3.7.4 populations in ecosystems Flashcards
Population
Group of organisms of same species, living in same place (habitat) at the same time
Community
All the populations of different species living in same place (habitat) at the same time
Ecosystem
Community with the abiotic interactions with the environment
Niche
Role of species within its habitat
If 2 species have the same niche, one will outcompete other
Abiotic conditions
Non-living features of ecosystem
E..g temp or pH
Biotic conditions
Living features of the ecosystem
E.g. predation, food supply
Ecologists studied a community of fish in a lake. They found that each species of fish had adaptations to its niche. One of these adaptations was the shape of its mouth.
Suggest how the shape of mouth is an adaptation to its niche. (2 marks)
Different mouth eats different food
Competition between species (interspecific) reduced
Suggest and explain one advantage to the fish of occupying different depths in the lake. (2 marks)
Less/no competition
For food/prey/O2
Carrying capacity
Maximum stable population size an ecosystem can support
Interspecific competition
Competition between species
Reduces resources available to both > limits both pop
If one species better adapted, it will outcompete others
Intraspecific competition
Competition within a species
Smaller population = less competition > better for growth and reproduction
Larger population = more competition > less growth and reproduction > smaller pop
Predation
Population sizes of predators and prey are interlinked
Increased predator population size> more prey eaten > prey population falls
Less food for predators > predator pop size falls > prey pop rises > predator pop rises again
Random quadrats
2 tape measures at right angles
Randomly generate coordinates and place quadrat there
Count frequency of species in quadrat
Calculate mean per quadrat
Calc pop size by mean x no quadrats
Quadrants along belt transect
Used to look at changes in distribution
Lay tape ensure along gradient
Place quadrats at regular intervals
Count frequency/percentage cover in quadrats
Mark release capture
Capture, mark (discrete, nontoxic), release
Leave enough time for organisms to randomly distribute before collecting 2nd sample
Pop size = (sample 1 x sample 2) / number marked in sample 2
Assumptions made for mark release capture
Sufficient time for marked individuals to mix within pop
Mark not removed/ doesnt affect chances of survival
No immigration
No births/deaths
Succession
Colonisation by pioneer species
Pioneer species change abiotic conditions and make env less hostile e.g. dies and decomposes to form soil that can retain water
Env becomes more suitable for other species with different adaptations and may be less suitable for the previous species - better adapted species outcompetes previous species
As succession goes on, biodiversity increases
Climax community: final, stable community
Conservation of habitats
Prevent succession and stop a climax community from forming: plagioclimax
Ensure ecosystem is preserved
