Populations in ecosystems (19) Flashcards
What is a community?
all the different species that live in one area and interact with each other
What is an ecosystem?
all living organisms found in one area, combined with non-living aspects of their environment
What is intraspecific competition?
competition between organisms of the same species
What is interspecific competition?
competition between organisms of different species
What are biotic features?
living features of an ecosystem
What are the 3 examples of biotic features?
predators
disease
food
What are abiotic features?
non-living features of an ecosystem
What are 5 examples of abiotic features?
temperature
pollution
light intensity
pH
water/humidity
What are 6 resources organisms might compete for?
food
water
shelter
mates
minerals
light
What is a habitat?
place where an organism lives within an ecosystem
What is a niche?
role of a species within its habitat, consisting of both its biotic and abiotic interactions
What is meant by carrying capacity?
max size of a population an ecosystem can support
What are the 3 stages of the pattern of typical predator-prey relationships?
1) prey is eaten by predator so prey population decreases and predator population increases
2) fewer prey means more competition for food so predator population decreases
3) fewer predators means more prey survives and cycle begins again
How are quadrats used for estimating population size?
can be placed on grid coordinates, or at intervals along a belt transect, and results are reported as either a % cover or frequency
What type of organisms can quadrats be used on?
slow-moving organisms
non-motile organisms
What type of organisms can the mark-release-recapture method be used on?
fast-moving organisms
motile organisms
How is the mark-release-recapture method used for estimating population size?
1) sample of species is captured, marked and released back into same area they were caught
2) after a certain period of time another sample of the same species is captured and the number of marked organisms are counted
What 2 ways can population size be estimated?
quadrats
mark-release-recapture method
What is the equation for estimated population size?
(total number of individuals in first sample x total number of individuals in second sample)
____________________________
number of individuals recaptured
What 5 assumptions does the mark-release-recapture method make?
1) marked individuals distribute evenly
2) no migration in/out population
3) few births or deaths
4) mark does not come off
5) method of marking does not affect survival
What are 3 reasons why ecosystems described as being dynamic?
- populations constantly rise and fall
- any small change can have a large effect
- biotic + abiotic factors may alter the ecosystem conditions
What is meant by conservation?
protection and management of species and habitats in order to maintain biodiversity
What is primary succession?
where an area previously devoid of life is colonised by a community of organisms
What are the 3 steps in the process of primary succession?
1) pioneer species can survive harsh conditions and colonise the area
2) they change abiotic factors of their environment such as decomposition which adds nutrients to the ground
3) overtime this allows more complex organisms to survive
What is meant by climax community?
final stage of primary succession where ecosystem is balanced and stable
How is climax community reached?
when soil is rich enough to support large trees or shrubs, and environment no longer changes
How might succession be managed in order to aid conservation?
sometimes succession needs to be prevented in order to preserve an ecosystem at a certain point (this is known as plagioclimax)
What is an example of managing succession in order to aid conservation?
stopping moorland from progressing into spruce forest
What are 2 features of a climax community?
- abiotic factors are constant
- populations are stable
