. basic soil able to retain water, new organisms w/ diff. adaptations move, grow + die, making soil richer - larger plants grow
- New species change env so less suitable for previous species
Outline what happens during (secondary) succession
- Pioneer species = larger plants
- Each stage, diff plants + animals better adapted outcompete previous species, become dominant species
- As succession goes on, ecosystem becomes complex + biodiversity inc
- Final stage = climax community
- Won’t change bc in a steady state
Define climax community
Stable/final community
The species making up the climax community depends on what?
Climate
Define plagioclimax
When human activity artificially prevent sucession, preventing climax community from developing
Define conservation
Protection + management of ecosystems in a sustainable way
What are different ways to manage succession as a way of conserving?
- Animal grazing - eat growing points
- Managed fires - secondary succession will occur
Give examples of different conserving techniques
- Plants use seedbanks, stores seeds from diff plant species. If plant becomes extinct, stored plants used
- Fishing quotas limits amount of certain fish species caught
- Protected areas (nature reserves) protect habitats by restricting urban development, industrial development + farming
- Endangered species bred in captivity
